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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:47:55 +0000
commit2aadc03ef15cb5ca5cc2af8a7c08e070742f0ac4 (patch)
tree033cc839730fda84ff08db877037977be94e5e3a /vendor/regex-automata/src/util/interpolate.rs
parentInitial commit. (diff)
downloadcargo-upstream.tar.xz
cargo-upstream.zip
Adding upstream version 0.70.1+ds1.upstream/0.70.1+ds1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+/*!
+Provides routines for interpolating capture group references.
+
+That is, if a replacement string contains references like `$foo` or `${foo1}`,
+then they are replaced with the corresponding capture values for the groups
+named `foo` and `foo1`, respectively. Similarly, syntax like `$1` and `${1}`
+is supported as well, with `1` corresponding to a capture group index and not
+a name.
+
+This module provides the free functions [`string`] and [`bytes`], which
+interpolate Rust Unicode strings and byte strings, respectively.
+
+# Format
+
+These routines support two different kinds of capture references: unbraced and
+braced.
+
+For the unbraced format, the format supported is `$ref` where `name` can be
+any character in the class `[0-9A-Za-z_]`. `ref` is always the longest
+possible parse. So for example, `$1a` corresponds to the capture group named
+`1a` and not the capture group at index `1`. If `ref` matches `^[0-9]+$`, then
+it is treated as a capture group index itself and not a name.
+
+For the braced format, the format supported is `${ref}` where `ref` can be any
+sequence of bytes except for `}`. If no closing brace occurs, then it is not
+considered a capture reference. As with the unbraced format, if `ref` matches
+`^[0-9]+$`, then it is treated as a capture group index and not a name.
+
+The braced format is useful for exerting precise control over the name of the
+capture reference. For example, `${1}a` corresponds to the capture group
+reference `1` followed by the letter `a`, where as `$1a` (as mentioned above)
+corresponds to the capture group reference `1a`. The braced format is also
+useful for expressing capture group names that use characters not supported by
+the unbraced format. For example, `${foo[bar].baz}` refers to the capture group
+named `foo[bar].baz`.
+
+If a capture group reference is found and it does not refer to a valid capture
+group, then it will be replaced with the empty string.
+
+To write a literal `$`, use `$$`.
+
+To be clear, and as exhibited via the type signatures in the routines in this
+module, it is impossible for a replacement string to be invalid. A replacement
+string may not have the intended semantics, but the interpolation procedure
+itself can never fail.
+*/
+
+use alloc::{string::String, vec::Vec};
+
+use crate::util::memchr::memchr;
+
+/// Accepts a replacement string and interpolates capture references with their
+/// corresponding values.
+///
+/// `append` should be a function that appends the string value of a capture
+/// group at a particular index to the string given. If the capture group
+/// index is invalid, then nothing should be appended.
+///
+/// `name_to_index` should be a function that maps a capture group name to a
+/// capture group index. If the given name doesn't exist, then `None` should
+/// be returned.
+///
+/// Finally, `dst` is where the final interpolated contents should be written.
+/// If `replacement` contains no capture group references, then `dst` will be
+/// equivalent to `replacement`.
+///
+/// See the [module documentation](self) for details about the format
+/// supported.
+///
+/// # Example
+///
+/// ```
+/// use regex_automata::util::interpolate;
+///
+/// let mut dst = String::new();
+/// interpolate::string(
+/// "foo $bar baz",
+/// |index, dst| {
+/// if index == 0 {
+/// dst.push_str("BAR");
+/// }
+/// },
+/// |name| {
+/// if name == "bar" {
+/// Some(0)
+/// } else {
+/// None
+/// }
+/// },
+/// &mut dst,
+/// );
+/// assert_eq!("foo BAR baz", dst);
+/// ```
+pub fn string(
+ mut replacement: &str,
+ mut append: impl FnMut(usize, &mut String),
+ mut name_to_index: impl FnMut(&str) -> Option<usize>,
+ dst: &mut String,
+) {
+ while !replacement.is_empty() {
+ match memchr(b'$', replacement.as_bytes()) {
+ None => break,
+ Some(i) => {
+ dst.push_str(&replacement[..i]);
+ replacement = &replacement[i..];
+ }
+ }
+ // Handle escaping of '$'.
