Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

10 files changed, 5589 insertions, 0 deletions

diff --git a/third_party/rust/askama_shared/src/error.rs b/third_party/rust/askama_shared/src/error.rs
new file mode 100644
index 0000000000..98f2703323
--- /dev/null
+++ b/third_party/rust/askama_shared/src/error.rs
@@ -0,0 +1,95 @@
+use std::fmt::{self, Display};
+
+pub type Result<I, E = Error> = ::std::result::Result<I, E>;
+
+/// askama error type
+///
+/// # Feature Interaction
+///
+/// If the feature `serde_json` is enabled an
+/// additional error variant `Json` is added.
+///
+/// # Why not `failure`/`error-chain`?
+///
+/// Error from `error-chain` are not `Sync` which
+/// can lead to problems e.g. when this is used
+/// by a crate which use `failure`. Implementing
+/// `Fail` on the other hand prevents the implementation
+/// of `std::error::Error` until specialization lands
+/// on stable. While errors impl. `Fail` can be
+/// converted to a type impl. `std::error::Error`
+/// using a adapter the benefits `failure` would
+/// bring to this crate are small, which is why
+/// `std::error::Error` was used.
+///
+#[non_exhaustive]
+#[derive(Debug)]
+pub enum Error {
+    /// formatting error
+    Fmt(fmt::Error),
+
+    /// an error raised by using `?` in a template
+    Custom(Box<dyn std::error::Error + Send + Sync>),
+
+    /// json conversion error
+    #[cfg(feature = "serde_json")]
+    Json(::serde_json::Error),
+
+    /// yaml conversion error
+    #[cfg(feature = "serde_yaml")]
+    Yaml(::serde_yaml::Error),
+}
+
+impl std::error::Error for Error {
+    fn cause(&self) -> Option<&dyn std::error::Error> {
+        match *self {
+            Error::Fmt(ref err) => err.source(),
+            Error::Custom(ref err) => Some(err.as_ref()),
+            #[cfg(feature = "serde_json")]
+            Error::Json(ref err) => err.source(),
+            #[cfg(feature = "serde_yaml")]
+            Error::Yaml(ref err) => err.source(),
+        }
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Fmt(err) => write!(formatter, "formatting error: {}", err),
+            Error::Custom(err) => write!(formatter, "{}", err),
+            #[cfg(feature = "serde_json")]
+            Error::Json(err) => write!(formatter, "json conversion error: {}", err),
+            #[cfg(feature = "serde_yaml")]
+            Error::Yaml(err) => write!(formatter, "yaml conversion error: {}", err),
+        }
+    }
+}
+
+impl From<fmt::Error> for Error {
+    fn from(err: fmt::Error) -> Self {
+        Error::Fmt(err)
+    }
+}
+
+#[cfg(feature = "serde_json")]
+impl From<::serde_json::Error> for Error {
+    fn from(err: ::serde_json::Error) -> Self {
+        Error::Json(err)
+    }
+}
+
+#[cfg(feature = "serde_yaml")]
+impl From<::serde_yaml::Error> for Error {
+    fn from(err: ::serde_yaml::Error) -> Self {
+        Error::Yaml(err)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Error;
+
+    trait AssertSendSyncStatic: Send + Sync + 'static {}
+    impl AssertSendSyncStatic for Error {}
+}
diff --git a/third_party/rust/askama_shared/src/filters/json.rs b/third_party/rust/askama_shared/src/filters/json.rs
new file mode 100644
index 0000000000..e94e50c1be
--- /dev/null
+++ b/third_party/rust/askama_shared/src/filters/json.rs
@@ -0,0 +1,44 @@
+use crate::error::{Error, Result};
+use askama_escape::JsonEscapeBuffer;
+use serde::Serialize;
+use serde_json::to_writer_pretty;
+
+/// Serialize to JSON (requires `json` feature)
+///
+/// The generated string does not contain ampersands `&`, chevrons `< >`, or apostrophes `'`.
+/// To use it in a `<script>` you can combine it with the safe filter:
+///
+/// ``` html
+/// <script>
+/// var data = {{data|json|safe}};
+/// </script>
+/// ```
+///
+/// To use it in HTML attributes, you can either use it in quotation marks `"{{data|json}}"` as is,
+/// or in apostrophes with the (optional) safe filter `'{{data|json|safe}}'`.
+/// In HTML texts the output of e.g. `<pre>{{data|json|safe}}</pre>` is safe, too.
+pub fn json<S: Serialize>(s: S) -> Result<String> {
+    let mut writer = JsonEscapeBuffer::new();
+    to_writer_pretty(&mut writer, &s).map_err(Error::from)?;
+    Ok(writer.finish())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_json() {
+        assert_eq!(json(true).unwrap(), "true");
+        assert_eq!(json("foo").unwrap(), r#""foo""#);
+        assert_eq!(json(&true).unwrap(), "true");
+        assert_eq!(json(&"foo").unwrap(), r#""foo""#);
+        assert_eq!(
+            json(&vec!["foo", "bar"]).unwrap(),
+            r#"[
+  "foo",
+  "bar"
+]"#
+        );
+    }
+}
diff --git a/third_party/rust/askama_shared/src/filters/mod.rs b/third_party/rust/askama_shared/src/filters/mod.rs
new file mode 100644
index 0000000000..9fb10d2fec
--- /dev/null
+++ b/third_party/rust/askama_shared/src/filters/mod.rs
@@ -0,0 +1,675 @@
+//! Module for built-in filter functions
+//!
+//! Contains all the built-in filter functions for use in templates.
+//! You can define your own filters, as well.
+//! For more information, read the [book](https://djc.github.io/askama/filters.html).
+#![allow(clippy::trivially_copy_pass_by_ref)]
+
+use std::fmt;
+
+#[cfg(feature = "serde_json")]
+mod json;
+#[cfg(feature = "serde_json")]
+pub use self::json::json;
+
+#[cfg(feature = "serde_yaml")]
+mod yaml;
+#[cfg(feature = "serde_yaml")]
+pub use self::yaml::yaml;
+
+#[allow(unused_imports)]
+use crate::error::Error::Fmt;
+use askama_escape::{Escaper, MarkupDisplay};
+#[cfg(feature = "humansize")]
+use humansize::{file_size_opts, FileSize};
+#[cfg(feature = "num-traits")]
+use num_traits::{cast::NumCast, Signed};
+#[cfg(feature = "percent-encoding")]
+use percent_encoding::{utf8_percent_encode, AsciiSet, NON_ALPHANUMERIC};
+
+use super::Result;
+
+#[cfg(feature = "percent-encoding")]
+// Urlencode char encoding set. Only the characters in the unreserved set don't
+// have any special purpose in any part of a URI and can be safely left
+// unencoded as specified in https://tools.ietf.org/html/rfc3986.html#section-2.3
+const URLENCODE_STRICT_SET: &AsciiSet = &NON_ALPHANUMERIC
+    .remove(b'_')
+    .remove(b'.')
+    .remove(b'-')
+    .remove(b'~');
+
+#[cfg(feature = "percent-encoding")]
+// Same as URLENCODE_STRICT_SET, but preserves forward slashes for encoding paths
+const URLENCODE_SET: &AsciiSet = &URLENCODE_STRICT_SET.remove(b'/');
+
+// This is used by the code generator to decide whether a named filter is part of
+// Askama or should refer to a local `filters` module. It should contain all the
+// filters shipped with Askama, even the optional ones (since optional inclusion
+// in the const vector based on features seems impossible right now).
+pub const BUILT_IN_FILTERS: &[&str] = &[
+    "abs",
+    "capitalize",
+    "center",
+    "e",
+    "escape",
+    "filesizeformat",
+    "fmt",
+    "format",
+    "indent",
+    "into_f64",
+    "into_isize",
+    "join",
+    "linebreaks",
+    "linebreaksbr",
+    "paragraphbreaks",
+    "lower",
+    "lowercase",
+    "safe",
+    "trim",
+    "truncate",
+    "upper",
+    "uppercase",
+    "urlencode",
+    "urlencode_strict",
+    "wordcount",
+    // optional features, reserve the names anyway:
+    "json",
+    "markdown",
+    "yaml",
+];
+
+/// Marks a string (or other `Display` type) as safe
+///
+/// Use this is you want to allow markup in an expression, or if you know
+/// that the expression's contents don't need to be escaped.
+///
+/// Askama will automatically insert the first (`Escaper`) argument,
+/// so this filter only takes a single argument of any type that implements
+/// `Display`.
+pub fn safe<E, T>(e: E, v: T) -> Result<MarkupDisplay<E, T>>
+where
+    E: Escaper,
+    T: fmt::Display,
+{
+    Ok(MarkupDisplay::new_safe(v, e))
+}
+
+/// Escapes `&`, `<` and `>` in strings
+///
+/// Askama will automatically insert the first (`Escaper`) argument,
+/// so this filter only takes a single argument of any type that implements
+/// `Display`.
+pub fn escape<E, T>(e: E, v: T) -> Result<MarkupDisplay<E, T>>
+where
+    E: Escaper,
+    T: fmt::Display,
+{
+    Ok(MarkupDisplay::new_unsafe(v, e))
+}
+
+#[cfg(feature = "humansize")]
+/// Returns adequate string representation (in KB, ..) of number of bytes
+pub fn filesizeformat<B: FileSize>(b: &B) -> Result<String> {
+    b.file_size(file_size_opts::DECIMAL)
+        .map_err(|_| Fmt(fmt::Error))
+}
+
+#[cfg(feature = "percent-encoding")]
+/// Percent-encodes the argument for safe use in URI; does not encode `/`.
+///
+/// This should be safe for all parts of URI (paths segments, query keys, query
+/// values). In the rare case that the server can't deal with forward slashes in
+/// the query string, use [`urlencode_strict`], which encodes them as well.
+///
+/// Encodes all characters except ASCII letters, digits, and `_.-~/`. In other
+/// words, encodes all characters which are not in the unreserved set,
+/// as specified by [RFC3986](https://tools.ietf.org/html/rfc3986#section-2.3),
+/// with the exception of `/`.
+///
+/// ```none,ignore
+/// <a href="/metro{{ "/stations/Château d'Eau"|urlencode }}">Station</a>
+/// <a href="/page?text={{ "look, unicode/emojis ✨"|urlencode }}">Page</a>
+/// ```
+///
+/// To encode `/` as well, see [`urlencode_strict`](./fn.urlencode_strict.html).
+///
+/// [`urlencode_strict`]: ./fn.urlencode_strict.html
+pub fn urlencode<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(utf8_percent_encode(&s, URLENCODE_SET).to_string())
+}
+
+#[cfg(feature = "percent-encoding")]
+/// Percent-encodes the argument for safe use in URI; encodes `/`.
+///
+/// Use this filter for encoding query keys and values in the rare case that
+/// the server can't process them unencoded.
+///
+/// Encodes all characters except ASCII letters, digits, and `_.-~`. In other
+/// words, encodes all characters which are not in the unreserved set,
+/// as specified by [RFC3986](https://tools.ietf.org/html/rfc3986#section-2.3).
+///
+/// ```none,ignore
+/// <a href="/page?text={{ "look, unicode/emojis ✨"|urlencode_strict }}">Page</a>
+/// ```
+///
+/// If you want to preserve `/`, see [`urlencode`](./fn.urlencode.html).
+pub fn urlencode_strict<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(utf8_percent_encode(&s, URLENCODE_STRICT_SET).to_string())
+}
+
+/// Formats arguments according to the specified format
+///
+/// The *second* argument to this filter must be a string literal (as in normal
+/// Rust). The two arguments are passed through to the `format!()`
+/// [macro](https://doc.rust-lang.org/stable/std/macro.format.html) by
+/// the Askama code generator, but the order is swapped to support filter
+/// composition.
+///
+/// ```ignore
+/// {{ value | fmt("{:?}") }}
+/// ```
+///
+/// Compare with [format](./fn.format.html).
+pub fn fmt() {}
+
+/// Formats arguments according to the specified format
+///
+/// The first argument to this filter must be a string literal (as in normal
+/// Rust). All arguments are passed through to the `format!()`
+/// [macro](https://doc.rust-lang.org/stable/std/macro.format.html) by
+/// the Askama code generator.
+///
+/// ```ignore
+/// {{ "{:?}{:?}" | format(value, other_value) }}
+/// ```
+///
+/// Compare with [fmt](./fn.fmt.html).
+pub fn format() {}
+
+/// Replaces line breaks in plain text with appropriate HTML
+///
+/// A single newline becomes an HTML line break `<br>` and a new line
+/// followed by a blank line becomes a paragraph break `<p>`.
+pub fn linebreaks<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    let linebroken = s.replace("\n\n", "</p><p>").replace('\n', "<br/>");
+
+    Ok(format!("<p>{}</p>", linebroken))
+}
+
+/// Converts all newlines in a piece of plain text to HTML line breaks
+pub fn linebreaksbr<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(s.replace('\n', "<br/>"))
+}
+
+/// Replaces only paragraph breaks in plain text with appropriate HTML
+///
+/// A new line followed by a blank line becomes a paragraph break `<p>`.
+/// Paragraph tags only wrap content; empty paragraphs are removed.
+/// No `<br/>` tags are added.
+pub fn paragraphbreaks<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    let linebroken = s.replace("\n\n", "</p><p>").replace("<p></p>", "");
+
+    Ok(format!("<p>{}</p>", linebroken))
+}
+
+/// Converts to lowercase
+pub fn lower<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(s.to_lowercase())
+}
+
+/// Alias for the `lower()` filter
+pub fn lowercase<T: fmt::Display>(s: T) -> Result<String> {
+    lower(s)
+}
+
+/// Converts to uppercase
+pub fn upper<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(s.to_uppercase())
+}
+
+/// Alias for the `upper()` filter
+pub fn uppercase<T: fmt::Display>(s: T) -> Result<String> {
+    upper(s)
+}
+
+/// Strip leading and trailing whitespace
+pub fn trim<T: fmt::Display>(s: T) -> Result<String> {
+    let s = s.to_string();
+    Ok(s.trim().to_owned())
+}
+
+/// Limit string length, appends '...' if truncated
+pub fn truncate<T: fmt::Display>(s: T, len: usize) -> Result<String> {
+    let mut s = s.to_string();
+    if s.len() > len {
+        let mut real_len = len;
+        while !s.is_char_boundary(real_len) {
+            real_len += 1;
+        }
+        s.truncate(real_len);
+        s.push_str("...");
+    }
+    Ok(s)
+}
+
+/// Indent lines with `width` spaces
+pub fn indent<T: fmt::Display>(s: T, width: usize) -> Result<String> {
+    let s = s.to_string();
+
+    let mut indented = String::new();
+
+    for (i, c) in s.char_indices() {
+        indented.push(c);
+
+        if c == '\n' && i < s.len() - 1 {
+            for _ in 0..width {
+                indented.push(' ');
+            }
+        }
+    }
+
+    Ok(indented)
+}
+
+#[cfg(feature = "num-traits")]
+/// Casts number to f64
+pub fn into_f64<T>(number: T) -> Result<f64>
+where
+    T: NumCast,
+{
+    number.to_f64().ok_or(Fmt(fmt::Error))
+}
+
+#[cfg(feature = "num-traits")]
+/// Casts number to isize
+pub fn into_isize<T>(number: T) -> Result<isize>
+where
+    T: NumCast,
+{
+    number.to_isize().ok_or(Fmt(fmt::Error))
+}
+
+/// Joins iterable into a string separated by provided argument
+pub fn join<T, I, S>(input: I, separator: S) -> Result<String>
+where
+    T: fmt::Display,
+    I: Iterator<Item = T>,
+    S: AsRef<str>,
+{
+    let separator: &str = separator.as_ref();
+
+    let mut rv = String::new();
+
+    for (num, item) in input.enumerate() {
+        if num > 0 {
+            rv.push_str(separator);
+        }
+
+        rv.push_str(&format!("{}", item));
+    }
+
+    Ok(rv)
+}
+
+#[cfg(feature = "num-traits")]
+/// Absolute value
+pub fn abs<T>(number: T) -> Result<T>
+where
+    T: Signed,
+{
+    Ok(number.abs())
+}
+
+/// Capitalize a value. The first character will be uppercase, all others lowercase.