+ if replacement.as_bytes().get(1).map_or(false, |&b| b == b'$') {
+ dst.push_str("$");
+ replacement = &replacement[2..];
+ continue;
+ }
+ debug_assert!(!replacement.is_empty());
+ let cap_ref = match find_cap_ref(replacement.as_bytes()) {
+ Some(cap_ref) => cap_ref,
+ None => {
+ dst.push_str("$");
+ replacement = &replacement[1..];
+ continue;
+ }
+ };
+ replacement = &replacement[cap_ref.end..];
+ match cap_ref.cap {
+ Ref::Number(i) => append(i, dst),
+ Ref::Named(name) => {
+ if let Some(i) = name_to_index(name) {
+ append(i, dst);
+ }
+ }
+ }
+ }
+ dst.push_str(replacement);
+}
+
+/// Accepts a replacement byte string and interpolates capture references with
+/// their corresponding values.
+///
+/// `append` should be a function that appends the byte string value of a
+/// capture group at a particular index to the byte string given. If the
+/// capture group index is invalid, then nothing should be appended.
+///
+/// `name_to_index` should be a function that maps a capture group name to a
+/// capture group index. If the given name doesn't exist, then `None` should
+/// be returned.
+///
+/// Finally, `dst` is where the final interpolated contents should be written.
+/// If `replacement` contains no capture group references, then `dst` will be
+/// equivalent to `replacement`.
+///
+/// See the [module documentation](self) for details about the format
+/// supported.
+///
+/// # Example
+///
+/// ```
+/// use regex_automata::util::interpolate;
+///
+/// let mut dst = vec![];
+/// interpolate::bytes(
+/// b"foo $bar baz",
+/// |index, dst| {
+/// if index == 0 {
+/// dst.extend_from_slice(b"BAR");
+/// }
+/// },
+/// |name| {
+/// if name == "bar" {
+/// Some(0)
+/// } else {
+/// None
+/// }
+/// },
+/// &mut dst,
+/// );
+/// assert_eq!(&b"foo BAR baz"[..], dst);
+/// ```
+pub fn bytes(
+ mut replacement: &[u8],
+ mut append: impl FnMut(usize, &mut Vec<u8>),
+ mut name_to_index: impl FnMut(&str) -> Option<usize>,
+ dst: &mut Vec<u8>,
+) {
+ while !replacement.is_empty() {
+ match memchr(b'$', replacement) {
+ None => break,
+ Some(i) => {
+ dst.extend_from_slice(&replacement[..i]);
+ replacement = &replacement[i..];
+ }
+ }
+ // Handle escaping of '$'.
+ if replacement.get(1).map_or(false, |&b| b == b'$') {
+ dst.push(b'$');
+ replacement = &replacement[2..];
+ continue;
+ }
+ debug_assert!(!replacement.is_empty());
+ let cap_ref = match find_cap_ref(replacement) {
+ Some(cap_ref) => cap_ref,
+ None => {
+ dst.push(b'$');
+ replacement = &replacement[1..];
+ continue;
+ }
+ };
+ replacement = &replacement[cap_ref.end..];
+ match cap_ref.cap {
+ Ref::Number(i) => append(i, dst),
+ Ref::Named(name) => {
+ if let Some(i) = name_to_index(name) {
+ append(i, dst);
+ }
+ }
+ }
+ }
+ dst.extend_from_slice(replacement);
+}
+
+/// `CaptureRef` represents a reference to a capture group inside some text.
+/// The reference is either a capture group name or a number.
+///
+/// It is also tagged with the position in the text following the
+/// capture reference.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+struct CaptureRef<'a> {
+ cap: Ref<'a>,
+ end: usize,
+}
+
+/// A reference to a capture group in some text.
+///
+/// e.g., `$2`, `$foo`, `${foo}`.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum Ref<'a> {
+ Named(&'a str),
+ Number(usize),
+}
+
+impl<'a> From<&'a str> for Ref<'a> {
+ fn from(x: &'a str) -> Ref<'a> {
+ Ref::Named(x)
+ }
+}
+
+impl From<usize> for Ref<'static> {
+ fn from(x: usize) -> Ref<'static> {
+ Ref::Number(x)
+ }
+}
+
+/// Parses a possible reference to a capture group name in the given text,
+/// starting at the beginning of `replacement`.
+///
+/// If no such valid reference could be found, None is returned.
+///
+/// Note that this returns a "possible" reference because this routine doesn't
+/// know whether the reference is to a valid group or not. If it winds up not
+/// being a valid reference, then it should be replaced with the empty string.
+fn find_cap_ref(replacement: &[u8]) -> Option<CaptureRef<'_>> {
+ let mut i = 0;
+ let rep: &[u8] = replacement;
+ if rep.len() <= 1 || rep[0] != b'$' {
+ return None;
+ }
+ i += 1;
+ if rep[i] == b'{' {
+ return find_cap_ref_braced(rep, i + 1);
+ }
+ let mut cap_end = i;
+ while rep.get(cap_end).copied().map_or(false, is_valid_cap_letter) {
+ cap_end += 1;
+ }
+ if cap_end == i {
+ return None;
+ }
+ // We just verified that the range 0..cap_end is valid ASCII, so it must
+ // therefore be valid UTF-8. If we really cared, we could avoid this UTF-8
+ // check via an unchecked conversion or by parsing the number straight from
+ // &[u8].
+ let cap = core::str::from_utf8(&rep[i..cap_end])
+ .expect("valid UTF-8 capture name");
+ Some(CaptureRef {
+ cap: match cap.parse::<usize>() {
+ Ok(i) => Ref::Number(i),
+ Err(_) => Ref::Named(cap),
+ },
+ end: cap_end,
+ })
+}
+
+/// Looks for a braced reference, e.g., `${foo1}`. This assumes that an opening
+/// brace has been found at `i-1` in `rep`. This then looks for a closing
+/// brace and returns the capture reference within the brace.
+fn find_cap_ref_braced(rep: &[u8], mut i: usize) -> Option<CaptureRef<'_>> {
+ assert_eq!(b'{', rep[i.checked_sub(1).unwrap()]);
+ let start = i;
+ while rep.get(i).map_or(false, |&b| b != b'}') {
+ i += 1;
+ }
+ if !rep.get(i).map_or(false, |&b| b == b'}') {
+ return None;
+ }
+ // When looking at braced names, we don't put any restrictions on the name,
+ // so it's possible it could be invalid UTF-8. But a capture group name
+ // can never be invalid UTF-8, so if we have invalid UTF-8, then we can
+ // safely return None.
+ let cap = match core::str::from_utf8(&rep[start..i]) {
+ Err(_) => return None,
+ Ok(cap) => cap,
+ };
+ Some(CaptureRef {
+ cap: match cap.parse::<usize>() {
+ Ok(i) => Ref::Number(i),
+ Err(_) => Ref::Named(cap),
+ },
+ end: i + 1,
+ })
+}
+
+/// Returns true if and only if the given byte is allowed in a capture name
+/// written in non-brace form.
+fn is_valid_cap_letter(b: u8) -> bool {
+ match b {
+ b'0'..=b'9' | b'a'..=b'z' | b'A'..=b'Z' | b'_' => true,
+ _ => false,
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use alloc::{string::String, vec, vec::Vec};
+
+ use super::{find_cap_ref, CaptureRef};
+
+ macro_rules! find {
+ ($name:ident, $text:expr) => {
+ #[test]
+ fn $name() {
+ assert_eq!(None, find_cap_ref($text.as_bytes()));
+ }
+ };
+ ($name:ident, $text:expr, $capref:expr) => {
+ #[test]
+ fn $name() {
+ assert_eq!(Some($capref), find_cap_ref($text.as_bytes()));
+ }
+ };
+ }
+
+ macro_rules! c {
+ ($name_or_number:expr, $pos:expr) => {
+ CaptureRef { cap: $name_or_number.into(), end: $pos }
+ };
+ }
+
+ find!(find_cap_ref1, "$foo", c!("foo", 4));
+ find!(find_cap_ref2, "${foo}", c!("foo", 6));
+ find!(find_cap_ref3, "$0", c!(0, 2));
+ find!(find_cap_ref4, "$5", c!(5, 2));