+pub fn capitalize<T: fmt::Display>(s: T) -> Result<String> {
+    let mut s = s.to_string();
+
+    match s.get_mut(0..1).map(|s| {
+        s.make_ascii_uppercase();
+        &*s
+    }) {
+        None => Ok(s),
+        _ => {
+            s.get_mut(1..).map(|s| {
+                s.make_ascii_lowercase();
+                &*s
+            });
+            Ok(s)
+        }
+    }
+}
+
+/// Centers the value in a field of a given width
+pub fn center(src: &dyn fmt::Display, dst_len: usize) -> Result<String> {
+    let src = src.to_string();
+    let len = src.len();
+
+    if dst_len <= len {
+        Ok(src)
+    } else {
+        let diff = dst_len - len;
+        let mid = diff / 2;
+        let r = diff % 2;
+        let mut buf = String::with_capacity(dst_len);
+
+        for _ in 0..mid {
+            buf.push(' ');
+        }
+
+        buf.push_str(&src);
+
+        for _ in 0..mid + r {
+            buf.push(' ');
+        }
+
+        Ok(buf)
+    }
+}
+
+/// Count the words in that string
+pub fn wordcount<T: fmt::Display>(s: T) -> Result<usize> {
+    let s = s.to_string();
+
+    Ok(s.split_whitespace().count())
+}
+
+#[cfg(feature = "markdown")]
+pub fn markdown<E, S>(
+    e: E,
+    s: S,
+    options: Option<&comrak::ComrakOptions>,
+) -> Result<MarkupDisplay<E, String>>
+where
+    E: Escaper,
+    S: AsRef<str>,
+{
+    use comrak::{
+        markdown_to_html, ComrakExtensionOptions, ComrakOptions, ComrakParseOptions,
+        ComrakRenderOptions,
+    };
+
+    const DEFAULT_OPTIONS: ComrakOptions = ComrakOptions {
+        extension: ComrakExtensionOptions {
+            strikethrough: true,
+            tagfilter: true,
+            table: true,
+            autolink: true,
+            // default:
+            tasklist: false,
+            superscript: false,
+            header_ids: None,
+            footnotes: false,
+            description_lists: false,
+            front_matter_delimiter: None,
+        },
+        parse: ComrakParseOptions {
+            // default:
+            smart: false,
+            default_info_string: None,
+        },
+        render: ComrakRenderOptions {
+            unsafe_: false,
+            escape: true,
+            // default:
+            hardbreaks: false,
+            github_pre_lang: false,
+            width: 0,
+        },
+    };
+
+    let s = markdown_to_html(s.as_ref(), options.unwrap_or(&DEFAULT_OPTIONS));
+    Ok(MarkupDisplay::new_safe(s, e))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[cfg(feature = "num-traits")]
+    use std::f64::INFINITY;
+
+    #[cfg(feature = "humansize")]
+    #[test]
+    fn test_filesizeformat() {
+        assert_eq!(filesizeformat(&0).unwrap(), "0 B");
+        assert_eq!(filesizeformat(&999u64).unwrap(), "999 B");
+        assert_eq!(filesizeformat(&1000i32).unwrap(), "1 KB");
+        assert_eq!(filesizeformat(&1023).unwrap(), "1.02 KB");
+        assert_eq!(filesizeformat(&1024usize).unwrap(), "1.02 KB");
+    }
+
+    #[cfg(feature = "percent-encoding")]
+    #[test]
+    fn test_urlencoding() {
+        // Unreserved (https://tools.ietf.org/html/rfc3986.html#section-2.3)
+        // alpha / digit
+        assert_eq!(urlencode(&"AZaz09").unwrap(), "AZaz09");
+        assert_eq!(urlencode_strict(&"AZaz09").unwrap(), "AZaz09");
+        // other
+        assert_eq!(urlencode(&"_.-~").unwrap(), "_.-~");
+        assert_eq!(urlencode_strict(&"_.-~").unwrap(), "_.-~");
+
+        // Reserved (https://tools.ietf.org/html/rfc3986.html#section-2.2)
+        // gen-delims
+        assert_eq!(urlencode(&":/?#[]@").unwrap(), "%3A/%3F%23%5B%5D%40");
+        assert_eq!(
+            urlencode_strict(&":/?#[]@").unwrap(),
+            "%3A%2F%3F%23%5B%5D%40"
+        );
+        // sub-delims
+        assert_eq!(
+            urlencode(&"!$&'()*+,;=").unwrap(),
+            "%21%24%26%27%28%29%2A%2B%2C%3B%3D"
+        );
+        assert_eq!(
+            urlencode_strict(&"!$&'()*+,;=").unwrap(),
+            "%21%24%26%27%28%29%2A%2B%2C%3B%3D"
+        );
+
+        // Other
+        assert_eq!(
+            urlencode(&"žŠďŤňĚáÉóŮ").unwrap(),
+            "%C5%BE%C5%A0%C4%8F%C5%A4%C5%88%C4%9A%C3%A1%C3%89%C3%B3%C5%AE"
+        );
+        assert_eq!(
+            urlencode_strict(&"žŠďŤňĚáÉóŮ").unwrap(),
+            "%C5%BE%C5%A0%C4%8F%C5%A4%C5%88%C4%9A%C3%A1%C3%89%C3%B3%C5%AE"
+        );
+
+        // Ferris
+        assert_eq!(urlencode(&"🦀").unwrap(), "%F0%9F%A6%80");
+        assert_eq!(urlencode_strict(&"🦀").unwrap(), "%F0%9F%A6%80");
+    }
+
+    #[test]
+    fn test_linebreaks() {
+        assert_eq!(
+            linebreaks(&"Foo\nBar Baz").unwrap(),
+            "<p>Foo<br/>Bar Baz</p>"
+        );
+        assert_eq!(
+            linebreaks(&"Foo\nBar\n\nBaz").unwrap(),
+            "<p>Foo<br/>Bar</p><p>Baz</p>"
+        );
+    }
+
+    #[test]
+    fn test_linebreaksbr() {
+        assert_eq!(linebreaksbr(&"Foo\nBar").unwrap(), "Foo<br/>Bar");
+        assert_eq!(
+            linebreaksbr(&"Foo\nBar\n\nBaz").unwrap(),
+            "Foo<br/>Bar<br/><br/>Baz"
+        );
+    }
+
+    #[test]
+    fn test_paragraphbreaks() {
+        assert_eq!(
+            paragraphbreaks(&"Foo\nBar Baz").unwrap(),
+            "<p>Foo\nBar Baz</p>"
+        );
+        assert_eq!(
+            paragraphbreaks(&"Foo\nBar\n\nBaz").unwrap(),
+            "<p>Foo\nBar</p><p>Baz</p>"
+        );
+        assert_eq!(
+            paragraphbreaks(&"Foo\n\n\n\n\nBar\n\nBaz").unwrap(),
+            "<p>Foo</p><p>\nBar</p><p>Baz</p>"
+        );
+    }
+
+    #[test]
+    fn test_lower() {
+        assert_eq!(lower(&"Foo").unwrap(), "foo");
+        assert_eq!(lower(&"FOO").unwrap(), "foo");
+        assert_eq!(lower(&"FooBar").unwrap(), "foobar");
+        assert_eq!(lower(&"foo").unwrap(), "foo");
+    }
+
+    #[test]
+    fn test_upper() {
+        assert_eq!(upper(&"Foo").unwrap(), "FOO");
+        assert_eq!(upper(&"FOO").unwrap(), "FOO");
+        assert_eq!(upper(&"FooBar").unwrap(), "FOOBAR");
+        assert_eq!(upper(&"foo").unwrap(), "FOO");
+    }
+
+    #[test]
+    fn test_trim() {
+        assert_eq!(trim(&" Hello\tworld\t").unwrap(), "Hello\tworld");
+    }
+
+    #[test]
+    fn test_truncate() {
+        assert_eq!(truncate(&"hello", 2).unwrap(), "he...");
+        let a = String::from("您好");
+        assert_eq!(a.len(), 6);
+        assert_eq!(String::from("您").len(), 3);
+        assert_eq!(truncate(&"您好", 1).unwrap(), "您...");
+        assert_eq!(truncate(&"您好", 2).unwrap(), "您...");
+        assert_eq!(truncate(&"您好", 3).unwrap(), "您...");
+        assert_eq!(truncate(&"您好", 4).unwrap(), "您好...");
+        assert_eq!(truncate(&"您好", 6).unwrap(), "您好");
+        assert_eq!(truncate(&"您好", 7).unwrap(), "您好");
+        let s = String::from("🤚a🤚");
+        assert_eq!(s.len(), 9);
+        assert_eq!(String::from("🤚").len(), 4);
+        assert_eq!(truncate(&"🤚a🤚", 1).unwrap(), "🤚...");
+        assert_eq!(truncate(&"🤚a🤚", 2).unwrap(), "🤚...");
+        assert_eq!(truncate(&"🤚a🤚", 3).unwrap(), "🤚...");
+        assert_eq!(truncate(&"🤚a🤚", 4).unwrap(), "🤚...");
+        assert_eq!(truncate(&"🤚a🤚", 5).unwrap(), "🤚a...");
+        assert_eq!(truncate(&"🤚a🤚", 6).unwrap(), "🤚a🤚...");
+        assert_eq!(truncate(&"🤚a🤚", 9).unwrap(), "🤚a🤚");
+        assert_eq!(truncate(&"🤚a🤚", 10).unwrap(), "🤚a🤚");
+    }
+
+    #[test]
+    fn test_indent() {
+        assert_eq!(indent(&"hello", 2).unwrap(), "hello");
+        assert_eq!(indent(&"hello\n", 2).unwrap(), "hello\n");
+        assert_eq!(indent(&"hello\nfoo", 2).unwrap(), "hello\n  foo");
+        assert_eq!(
+            indent(&"hello\nfoo\n bar", 4).unwrap(),
+            "hello\n    foo\n     bar"
+        );
+    }
+
+    #[cfg(feature = "num-traits")]
+    #[test]
+    #[allow(clippy::float_cmp)]
+    fn test_into_f64() {
+        assert_eq!(into_f64(1).unwrap(), 1.0_f64);
+        assert_eq!(into_f64(1.9).unwrap(), 1.9_f64);
+        assert_eq!(into_f64(-1.9).unwrap(), -1.9_f64);
+        assert_eq!(into_f64(INFINITY as f32).unwrap(), INFINITY);
+        assert_eq!(into_f64(-INFINITY as f32).unwrap(), -INFINITY);
+    }
+
+    #[cfg(feature = "num-traits")]
+    #[test]
+    fn test_into_isize() {
+        assert_eq!(into_isize(1).unwrap(), 1_isize);
+        assert_eq!(into_isize(1.9).unwrap(), 1_isize);
+        assert_eq!(into_isize(-1.9).unwrap(), -1_isize);
+        assert_eq!(into_isize(1.5_f64).unwrap(), 1_isize);
+        assert_eq!(into_isize(-1.5_f64).unwrap(), -1_isize);
+        match into_isize(INFINITY) {
+            Err(Fmt(fmt::Error)) => {}
+            _ => panic!("Should return error of type Err(Fmt(fmt::Error))"),
+        };
+    }
+
+    #[allow(clippy::needless_borrow)]
+    #[test]
+    fn test_join() {
+        assert_eq!(
+            join((&["hello", "world"]).iter(), ", ").unwrap(),
+            "hello, world"
+        );
+        assert_eq!(join((&["hello"]).iter(), ", ").unwrap(), "hello");
+
+        let empty: &[&str] = &[];
+        assert_eq!(join(empty.iter(), ", ").unwrap(), "");
+
+        let input: Vec<String> = vec!["foo".into(), "bar".into(), "bazz".into()];
+        assert_eq!(join(input.iter(), ":").unwrap(), "foo:bar:bazz");
+
+        let input: &[String] = &["foo".into(), "bar".into()];
+        assert_eq!(join(input.iter(), ":").unwrap(), "foo:bar");
+
+        let real: String = "blah".into();
+        let input: Vec<&str> = vec![&real];
+        assert_eq!(join(input.iter(), ";").unwrap(), "blah");
+
+        assert_eq!(
+            join((&&&&&["foo", "bar"]).iter(), ", ").unwrap(),
+            "foo, bar"
+        );
+    }
+
+    #[cfg(feature = "num-traits")]
+    #[test]
+    #[allow(clippy::float_cmp)]
+    fn test_abs() {
+        assert_eq!(abs(1).unwrap(), 1);
+        assert_eq!(abs(-1).unwrap(), 1);
+        assert_eq!(abs(1.0).unwrap(), 1.0);
+        assert_eq!(abs(-1.0).unwrap(), 1.0);
+        assert_eq!(abs(1.0_f64).unwrap(), 1.0_f64);
+        assert_eq!(abs(-1.0_f64).unwrap(), 1.0_f64);
+    }
+
+    #[test]
+    fn test_capitalize() {
+        assert_eq!(capitalize(&"foo").unwrap(), "Foo".to_string());
+        assert_eq!(capitalize(&"f").unwrap(), "F".to_string());
+        assert_eq!(capitalize(&"fO").unwrap(), "Fo".to_string());
+        assert_eq!(capitalize(&"").unwrap(), "".to_string());
+        assert_eq!(capitalize(&"FoO").unwrap(), "Foo".to_string());
+        assert_eq!(capitalize(&"foO BAR").unwrap(), "Foo bar".to_string());
+    }
+
+    #[test]
+    fn test_center() {
+        assert_eq!(center(&"f", 3).unwrap(), " f ".to_string());
+        assert_eq!(center(&"f", 4).unwrap(), " f  ".to_string());
+        assert_eq!(center(&"foo", 1).unwrap(), "foo".to_string());
+        assert_eq!(center(&"foo bar", 8).unwrap(), "foo bar ".to_string());
+    }
+
+    #[test]
+    fn test_wordcount() {
+        assert_eq!(wordcount(&"").unwrap(), 0);
+        assert_eq!(wordcount(&" \n\t").unwrap(), 0);
+        assert_eq!(wordcount(&"foo").unwrap(), 1);
+        assert_eq!(wordcount(&"foo bar").unwrap(), 2);
+    }
+}
diff --git a/third_party/rust/askama_shared/src/filters/yaml.rs b/third_party/rust/askama_shared/src/filters/yaml.rs
new file mode 100644
index 0000000000..d71e6303e4
--- /dev/null
+++ b/third_party/rust/askama_shared/src/filters/yaml.rs
@@ -0,0 +1,34 @@
+use crate::error::{Error, Result};
+use askama_escape::{Escaper, MarkupDisplay};
+use serde::Serialize;
+
+/// Serialize to YAML (requires `serde_yaml` feature)
+///
+/// ## Errors
+///
+/// This will panic if `S`'s implementation of `Serialize` decides to fail,
+/// or if `T` contains a map with non-string keys.
+pub fn yaml<E: Escaper, S: Serialize>(e: E, s: S) -> Result<MarkupDisplay<E, String>> {
+    match serde_yaml::to_string(&s) {
+        Ok(s) => Ok(MarkupDisplay::new_safe(s, e)),
+        Err(e) => Err(Error::from(e)),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use askama_escape::Html;
+
+    #[test]
+    fn test_yaml() {
+        assert_eq!(yaml(Html, true).unwrap().to_string(), "---\ntrue");
+        assert_eq!(yaml(Html, "foo").unwrap().to_string(), "---\nfoo");
+        assert_eq!(yaml(Html, &true).unwrap().to_string(), "---\ntrue");
+        assert_eq!(yaml(Html, &"foo").unwrap().to_string(), "---\nfoo");
+        assert_eq!(
+            yaml(Html, &vec!["foo", "bar"]).unwrap().to_string(),
+            "---\n- foo\n- bar"
+        );
+    }
+}
diff --git a/third_party/rust/askama_shared/src/generator.rs b/third_party/rust/askama_shared/src/generator.rs
new file mode 100644
index 0000000000..99971392dc
--- /dev/null
+++ b/third_party/rust/askama_shared/src/generator.rs
@@ -0,0 +1,1895 @@
+use super::{get_template_source, CompileError, Integrations};
+use crate::filters;
+use crate::heritage::{Context, Heritage};
+use crate::input::{Source, TemplateInput};
+use crate::parser::{parse, Cond, CondTest, Expr, Loop, Node, Target, When, Ws};
+
+use proc_macro2::Span;
+
+use quote::{quote, ToTokens};
+
+use std::collections::HashMap;
+use std::path::Path;
+use std::{cmp, hash, mem, str};
+
+pub fn generate<S: std::hash::BuildHasher>(
+    input: &TemplateInput<'_>,
+    contexts: &HashMap<&Path, Context<'_>, S>,
+    heritage: Option<&Heritage<'_>>,
+    integrations: Integrations,
+) -> Result<String, CompileError> {
+    Generator::new(input, contexts, heritage, integrations, MapChain::new())
+        .build(&contexts[input.path.as_path()])
+}
+
+struct Generator<'a, S: std::hash::BuildHasher> {
+    // The template input state: original struct AST and attributes
+    input: &'a TemplateInput<'a>,
+    // All contexts, keyed by the package-relative template path
+    contexts: &'a HashMap<&'a Path, Context<'a>, S>,
+    // The heritage contains references to blocks and their ancestry
+    heritage: Option<&'a Heritage<'a>>,
+    // What integrations need to be generated
+    integrations: Integrations,
+    // Variables accessible directly from the current scope (not redirected to context)
+    locals: MapChain<'a, &'a str, LocalMeta>,
+    // Suffix whitespace from the previous literal. Will be flushed to the
+    // output buffer unless suppressed by whitespace suppression on the next
+    // non-literal.
+    next_ws: Option<&'a str>,
+    // Whitespace suppression from the previous non-literal. Will be used to
+    // determine whether to flush prefix whitespace from the next literal.
+    skip_ws: bool,
+    // If currently in a block, this will contain the name of a potential parent block
+    super_block: Option<(&'a str, usize)>,
+    // buffer for writable
+    buf_writable: Vec<Writable<'a>>,
+    // Counter for write! hash named arguments
+    named: usize,
+}
+
+impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
+    fn new<'n>(
+        input: &'n TemplateInput<'_>,
+        contexts: &'n HashMap<&'n Path, Context<'n>, S>,
+        heritage: Option<&'n Heritage<'_>>,
+        integrations: Integrations,
+        locals: MapChain<'n, &'n str, LocalMeta>,
+    ) -> Generator<'n, S> {
+        Generator {
+            input,
+            contexts,
+            heritage,
+            integrations,
+            locals,
+            next_ws: None,
+            skip_ws: false,
+            super_block: None,
+            buf_writable: vec![],
+            named: 0,
+        }
+    }
+
+    fn child(&mut self) -> Generator<'_, S> {
+        let locals = MapChain::with_parent(&self.locals);
+        Self::new(
+            self.input,
+            self.contexts,
+            self.heritage,
+            self.integrations,
+            locals,
+        )
+    }
+
+    // Takes a Context and generates the relevant implementations.
+    fn build(mut self, ctx: &'a Context<'_>) -> Result<String, CompileError> {
+        let mut buf = Buffer::new(0);
+        if !ctx.blocks.is_empty() {
+            if let Some(parent) = self.input.parent {
+                self.deref_to_parent(&mut buf, parent)?;
+            }
+        };
+
+        self.impl_template(ctx, &mut buf)?;
+        self.impl_display(&mut buf)?;
+
+        if self.integrations.actix {
+            self.impl_actix_web_responder(&mut buf)?;
+        }
+        if self.integrations.axum {
+            self.impl_axum_into_response(&mut buf)?;
+        }
+        if self.integrations.gotham {
+            self.impl_gotham_into_response(&mut buf)?;
+        }
+        if self.integrations.mendes {
+            self.impl_mendes_responder(&mut buf)?;
+        }
+        if self.integrations.rocket {
+            self.impl_rocket_responder(&mut buf)?;
+        }
+        if self.integrations.tide {
+            self.impl_tide_integrations(&mut buf)?;
+        }
+        if self.integrations.warp {
+            self.impl_warp_reply(&mut buf)?;
+        }
+        Ok(buf.buf)
+    }
+
+    // Implement `Template` for the given context struct.
+    fn impl_template(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+    ) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama::Template", None)?;
+        buf.writeln(
+            "fn render_into(&self, writer: &mut (impl ::std::fmt::Write + ?Sized)) -> \
+             ::askama::Result<()> {",
+        )?;
+
+        // Make sure the compiler understands that the generated code depends on the template files.
+        for path in self.contexts.keys() {
+            // Skip the fake path of templates defined in rust source.
+            let path_is_valid = match self.input.source {
+                Source::Path(_) => true,
+                Source::Source(_) => path != &self.input.path,
+            };
+            if path_is_valid {
+                let path = path.to_str().unwrap();
+                buf.writeln(
+                    &quote! {
+                        include_bytes!(#path);
+                    }
+                    .to_string(),
+                )?;
+            }
+        }
+
+        let size_hint = if let Some(heritage) = self.heritage {
+            self.handle(heritage.root, heritage.root.nodes, buf, AstLevel::Top)
+        } else {
+            self.handle(ctx, ctx.nodes, buf, AstLevel::Top)
+        }?;
+
+        self.flush_ws(Ws(false, false));
+        buf.writeln("::askama::Result::Ok(())")?;
+        buf.writeln("}")?;
+
+        buf.writeln("const EXTENSION: ::std::option::Option<&'static ::std::primitive::str> = ")?;
+        buf.writeln(&format!("{:?}", self.input.extension()))?;
+        buf.writeln(";")?;
+
+        buf.writeln("const SIZE_HINT: ::std::primitive::usize = ")?;
+        buf.writeln(&format!("{}", size_hint))?;
+        buf.writeln(";")?;
+
+        buf.writeln("const MIME_TYPE: &'static ::std::primitive::str = ")?;
+        buf.writeln(&format!("{:?}", &self.input.mime_type))?;
+        buf.writeln(";")?;
+
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    // Implement `Deref<Parent>` for an inheriting context struct.
+    fn deref_to_parent(
+        &mut self,
+        buf: &mut Buffer,
+        parent_type: &syn::Type,
+    ) -> Result<(), CompileError> {
+        self.write_header(buf, "::std::ops::Deref", None)?;
+        buf.writeln(&format!(
+            "type Target = {};",
+            parent_type.into_token_stream()
+        ))?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn deref(&self) -> &Self::Target {")?;
+        buf.writeln("&self._parent")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement `Display` for the given context struct.
+    fn impl_display(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::std::fmt::Display", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {")?;
+        buf.writeln("::askama::Template::render_into(self, f).map_err(|_| ::std::fmt::Error {})")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement Actix-web's `Responder`.
+    fn impl_actix_web_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_actix::actix_web::Responder", None)?;
+        buf.writeln("type Body = ::askama_actix::actix_web::body::BoxBody;")?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn respond_to(self, _req: &::askama_actix::actix_web::HttpRequest) \
+             -> ::askama_actix::actix_web::HttpResponse<Self::Body> {",
+        )?;
+        buf.writeln("<Self as ::askama_actix::TemplateToResponse>::to_response(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement Axum's `IntoResponse`.
+    fn impl_axum_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_axum::IntoResponse", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn into_response(self)\
+             -> ::askama_axum::Response<::askama_axum::BoxBody> {",
+        )?;
+        let ext = self.input.extension().unwrap_or("txt");
+        buf.writeln(&format!("::askama_axum::into_response(&self, {:?})", ext))?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement gotham's `IntoResponse`.
+    fn impl_gotham_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_gotham::IntoResponse", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn into_response(self, _state: &::askama_gotham::State)\
+             -> ::askama_gotham::Response<::askama_gotham::Body> {",
+        )?;
+        let ext = self.input.extension().unwrap_or("txt");
+        buf.writeln(&format!("::askama_gotham::respond(&self, {:?})", ext))?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement mendes' `Responder`.
+    fn impl_mendes_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let param = syn::parse_str("A: ::mendes::Application").unwrap();
+
+        let mut generics = self.input.ast.generics.clone();
+        generics.params.push(param);
+        let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
+        let (impl_generics, _, where_clause) = generics.split_for_impl();
+
+        let mut where_clause = match where_clause {
+            Some(clause) => clause.clone(),
+            None => syn::WhereClause {
+                where_token: syn::Token![where](Span::call_site()),
+                predicates: syn::punctuated::Punctuated::new(),
+            },
+        };
+
+        where_clause
+            .predicates
+            .push(syn::parse_str("A::ResponseBody: From<String>").unwrap());
+        where_clause
+            .predicates
+            .push(syn::parse_str("A::Error: From<::askama_mendes::Error>").unwrap());
+
+        buf.writeln(
+            format!(
+                "{} {} for {} {} {{",
+                quote!(impl#impl_generics),
+                "::mendes::application::IntoResponse<A>",
+                self.input.ast.ident,
+                quote!(#orig_ty_generics #where_clause),
+            )
+            .as_ref(),
+        )?;
+
+        buf.writeln(
+            "fn into_response(self, app: &A, req: &::mendes::http::request::Parts) \
+             -> ::mendes::http::Response<A::ResponseBody> {",
+        )?;
+
+        buf.writeln(&format!(
+            "::askama_mendes::into_response(app, req, &self, {:?})",
+            self.input.extension()
+        ))?;
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    // Implement Rocket's `Responder`.
+    fn impl_rocket_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let lifetime = syn::Lifetime::new("'askama", Span::call_site());
+        let param = syn::GenericParam::Lifetime(syn::LifetimeDef::new(lifetime));
+        self.write_header(
+            buf,
+            "::askama_rocket::Responder<'askama>",
+            Some(vec![param]),
+        )?;
+
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn respond_to(self, _: &::askama_rocket::Request) \
+             -> ::askama_rocket::Result<'askama> {",
+        )?;
+        let ext = self.input.extension().unwrap_or("txt");
+        buf.writeln(&format!("::askama_rocket::respond(&self, {:?})", ext))?;
+
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    fn impl_tide_integrations(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let ext = self.input.extension().unwrap_or("txt");
+
+        self.write_header(
+            buf,
+            "::std::convert::TryInto<::askama_tide::tide::Body>",
+            None,
+        )?;
+        buf.writeln(
+            "type Error = ::askama_tide::askama::Error;\n\
+            #[inline]\n\
+            fn try_into(self) -> ::askama_tide::askama::Result<::askama_tide::tide::Body> {",
+        )?;
+        buf.writeln(&format!("::askama_tide::try_into_body(&self, {:?})", &ext))?;
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+
+        buf.writeln("#[allow(clippy::from_over_into)]")?;
+        self.write_header(buf, "Into<::askama_tide::tide::Response>", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn into(self) -> ::askama_tide::tide::Response {")?;
+        buf.writeln(&format!("::askama_tide::into_response(&self, {:?})", ext))?;
+        buf.writeln("}\n}")
+    }
+
+    fn impl_warp_reply(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_warp::warp::reply::Reply", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn into_response(self) -> ::askama_warp::warp::reply::Response {")?;
+        let ext = self.input.extension().unwrap_or("txt");
+        buf.writeln(&format!("::askama_warp::reply(&self, {:?})", ext))?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Writes header for the `impl` for `TraitFromPathName` or `Template`
+    // for the given context struct.
+    fn write_header(
+        &mut self,
+        buf: &mut Buffer,
+        target: &str,
+        params: Option<Vec<syn::GenericParam>>,
+    ) -> Result<(), CompileError> {
+        let mut generics = self.input.ast.generics.clone();
+        if let Some(params) = params {
+            for param in params {
+                generics.params.push(param);
+            }
+        }
+        let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
+        let (impl_generics, _, where_clause) = generics.split_for_impl();
+        buf.writeln(
+            format!(
+                "{} {} for {}{} {{",
+                quote!(impl#impl_generics),
+                target,
+                self.input.ast.ident,
+                quote!(#orig_ty_generics #where_clause),
+            )
+            .as_ref(),
+        )
+    }
+
+    /* Helper methods for handling node types */
+
+    fn handle(
+        &mut self,
+        ctx: &'a Context<'_>,
+        nodes: &'a [Node<'_>],
+        buf: &mut Buffer,
+        level: AstLevel,
+    ) -> Result<usize, CompileError> {
+        let mut size_hint = 0;
+        for n in nodes {
+            match *n {
+                Node::Lit(lws, val, rws) => {
+                    self.visit_lit(lws, val, rws);
+                }
+                Node::Comment(ws) => {
+                    self.write_comment(ws);
+                }
+                Node::Expr(ws, ref val) => {
+                    self.write_expr(ws, val);
+                }
+                Node::LetDecl(ws, ref var) => {
+                    self.write_let_decl(buf, ws, var)?;
+                }
+                Node::Let(ws, ref var, ref val) => {
+                    self.write_let(buf, ws, var, val)?;
+                }
+                Node::Cond(ref conds, ws) => {
+                    self.write_cond(ctx, buf, conds, ws)?;
+                }
+                Node::Match(ws1, ref expr, ref arms, ws2) => {
+                    self.write_match(ctx, buf, ws1, expr, arms, ws2)?;
+                }
+                Node::Loop(ref loop_block) => {
+                    self.write_loop(ctx, buf, loop_block)?;
+                }
+                Node::BlockDef(ws1, name, _, ws2) => {
+                    self.write_block(buf, Some(name), Ws(ws1.0, ws2.1))?;
+                }
+                Node::Include(ws, path) => {
+                    size_hint += self.handle_include(ctx, buf, ws, path)?;
+                }
+                Node::Call(ws, scope, name, ref args) => {
+                    size_hint += self.write_call(ctx, buf, ws, scope, name, args)?;
+                }
+                Node::Macro(_, ref m) => {
+                    if level != AstLevel::Top {
+                        return Err("macro blocks only allowed at the top level".into());
+                    }
+                    self.flush_ws(m.ws1);
+                    self.prepare_ws(m.ws2);
+                }
+                Node::Raw(ws1, lws, val, rws, ws2) => {
+                    self.handle_ws(ws1);
+                    self.visit_lit(lws, val, rws);
+                    self.handle_ws(ws2);
+                }
+                Node::Import(ws, _, _) => {
+                    if level != AstLevel::Top {
+                        return Err("import blocks only allowed at the top level".into());
+                    }
+                    self.handle_ws(ws);
+                }
+                Node::Extends(_) => {
+                    if level != AstLevel::Top {
+                        return Err("extend blocks only allowed at the top level".into());
+                    }
+                    // No whitespace handling: child template top-level is not used,
+                    // except for the blocks defined in it.
+                }
+                Node::Break(ws) => {
+                    self.handle_ws(ws);
+                    self.write_buf_writable(buf)?;
+                    buf.writeln("break;")?;
+                }
+                Node::Continue(ws) => {
+                    self.handle_ws(ws);
+                    self.write_buf_writable(buf)?;
+                    buf.writeln("continue;")?;
+                }
+            }
+        }
+
+        if AstLevel::Top == level {
+            size_hint += self.write_buf_writable(buf)?;
+        }
+        Ok(size_hint)
+    }
+
+    fn write_cond(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        conds: &'a [Cond<'_>],
+        ws: Ws,
+    ) -> Result<usize, CompileError> {
+        let mut flushed = 0;
+        let mut arm_sizes = Vec::new();
+        let mut has_else = false;
+        for (i, &(cws, ref cond, ref nodes)) in conds.iter().enumerate() {
+            self.handle_ws(cws);
+            flushed += self.write_buf_writable(buf)?;
+            if i > 0 {
+                self.locals.pop();
+            }
+
+            self.locals.push();
+            let mut arm_size = 0;
+            if let Some(CondTest { target, expr }) = cond {
+                if i == 0 {
+                    buf.write("if ");
+                } else {
+                    buf.dedent()?;
+                    buf.write("} else if ");
+                }
+
+                if let Some(target) = target {
+                    let mut expr_buf = Buffer::new(0);
+                    self.visit_expr(&mut expr_buf, expr)?;
+                    buf.write("let ");
+                    self.visit_target(buf, true, true, target);
+                    buf.write(" = &(");
+                    buf.write(&expr_buf.buf);
+                    buf.write(")");
+                } else {
+                    // The following syntax `*(&(...) as &bool)` is used to
+                    // trigger Rust's automatic dereferencing, to coerce
+                    // e.g. `&&&&&bool` to `bool`. First `&(...) as &bool`
+                    // coerces e.g. `&&&bool` to `&bool`. Then `*(&bool)`
+                    // finally dereferences it to `bool`.
+                    buf.write("*(&(");
+                    let expr_code = self.visit_expr_root(expr)?;
+                    buf.write(&expr_code);
+                    buf.write(") as &bool)");
+                }
+            } else {
+                buf.dedent()?;
+                buf.write("} else");
+                has_else = true;
+            }
+
+            buf.writeln(" {")?;
+
+            arm_size += self.handle(ctx, nodes, buf, AstLevel::Nested)?;
+            arm_sizes.push(arm_size);
+        }
+        self.handle_ws(ws);
+        flushed += self.write_buf_writable(buf)?;
+        buf.writeln("}")?;
+
+        self.locals.pop();
+
+        if !has_else {
+            arm_sizes.push(0);
+        }
+        Ok(flushed + median(&mut arm_sizes))
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn write_match(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws1: Ws,
+        expr: &Expr<'_>,
+        arms: &'a [When<'_>],
+        ws2: Ws,
+    ) -> Result<usize, CompileError> {
+        self.flush_ws(ws1);
+        let flushed = self.write_buf_writable(buf)?;
+        let mut arm_sizes = Vec::new();
+
+        let expr_code = self.visit_expr_root(expr)?;
+        buf.writeln(&format!("match &{} {{", expr_code))?;
+
+        let mut arm_size = 0;
+        for (i, arm) in arms.iter().enumerate() {
+            let &(ws, ref target, ref body) = arm;
+            self.handle_ws(ws);
+
+            if i > 0 {
+                arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
+
+                buf.writeln("}")?;
+                self.locals.pop();
+            }
+
+            self.locals.push();
+            self.visit_target(buf, true, true, target);
+            buf.writeln(" => {")?;
+
+            arm_size = self.handle(ctx, body, buf, AstLevel::Nested)?;
+        }
+
+        self.handle_ws(ws2);
+        arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
+        buf.writeln("}")?;
+        self.locals.pop();
+
+        buf.writeln("}")?;
+
+        Ok(flushed + median(&mut arm_sizes))
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn write_loop(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        loop_block: &'a Loop<'_>,
+    ) -> Result<usize, CompileError> {
+        self.handle_ws(loop_block.ws1);
+        self.locals.push();
+
+        let expr_code = self.visit_expr_root(&loop_block.iter)?;
+
+        let flushed = self.write_buf_writable(buf)?;
+        buf.writeln("{")?;
+        buf.writeln("let mut _did_loop = false;")?;
+        match loop_block.iter {
+            Expr::Range(_, _, _) => buf.writeln(&format!("let _iter = {};", expr_code)),
+            Expr::Array(..) => buf.writeln(&format!("let _iter = {}.iter();", expr_code)),
+            // If `iter` is a call then we assume it's something that returns
+            // an iterator. If not then the user can explicitly add the needed
+            // call without issues.
+            Expr::Call(..) | Expr::Index(..) => {
+                buf.writeln(&format!("let _iter = ({}).into_iter();", expr_code))
+            }
+            // If accessing `self` then it most likely needs to be
+            // borrowed, to prevent an attempt of moving.
+            _ if expr_code.starts_with("self.") => {
+                buf.writeln(&format!("let _iter = (&{}).into_iter();", expr_code))
+            }
+            // If accessing a field then it most likely needs to be
+            // borrowed, to prevent an attempt of moving.
+            Expr::Attr(..) => buf.writeln(&format!("let _iter = (&{}).into_iter();", expr_code)),
+            // Otherwise, we borrow `iter` assuming that it implements `IntoIterator`.
+            _ => buf.writeln(&format!("let _iter = ({}).into_iter();", expr_code)),
+        }?;
+        if let Some(cond) = &loop_block.cond {
+            self.locals.push();
+            buf.write("let _iter = _iter.filter(|");
+            self.visit_target(buf, true, true, &loop_block.var);
+            buf.write("| -> bool {");
+            self.visit_expr(buf, cond)?;
+            buf.writeln("});")?;
+            self.locals.pop();
+        }
+
+        self.locals.push();
+        buf.write("for (");
+        self.visit_target(buf, true, true, &loop_block.var);
+        buf.writeln(", _loop_item) in ::askama::helpers::TemplateLoop::new(_iter) {")?;
+
+        buf.writeln("_did_loop = true;")?;
+        let mut size_hint1 = self.handle(ctx, &loop_block.body, buf, AstLevel::Nested)?;
+        self.handle_ws(loop_block.ws2);
+        size_hint1 += self.write_buf_writable(buf)?;
+        self.locals.pop();
+        buf.writeln("}")?;
+
+        buf.writeln("if !_did_loop {")?;
+        self.locals.push();
+        let mut size_hint2 = self.handle(ctx, &loop_block.else_block, buf, AstLevel::Nested)?;
+        self.handle_ws(loop_block.ws3);
+        size_hint2 += self.write_buf_writable(buf)?;
+        self.locals.pop();
+        buf.writeln("}")?;
+
+        buf.writeln("}")?;
+
+        Ok(flushed + ((size_hint1 * 3) + size_hint2) / 2)
+    }
+
+    fn write_call(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws: Ws,
+        scope: Option<&str>,
+        name: &str,
+        args: &[Expr<'_>],
+    ) -> Result<usize, CompileError> {
+        if name == "super" {
+            return self.write_block(buf, None, ws);
+        }
+
+        let (def, own_ctx) = match scope {
+            Some(s) => {
+                let path = ctx.imports.get(s).ok_or_else(|| {
+                    CompileError::from(format!("no import found for scope {:?}", s))
+                })?;
+                let mctx = self.contexts.get(path.as_path()).ok_or_else(|| {
+                    CompileError::from(format!("context for {:?} not found", path))
+                })?;
+                let def = mctx.macros.get(name).ok_or_else(|| {
+                    CompileError::from(format!("macro {:?} not found in scope {:?}", name, s))
+                })?;
+                (def, mctx)
+            }
+            None => {
+                let def = ctx
+                    .macros
+                    .get(name)
+                    .ok_or_else(|| CompileError::from(format!("macro {:?} not found", name)))?;
+                (def, ctx)
+            }
+        };
+
+        self.flush_ws(ws); // Cannot handle_ws() here: whitespace from macro definition comes first
+        self.locals.push();
+        self.write_buf_writable(buf)?;
+        buf.writeln("{")?;
+        self.prepare_ws(def.ws1);
+
+        let mut names = Buffer::new(0);
+        let mut values = Buffer::new(0);
+        let mut is_first_variable = true;
+        for (i, arg) in def.args.iter().enumerate() {
+            let expr = args.get(i).ok_or_else(|| {
+                CompileError::from(format!("macro {:?} takes more than {} arguments", name, i))
+            })?;
+
+            match expr {
+                // If `expr` is already a form of variable then
+                // don't reintroduce a new variable. This is
+                // to avoid moving non-copyable values.
+                Expr::Var(name) => {
+                    let var = self.locals.resolve_or_self(name);
+                    self.locals.insert(arg, LocalMeta::with_ref(var));
+                }
+                Expr::Attr(obj, attr) => {
+                    let mut attr_buf = Buffer::new(0);
+                    self.visit_attr(&mut attr_buf, obj, attr)?;
+
+                    let var = self.locals.resolve(&attr_buf.buf).unwrap_or(attr_buf.buf);
+                    self.locals.insert(arg, LocalMeta::with_ref(var));
+                }
+                // Everything else still needs to become variables,
+                // to avoid having the same logic be executed
+                // multiple times, e.g. in the case of macro
+                // parameters being used multiple times.
+                _ => {
+                    if is_first_variable {
+                        is_first_variable = false
+                    } else {
+                        names.write(", ");
+                        values.write(", ");
+                    }
+                    names.write(arg);
+
+                    values.write("(");
+                    values.write(&self.visit_expr_root(expr)?);
+                    values.write(")");
+                    self.locals.insert_with_default(arg);
+                }
+            }
+        }
+
+        debug_assert_eq!(names.buf.is_empty(), values.buf.is_empty());
+        if !names.buf.is_empty() {
+            buf.writeln(&format!("let ({}) = ({});", names.buf, values.buf))?;
+        }
+
+        let mut size_hint = self.handle(own_ctx, &def.nodes, buf, AstLevel::Nested)?;
+
+        self.flush_ws(def.ws2);
+        size_hint += self.write_buf_writable(buf)?;
+        buf.writeln("}")?;
+        self.locals.pop();
+        self.prepare_ws(ws);
+        Ok(size_hint)
+    }
+
+    fn handle_include(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws: Ws,
+        path: &str,
+    ) -> Result<usize, CompileError> {
+        self.flush_ws(ws);
+        self.write_buf_writable(buf)?;
+        let path = self
+            .input
+            .config
+            .find_template(path, Some(&self.input.path))?;
+        let src = get_template_source(&path)?;
+        let nodes = parse(&src, self.input.syntax)?;
+
+        // Make sure the compiler understands that the generated code depends on the template file.
+        {
+            let path = path.to_str().unwrap();
+            buf.writeln(
+                &quote! {
+                    include_bytes!(#path);
+                }
+                .to_string(),
+            )?;
+        }
+
+        let size_hint = {
+            // Since nodes must not outlive the Generator, we instantiate
+            // a nested Generator here to handle the include's nodes.
+            let mut gen = self.child();
+            let mut size_hint = gen.handle(ctx, &nodes, buf, AstLevel::Nested)?;
+            size_hint += gen.write_buf_writable(buf)?;
+            size_hint
+        };
+        self.prepare_ws(ws);
+        Ok(size_hint)
+    }
+
+    fn write_let_decl(
+        &mut self,
+        buf: &mut Buffer,
+        ws: Ws,
+        var: &'a Target<'_>,
+    ) -> Result<(), CompileError> {
+        self.handle_ws(ws);
+        self.write_buf_writable(buf)?;
+        buf.write("let ");
+        self.visit_target(buf, false, true, var);
+        buf.writeln(";")
+    }
+
+    fn is_shadowing_variable(&self, var: &Target<'a>) -> Result<bool, CompileError> {
+        match var {
+            Target::Name(name) => {
+                let name = normalize_identifier(name);
+                match self.locals.get(&name) {
+                    // declares a new variable
+                    None => Ok(false),
+                    // an initialized variable gets shadowed
+                    Some(meta) if meta.initialized => Ok(true),
+                    // initializes a variable that was introduced in a LetDecl before
+                    _ => Ok(false),
+                }
+            }
+            Target::Tuple(_, targets) => {
+                for target in targets {
+                    match self.is_shadowing_variable(target) {
+                        Ok(false) => continue,
+                        outcome => return outcome,
+                    }
+                }
+                Ok(false)
+            }
+            Target::Struct(_, named_targets) => {
+                for (_, target) in named_targets {
+                    match self.is_shadowing_variable(target) {
+                        Ok(false) => continue,
+                        outcome => return outcome,
+                    }
+                }
+                Ok(false)
+            }
+            _ => Err("literals are not allowed on the left-hand side of an assignment".into()),
+        }
+    }
+
+    fn write_let(
+        &mut self,
+        buf: &mut Buffer,
+        ws: Ws,
+        var: &'a Target<'_>,
+        val: &Expr<'_>,
+    ) -> Result<(), CompileError> {
+        self.handle_ws(ws);
+        let mut expr_buf = Buffer::new(0);
+        self.visit_expr(&mut expr_buf, val)?;
+
+        let shadowed = self.is_shadowing_variable(var)?;
+        if shadowed {
+            // Need to flush the buffer if the variable is being shadowed,
+            // to ensure the old variable is used.
+            self.write_buf_writable(buf)?;
+        }
+        if shadowed
+            || !matches!(var, &Target::Name(_))
+            || matches!(var, Target::Name(name) if self.locals.get(name).is_none())
+        {
+            buf.write("let ");
+        }
+
+        self.visit_target(buf, true, true, var);
+        buf.writeln(&format!(" = {};", &expr_buf.buf))
+    }
+
+    // If `name` is `Some`, this is a call to a block definition, and we have to find
+    // the first block for that name from the ancestry chain. If name is `None`, this
+    // is from a `super()` call, and we can get the name from `self.super_block`.
+    fn write_block(
+        &mut self,
+        buf: &mut Buffer,
+        name: Option<&'a str>,
+        outer: Ws,
+    ) -> Result<usize, CompileError> {
+        // Flush preceding whitespace according to the outer WS spec
+        self.flush_ws(outer);
+
+        let prev_block = self.super_block;
+        let cur = match (name, prev_block) {
+            // The top-level context contains a block definition
+            (Some(cur_name), None) => (cur_name, 0),
+            // A block definition contains a block definition of the same name
+            (Some(cur_name), Some((prev_name, _))) if cur_name == prev_name => {
+                return Err(format!("cannot define recursive blocks ({})", cur_name).into());
+            }
+            // A block definition contains a definition of another block
+            (Some(cur_name), Some((_, _))) => (cur_name, 0),
+            // `super()` was called inside a block
+            (None, Some((prev_name, gen))) => (prev_name, gen + 1),
+            // `super()` is called from outside a block
+            (None, None) => return Err("cannot call 'super()' outside block".into()),
+        };
+        self.super_block = Some(cur);
+
+        // Get the block definition from the heritage chain
+        let heritage = self
+            .heritage
+            .as_ref()
+            .ok_or_else(|| CompileError::from("no block ancestors available"))?;
+        let (ctx, def) = heritage.blocks[cur.0].get(cur.1).ok_or_else(|| {
+            CompileError::from(match name {
+                None => format!("no super() block found for block '{}'", cur.0),
+                Some(name) => format!("no block found for name '{}'", name),
+            })
+        })?;
+
+        // Get the nodes and whitespace suppression data from the block definition
+        let (ws1, nodes, ws2) = if let Node::BlockDef(ws1, _, nodes, ws2) = def {
+            (ws1, nodes, ws2)
+        } else {
+            unreachable!()
+        };
+
+        // Handle inner whitespace suppression spec and process block nodes
+        self.prepare_ws(*ws1);
+        self.locals.push();
+        let size_hint = self.handle(ctx, nodes, buf, AstLevel::Block)?;
+
+        if !self.locals.is_current_empty() {
+            // Need to flush the buffer before popping the variable stack
+            self.write_buf_writable(buf)?;
+        }
+
+        self.locals.pop();
+        self.flush_ws(*ws2);
+
+        // Restore original block context and set whitespace suppression for
+        // succeeding whitespace according to the outer WS spec
+        self.super_block = prev_block;
+        self.prepare_ws(outer);
+        Ok(size_hint)
+    }
+
+    fn write_expr(&mut self, ws: Ws, s: &'a Expr<'a>) {
+        self.handle_ws(ws);
+        self.buf_writable.push(Writable::Expr(s));
+    }
+
+    // Write expression buffer and empty
+    fn write_buf_writable(&mut self, buf: &mut Buffer) -> Result<usize, CompileError> {
+        if self.buf_writable.is_empty() {
+            return Ok(0);
+        }
+
+        if self
+            .buf_writable
+            .iter()
+            .all(|w| matches!(w, Writable::Lit(_)))
+        {
+            let mut buf_lit = Buffer::new(0);
+            for s in mem::take(&mut self.buf_writable) {
+                if let Writable::Lit(s) = s {
+                    buf_lit.write(s);
+                };
+            }
+            buf.writeln(&format!("writer.write_str({:#?})?;", &buf_lit.buf))?;
+            return Ok(buf_lit.buf.len());
+        }
+
+        let mut size_hint = 0;
+        let mut buf_format = Buffer::new(0);
+        let mut buf_expr = Buffer::new(buf.indent + 1);
+        let mut expr_cache = HashMap::with_capacity(self.buf_writable.len());
+        for s in mem::take(&mut self.buf_writable) {
+            match s {
+                Writable::Lit(s) => {
+                    buf_format.write(&s.replace('{', "{{").replace('}', "}}"));
+                    size_hint += s.len();
+                }
+                Writable::Expr(s) => {
+                    use self::DisplayWrap::*;
+                    let mut expr_buf = Buffer::new(0);
+                    let wrapped = self.visit_expr(&mut expr_buf, s)?;
+                    let expression = match wrapped {
+                        Wrapped => expr_buf.buf,
+                        Unwrapped => format!(
+                            "::askama::MarkupDisplay::new_unsafe(&({}), {})",
+                            expr_buf.buf, self.input.escaper
+                        ),
+                    };
+
+                    use std::collections::hash_map::Entry;
+                    let id = match expr_cache.entry(expression.clone()) {
+                        Entry::Occupied(e) => *e.get(),
+                        Entry::Vacant(e) => {
+                            let id = self.named;
+                            self.named += 1;
+
+                            buf_expr.write(&format!("expr{} = ", id));
+                            buf_expr.write("&");
+                            buf_expr.write(&expression);
+                            buf_expr.writeln(",")?;
+
+                            e.insert(id);
+                            id
+                        }
+                    };
+
+                    buf_format.write(&format!("{{expr{}}}", id));
+                    size_hint += 3;
+                }
+            }
+        }
+
+        buf.writeln("::std::write!(")?;
+        buf.indent();
+        buf.writeln("writer,")?;
+        buf.writeln(&format!("{:#?},", &buf_format.buf))?;
+        buf.writeln(buf_expr.buf.trim())?;
+        buf.dedent()?;
+        buf.writeln(")?;")?;
+        Ok(size_hint)
+    }
+
+    fn visit_lit(&mut self, lws: &'a str, val: &'a str, rws: &'a str) {
+        assert!(self.next_ws.is_none());
+        if !lws.is_empty() {
+            if self.skip_ws {
+                self.skip_ws = false;
+            } else if val.is_empty() {
+                assert!(rws.is_empty());
+                self.next_ws = Some(lws);
+            } else {
+                self.buf_writable.push(Writable::Lit(lws));
+            }
+        }
+
+        if !val.is_empty() {
+            self.buf_writable.push(Writable::Lit(val));
+        }
+
+        if !rws.is_empty() {
+            self.next_ws = Some(rws);
+        }
+    }
+
+    fn write_comment(&mut self, ws: Ws) {
+        self.handle_ws(ws);
+    }
+
+    /* Visitor methods for expression types */
+
+    fn visit_expr_root(&mut self, expr: &Expr<'_>) -> Result<String, CompileError> {
+        let mut buf = Buffer::new(0);
+        self.visit_expr(&mut buf, expr)?;
+        Ok(buf.buf)
+    }
+
+    fn visit_expr(
+        &mut self,
+        buf: &mut Buffer,
+        expr: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        Ok(match *expr {
+            Expr::BoolLit(s) => self.visit_bool_lit(buf, s),
+            Expr::NumLit(s) => self.visit_num_lit(buf, s),
+            Expr::StrLit(s) => self.visit_str_lit(buf, s),
+            Expr::CharLit(s) => self.visit_char_lit(buf, s),
+            Expr::Var(s) => self.visit_var(buf, s),
+            Expr::Path(ref path) => self.visit_path(buf, path),
+            Expr::Array(ref elements) => self.visit_array(buf, elements)?,
+            Expr::Attr(ref obj, name) => self.visit_attr(buf, obj, name)?,
+            Expr::Index(ref obj, ref key) => self.visit_index(buf, obj, key)?,
+            Expr::Filter(name, ref args) => self.visit_filter(buf, name, args)?,
+            Expr::Unary(op, ref inner) => self.visit_unary(buf, op, inner)?,
+            Expr::BinOp(op, ref left, ref right) => self.visit_binop(buf, op, left, right)?,
+            Expr::Range(op, ref left, ref right) => self.visit_range(buf, op, left, right)?,
+            Expr::Group(ref inner) => self.visit_group(buf, inner)?,
+            Expr::Call(ref obj, ref args) => self.visit_call(buf, obj, args)?,
+            Expr::RustMacro(name, args) => self.visit_rust_macro(buf, name, args),
+            Expr::Try(ref expr) => self.visit_try(buf, expr.as_ref())?,
+            Expr::Tuple(ref exprs) => self.visit_tuple(buf, exprs)?,
+        })
+    }
+
+    fn visit_try(
+        &mut self,
+        buf: &mut Buffer,
+        expr: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("::core::result::Result::map_err(");
+        self.visit_expr(buf, expr)?;
+        buf.write(", |err| ::askama::shared::Error::Custom(::core::convert::Into::into(err)))?");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_rust_macro(&mut self, buf: &mut Buffer, name: &str, args: &str) -> DisplayWrap {
+        buf.write(name);
+        buf.write("!(");
+        buf.write(args);
+        buf.write(")");
+
+        DisplayWrap::Unwrapped
+    }
+
+    #[cfg(not(feature = "markdown"))]
+    fn _visit_markdown_filter(
+        &mut self,
+        _buf: &mut Buffer,
+        _args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        Err("the `markdown` filter requires the `markdown` feature to be enabled".into())
+    }
+
+    #[cfg(feature = "markdown")]
+    fn _visit_markdown_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        let (md, options) = match args {
+            [md] => (md, None),
+            [md, options] => (md, Some(options)),
+            _ => return Err("markdown filter expects no more than one option argument".into()),
+        };
+
+        buf.write(&format!(
+            "::askama::filters::markdown({}, ",
+            self.input.escaper
+        ));
+        self.visit_expr(buf, md)?;
+        match options {
+            Some(options) => {
+                buf.write(", ::core::option::Option::Some(");
+                self.visit_expr(buf, options)?;
+                buf.write(")");
+            }
+            None => buf.write(", ::core::option::Option::None"),
+        }
+        buf.write(")?");
+
+        Ok(DisplayWrap::Wrapped)
+    }
+
+    fn visit_filter(
+        &mut self,
+        buf: &mut Buffer,
+        mut name: &str,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        if matches!(name, "escape" | "e") {
+            self._visit_escape_filter(buf, args)?;
+            return Ok(DisplayWrap::Wrapped);
+        } else if name == "format" {
+            self._visit_format_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "fmt" {
+            self._visit_fmt_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "join" {
+            self._visit_join_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "markdown" {
+            return self._visit_markdown_filter(buf, args);
+        }
+
+        if name == "tojson" {
+            name = "json";
+        }
+
+        #[cfg(not(feature = "json"))]
+        if name == "json" {
+            return Err("the `json` filter requires the `serde-json` feature to be enabled".into());
+        }
+        #[cfg(not(feature = "yaml"))]
+        if name == "yaml" {
+            return Err("the `yaml` filter requires the `serde-yaml` feature to be enabled".into());
+        }
+
+        const FILTERS: [&str; 2] = ["safe", "yaml"];
+        if FILTERS.contains(&name) {
+            buf.write(&format!(
+                "::askama::filters::{}({}, ",
+                name, self.input.escaper
+            ));
+        } else if filters::BUILT_IN_FILTERS.contains(&name) {
+            buf.write(&format!("::askama::filters::{}(", name));
+        } else {
+            buf.write(&format!("filters::{}(", name));
+        }
+
+        self._visit_args(buf, args)?;
+        buf.write(")?");
+        Ok(match FILTERS.contains(&name) {
+            true => DisplayWrap::Wrapped,
+            false => DisplayWrap::Unwrapped,
+        })
+    }
+
+    fn _visit_escape_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        if args.len() > 2 {
+            return Err("only two arguments allowed to escape filter".into());
+        }
+        let opt_escaper = match args.get(1) {
+            Some(Expr::StrLit(name)) => Some(*name),
+            Some(_) => return Err("invalid escaper type for escape filter".into()),
+            None => None,
+        };
+        let escaper = match opt_escaper {
+            Some(name) => self
+                .input
+                .config
+                .escapers
+                .iter()
+                .find_map(|(escapers, escaper)| escapers.contains(name).then(|| escaper))
+                .ok_or_else(|| CompileError::from("invalid escaper for escape filter"))?,
+            None => self.input.escaper,
+        };
+        buf.write("::askama::filters::escape(");
+        buf.write(escaper);
+        buf.write(", ");
+        self._visit_args(buf, &args[..1])?;
+        buf.write(")?");
+        Ok(())
+    }
+
+    fn _visit_format_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("format!(");
+        if let Some(Expr::StrLit(v)) = args.first() {
+            self.visit_str_lit(buf, v);
+            if args.len() > 1 {
+                buf.write(", ");
+            }
+        } else {
+            return Err("invalid expression type for format filter".into());
+        }
+        self._visit_args(buf, &args[1..])?;
+        buf.write(")");
+        Ok(())
+    }
+
+    fn _visit_fmt_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("format!(");
+        if let Some(Expr::StrLit(v)) = args.get(1) {
+            self.visit_str_lit(buf, v);
+            buf.write(", ");
+        } else {
+            return Err("invalid expression type for fmt filter".into());
+        }
+        self._visit_args(buf, &args[0..1])?;
+        if args.len() > 2 {
+            return Err("only two arguments allowed to fmt filter".into());
+        }
+        buf.write(")");
+        Ok(())
+    }
+
+    // Force type coercion on first argument to `join` filter (see #39).
+    fn _visit_join_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("::askama::filters::join((&");
+        for (i, arg) in args.iter().enumerate() {
+            if i > 0 {
+                buf.write(", &");
+            }
+            self.visit_expr(buf, arg)?;
+            if i == 0 {
+                buf.write(").into_iter()");
+            }
+        }
+        buf.write(")?");
+        Ok(())
+    }
+
+    fn _visit_args(&mut self, buf: &mut Buffer, args: &[Expr<'_>]) -> Result<(), CompileError> {
+        if args.is_empty() {
+            return Ok(());
+        }
+
+        for (i, arg) in args.iter().enumerate() {
+            if i > 0 {
+                buf.write(", ");
+            }
+
+            let borrow = !arg.is_copyable();
+            if borrow {
+                buf.write("&(");
+            }
+
+            match arg {
+                Expr::Call(left, _) if !matches!(left.as_ref(), Expr::Path(_)) => {
+                    buf.writeln("{")?;
+                    self.visit_expr(buf, arg)?;
+                    buf.writeln("}")?;
+                }
+                _ => {
+                    self.visit_expr(buf, arg)?;
+                }
+            }
+
+            if borrow {
+                buf.write(")");
+            }
+        }
+        Ok(())
+    }
+
+    fn visit_attr(
+        &mut self,
+        buf: &mut Buffer,
+        obj: &Expr<'_>,
+        attr: &str,
+    ) -> Result<DisplayWrap, CompileError> {
+        if let Expr::Var(name) = *obj {
+            if name == "loop" {
+                if attr == "index" {
+                    buf.write("(_loop_item.index + 1)");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "index0" {
+                    buf.write("_loop_item.index");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "first" {
+                    buf.write("_loop_item.first");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "last" {
+                    buf.write("_loop_item.last");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else {
+                    return Err("unknown loop variable".into());
+                }
+            }
+        }
+        self.visit_expr(buf, obj)?;
+        buf.write(&format!(".{}", normalize_identifier(attr)));
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_index(
+        &mut self,
+        buf: &mut Buffer,
+        obj: &Expr<'_>,
+        key: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("&");
+        self.visit_expr(buf, obj)?;
+        buf.write("[");
+        self.visit_expr(buf, key)?;
+        buf.write("]");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_call(
+        &mut self,
+        buf: &mut Buffer,
+        left: &Expr<'_>,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        match left {
+            Expr::Attr(left, method) if **left == Expr::Var("loop") => match *method {
+                "cycle" => match args {
+                    [arg] => {
+                        if matches!(arg, Expr::Array(arr) if arr.is_empty()) {
+                            return Err("loop.cycle(…) cannot use an empty array".into());
+                        }
+                        buf.write("({");
+                        buf.write("let _cycle = &(");
+                        self.visit_expr(buf, arg)?;
+                        buf.writeln(");")?;
+                        buf.writeln("let _len = _cycle.len();")?;
+                        buf.writeln("if _len == 0 {")?;
+                        buf.writeln("return ::core::result::Result::Err(::askama::Error::Fmt(::core::fmt::Error));")?;
+                        buf.writeln("}")?;
+                        buf.writeln("_cycle[_loop_item.index % _len]")?;
+                        buf.writeln("})")?;
+                    }
+                    _ => return Err("loop.cycle(…) expects exactly one argument".into()),
+                },
+                s => return Err(format!("unknown loop method: {:?}", s).into()),
+            },
+            left => {
+                match left {
+                    Expr::Var(name) => match self.locals.resolve(name) {
+                        Some(resolved) => buf.write(&resolved),
+                        None => buf.write(&format!("(&self.{})", normalize_identifier(name))),
+                    },
+                    left => {
+                        self.visit_expr(buf, left)?;
+                    }
+                }
+
+                buf.write("(");
+                self._visit_args(buf, args)?;
+                buf.write(")");
+            }
+        }
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_unary(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        inner: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write(op);
+        self.visit_expr(buf, inner)?;
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_range(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        left: &Option<Box<Expr<'_>>>,
+        right: &Option<Box<Expr<'_>>>,
+    ) -> Result<DisplayWrap, CompileError> {
+        if let Some(left) = left {
+            self.visit_expr(buf, left)?;
+        }
+        buf.write(op);
+        if let Some(right) = right {
+            self.visit_expr(buf, right)?;
+        }
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_binop(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        left: &Expr<'_>,
+        right: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        self.visit_expr(buf, left)?;
+        buf.write(&format!(" {} ", op));
+        self.visit_expr(buf, right)?;
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_group(
+        &mut self,
+        buf: &mut Buffer,
+        inner: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("(");
+        self.visit_expr(buf, inner)?;
+        buf.write(")");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_tuple(
+        &mut self,
+        buf: &mut Buffer,
+        exprs: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("(");
+        for (index, expr) in exprs.iter().enumerate() {
+            if index > 0 {
+                buf.write(" ");
+            }
+            self.visit_expr(buf, expr)?;
+            buf.write(",");
+        }
+        buf.write(")");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_array(
+        &mut self,
+        buf: &mut Buffer,
+        elements: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("[");
+        for (i, el) in elements.iter().enumerate() {
+            if i > 0 {
+                buf.write(", ");
+            }
+            self.visit_expr(buf, el)?;
+        }
+        buf.write("]");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_path(&mut self, buf: &mut Buffer, path: &[&str]) -> DisplayWrap {
+        for (i, part) in path.iter().enumerate() {
+            if i > 0 {
+                buf.write("::");
+            }
+            buf.write(part);
+        }
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_var(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        if s == "self" {
+            buf.write(s);
+            return DisplayWrap::Unwrapped;
+        }
+
+        buf.write(normalize_identifier(&self.locals.resolve_or_self(s)));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_bool_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(s);
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_str_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(&format!("\"{}\"", s));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_char_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(&format!("'{}'", s));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_num_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(s);
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_target(
+        &mut self,
+        buf: &mut Buffer,
+        initialized: bool,
+        first_level: bool,
+        target: &Target<'a>,
+    ) {
+        match target {
+            Target::Name("_") => {
+                buf.write("_");
+            }
+            Target::Name(name) => {
+                let name = normalize_identifier(name);
+                match initialized {
+                    true => self.locals.insert(name, LocalMeta::initialized()),
+                    false => self.locals.insert_with_default(name),
+                }
+                buf.write(name);
+            }
+            Target::Tuple(path, targets) => {
+                buf.write(&path.join("::"));
+                buf.write("(");
+                for target in targets {
+                    self.visit_target(buf, initialized, false, target);
+                    buf.write(",");
+                }
+                buf.write(")");
+            }
+            Target::Struct(path, targets) => {
+                buf.write(&path.join("::"));
+                buf.write(" { ");
+                for (name, target) in targets {
+                    buf.write(normalize_identifier(name));
+                    buf.write(": ");
+                    self.visit_target(buf, initialized, false, target);
+                    buf.write(",");
+                }
+                buf.write(" }");
+            }
+            Target::Path(path) => {
+                self.visit_path(buf, path);
+            }
+            Target::StrLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_str_lit(buf, s);
+            }
+            Target::NumLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_num_lit(buf, s);
+            }
+            Target::CharLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_char_lit(buf, s);
+            }
+            Target::BoolLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                buf.write(s);
+            }
+        }
+    }
+
+    /* Helper methods for dealing with whitespace nodes */
+
+    // Combines `flush_ws()` and `prepare_ws()` to handle both trailing whitespace from the
+    // preceding literal and leading whitespace from the succeeding literal.
+    fn handle_ws(&mut self, ws: Ws) {
+        self.flush_ws(ws);
+        self.prepare_ws(ws);
+    }
+
+    // If the previous literal left some trailing whitespace in `next_ws` and the
+    // prefix whitespace suppressor from the given argument, flush that whitespace.
+    // In either case, `next_ws` is reset to `None` (no trailing whitespace).
+    fn flush_ws(&mut self, ws: Ws) {
+        if self.next_ws.is_some() && !ws.0 {
+            let val = self.next_ws.unwrap();
+            if !val.is_empty() {
+                self.buf_writable.push(Writable::Lit(val));
+            }
+        }
+        self.next_ws = None;
+    }
+
+    // Sets `skip_ws` to match the suffix whitespace suppressor from the given
+    // argument, to determine whether to suppress leading whitespace from the
+    // next literal.
+    fn prepare_ws(&mut self, ws: Ws) {
+        self.skip_ws = ws.1;
+    }
+}
+
+struct Buffer {
+    // The buffer to generate the code into
+    buf: String,
+    // The current level of indentation (in spaces)
+    indent: u8,
+    // Whether the output buffer is currently at the start of a line
+    start: bool,
+}
+
+impl Buffer {
+    fn new(indent: u8) -> Self {
+        Self {
+            buf: String::new(),
+            indent,
+            start: true,
+        }
+    }
+
+    fn writeln(&mut self, s: &str) -> Result<(), CompileError> {
+        if s == "}" {
+            self.dedent()?;
+        }
+        if !s.is_empty() {
+            self.write(s);
+        }
+        self.buf.push('\n');
+        if s.ends_with('{') {
+            self.indent();
+        }
+        self.start = true;
+        Ok(())
+    }
+
+    fn write(&mut self, s: &str) {
+        if self.start {
+            for _ in 0..(self.indent * 4) {
+                self.buf.push(' ');
+            }
+            self.start = false;
+        }
+        self.buf.push_str(s);
+    }
+
+    fn indent(&mut self) {
+        self.indent += 1;
+    }
+
+    fn dedent(&mut self) -> Result<(), CompileError> {
+        if self.indent == 0 {
+            return Err("dedent() called while indentation == 0".into());
+        }
+        self.indent -= 1;
+        Ok(())
+    }
+}
+
+#[derive(Clone, Default)]
+struct LocalMeta {
+    refs: Option<String>,
+    initialized: bool,
+}
+
+impl LocalMeta {
+    fn initialized() -> Self {
+        Self {
+            refs: None,
+            initialized: true,
+        }
+    }
+
+    fn with_ref(refs: String) -> Self {
+        Self {
+            refs: Some(refs),
+            initialized: true,
+        }
+    }
+}
+
+// type SetChain<'a, T> = MapChain<'a, T, ()>;
+
+#[derive(Debug)]
+struct MapChain<'a, K, V>
+where
+    K: cmp::Eq + hash::Hash,
+{
+    parent: Option<&'a MapChain<'a, K, V>>,
+    scopes: Vec<HashMap<K, V>>,
+}
+
+impl<'a, K: 'a, V: 'a> MapChain<'a, K, V>
+where
+    K: cmp::Eq + hash::Hash,
+{
+    fn new() -> MapChain<'a, K, V> {
+        MapChain {
+            parent: None,
+            scopes: vec![HashMap::new()],
+        }
+    }
+
+    fn with_parent<'p>(parent: &'p MapChain<'_, K, V>) -> MapChain<'p, K, V> {
+        MapChain {
+            parent: Some(parent),
+            scopes: vec![HashMap::new()],
+        }
+    }
+
+    /// Iterates the scopes in reverse and returns `Some(LocalMeta)`
+    /// from the first scope where `key` exists.
+    fn get(&self, key: &K) -> Option<&V> {
+        let scopes = self.scopes.iter().rev();
+        scopes
+            .filter_map(|set| set.get(key))
+            .next()
+            .or_else(|| self.parent.and_then(|set| set.get(key)))
+    }
+
+    fn is_current_empty(&self) -> bool {
+        self.scopes.last().unwrap().is_empty()
+    }
+
+    fn insert(&mut self, key: K, val: V) {
+        self.scopes.last_mut().unwrap().insert(key, val);
+
+        // Note that if `insert` returns `Some` then it implies
+        // an identifier is reused. For e.g. `{% macro f(a, a) %}`
+        // and `{% let (a, a) = ... %}` then this results in a
+        // generated template, which when compiled fails with the
+        // compile error "identifier `a` used more than once".
+    }
+
+    fn insert_with_default(&mut self, key: K)
+    where
+        V: Default,
+    {
+        self.insert(key, V::default());
+    }
+
+    fn push(&mut self) {
+        self.scopes.push(HashMap::new());
+    }
+
+    fn pop(&mut self) {
+        self.scopes.pop().unwrap();
+        assert!(!self.scopes.is_empty());
+    }
+}
+
+impl MapChain<'_, &str, LocalMeta> {
+    fn resolve(&self, name: &str) -> Option<String> {
+        let name = normalize_identifier(name);
+        self.get(&name).map(|meta| match &meta.refs {
+            Some(expr) => expr.clone(),
+            None => name.to_string(),
+        })
+    }
+
+    fn resolve_or_self(&self, name: &str) -> String {
+        let name = normalize_identifier(name);
+        self.resolve(name)
+            .unwrap_or_else(|| format!("self.{}", name))
+    }
+}
+
+fn median(sizes: &mut [usize]) -> usize {
+    sizes.sort_unstable();
+    if sizes.len() % 2 == 1 {
+        sizes[sizes.len() / 2]
+    } else {
+        (sizes[sizes.len() / 2 - 1] + sizes[sizes.len() / 2]) / 2
+    }
+}
+
+#[derive(Clone, PartialEq)]
+enum AstLevel {
+    Top,
+    Block,
+    Nested,
+}
+
+impl Copy for AstLevel {}
+
+#[derive(Clone)]
+enum DisplayWrap {
+    Wrapped,
+    Unwrapped,
+}
+
+impl Copy for DisplayWrap {}
+
+#[derive(Debug)]
+enum Writable<'a> {
+    Lit(&'a str),
+    Expr(&'a Expr<'a>),
+}
+
+// Identifiers to be replaced with raw identifiers, so as to avoid
+// collisions between template syntax and Rust's syntax. In particular
+// [Rust keywords](https://doc.rust-lang.org/reference/keywords.html)
+// should be replaced, since they're not reserved words in Askama
+// syntax but have a high probability of causing problems in the
+// generated code.
+//
+// This list excludes the Rust keywords *self*, *Self*, and *super*
+// because they are not allowed to be raw identifiers, and *loop*
+// because it's used something like a keyword in the template
+// language.
+static USE_RAW: [(&str, &str); 47] = [
+    ("as", "r#as"),
+    ("break", "r#break"),
+    ("const", "r#const"),
+    ("continue", "r#continue"),
+    ("crate", "r#crate"),
+    ("else", "r#else"),
+    ("enum", "r#enum"),
+    ("extern", "r#extern"),
+    ("false", "r#false"),
+    ("fn", "r#fn"),
+    ("for", "r#for"),
+    ("if", "r#if"),
+    ("impl", "r#impl"),
+    ("in", "r#in"),
+    ("let", "r#let"),
+    ("match", "r#match"),
+    ("mod", "r#mod"),
+    ("move", "r#move"),
+    ("mut", "r#mut"),
+    ("pub", "r#pub"),
+    ("ref", "r#ref"),
+    ("return", "r#return"),
+    ("static", "r#static"),
+    ("struct", "r#struct"),
+    ("trait", "r#trait"),
+    ("true", "r#true"),
+    ("type", "r#type"),
+    ("unsafe", "r#unsafe"),
+    ("use", "r#use"),
+    ("where", "r#where"),
+    ("while", "r#while"),
+    ("async", "r#async"),
+    ("await", "r#await"),
+    ("dyn", "r#dyn"),
+    ("abstract", "r#abstract"),
+    ("become", "r#become"),
+    ("box", "r#box"),
+    ("do", "r#do"),
+    ("final", "r#final"),
+    ("macro", "r#macro"),
+    ("override", "r#override"),
+    ("priv", "r#priv"),
+    ("typeof", "r#typeof"),
+    ("unsized", "r#unsized"),
+    ("virtual", "r#virtual"),
+    ("yield", "r#yield"),
+    ("try", "r#try"),
+];
+
+fn normalize_identifier(ident: &str) -> &str {
+    if let Some(word) = USE_RAW.iter().find(|x| x.0 == ident) {
+        word.1
+    } else {
+        ident
+    }
+}
diff --git a/third_party/rust/askama_shared/src/helpers/mod.rs b/third_party/rust/askama_shared/src/helpers/mod.rs
new file mode 100644
index 0000000000..79a1ada206
--- /dev/null
+++ b/third_party/rust/askama_shared/src/helpers/mod.rs
@@ -0,0 +1,48 @@
+use std::iter::{Enumerate, Peekable};
+
+pub struct TemplateLoop<I>
+where
+    I: Iterator,
+{
+    iter: Peekable<Enumerate<I>>,
+}
+
+impl<I> TemplateLoop<I>
+where
+    I: Iterator,
+{
+    #[inline]
+    pub fn new(iter: I) -> Self {
+        TemplateLoop {
+            iter: iter.enumerate().peekable(),
+        }
+    }
+}
+
+impl<I> Iterator for TemplateLoop<I>
+where
+    I: Iterator,
+{
+    type Item = (<I as Iterator>::Item, LoopItem);
+
+    #[inline]
+    fn next(&mut self) -> Option<(<I as Iterator>::Item, LoopItem)> {
+        self.iter.next().map(|(index, item)| {
+            (
+                item,
+                LoopItem {
+                    index,
+                    first: index == 0,
+                    last: self.iter.peek().is_none(),
+                },
+            )
+        })
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct LoopItem {
+    pub index: usize,
+    pub first: bool,
+    pub last: bool,
+}
diff --git a/third_party/rust/askama_shared/src/heritage.rs b/third_party/rust/askama_shared/src/heritage.rs
new file mode 100644
index 0000000000..8dd97e2e69
--- /dev/null
+++ b/third_party/rust/askama_shared/src/heritage.rs
@@ -0,0 +1,125 @@
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+
+use crate::parser::{Expr, Loop, Macro, Node};
+use crate::{CompileError, Config};
+
+pub struct Heritage<'a> {
+    pub root: &'a Context<'a>,
+    pub blocks: BlockAncestry<'a>,
+}
+
+impl Heritage<'_> {
+    pub fn new<'n, S: std::hash::BuildHasher>(
+        mut ctx: &'n Context<'n>,
+        contexts: &'n HashMap<&'n Path, Context<'n>, S>,
+    ) -> Heritage<'n> {
+        let mut blocks: BlockAncestry<'n> = ctx
+            .blocks
+            .iter()
+            .map(|(name, def)| (*name, vec![(ctx, *def)]))
+            .collect();
+
+        while let Some(ref path) = ctx.extends {
+            ctx = &contexts[path.as_path()];
+            for (name, def) in &ctx.blocks {
+                blocks.entry(name).or_insert_with(Vec::new).push((ctx, def));
+            }
+        }
+
+        Heritage { root: ctx, blocks }
+    }
+}
+
+type BlockAncestry<'a> = HashMap<&'a str, Vec<(&'a Context<'a>, &'a Node<'a>)>>;
+
+pub struct Context<'a> {
+    pub nodes: &'a [Node<'a>],
+    pub extends: Option<PathBuf>,
+    pub blocks: HashMap<&'a str, &'a Node<'a>>,
+    pub macros: HashMap<&'a str, &'a Macro<'a>>,
+    pub imports: HashMap<&'a str, PathBuf>,
+}
+
+impl Context<'_> {
+    pub fn new<'n>(
+        config: &Config<'_>,
+        path: &Path,
+        nodes: &'n [Node<'n>],
+    ) -> Result<Context<'n>, CompileError> {
+        let mut extends = None;
+        let mut blocks = Vec::new();
+        let mut macros = HashMap::new();
+        let mut imports = HashMap::new();
+        let mut nested = vec![nodes];
+        let mut top = true;
+
+        while let Some(nodes) = nested.pop() {
+            for n in nodes {
+                match n {
+                    Node::Extends(Expr::StrLit(extends_path)) if top => match extends {
+                        Some(_) => return Err("multiple extend blocks found".into()),
+                        None => {
+                            extends = Some(config.find_template(extends_path, Some(path))?);
+                        }
+                    },
+                    Node::Macro(name, m) if top => {
+                        macros.insert(*name, m);
+                    }
+                    Node::Import(_, import_path, scope) if top => {
+                        let path = config.find_template(import_path, Some(path))?;
+                        imports.insert(*scope, path);
+                    }
+                    Node::Extends(_) | Node::Macro(_, _) | Node::Import(_, _, _) if !top => {
+                        return Err(
+                            "extends, macro or import blocks not allowed below top level".into(),
+                        );
+                    }
+                    def @ Node::BlockDef(_, _, _, _) => {
+                        blocks.push(def);
+                        if let Node::BlockDef(_, _, nodes, _) = def {
+                            nested.push(nodes);
+                        }
+                    }
+                    Node::Cond(branches, _) => {
+                        for (_, _, nodes) in branches {
+                            nested.push(nodes);
+                        }
+                    }
+                    Node::Loop(Loop {
+                        body, else_block, ..
+                    }) => {
+                        nested.push(body);
+                        nested.push(else_block);
+                    }
+                    Node::Match(_, _, arms, _) => {
+                        for (_, _, arm) in arms {
+                            nested.push(arm);
+                        }
+                    }
+                    _ => {}
+                }
+            }
+            top = false;
+        }
+
+        let blocks: HashMap<_, _> = blocks
+            .iter()
+            .map(|def| {
+                if let Node::BlockDef(_, name, _, _) = def {
+                    (*name, *def)
+                } else {
+                    unreachable!()
+                }
+            })
+            .collect();
+
+        Ok(Context {
+            nodes,
+            extends,
+            blocks,
+            macros,
+            imports,
+        })
+    }
+}
diff --git a/third_party/rust/askama_shared/src/input.rs b/third_party/rust/askama_shared/src/input.rs
new file mode 100644
index 0000000000..f7eac2336a
--- /dev/null
+++ b/third_party/rust/askama_shared/src/input.rs
@@ -0,0 +1,336 @@
+use crate::{CompileError, Config, Syntax};
+
+use std::path::{Path, PathBuf};
+use std::str::FromStr;
+
+use mime::Mime;
+use quote::ToTokens;
+
+pub struct TemplateInput<'a> {
+    pub ast: &'a syn::DeriveInput,
+    pub config: &'a Config<'a>,
+    pub syntax: &'a Syntax<'a>,
+    pub source: Source,
+    pub print: Print,
+    pub escaper: &'a str,
+    pub ext: Option<String>,
+    pub mime_type: String,
+    pub parent: Option<&'a syn::Type>,
+    pub path: PathBuf,
+}
+
+impl TemplateInput<'_> {
+    /// Extract the template metadata from the `DeriveInput` structure. This
+    /// mostly recovers the data for the `TemplateInput` fields from the
+    /// `template()` attribute list fields; it also finds the of the `_parent`
+    /// field, if any.
+    pub fn new<'n>(
+        ast: &'n syn::DeriveInput,
+        config: &'n Config<'_>,
+    ) -> Result<TemplateInput<'n>, CompileError> {
+        // Check that an attribute called `template()` exists once and that it is
+        // the proper type (list).
+        let mut template_args = None;
+        for attr in &ast.attrs {
+            let ident = match attr.path.get_ident() {
+                Some(ident) => ident,
+                None => continue,
+            };
+
+            if ident == "template" {
+                if template_args.is_some() {
+                    return Err("duplicated 'template' attribute".into());
+                }
+
+                match attr.parse_meta() {
+                    Ok(syn::Meta::List(syn::MetaList { nested, .. })) => {
+                        template_args = Some(nested);
+                    }
+                    Ok(_) => return Err("'template' attribute must be a list".into()),
+                    Err(e) => return Err(format!("unable to parse attribute: {}", e).into()),
+                }
+            }
+        }
+        let template_args =
+            template_args.ok_or_else(|| CompileError::from("no attribute 'template' found"))?;
+
+        // Loop over the meta attributes and find everything that we
+        // understand. Return a CompileError if something is not right.
+        // `source` contains an enum that can represent `path` or `source`.
+        let mut source = None;
+        let mut print = Print::None;
+        let mut escaping = None;
+        let mut ext = None;
+        let mut syntax = None;
+        for item in template_args {
+            let pair = match item {
+                syn::NestedMeta::Meta(syn::Meta::NameValue(ref pair)) => pair,
+                _ => {
+                    return Err(format!(
+                        "unsupported attribute argument {:?}",
+                        item.to_token_stream()
+                    )
+                    .into())
+                }
+            };
+            let ident = match pair.path.get_ident() {
+                Some(ident) => ident,
+                None => unreachable!("not possible in syn::Meta::NameValue(…)"),
+            };
+
+            if ident == "path" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    if source.is_some() {
+                        return Err("must specify 'source' or 'path', not both".into());
+                    }
+                    source = Some(Source::Path(s.value()));
+                } else {
+                    return Err("template path must be string literal".into());
+                }
+            } else if ident == "source" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    if source.is_some() {
+                        return Err("must specify 'source' or 'path', not both".into());
+                    }
+                    source = Some(Source::Source(s.value()));
+                } else {
+                    return Err("template source must be string literal".into());
+                }
+            } else if ident == "print" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    print = s.value().parse()?;
+                } else {
+                    return Err("print value must be string literal".into());
+                }
+            } else if ident == "escape" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    escaping = Some(s.value());
+                } else {
+                    return Err("escape value must be string literal".into());
+                }
+            } else if ident == "ext" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    ext = Some(s.value());
+                } else {
+                    return Err("ext value must be string literal".into());
+                }
+            } else if ident == "syntax" {
+                if let syn::Lit::Str(ref s) = pair.lit {
+                    syntax = Some(s.value())
+                } else {
+                    return Err("syntax value must be string literal".into());
+                }
+            } else {
+                return Err(format!("unsupported attribute key {:?} found", ident).into());
+            }
+        }
+
+        // Validate the `source` and `ext` value together, since they are
+        // related. In case `source` was used instead of `path`, the value
+        // of `ext` is merged into a synthetic `path` value here.
+        let source = source.expect("template path or source not found in attributes");
+        let path = match (&source, &ext) {
+            (&Source::Path(ref path), _) => config.find_template(path, None)?,
+            (&Source::Source(_), Some(ext)) => PathBuf::from(format!("{}.{}", ast.ident, ext)),
+            (&Source::Source(_), None) => {
+                return Err("must include 'ext' attribute when using 'source' attribute".into())
+            }
+        };
+
+        // Check to see if a `_parent` field was defined on the context
+        // struct, and store the type for it for use in the code generator.
+        let parent = match ast.data {
+            syn::Data::Struct(syn::DataStruct {
+                fields: syn::Fields::Named(ref fields),
+                ..
+            }) => fields
+                .named
+                .iter()
+                .find(|f| f.ident.as_ref().filter(|name| *name == "_parent").is_some())
+                .map(|f| &f.ty),
+            _ => None,
+        };
+
+        if parent.is_some() {
+            eprint!(
+                "   --> in struct {}\n   = use of deprecated field '_parent'\n",
+                ast.ident
+            );
+        }
+
+        // Validate syntax
+        let syntax = syntax.map_or_else(
+            || Ok(config.syntaxes.get(config.default_syntax).unwrap()),
+            |s| {
+                config
+                    .syntaxes
+                    .get(&s)
+                    .ok_or_else(|| CompileError::from(format!("attribute syntax {} not exist", s)))
+            },
+        )?;
+
+        // Match extension against defined output formats
+
+        let escaping = escaping.unwrap_or_else(|| {
+            path.extension()
+                .map(|s| s.to_str().unwrap())
+                .unwrap_or("")
+                .to_string()
+        });
+
+        let mut escaper = None;
+        for (extensions, path) in &config.escapers {
+            if extensions.contains(&escaping) {
+                escaper = Some(path);
+                break;
+            }
+        }
+
+        let escaper = escaper.ok_or_else(|| {
+            CompileError::from(format!("no escaper defined for extension '{}'", escaping))
+        })?;
+
+        let mime_type =
+            extension_to_mime_type(ext_default_to_path(ext.as_deref(), &path).unwrap_or("txt"))
+                .to_string();
+
+        Ok(TemplateInput {
+            ast,
+            config,
+            syntax,
+            source,
+            print,
+            escaper,
+            ext,
+            mime_type,
+            parent,
+            path,
+        })
+    }
+
+    #[inline]
+    pub fn extension(&self) -> Option<&str> {
+        ext_default_to_path(self.ext.as_deref(), &self.path)
+    }
+}
+
+#[inline]
+pub fn ext_default_to_path<'a>(ext: Option<&'a str>, path: &'a Path) -> Option<&'a str> {
+    ext.or_else(|| extension(path))
+}
+
+fn extension(path: &Path) -> Option<&str> {
+    let ext = path.extension().map(|s| s.to_str().unwrap())?;
+
+    const JINJA_EXTENSIONS: [&str; 3] = ["j2", "jinja", "jinja2"];
+    if JINJA_EXTENSIONS.contains(&ext) {
+        Path::new(path.file_stem().unwrap())
+            .extension()
+            .map(|s| s.to_str().unwrap())
+            .or(Some(ext))
+    } else {
+        Some(ext)
+    }
+}
+
+pub enum Source {
+    Path(String),
+    Source(String),
+}
+
+#[derive(PartialEq)]
+pub enum Print {
+    All,
+    Ast,
+    Code,
+    None,
+}
+
+impl FromStr for Print {
+    type Err = CompileError;
+
+    fn from_str(s: &str) -> Result<Print, Self::Err> {
+        use self::Print::*;
+        Ok(match s {
+            "all" => All,
+            "ast" => Ast,
+            "code" => Code,
+            "none" => None,
+            v => return Err(format!("invalid value for print option: {}", v,).into()),
+        })
+    }
+}
+
+#[doc(hidden)]
+pub fn extension_to_mime_type(ext: &str) -> Mime {
+    let basic_type = mime_guess::from_ext(ext).first_or_octet_stream();
+    for (simple, utf_8) in &TEXT_TYPES {
+        if &basic_type == simple {
+            return utf_8.clone();
+        }
+    }
+    basic_type
+}
+
+const TEXT_TYPES: [(Mime, Mime); 6] = [
+    (mime::TEXT_PLAIN, mime::TEXT_PLAIN_UTF_8),
+    (mime::TEXT_HTML, mime::TEXT_HTML_UTF_8),
+    (mime::TEXT_CSS, mime::TEXT_CSS_UTF_8),
+    (mime::TEXT_CSV, mime::TEXT_CSV_UTF_8),
+    (
+        mime::TEXT_TAB_SEPARATED_VALUES,
+        mime::TEXT_TAB_SEPARATED_VALUES_UTF_8,
+    ),
+    (
+        mime::APPLICATION_JAVASCRIPT,
+        mime::APPLICATION_JAVASCRIPT_UTF_8,
+    ),
+];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_ext() {
+        assert_eq!(extension(Path::new("foo-bar.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo-bar.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.unknown")), Some("unknown"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo/bar/baz.unknown")), Some("unknown"));
+    }
+
+    #[test]
+    fn test_double_ext() {
+        assert_eq!(extension(Path::new("foo-bar.html.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo-bar.txt.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.txt.unknown")), Some("unknown"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.html.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.html")), Some("html"));
+        assert_eq!(
+            extension(Path::new("foo/bar/baz.txt.unknown")),
+            Some("unknown")
+        );
+    }
+
+    #[test]
+    fn test_skip_jinja_ext() {
+        assert_eq!(extension(Path::new("foo-bar.html.j2")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.html.jinja")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.html.jinja2")), Some("html"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.j2")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.jinja")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.jinja2")), Some("txt"));
+    }
+
+    #[test]
+    fn test_only_jinja_ext() {
+        assert_eq!(extension(Path::new("foo-bar.j2")), Some("j2"));
+        assert_eq!(extension(Path::new("foo-bar.jinja")), Some("jinja"));
+        assert_eq!(extension(Path::new("foo-bar.jinja2")), Some("jinja2"));
+    }
+}
diff --git a/third_party/rust/askama_shared/src/lib.rs b/third_party/rust/askama_shared/src/lib.rs
new file mode 100644
index 0000000000..994662c5f4
--- /dev/null
+++ b/third_party/rust/askama_shared/src/lib.rs
@@ -0,0 +1,538 @@
+#![cfg_attr(feature = "cargo-clippy", allow(unused_parens))]
+#![forbid(unsafe_code)]
+#![deny(elided_lifetimes_in_paths)]
+#![deny(unreachable_pub)]
+
+use std::borrow::Cow;
+use std::collections::{BTreeMap, HashSet};
+use std::convert::TryFrom;
+use std::path::{Path, PathBuf};
+use std::{env, fmt, fs};
+
+use proc_macro2::{Span, TokenStream};
+#[cfg(feature = "serde")]
+use serde::Deserialize;
+
+pub use crate::input::extension_to_mime_type;
+pub use askama_escape::MarkupDisplay;
+
+mod error;
+pub use crate::error::{Error, Result};
+pub mod filters;
+#[doc(hidden)]
+pub mod generator;
+pub mod helpers;
+#[doc(hidden)]
+pub mod heritage;
+#[doc(hidden)]
+pub mod input;
+#[doc(hidden)]
+pub mod parser;
+
+#[derive(Debug)]
+pub struct Config<'a> {
+    pub dirs: Vec<PathBuf>,
+    pub syntaxes: BTreeMap<String, Syntax<'a>>,
+    pub default_syntax: &'a str,
+    pub escapers: Vec<(HashSet<String>, String)>,
+}
+
+impl Config<'_> {
+    pub fn new(s: &str) -> std::result::Result<Config<'_>, CompileError> {
+        let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        let default_dirs = vec![root.join("templates")];
+
+        let mut syntaxes = BTreeMap::new();
+        syntaxes.insert(DEFAULT_SYNTAX_NAME.to_string(), Syntax::default());
+
+        let raw = if s.is_empty() {
+            RawConfig::default()
+        } else {
+            RawConfig::from_toml_str(s)?
+        };
+
+        let (dirs, default_syntax) = match raw.general {
+            Some(General {
+                dirs,
+                default_syntax,
+            }) => (
+                dirs.map_or(default_dirs, |v| {
+                    v.into_iter().map(|dir| root.join(dir)).collect()
+                }),
+                default_syntax.unwrap_or(DEFAULT_SYNTAX_NAME),
+            ),
+            None => (default_dirs, DEFAULT_SYNTAX_NAME),
+        };
+
+        if let Some(raw_syntaxes) = raw.syntax {
+            for raw_s in raw_syntaxes {
+                let name = raw_s.name;
+
+                if syntaxes
+                    .insert(name.to_string(), Syntax::try_from(raw_s)?)
+                    .is_some()
+                {
+                    return Err(format!("syntax \"{}\" is already defined", name).into());
+                }
+            }
+        }
+
+        if !syntaxes.contains_key(default_syntax) {
+            return Err(format!("default syntax \"{}\" not found", default_syntax).into());
+        }
+
+        let mut escapers = Vec::new();
+        if let Some(configured) = raw.escaper {
+            for escaper in configured {
+                escapers.push((
+                    escaper
+                        .extensions
+                        .iter()
+                        .map(|ext| (*ext).to_string())
+                        .collect(),
+                    escaper.path.to_string(),
+                ));
+            }
+        }
+        for (extensions, path) in DEFAULT_ESCAPERS {
+            escapers.push((str_set(extensions), (*path).to_string()));
+        }
+
+        Ok(Config {
+            dirs,
+            syntaxes,
+            default_syntax,
+            escapers,
+        })
+    }
+
+    pub fn find_template(
+        &self,
+        path: &str,
+        start_at: Option<&Path>,
+    ) -> std::result::Result<PathBuf, CompileError> {
+        if let Some(root) = start_at {
+            let relative = root.with_file_name(path);
+            if relative.exists() {
+                return Ok(relative);
+            }
+        }
+
+        for dir in &self.dirs {
+            let rooted = dir.join(path);
+            if rooted.exists() {
+                return Ok(rooted);
+            }
+        }
+
+        Err(format!(
+            "template {:?} not found in directories {:?}",
+            path, self.dirs
+        )
+        .into())
+    }
+}
+
+#[derive(Debug)]
+pub struct Syntax<'a> {
+    pub block_start: &'a str,
+    pub block_end: &'a str,
+    pub expr_start: &'a str,
+    pub expr_end: &'a str,
+    pub comment_start: &'a str,
+    pub comment_end: &'a str,
+}
+
+impl Default for Syntax<'_> {
+    fn default() -> Self {
+        Self {
+            block_start: "{%",
+            block_end: "%}",
+            expr_start: "{{",
+            expr_end: "}}",
+            comment_start: "{#",
+            comment_end: "#}",
+        }
+    }
+}
+
+impl<'a> TryFrom<RawSyntax<'a>> for Syntax<'a> {
+    type Error = CompileError;
+
+    fn try_from(raw: RawSyntax<'a>) -> std::result::Result<Self, Self::Error> {
+        let default = Self::default();
+        let syntax = Self {
+            block_start: raw.block_start.unwrap_or(default.block_start),
+            block_end: raw.block_end.unwrap_or(default.block_end),
+            expr_start: raw.expr_start.unwrap_or(default.expr_start),
+            expr_end: raw.expr_end.unwrap_or(default.expr_end),
+            comment_start: raw.comment_start.unwrap_or(default.comment_start),
+            comment_end: raw.comment_end.unwrap_or(default.comment_end),
+        };
+
+        if syntax.block_start.len() != 2
+            || syntax.block_end.len() != 2
+            || syntax.expr_start.len() != 2
+            || syntax.expr_end.len() != 2
+            || syntax.comment_start.len() != 2
+            || syntax.comment_end.len() != 2
+        {
+            return Err("length of delimiters must be two".into());
+        }
+
+        let bs = syntax.block_start.as_bytes()[0];
+        let be = syntax.block_start.as_bytes()[1];
+        let cs = syntax.comment_start.as_bytes()[0];
+        let ce = syntax.comment_start.as_bytes()[1];
+        let es = syntax.block_start.as_bytes()[0];
+        let ee = syntax.block_start.as_bytes()[1];
+        if !((bs == cs && bs == es) || (be == ce && be == ee)) {
+            return Err(format!("bad delimiters block_start: {}, comment_start: {}, expr_start: {}, needs one of the two characters in common", syntax.block_start, syntax.comment_start, syntax.expr_start).into());
+        }
+
+        Ok(syntax)
+    }
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+#[derive(Default)]
+struct RawConfig<'d> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    general: Option<General<'d>>,
+    syntax: Option<Vec<RawSyntax<'d>>>,
+    escaper: Option<Vec<RawEscaper<'d>>>,
+}
+
+impl RawConfig<'_> {
+    #[cfg(feature = "config")]
+    fn from_toml_str(s: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+        toml::from_str(s).map_err(|e| format!("invalid TOML in {}: {}", CONFIG_FILE_NAME, e).into())
+    }
+
+    #[cfg(not(feature = "config"))]
+    fn from_toml_str(_: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+        Err("TOML support not available".into())
+    }
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct General<'a> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    dirs: Option<Vec<&'a str>>,
+    default_syntax: Option<&'a str>,
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct RawSyntax<'a> {
+    name: &'a str,
+    block_start: Option<&'a str>,
+    block_end: Option<&'a str>,
+    expr_start: Option<&'a str>,
+    expr_end: Option<&'a str>,
+    comment_start: Option<&'a str>,
+    comment_end: Option<&'a str>,
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct RawEscaper<'a> {
+    path: &'a str,
+    extensions: Vec<&'a str>,
+}
+
+pub fn read_config_file() -> std::result::Result<String, CompileError> {
+    let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+    let filename = root.join(CONFIG_FILE_NAME);
+    if filename.exists() {
+        fs::read_to_string(&filename)
+            .map_err(|_| format!("unable to read {:?}", filename.to_str().unwrap()).into())
+    } else {
+        Ok("".to_string())
+    }
+}
+
+fn str_set<T>(vals: &[T]) -> HashSet<String>
+where
+    T: ToString,
+{
+    vals.iter().map(|s| s.to_string()).collect()
+}
+
+#[allow(clippy::match_wild_err_arm)]
+pub fn get_template_source(tpl_path: &Path) -> std::result::Result<String, CompileError> {
+    match fs::read_to_string(tpl_path) {
+        Err(_) => Err(format!(
+            "unable to open template file '{}'",
+            tpl_path.to_str().unwrap()
+        )
+        .into()),
+        Ok(mut source) => {
+            if source.ends_with('\n') {
+                let _ = source.pop();
+            }
+            Ok(source)
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct Integrations {
+    pub actix: bool,
+    pub axum: bool,
+    pub gotham: bool,
+    pub mendes: bool,
+    pub rocket: bool,
+    pub tide: bool,
+    pub warp: bool,
+}
+
+static CONFIG_FILE_NAME: &str = "askama.toml";
+static DEFAULT_SYNTAX_NAME: &str = "default";
+static DEFAULT_ESCAPERS: &[(&[&str], &str)] = &[
+    (&["html", "htm", "xml"], "::askama::Html"),
+    (&["md", "none", "txt", "yml", ""], "::askama::Text"),
+    (&["j2", "jinja", "jinja2"], "::askama::Html"),
+];
+
+#[derive(Debug, Clone)]
+pub struct CompileError {
+    msg: Cow<'static, str>,
+    span: Span,
+}
+
+impl CompileError {
+    pub fn new<S: Into<Cow<'static, str>>>(s: S, span: Span) -> Self {
+        Self {
+            msg: s.into(),
+            span,
+        }
+    }
+
+    pub fn to_compile_error(self) -> TokenStream {
+        syn::Error::new(self.span, self.msg).to_compile_error()
+    }
+}
+
+impl std::error::Error for CompileError {}
+
+impl fmt::Display for CompileError {
+    #[inline]
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.write_str(&self.msg)
+    }
+}
+
+impl From<&'static str> for CompileError {
+    #[inline]
+    fn from(s: &'static str) -> Self {
+        Self::new(s, Span::call_site())
+    }
+}
+
+impl From<String> for CompileError {
+    #[inline]
+    fn from(s: String) -> Self {
+        Self::new(s, Span::call_site())
+    }
+}
+
+#[cfg(test)]
+#[allow(clippy::blacklisted_name)]
+mod tests {
+    use super::*;
+    use std::env;
+    use std::path::{Path, PathBuf};
+
+    #[test]
+    fn get_source() {
+        let path = Config::new("")
+            .and_then(|config| config.find_template("b.html", None))
+            .unwrap();
+        assert_eq!(get_template_source(&path).unwrap(), "bar");
+    }
+
+    #[test]
+    fn test_default_config() {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("templates");
+        let config = Config::new("").unwrap();
+        assert_eq!(config.dirs, vec![root]);
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn test_config_dirs() {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("tpl");
+        let config = Config::new("[general]\ndirs = [\"tpl\"]").unwrap();
+        assert_eq!(config.dirs, vec![root]);
+    }
+
+    fn assert_eq_rooted(actual: &Path, expected: &str) {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("templates");
+        let mut inner = PathBuf::new();
+        inner.push(expected);
+        assert_eq!(actual.strip_prefix(root).unwrap(), inner);
+    }
+
+    #[test]
+    fn find_absolute() {
+        let config = Config::new("").unwrap();
+        let root = config.find_template("a.html", None).unwrap();
+        let path = config.find_template("sub/b.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/b.html");
+    }
+
+    #[test]
+    #[should_panic]
+    fn find_relative_nonexistent() {
+        let config = Config::new("").unwrap();
+        let root = config.find_template("a.html", None).unwrap();
+        config.find_template("c.html", Some(&root)).unwrap();
+    }
+
+    #[test]
+    fn find_relative() {
+        let config = Config::new("").unwrap();
+        let root = config.find_template("sub/b.html", None).unwrap();
+        let path = config.find_template("c.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/c.html");
+    }
+
+    #[test]
+    fn find_relative_sub() {
+        let config = Config::new("").unwrap();
+        let root = config.find_template("sub/b.html", None).unwrap();
+        let path = config.find_template("sub1/d.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/sub1/d.html");
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn add_syntax() {
+        let raw_config = r#"
+        [general]
+        default_syntax = "foo"
+
+        [[syntax]]
+        name = "foo"
+        block_start = "{<"
+
+        [[syntax]]
+        name = "bar"
+        expr_start = "{!"
+        "#;
+
+        let default_syntax = Syntax::default();
+        let config = Config::new(raw_config).unwrap();
+        assert_eq!(config.default_syntax, "foo");
+
+        let foo = config.syntaxes.get("foo").unwrap();
+        assert_eq!(foo.block_start, "{<");
+        assert_eq!(foo.block_end, default_syntax.block_end);
+        assert_eq!(foo.expr_start, default_syntax.expr_start);
+        assert_eq!(foo.expr_end, default_syntax.expr_end);
+        assert_eq!(foo.comment_start, default_syntax.comment_start);
+        assert_eq!(foo.comment_end, default_syntax.comment_end);
+
+        let bar = config.syntaxes.get("bar").unwrap();
+        assert_eq!(bar.block_start, default_syntax.block_start);
+        assert_eq!(bar.block_end, default_syntax.block_end);
+        assert_eq!(bar.expr_start, "{!");
+        assert_eq!(bar.expr_end, default_syntax.expr_end);
+        assert_eq!(bar.comment_start, default_syntax.comment_start);
+        assert_eq!(bar.comment_end, default_syntax.comment_end);
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn add_syntax_two() {
+        let raw_config = r#"
+        syntax = [{ name = "foo", block_start = "{<" },
+                  { name = "bar", expr_start = "{!" } ]
+
+        [general]
+        default_syntax = "foo"
+        "#;
+
+        let default_syntax = Syntax::default();
+        let config = Config::new(raw_config).unwrap();
+        assert_eq!(config.default_syntax, "foo");
+
+        let foo = config.syntaxes.get("foo").unwrap();
+        assert_eq!(foo.block_start, "{<");
+        assert_eq!(foo.block_end, default_syntax.block_end);
+        assert_eq!(foo.expr_start, default_syntax.expr_start);
+        assert_eq!(foo.expr_end, default_syntax.expr_end);
+        assert_eq!(foo.comment_start, default_syntax.comment_start);
+        assert_eq!(foo.comment_end, default_syntax.comment_end);
+
+        let bar = config.syntaxes.get("bar").unwrap();
+        assert_eq!(bar.block_start, default_syntax.block_start);
+        assert_eq!(bar.block_end, default_syntax.block_end);
+        assert_eq!(bar.expr_start, "{!");
+        assert_eq!(bar.expr_end, default_syntax.expr_end);
+        assert_eq!(bar.comment_start, default_syntax.comment_start);
+        assert_eq!(bar.comment_end, default_syntax.comment_end);
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn use_default_at_syntax_name() {
+        let raw_config = r#"
+        syntax = [{ name = "default" }]
+        "#;
+
+        let _config = Config::new(raw_config).unwrap();
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn duplicated_syntax_name_on_list() {
+        let raw_config = r#"
+        syntax = [{ name = "foo", block_start = "~<" },
+                  { name = "foo", block_start = "%%" } ]
+        "#;
+
+        let _config = Config::new(raw_config).unwrap();
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn is_not_exist_default_syntax() {
+        let raw_config = r#"
+        [general]
+        default_syntax = "foo"
+        "#;
+
+        let _config = Config::new(raw_config).unwrap();
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn escape_modes() {
+        let config = Config::new(
+            r#"
+            [[escaper]]
+            path = "::askama::Js"
+            extensions = ["js"]
+        "#,
+        )
+        .unwrap();
+        assert_eq!(
+            config.escapers,
+            vec![
+                (str_set(&["js"]), "::askama::Js".into()),
+                (str_set(&["html", "htm", "xml"]), "::askama::Html".into()),
+                (
+                    str_set(&["md", "none", "txt", "yml", ""]),
+                    "::askama::Text".into()
+                ),
+                (str_set(&["j2", "jinja", "jinja2"]), "::askama::Html".into()),
+            ]
+        );
+    }
+}
diff --git a/third_party/rust/askama_shared/src/parser.rs b/third_party/rust/askama_shared/src/parser.rs
new file mode 100644
index 0000000000..900e71ad7f
--- /dev/null
+++ b/third_party/rust/askama_shared/src/parser.rs
@@ -0,0 +1,1799 @@
+use std::cell::Cell;
+use std::str;
+
+use nom::branch::alt;
+use nom::bytes::complete::{escaped, is_not, tag, take_till, take_until};
+use nom::character::complete::{anychar, char, digit1};
+use nom::combinator::{complete, consumed, cut, eof, map, not, opt, peek, recognize, value};
+use nom::error::{Error, ErrorKind};
+use nom::multi::{fold_many0, many0, many1, separated_list0, separated_list1};
+use nom::sequence::{delimited, pair, preceded, terminated, tuple};
+use nom::{self, error_position, AsChar, IResult, InputTakeAtPosition};
+
+use crate::{CompileError, Syntax};
+
+#[derive(Debug, PartialEq)]
+pub enum Node<'a> {
+    Lit(&'a str, &'a str, &'a str),
+    Comment(Ws),
+    Expr(Ws, Expr<'a>),
+    Call(Ws, Option<&'a str>, &'a str, Vec<Expr<'a>>),
+    LetDecl(Ws, Target<'a>),
+    Let(Ws, Target<'a>, Expr<'a>),
+    Cond(Vec<Cond<'a>>, Ws),
+    Match(Ws, Expr<'a>, Vec<When<'a>>, Ws),
+    Loop(Loop<'a>),
+    Extends(Expr<'a>),
+    BlockDef(Ws, &'a str, Vec<Node<'a>>, Ws),
+    Include(Ws, &'a str),
+    Import(Ws, &'a str, &'a str),
+    Macro(&'a str, Macro<'a>),
+    Raw(Ws, &'a str, &'a str, &'a str, Ws),
+    Break(Ws),
+    Continue(Ws),
+}
+
+#[derive(Debug, PartialEq)]
+pub struct Loop<'a> {
+    pub ws1: Ws,
+    pub var: Target<'a>,
+    pub iter: Expr<'a>,
+    pub cond: Option<Expr<'a>>,
+    pub body: Vec<Node<'a>>,
+    pub ws2: Ws,
+    pub else_block: Vec<Node<'a>>,
+    pub ws3: Ws,
+}
+
+#[derive(Debug, PartialEq)]
+pub enum Expr<'a> {
+    BoolLit(&'a str),
+    NumLit(&'a str),
+    StrLit(&'a str),
+    CharLit(&'a str),
+    Var(&'a str),
+    Path(Vec<&'a str>),
+    Array(Vec<Expr<'a>>),
+    Attr(Box<Expr<'a>>, &'a str),
+    Index(Box<Expr<'a>>, Box<Expr<'a>>),
+    Filter(&'a str, Vec<Expr<'a>>),
+    Unary(&'a str, Box<Expr<'a>>),
+    BinOp(&'a str, Box<Expr<'a>>, Box<Expr<'a>>),
+    Range(&'a str, Option<Box<Expr<'a>>>, Option<Box<Expr<'a>>>),
+    Group(Box<Expr<'a>>),
+    Tuple(Vec<Expr<'a>>),
+    Call(Box<Expr<'a>>, Vec<Expr<'a>>),
+    RustMacro(&'a str, &'a str),
+    Try(Box<Expr<'a>>),
+}
+
+impl Expr<'_> {
+    /// Returns `true` if enough assumptions can be made,
+    /// to determine that `self` is copyable.
+    pub fn is_copyable(&self) -> bool {
+        self.is_copyable_within_op(false)
+    }
+
+    fn is_copyable_within_op(&self, within_op: bool) -> bool {
+        use Expr::*;
+        match self {
+            BoolLit(_) | NumLit(_) | StrLit(_) | CharLit(_) => true,
+            Unary(.., expr) => expr.is_copyable_within_op(true),
+            BinOp(_, lhs, rhs) => {
+                lhs.is_copyable_within_op(true) && rhs.is_copyable_within_op(true)
+            }
+            Range(..) => true,
+            // The result of a call likely doesn't need to be borrowed,
+            // as in that case the call is more likely to return a
+            // reference in the first place then.
+            Call(..) | Path(..) => true,
+            // If the `expr` is within a `Unary` or `BinOp` then
+            // an assumption can be made that the operand is copy.
+            // If not, then the value is moved and adding `.clone()`
+            // will solve that issue. However, if the operand is
+            // implicitly borrowed, then it's likely not even possible
+            // to get the template to compile.
+            _ => within_op && self.is_attr_self(),
+        }
+    }
+
+    /// Returns `true` if this is an `Attr` where the `obj` is `"self"`.
+    pub fn is_attr_self(&self) -> bool {
+        match self {
+            Expr::Attr(obj, _) if matches!(obj.as_ref(), Expr::Var("self")) => true,
+            Expr::Attr(obj, _) if matches!(obj.as_ref(), Expr::Attr(..)) => obj.is_attr_self(),
+            _ => false,
+        }
+    }
+}
+
+pub type When<'a> = (Ws, Target<'a>, Vec<Node<'a>>);
+
+#[derive(Debug, PartialEq)]
+pub struct Macro<'a> {
+    pub ws1: Ws,
+    pub args: Vec<&'a str>,
+    pub nodes: Vec<Node<'a>>,
+    pub ws2: Ws,
+}
+
+#[derive(Debug, PartialEq)]
+pub enum Target<'a> {
+    Name(&'a str),
+    Tuple(Vec<&'a str>, Vec<Target<'a>>),
+    Struct(Vec<&'a str>, Vec<(&'a str, Target<'a>)>),
+    NumLit(&'a str),
+    StrLit(&'a str),
+    CharLit(&'a str),
+    BoolLit(&'a str),
+    Path(Vec<&'a str>),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Ws(pub bool, pub bool);
+
+pub type Cond<'a> = (Ws, Option<CondTest<'a>>, Vec<Node<'a>>);
+
+#[derive(Debug, PartialEq)]
+pub struct CondTest<'a> {
+    pub target: Option<Target<'a>>,
+    pub expr: Expr<'a>,
+}
+
+fn is_ws(c: char) -> bool {
+    matches!(c, ' ' | '\t' | '\r' | '\n')
+}
+
+fn not_ws(c: char) -> bool {
+    !is_ws(c)
+}
+
+fn ws<'a, O>(
+    inner: impl FnMut(&'a str) -> IResult<&'a str, O>,
+) -> impl FnMut(&'a str) -> IResult<&'a str, O> {
+    delimited(take_till(not_ws), inner, take_till(not_ws))
+}
+
+fn split_ws_parts(s: &str) -> Node<'_> {
+    let trimmed_start = s.trim_start_matches(is_ws);
+    let len_start = s.len() - trimmed_start.len();
+    let trimmed = trimmed_start.trim_end_matches(is_ws);
+    Node::Lit(&s[..len_start], trimmed, &trimmed_start[trimmed.len()..])
+}
+
+/// Skips input until `end` was found, but does not consume it.
+/// Returns tuple that would be returned when parsing `end`.
+fn skip_till<'a, O>(
+    end: impl FnMut(&'a str) -> IResult<&'a str, O>,
+) -> impl FnMut(&'a str) -> IResult<&'a str, (&'a str, O)> {
+    enum Next<O> {
+        IsEnd(O),
+        NotEnd(char),
+    }
+    let mut next = alt((map(end, Next::IsEnd), map(anychar, Next::NotEnd)));
+    move |start: &'a str| {
+        let mut i = start;
+        loop {
+            let (j, is_end) = next(i)?;
+            match is_end {
+                Next::IsEnd(lookahead) => return Ok((i, (j, lookahead))),
+                Next::NotEnd(_) => i = j,
+            }
+        }
+    }
+}
+
+struct State<'a> {
+    syntax: &'a Syntax<'a>,
+    loop_depth: Cell<usize>,
+}
+
+fn take_content<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let p_start = alt((
+        tag(s.syntax.block_start),
+        tag(s.syntax.comment_start),
+        tag(s.syntax.expr_start),
+    ));
+
+    let (i, _) = not(eof)(i)?;
+    let (i, content) = opt(recognize(skip_till(p_start)))(i)?;
+    let (i, content) = match content {
+        Some("") => {
+            // {block,comment,expr}_start follows immediately.
+            return Err(nom::Err::Error(error_position!(i, ErrorKind::TakeUntil)));
+        }
+        Some(content) => (i, content),
+        None => ("", i), // there is no {block,comment,expr}_start: take everything
+    };
+    Ok((i, split_ws_parts(content)))
+}
+
+fn identifier(input: &str) -> IResult<&str, &str> {
+    recognize(pair(identifier_start, opt(identifier_tail)))(input)
+}
+
+fn identifier_start(s: &str) -> IResult<&str, &str> {
+    s.split_at_position1_complete(
+        |c| !(c.is_alpha() || c == '_' || c >= '\u{0080}'),
+        nom::error::ErrorKind::Alpha,
+    )
+}
+
+fn identifier_tail(s: &str) -> IResult<&str, &str> {
+    s.split_at_position1_complete(
+        |c| !(c.is_alphanum() || c == '_' || c >= '\u{0080}'),
+        nom::error::ErrorKind::Alpha,
+    )
+}
+
+fn bool_lit(i: &str) -> IResult<&str, &str> {
+    alt((tag("false"), tag("true")))(i)
+}
+
+fn expr_bool_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(bool_lit, Expr::BoolLit)(i)
+}
+
+fn variant_bool_lit(i: &str) -> IResult<&str, Target<'_>> {
+    map(bool_lit, Target::BoolLit)(i)
+}
+
+fn num_lit(i: &str) -> IResult<&str, &str> {
+    recognize(pair(digit1, opt(pair(char('.'), digit1))))(i)
+}
+
+fn expr_num_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(num_lit, Expr::NumLit)(i)
+}
+
+fn expr_array_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    delimited(
+        ws(char('[')),
+        map(separated_list1(ws(char(',')), expr_any), Expr::Array),
+        ws(char(']')),
+    )(i)
+}
+
+fn variant_num_lit(i: &str) -> IResult<&str, Target<'_>> {
+    map(num_lit, Target::NumLit)(i)
+}
+
+fn str_lit(i: &str) -> IResult<&str, &str> {
+    let (i, s) = delimited(
+        char('"'),
+        opt(escaped(is_not("\\\""), '\\', anychar)),
+        char('"'),
+    )(i)?;
+    Ok((i, s.unwrap_or_default()))
+}
+
+fn expr_str_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(str_lit, Expr::StrLit)(i)
+}
+
+fn variant_str_lit(i: &str) -> IResult<&str, Target<'_>> {
+    map(str_lit, Target::StrLit)(i)
+}
+
+fn char_lit(i: &str) -> IResult<&str, &str> {
+    let (i, s) = delimited(
+        char('\''),
+        opt(escaped(is_not("\\\'"), '\\', anychar)),
+        char('\''),
+    )(i)?;
+    Ok((i, s.unwrap_or_default()))
+}
+
+fn expr_char_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(char_lit, Expr::CharLit)(i)
+}
+
+fn variant_char_lit(i: &str) -> IResult<&str, Target<'_>> {
+    map(char_lit, Target::CharLit)(i)
+}
+
+fn expr_var(i: &str) -> IResult<&str, Expr<'_>> {
+    map(identifier, Expr::Var)(i)
+}
+
+fn path(i: &str) -> IResult<&str, Vec<&str>> {
+    let root = opt(value("", ws(tag("::"))));
+    let tail = separated_list1(ws(tag("::")), identifier);
+
+    match tuple((root, identifier, ws(tag("::")), tail))(i) {
+        Ok((i, (root, start, _, rest))) => {
+            let mut path = Vec::new();
+            path.extend(root);
+            path.push(start);
+            path.extend(rest);
+            Ok((i, path))
+        }
+        Err(err) => {
+            if let Ok((i, name)) = identifier(i) {
+                // The returned identifier can be assumed to be path if:
+                // - Contains both a lowercase and uppercase character, i.e. a type name like `None`
+                // - Doesn't contain any lowercase characters, i.e. it's a constant
+                // In short, if it contains any uppercase characters it's a path.
+                if name.contains(char::is_uppercase) {
+                    return Ok((i, vec![name]));
+                }
+            }
+
+            // If `identifier()` fails then just return the original error
+            Err(err)
+        }
+    }
+}
+
+fn expr_path(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, path) = path(i)?;
+    Ok((i, Expr::Path(path)))
+}
+
+fn named_target(i: &str) -> IResult<&str, (&str, Target<'_>)> {
+    let (i, (src, target)) = pair(identifier, opt(preceded(ws(char(':')), target)))(i)?;
+    Ok((i, (src, target.unwrap_or(Target::Name(src)))))
+}
+
+fn variant_lit(i: &str) -> IResult<&str, Target<'_>> {
+    alt((
+        variant_str_lit,
+        variant_char_lit,
+        variant_num_lit,
+        variant_bool_lit,
+    ))(i)
+}
+
+fn target(i: &str) -> IResult<&str, Target<'_>> {
+    let mut opt_opening_paren = map(opt(ws(char('('))), |o| o.is_some());
+    let mut opt_closing_paren = map(opt(ws(char(')'))), |o| o.is_some());
+    let mut opt_opening_brace = map(opt(ws(char('{'))), |o| o.is_some());
+
+    let (i, lit) = opt(variant_lit)(i)?;
+    if let Some(lit) = lit {
+        return Ok((i, lit));
+    }
+
+    // match tuples and unused parentheses
+    let (i, target_is_tuple) = opt_opening_paren(i)?;
+    if target_is_tuple {
+        let (i, is_empty_tuple) = opt_closing_paren(i)?;
+        if is_empty_tuple {
+            return Ok((i, Target::Tuple(Vec::new(), Vec::new())));
+        }
+
+        let (i, first_target) = target(i)?;
+        let (i, is_unused_paren) = opt_closing_paren(i)?;
+        if is_unused_paren {
+            return Ok((i, first_target));
+        }
+
+        let mut targets = vec![first_target];
+        let (i, _) = cut(tuple((
+            fold_many0(
+                preceded(ws(char(',')), target),
+                || (),
+                |_, target| {
+                    targets.push(target);
+                },
+            ),
+            opt(ws(char(','))),
+            ws(cut(char(')'))),
+        )))(i)?;
+        return Ok((i, Target::Tuple(Vec::new(), targets)));
+    }
+
+    // match structs
+    let (i, path) = opt(path)(i)?;
+    if let Some(path) = path {
+        let i_before_matching_with = i;
+        let (i, _) = opt(ws(tag("with")))(i)?;
+
+        let (i, is_unnamed_struct) = opt_opening_paren(i)?;
+        if is_unnamed_struct {
+            let (i, targets) = alt((
+                map(char(')'), |_| Vec::new()),
+                terminated(
+                    cut(separated_list1(ws(char(',')), target)),
+                    pair(opt(ws(char(','))), ws(cut(char(')')))),
+                ),
+            ))(i)?;
+            return Ok((i, Target::Tuple(path, targets)));
+        }
+
+        let (i, is_named_struct) = opt_opening_brace(i)?;
+        if is_named_struct {
+            let (i, targets) = alt((
+                map(char('}'), |_| Vec::new()),
+                terminated(
+                    cut(separated_list1(ws(char(',')), named_target)),
+                    pair(opt(ws(char(','))), ws(cut(char('}')))),
+                ),
+            ))(i)?;
+            return Ok((i, Target::Struct(path, targets)));
+        }
+
+        return Ok((i_before_matching_with, Target::Path(path)));
+    }
+
+    // neither literal nor struct nor path
+    map(identifier, Target::Name)(i)
+}
+
+fn arguments(i: &str) -> IResult<&str, Vec<Expr<'_>>> {
+    delimited(
+        ws(char('(')),
+        separated_list0(char(','), ws(expr_any)),
+        ws(char(')')),
+    )(i)
+}
+
+fn macro_arguments(i: &str) -> IResult<&str, &str> {
+    delimited(char('('), recognize(nested_parenthesis), char(')'))(i)
+}
+
+fn nested_parenthesis(i: &str) -> IResult<&str, ()> {
+    let mut nested = 0;
+    let mut last = 0;
+    let mut in_str = false;
+    let mut escaped = false;
+
+    for (i, b) in i.chars().enumerate() {
+        if !(b == '(' || b == ')') || !in_str {
+            match b {
+                '(' => nested += 1,
+                ')' => {
+                    if nested == 0 {
+                        last = i;
+                        break;
+                    }
+                    nested -= 1;
+                }
+                '"' => {
+                    if in_str {
+                        if !escaped {
+                            in_str = false;
+                        }
+                    } else {
+                        in_str = true;
+                    }
+                }
+                '\\' => {
+                    escaped = !escaped;
+                }
+                _ => (),
+            }
+        }
+
+        if escaped && b != '\\' {
+            escaped = false;
+        }
+    }
+
+    if nested == 0 {
+        Ok((&i[last..], ()))
+    } else {
+        Err(nom::Err::Error(error_position!(
+            i,
+            ErrorKind::SeparatedNonEmptyList
+        )))
+    }
+}
+
+fn parameters(i: &str) -> IResult<&str, Vec<&str>> {
+    delimited(
+        ws(char('(')),
+        separated_list0(char(','), ws(identifier)),
+        ws(char(')')),
+    )(i)
+}
+
+fn expr_group(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, expr) = preceded(ws(char('(')), opt(expr_any))(i)?;
+    let expr = match expr {
+        Some(expr) => expr,
+        None => {
+            let (i, _) = char(')')(i)?;
+            return Ok((i, Expr::Tuple(vec![])));
+        }
+    };
+
+    let (i, comma) = ws(opt(peek(char(','))))(i)?;
+    if comma.is_none() {
+        let (i, _) = char(')')(i)?;
+        return Ok((i, Expr::Group(Box::new(expr))));
+    }
+
+    let mut exprs = vec![expr];
+    let (i, _) = fold_many0(
+        preceded(char(','), ws(expr_any)),
+        || (),
+        |_, expr| {
+            exprs.push(expr);
+        },
+    )(i)?;
+    let (i, _) = pair(ws(opt(char(','))), char(')'))(i)?;
+    Ok((i, Expr::Tuple(exprs)))
+}
+
+fn expr_single(i: &str) -> IResult<&str, Expr<'_>> {
+    alt((
+        expr_bool_lit,
+        expr_num_lit,
+        expr_str_lit,
+        expr_char_lit,
+        expr_path,
+        expr_rust_macro,
+        expr_array_lit,
+        expr_var,
+        expr_group,
+    ))(i)
+}
+
+enum Suffix<'a> {
+    Attr(&'a str),
+    Index(Expr<'a>),
+    Call(Vec<Expr<'a>>),
+    Try,
+}
+
+fn expr_attr(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(
+        preceded(
+            ws(pair(char('.'), not(char('.')))),
+            cut(alt((num_lit, identifier))),
+        ),
+        Suffix::Attr,
+    )(i)
+}
+
+fn expr_index(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(
+        preceded(ws(char('[')), cut(terminated(expr_any, ws(char(']'))))),
+        Suffix::Index,
+    )(i)
+}
+
+fn expr_call(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(arguments, Suffix::Call)(i)
+}
+
+fn expr_try(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(preceded(take_till(not_ws), char('?')), |_| Suffix::Try)(i)
+}
+
+fn filter(i: &str) -> IResult<&str, (&str, Option<Vec<Expr<'_>>>)> {
+    let (i, (_, fname, args)) = tuple((char('|'), ws(identifier), opt(arguments)))(i)?;
+    Ok((i, (fname, args)))
+}
+
+fn expr_filtered(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (obj, filters)) = tuple((expr_prefix, many0(filter)))(i)?;
+
+    let mut res = obj;
+    for (fname, args) in filters {
+        res = Expr::Filter(fname, {
+            let mut args = match args {
+                Some(inner) => inner,
+                None => Vec::new(),
+            };
+            args.insert(0, res);
+            args
+        });
+    }
+
+    Ok((i, res))
+}
+
+fn expr_prefix(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (ops, mut expr)) = pair(many0(ws(alt((tag("!"), tag("-"))))), expr_suffix)(i)?;
+    for op in ops.iter().rev() {
+        expr = Expr::Unary(op, Box::new(expr));
+    }
+    Ok((i, expr))
+}
+
+fn expr_suffix(i: &str) -> IResult<&str, Expr<'_>> {
+    let (mut i, mut expr) = expr_single(i)?;
+    loop {
+        let (j, suffix) = opt(alt((expr_attr, expr_index, expr_call, expr_try)))(i)?;
+        i = j;
+        match suffix {
+            Some(Suffix::Attr(attr)) => expr = Expr::Attr(expr.into(), attr),
+            Some(Suffix::Index(index)) => expr = Expr::Index(expr.into(), index.into()),
+            Some(Suffix::Call(args)) => expr = Expr::Call(expr.into(), args),
+            Some(Suffix::Try) => expr = Expr::Try(expr.into()),
+            None => break,
+        }
+    }
+    Ok((i, expr))
+}
+
+fn expr_rust_macro(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (mname, _, args)) = tuple((identifier, char('!'), macro_arguments))(i)?;
+    Ok((i, Expr::RustMacro(mname, args)))
+}
+
+macro_rules! expr_prec_layer {
+    ( $name:ident, $inner:ident, $op:expr ) => {
+        fn $name(i: &str) -> IResult<&str, Expr<'_>> {
+            let (i, left) = $inner(i)?;
+            let (i, right) = many0(pair(
+                ws(tag($op)),
+                $inner,
+            ))(i)?;
+            Ok((
+                i,
+                right.into_iter().fold(left, |left, (op, right)| {
+                    Expr::BinOp(op, Box::new(left), Box::new(right))
+                }),
+            ))
+        }
+    };
+    ( $name:ident, $inner:ident, $( $op:expr ),+ ) => {
+        fn $name(i: &str) -> IResult<&str, Expr<'_>> {
+            let (i, left) = $inner(i)?;
+            let (i, right) = many0(pair(
+                ws(alt(($( tag($op) ),+,))),
+                $inner,
+            ))(i)?;
+            Ok((
+                i,
+                right.into_iter().fold(left, |left, (op, right)| {
+                    Expr::BinOp(op, Box::new(left), Box::new(right))
+                }),
+            ))
+        }
+    }
+}
+
+expr_prec_layer!(expr_muldivmod, expr_filtered, "*", "/", "%");
+expr_prec_layer!(expr_addsub, expr_muldivmod, "+", "-");
+expr_prec_layer!(expr_shifts, expr_addsub, ">>", "<<");
+expr_prec_layer!(expr_band, expr_shifts, "&");
+expr_prec_layer!(expr_bxor, expr_band, "^");
+expr_prec_layer!(expr_bor, expr_bxor, "|");
+expr_prec_layer!(expr_compare, expr_bor, "==", "!=", ">=", ">", "<=", "<");
+expr_prec_layer!(expr_and, expr_compare, "&&");
+expr_prec_layer!(expr_or, expr_and, "||");
+
+fn expr_any(i: &str) -> IResult<&str, Expr<'_>> {
+    let range_right = |i| pair(ws(alt((tag("..="), tag("..")))), opt(expr_or))(i);
+    alt((
+        map(range_right, |(op, right)| {
+            Expr::Range(op, None, right.map(Box::new))
+        }),
+        map(
+            pair(expr_or, opt(range_right)),
+            |(left, right)| match right {
+                Some((op, right)) => Expr::Range(op, Some(Box::new(left)), right.map(Box::new)),
+                None => left,
+            },
+        ),
+    ))(i)
+}
+
+fn expr_node<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_expr_start(i, s),
+        cut(tuple((opt(char('-')), ws(expr_any), opt(char('-')), |i| {
+            tag_expr_end(i, s)
+        }))),
+    ));
+    let (i, (_, (pws, expr, nws, _))) = p(i)?;
+    Ok((i, Node::Expr(Ws(pws.is_some(), nws.is_some()), expr)))
+}
+
+fn block_call(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("call")),
+        cut(tuple((
+            opt(tuple((ws(identifier), ws(tag("::"))))),
+            ws(identifier),
+            ws(arguments),
+            opt(char('-')),
+        ))),
+    ));
+    let (i, (pws, _, (scope, name, args, nws))) = p(i)?;
+    let scope = scope.map(|(scope, _)| scope);
+    Ok((
+        i,
+        Node::Call(Ws(pws.is_some(), nws.is_some()), scope, name, args),
+    ))
+}
+
+fn cond_if(i: &str) -> IResult<&str, CondTest<'_>> {
+    let mut p = preceded(
+        ws(tag("if")),
+        cut(tuple((
+            opt(delimited(
+                ws(alt((tag("let"), tag("set")))),
+                ws(target),
+                ws(char('=')),
+            )),
+            ws(expr_any),
+        ))),
+    );
+    let (i, (target, expr)) = p(i)?;
+    Ok((i, CondTest { target, expr }))
+}
+
+fn cond_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Cond<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(char('-')),
+        ws(tag("else")),
+        cut(tuple((
+            opt(cond_if),
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (cond, nws, _, block))) = p(i)?;
+    Ok((i, (Ws(pws.is_some(), nws.is_some()), cond, block)))
+}
+
+fn block_if<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(char('-')),
+        cond_if,
+        cut(tuple((
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(tuple((
+                |i| parse_template(i, s),
+                many0(|i| cond_block(i, s)),
+                cut(tuple((
+                    |i| tag_block_start(i, s),
+                    opt(char('-')),
+                    ws(tag("endif")),
+                    opt(char('-')),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, cond, (nws1, _, (block, elifs, (_, pws2, _, nws2))))) = p(i)?;
+
+    let mut res = vec![(Ws(pws1.is_some(), nws1.is_some()), Some(cond), block)];
+    res.extend(elifs);
+    Ok((i, Node::Cond(res, Ws(pws2.is_some(), nws2.is_some()))))
+}
+
+fn match_else_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, When<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(char('-')),
+        ws(tag("else")),
+        cut(tuple((
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (nws, _, block))) = p(i)?;
+    Ok((
+        i,
+        (Ws(pws.is_some(), nws.is_some()), Target::Name("_"), block),
+    ))
+}
+
+fn when_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, When<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(char('-')),
+        ws(tag("when")),
+        cut(tuple((
+            ws(target),
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (target, nws, _, block))) = p(i)?;
+    Ok((i, (Ws(pws.is_some(), nws.is_some()), target, block)))
+}
+
+fn block_match<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("match")),
+        cut(tuple((
+            ws(expr_any),
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(tuple((
+                ws(many0(ws(value((), |i| block_comment(i, s))))),
+                many1(|i| when_block(i, s)),
+                cut(tuple((
+                    opt(|i| match_else_block(i, s)),
+                    cut(tuple((
+                        ws(|i| tag_block_start(i, s)),
+                        opt(char('-')),
+                        ws(tag("endmatch")),
+                        opt(char('-')),
+                    ))),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, _, (expr, nws1, _, (_, arms, (else_arm, (_, pws2, _, nws2)))))) = p(i)?;
+
+    let mut arms = arms;
+    if let Some(arm) = else_arm {
+        arms.push(arm);
+    }
+
+    Ok((
+        i,
+        Node::Match(
+            Ws(pws1.is_some(), nws1.is_some()),
+            expr,
+            arms,
+            Ws(pws2.is_some(), nws2.is_some()),
+        ),
+    ))
+}
+
+fn block_let(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(alt((tag("let"), tag("set")))),
+        cut(tuple((
+            ws(target),
+            opt(tuple((ws(char('=')), ws(expr_any)))),
+            opt(char('-')),
+        ))),
+    ));
+    let (i, (pws, _, (var, val, nws))) = p(i)?;
+
+    Ok((
+        i,
+        if let Some((_, val)) = val {
+            Node::Let(Ws(pws.is_some(), nws.is_some()), var, val)
+        } else {
+            Node::LetDecl(Ws(pws.is_some(), nws.is_some()), var)
+        },
+    ))
+}
+
+fn parse_loop_content<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a>>> {
+    s.loop_depth.set(s.loop_depth.get() + 1);
+    let result = parse_template(i, s);
+    s.loop_depth.set(s.loop_depth.get() - 1);
+    result
+}
+
+fn block_for<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let if_cond = preceded(ws(tag("if")), cut(ws(expr_any)));
+    let else_block = |i| {
+        let mut p = preceded(
+            ws(tag("else")),
+            cut(tuple((
+                opt(tag("-")),
+                delimited(
+                    |i| tag_block_end(i, s),
+                    |i| parse_template(i, s),
+                    |i| tag_block_start(i, s),
+                ),
+                opt(tag("-")),
+            ))),
+        );
+        let (i, (pws, nodes, nws)) = p(i)?;
+        Ok((i, (pws.is_some(), nodes, nws.is_some())))
+    };
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("for")),
+        cut(tuple((
+            ws(target),
+            ws(tag("in")),
+            cut(tuple((
+                ws(expr_any),
+                opt(if_cond),
+                opt(char('-')),
+                |i| tag_block_end(i, s),
+                cut(tuple((
+                    |i| parse_loop_content(i, s),
+                    cut(tuple((
+                        |i| tag_block_start(i, s),
+                        opt(char('-')),
+                        opt(else_block),
+                        ws(tag("endfor")),
+                        opt(char('-')),
+                    ))),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, _, (var, _, (iter, cond, nws1, _, (body, (_, pws2, else_block, _, nws2)))))) =
+        p(i)?;
+    let (nws3, else_block, pws3) = else_block.unwrap_or_default();
+    Ok((
+        i,
+        Node::Loop(Loop {
+            ws1: Ws(pws1.is_some(), nws1.is_some()),
+            var,
+            iter,
+            cond,
+            body,
+            ws2: Ws(pws2.is_some(), nws3),
+            else_block,
+            ws3: Ws(pws3, nws2.is_some()),
+        }),
+    ))
+}
+
+fn block_extends(i: &str) -> IResult<&str, Node<'_>> {
+    let (i, (_, name)) = tuple((ws(tag("extends")), ws(expr_str_lit)))(i)?;
+    Ok((i, Node::Extends(name)))
+}
+
+fn block_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut start = tuple((
+        opt(char('-')),
+        ws(tag("block")),
+        cut(tuple((ws(identifier), opt(char('-')), |i| {
+            tag_block_end(i, s)
+        }))),
+    ));
+    let (i, (pws1, _, (name, nws1, _))) = start(i)?;
+
+    let mut end = cut(tuple((
+        |i| parse_template(i, s),
+        cut(tuple((
+            |i| tag_block_start(i, s),
+            opt(char('-')),
+            ws(tag("endblock")),
+            cut(tuple((opt(ws(tag(name))), opt(char('-'))))),
+        ))),
+    )));
+    let (i, (contents, (_, pws2, _, (_, nws2)))) = end(i)?;
+
+    Ok((
+        i,
+        Node::BlockDef(
+            Ws(pws1.is_some(), nws1.is_some()),
+            name,
+            contents,
+            Ws(pws2.is_some(), nws2.is_some()),
+        ),
+    ))
+}
+
+fn block_include(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("include")),
+        cut(pair(ws(str_lit), opt(char('-')))),
+    ));
+    let (i, (pws, _, (name, nws))) = p(i)?;
+    Ok((i, Node::Include(Ws(pws.is_some(), nws.is_some()), name)))
+}
+
+fn block_import(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("import")),
+        cut(tuple((
+            ws(str_lit),
+            ws(tag("as")),
+            cut(pair(ws(identifier), opt(char('-')))),
+        ))),
+    ));
+    let (i, (pws, _, (name, _, (scope, nws)))) = p(i)?;
+    Ok((
+        i,
+        Node::Import(Ws(pws.is_some(), nws.is_some()), name, scope),
+    ))
+}
+
+fn block_macro<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("macro")),
+        cut(tuple((
+            ws(identifier),
+            ws(parameters),
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            cut(tuple((
+                |i| parse_template(i, s),
+                cut(tuple((
+                    |i| tag_block_start(i, s),
+                    opt(char('-')),
+                    ws(tag("endmacro")),
+                    opt(char('-')),
+                ))),
+            ))),
+        ))),
+    ));
+
+    let (i, (pws1, _, (name, params, nws1, _, (contents, (_, pws2, _, nws2))))) = p(i)?;
+    assert_ne!(name, "super", "invalid macro name 'super'");
+
+    Ok((
+        i,
+        Node::Macro(
+            name,
+            Macro {
+                ws1: Ws(pws1.is_some(), nws1.is_some()),
+                args: params,
+                nodes: contents,
+                ws2: Ws(pws2.is_some(), nws2.is_some()),
+            },
+        ),
+    ))
+}
+
+fn block_raw<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let endraw = tuple((
+        |i| tag_block_start(i, s),
+        opt(char('-')),
+        ws(tag("endraw")),
+        opt(char('-')),
+        peek(|i| tag_block_end(i, s)),
+    ));
+
+    let mut p = tuple((
+        opt(char('-')),
+        ws(tag("raw")),
+        cut(tuple((
+            opt(char('-')),
+            |i| tag_block_end(i, s),
+            consumed(skip_till(endraw)),
+        ))),
+    ));
+
+    let (_, (pws1, _, (nws1, _, (contents, (i, (_, pws2, _, nws2, _)))))) = p(i)?;
+    let (lws, val, rws) = match split_ws_parts(contents) {
+        Node::Lit(lws, val, rws) => (lws, val, rws),
+        _ => unreachable!(),
+    };
+    let ws1 = Ws(pws1.is_some(), nws1.is_some());
+    let ws2 = Ws(pws2.is_some(), nws2.is_some());
+    Ok((i, Node::Raw(ws1, lws, val, rws, ws2)))
+}
+
+fn break_statement<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((opt(char('-')), ws(tag("break")), opt(char('-'))));
+    let (j, (pws, _, nws)) = p(i)?;
+    if s.loop_depth.get() == 0 {
+        return Err(nom::Err::Failure(error_position!(i, ErrorKind::Tag)));
+    }
+    Ok((j, Node::Break(Ws(pws.is_some(), nws.is_some()))))
+}
+
+fn continue_statement<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((opt(char('-')), ws(tag("continue")), opt(char('-'))));
+    let (j, (pws, _, nws)) = p(i)?;
+    if s.loop_depth.get() == 0 {
+        return Err(nom::Err::Failure(error_position!(i, ErrorKind::Tag)));
+    }
+    Ok((j, Node::Continue(Ws(pws.is_some(), nws.is_some()))))
+}
+
+fn block_node<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        alt((
+            block_call,
+            block_let,
+            |i| block_if(i, s),
+            |i| block_for(i, s),
+            |i| block_match(i, s),
+            block_extends,
+            block_include,
+            block_import,
+            |i| block_block(i, s),
+            |i| block_macro(i, s),
+            |i| block_raw(i, s),
+            |i| break_statement(i, s),
+            |i| continue_statement(i, s),
+        )),
+        cut(|i| tag_block_end(i, s)),
+    ));
+    let (i, (_, contents, _)) = p(i)?;
+    Ok((i, contents))
+}
+
+fn block_comment_body<'a>(mut i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    let mut level = 0;
+    loop {
+        let (end, tail) = take_until(s.syntax.comment_end)(i)?;
+        match take_until::<_, _, Error<_>>(s.syntax.comment_start)(i) {
+            Ok((start, _)) if start.as_ptr() < end.as_ptr() => {
+                level += 1;
+                i = &start[2..];
+            }
+            _ if level > 0 => {
+                level -= 1;
+                i = &end[2..];
+            }
+            _ => return Ok((end, tail)),
+        }
+    }
+}
+
+fn block_comment<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_comment_start(i, s),
+        cut(tuple((
+            opt(char('-')),
+            |i| block_comment_body(i, s),
+            |i| tag_comment_end(i, s),
+        ))),
+    ));
+    let (i, (_, (pws, tail, _))) = p(i)?;
+    Ok((i, Node::Comment(Ws(pws.is_some(), tail.ends_with('-')))))
+}
+
+fn parse_template<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a>>> {
+    many0(alt((
+        complete(|i| take_content(i, s)),
+        complete(|i| block_comment(i, s)),
+        complete(|i| expr_node(i, s)),
+        complete(|i| block_node(i, s)),
+    )))(i)
+}
+
+fn tag_block_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.block_start)(i)
+}
+fn tag_block_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.block_end)(i)
+}
+fn tag_comment_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.comment_start)(i)
+}
+fn tag_comment_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.comment_end)(i)
+}
+fn tag_expr_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.expr_start)(i)
+}
+fn tag_expr_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.expr_end)(i)
+}
+
+pub fn parse<'a>(src: &'a str, syntax: &'a Syntax<'a>) -> Result<Vec<Node<'a>>, CompileError> {
+    let state = State {
+        syntax,
+        loop_depth: Cell::new(0),
+    };
+    match parse_template(src, &state) {
+        Ok((left, res)) => {
+            if !left.is_empty() {
+                Err(format!("unable to parse template:\n\n{:?}", left).into())
+            } else {
+                Ok(res)
+            }
+        }
+
+        Err(nom::Err::Error(err)) | Err(nom::Err::Failure(err)) => {
+            let nom::error::Error { input, .. } = err;
+            let offset = src.len() - input.len();
+            let (source_before, source_after) = src.split_at(offset);
+
+            let source_after = match source_after.char_indices().enumerate().take(41).last() {
+                Some((40, (i, _))) => format!("{:?}...", &source_after[..i]),
+                _ => format!("{:?}", source_after),
+            };
+
+            let (row, last_line) = source_before.lines().enumerate().last().unwrap();
+            let column = last_line.chars().count();
+
+            let msg = format!(
+                "problems parsing template source at row {}, column {} near:\n{}",
+                row + 1,
+                column,
+                source_after,
+            );
+            Err(msg.into())
+        }
+
+        Err(nom::Err::Incomplete(_)) => Err("parsing incomplete".into()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{Expr, Node, Ws};
+    use crate::Syntax;
+
+    fn check_ws_split(s: &str, res: &(&str, &str, &str)) {
+        match super::split_ws_parts(s) {
+            Node::Lit(lws, s, rws) => {
+                assert_eq!(lws, res.0);
+                assert_eq!(s, res.1);
+                assert_eq!(rws, res.2);
+            }
+            _ => {
+                panic!("fail");
+            }
+        }
+    }
+
+    #[test]
+    fn test_ws_splitter() {
+        check_ws_split("", &("", "", ""));
+        check_ws_split("a", &("", "a", ""));
+        check_ws_split("\ta", &("\t", "a", ""));
+        check_ws_split("b\n", &("", "b", "\n"));
+        check_ws_split(" \t\r\n", &(" \t\r\n", "", ""));
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_block() {
+        super::parse("{% extend \"blah\" %}", &Syntax::default()).unwrap();
+    }
+
+    #[test]
+    fn test_parse_filter() {
+        use Expr::*;
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ strvar|e }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("e", vec![Var("strvar")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ 2|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![NumLit("2")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ -2|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![Unary("-", NumLit("2").into())]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1 - 2)|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter(
+                    "abs",
+                    vec![Group(
+                        BinOp("-", NumLit("1").into(), NumLit("2").into()).into()
+                    )]
+                ),
+            )],
+        );
+    }
+
+    #[test]
+    fn test_parse_numbers() {
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ 2 }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::NumLit("2"),)],
+        );
+        assert_eq!(
+            super::parse("{{ 2.5 }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::NumLit("2.5"),)],
+        );
+    }
+
+    #[test]
+    fn test_parse_var() {
+        let s = Syntax::default();
+
+        assert_eq!(
+            super::parse("{{ foo }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Var("foo"))],
+        );
+        assert_eq!(
+            super::parse("{{ foo_bar }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Var("foo_bar"))],
+        );
+
+        assert_eq!(
+            super::parse("{{ none }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Var("none"))],
+        );
+    }
+
+    #[test]
+    fn test_parse_const() {
+        let s = Syntax::default();
+
+        assert_eq!(
+            super::parse("{{ FOO }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Path(vec!["FOO"]))],
+        );
+        assert_eq!(
+            super::parse("{{ FOO_BAR }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Path(vec!["FOO_BAR"]))],
+        );
+
+        assert_eq!(
+            super::parse("{{ NONE }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Path(vec!["NONE"]))],
+        );
+    }
+
+    #[test]
+    fn test_parse_path() {
+        let s = Syntax::default();
+
+        assert_eq!(
+            super::parse("{{ None }}", &s).unwrap(),
+            vec![Node::Expr(Ws(false, false), Expr::Path(vec!["None"]))],
+        );
+        assert_eq!(
+            super::parse("{{ Some(123) }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Path(vec!["Some"])),
+                    vec![Expr::NumLit("123")]
+                ),
+            )],
+        );
+
+        assert_eq!(
+            super::parse("{{ Ok(123) }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(Box::new(Expr::Path(vec!["Ok"])), vec![Expr::NumLit("123")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ Err(123) }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(Box::new(Expr::Path(vec!["Err"])), vec![Expr::NumLit("123")]),
+            )],
+        );
+    }
+
+    #[test]
+    fn test_parse_var_call() {
+        assert_eq!(
+            super::parse("{{ function(\"123\", 3) }}", &Syntax::default()).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Var("function")),
+                    vec![Expr::StrLit("123"), Expr::NumLit("3")]
+                ),
+            )],
+        );
+    }
+
+    #[test]
+    fn test_parse_path_call() {
+        let s = Syntax::default();
+
+        assert_eq!(
+            super::parse("{{ Option::None }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Path(vec!["Option", "None"])
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ Option::Some(123) }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Path(vec!["Option", "Some"])),
+                    vec![Expr::NumLit("123")],
+                ),
+            )],
+        );
+
+        assert_eq!(
+            super::parse("{{ self::function(\"123\", 3) }}", &s).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Path(vec!["self", "function"])),
+                    vec![Expr::StrLit("123"), Expr::NumLit("3")],
+                ),
+            )],
+        );
+    }
+
+    #[test]
+    fn test_parse_root_path() {
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ std::string::String::new() }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Path(vec!["std", "string", "String", "new"])),
+                    vec![]
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ ::std::string::String::new() }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Expr::Call(
+                    Box::new(Expr::Path(vec!["", "std", "string", "String", "new"])),
+                    vec![]
+                ),
+            )],
+        );
+    }
+
+    #[test]
+    fn change_delimiters_parse_filter() {
+        let syntax = Syntax {
+            expr_start: "{~",
+            expr_end: "~}",
+            ..Syntax::default()
+        };
+
+        super::parse("{~ strvar|e ~}", &syntax).unwrap();
+    }
+
+    #[test]
+    fn test_precedence() {
+        use Expr::*;
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ a + b == c }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "==",
+                    BinOp("+", Var("a").into(), Var("b").into()).into(),
+                    Var("c").into(),
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a + b * c - d / e }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "-",
+                    BinOp(
+                        "+",
+                        Var("a").into(),
+                        BinOp("*", Var("b").into(), Var("c").into()).into(),
+                    )
+                    .into(),
+                    BinOp("/", Var("d").into(), Var("e").into()).into(),
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a * (b + c) / -d }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "/",
+                    BinOp(
+                        "*",
+                        Var("a").into(),
+                        Group(BinOp("+", Var("b").into(), Var("c").into()).into()).into()
+                    )
+                    .into(),
+                    Unary("-", Var("d").into()).into()
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a || b && c || d && e }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "||",
+                    BinOp(
+                        "||",
+                        Var("a").into(),
+                        BinOp("&&", Var("b").into(), Var("c").into()).into(),
+                    )
+                    .into(),
+                    BinOp("&&", Var("d").into(), Var("e").into()).into(),
+                )
+            )],
+        );
+    }
+
+    #[test]
+    fn test_associativity() {
+        use Expr::*;
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ a + b + c }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "+",
+                    BinOp("+", Var("a").into(), Var("b").into()).into(),
+                    Var("c").into()
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a * b * c }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "*",
+                    BinOp("*", Var("a").into(), Var("b").into()).into(),
+                    Var("c").into()
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a && b && c }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "&&",
+                    BinOp("&&", Var("a").into(), Var("b").into()).into(),
+                    Var("c").into()
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a + b - c + d }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "+",
+                    BinOp(
+                        "-",
+                        BinOp("+", Var("a").into(), Var("b").into()).into(),
+                        Var("c").into()
+                    )
+                    .into(),
+                    Var("d").into()
+                )
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a == b != c > d > e == f }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "==",
+                    BinOp(
+                        ">",
+                        BinOp(
+                            ">",
+                            BinOp(
+                                "!=",
+                                BinOp("==", Var("a").into(), Var("b").into()).into(),
+                                Var("c").into()
+                            )
+                            .into(),
+                            Var("d").into()
+                        )
+                        .into(),
+                        Var("e").into()
+                    )
+                    .into(),
+                    Var("f").into()
+                )
+            )],
+        );
+    }
+
+    #[test]
+    fn test_odd_calls() {
+        use Expr::*;
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ a[b](c) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Call(
+                    Box::new(Index(Box::new(Var("a")), Box::new(Var("b")))),
+                    vec![Var("c")],
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (a + b)(c) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Call(
+                    Box::new(Group(Box::new(BinOp(
+                        "+",
+                        Box::new(Var("a")),
+                        Box::new(Var("b"))
+                    )))),
+                    vec![Var("c")],
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ a + b(c) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "+",
+                    Box::new(Var("a")),
+                    Box::new(Call(Box::new(Var("b")), vec![Var("c")])),
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (-a)(b) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Call(
+                    Box::new(Group(Box::new(Unary("-", Box::new(Var("a")))))),
+                    vec![Var("b")],
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ -a(b) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Unary("-", Box::new(Call(Box::new(Var("a")), vec![Var("b")])),),
+            )],
+        );
+    }
+
+    #[test]
+    fn test_parse_comments() {
+        let s = &Syntax::default();
+
+        assert_eq!(
+            super::parse("{##}", s).unwrap(),
+            vec![Node::Comment(Ws(false, false))],
+        );
+        assert_eq!(
+            super::parse("{#- #}", s).unwrap(),
+            vec![Node::Comment(Ws(true, false))],
+        );
+        assert_eq!(
+            super::parse("{# -#}", s).unwrap(),
+            vec![Node::Comment(Ws(false, true))],
+        );
+        assert_eq!(
+            super::parse("{#--#}", s).unwrap(),
+            vec![Node::Comment(Ws(true, true))],
+        );
+
+        assert_eq!(
+            super::parse("{#- foo\n bar -#}", s).unwrap(),
+            vec![Node::Comment(Ws(true, true))],
+        );
+        assert_eq!(
+            super::parse("{#- foo\n {#- bar\n -#} baz -#}", s).unwrap(),
+            vec![Node::Comment(Ws(true, true))],
+        );
+        assert_eq!(
+            super::parse("{# foo {# bar #} {# {# baz #} qux #} #}", s).unwrap(),
+            vec![Node::Comment(Ws(false, false))],
+        );
+    }
+
+    #[test]
+    fn test_parse_tuple() {
+        use super::Expr::*;
+        let syntax = Syntax::default();
+        assert_eq!(
+            super::parse("{{ () }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Tuple(vec![]),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1) }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Group(Box::new(NumLit("1"))),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1,) }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Tuple(vec![NumLit("1")]),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1, ) }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Tuple(vec![NumLit("1")]),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1 ,) }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Tuple(vec![NumLit("1")]),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1 , ) }}", &syntax).unwrap(),
+            vec![Node::Expr(Ws(false, false), Tuple(vec![NumLit("1")]),)],
+        );
+        assert_eq!(
+            super::parse("{{ (1, 2) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Tuple(vec![NumLit("1"), NumLit("2")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1, 2,) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Tuple(vec![NumLit("1"), NumLit("2")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1, 2, 3) }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Tuple(vec![NumLit("1"), NumLit("2"), NumLit("3")]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ ()|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![Tuple(vec![])]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ () | abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp("|", Box::new(Tuple(vec![])), Box::new(Var("abs"))),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1)|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![Group(Box::new(NumLit("1")))]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1) | abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "|",
+                    Box::new(Group(Box::new(NumLit("1")))),
+                    Box::new(Var("abs"))
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1,)|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![Tuple(vec![NumLit("1")])]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1,) | abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "|",
+                    Box::new(Tuple(vec![NumLit("1")])),
+                    Box::new(Var("abs"))
+                ),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1, 2)|abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                Filter("abs", vec![Tuple(vec![NumLit("1"), NumLit("2")])]),
+            )],
+        );
+        assert_eq!(
+            super::parse("{{ (1, 2) | abs }}", &syntax).unwrap(),
+            vec![Node::Expr(
+                Ws(false, false),
+                BinOp(
+                    "|",
+                    Box::new(Tuple(vec![NumLit("1"), NumLit("2")])),
+                    Box::new(Var("abs"))
+                ),
+            )],
+        );
+    }
+}