+ find!(find_cap_ref5, "$10", c!(10, 3));
+ // See https://github.com/rust-lang/regex/pull/585
+ // for more on characters following numbers
+ find!(find_cap_ref6, "$42a", c!("42a", 4));
+ find!(find_cap_ref7, "${42}a", c!(42, 5));
+ find!(find_cap_ref8, "${42");
+ find!(find_cap_ref9, "${42 ");
+ find!(find_cap_ref10, " $0 ");
+ find!(find_cap_ref11, "$");
+ find!(find_cap_ref12, " ");
+ find!(find_cap_ref13, "");
+ find!(find_cap_ref14, "$1-$2", c!(1, 2));
+ find!(find_cap_ref15, "$1_$2", c!("1_", 3));
+ find!(find_cap_ref16, "$x-$y", c!("x", 2));
+ find!(find_cap_ref17, "$x_$y", c!("x_", 3));
+ find!(find_cap_ref18, "${#}", c!("#", 4));
+ find!(find_cap_ref19, "${Z[}", c!("Z[", 5));
+ find!(find_cap_ref20, "${¾}", c!("¾", 5));
+ find!(find_cap_ref21, "${¾a}", c!("¾a", 6));
+ find!(find_cap_ref22, "${a¾}", c!("a¾", 6));
+ find!(find_cap_ref23, "${☃}", c!("☃", 6));
+ find!(find_cap_ref24, "${a☃}", c!("a☃", 7));
+ find!(find_cap_ref25, "${☃a}", c!("☃a", 7));
+ find!(find_cap_ref26, "${名字}", c!("名字", 9));
+
+ fn interpolate_string(
+ mut name_to_index: Vec<(&'static str, usize)>,
+ caps: Vec<&'static str>,
+ replacement: &str,
+ ) -> String {
+ name_to_index.sort_by_key(|x| x.0);
+
+ let mut dst = String::new();
+ super::string(
+ replacement,
+ |i, dst| {
+ if let Some(&s) = caps.get(i) {
+ dst.push_str(s);
+ }
+ },
+ |name| -> Option<usize> {
+ name_to_index
+ .binary_search_by_key(&name, |x| x.0)
+ .ok()
+ .map(|i| name_to_index[i].1)
+ },
+ &mut dst,
+ );
+ dst
+ }
+
+ fn interpolate_bytes(
+ mut name_to_index: Vec<(&'static str, usize)>,
+ caps: Vec<&'static str>,
+ replacement: &str,
+ ) -> String {
+ name_to_index.sort_by_key(|x| x.0);
+
+ let mut dst = vec![];
+ super::bytes(
+ replacement.as_bytes(),
+ |i, dst| {
+ if let Some(&s) = caps.get(i) {
+ dst.extend_from_slice(s.as_bytes());
+ }
+ },
+ |name| -> Option<usize> {
+ name_to_index
+ .binary_search_by_key(&name, |x| x.0)
+ .ok()
+ .map(|i| name_to_index[i].1)
+ },
+ &mut dst,
+ );
+ String::from_utf8(dst).unwrap()
+ }
+
+ macro_rules! interp {
+ ($name:ident, $map:expr, $caps:expr, $hay:expr, $expected:expr $(,)*) => {
+ #[test]
+ fn $name() {
+ assert_eq!(
+ $expected,
+ interpolate_string($map, $caps, $hay),
+ "interpolate::string failed",
+ );
+ assert_eq!(
+ $expected,
+ interpolate_bytes($map, $caps, $hay),
+ "interpolate::bytes failed",
+ );
+ }
+ };
+ }
+
+ interp!(
+ interp1,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test $foo test",
+ "test xxx test",
+ );
+
+ interp!(
+ interp2,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test$footest",
+ "test",
+ );
+
+ interp!(
+ interp3,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test${foo}test",
+ "testxxxtest",
+ );
+
+ interp!(
+ interp4,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test$2test",
+ "test",
+ );
+
+ interp!(
+ interp5,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test${2}test",
+ "testxxxtest",
+ );
+
+ interp!(
+ interp6,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test $$foo test",
+ "test $foo test",
+ );
+
+ interp!(
+ interp7,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "test $foo",
+ "test xxx",
+ );
+
+ interp!(
+ interp8,
+ vec![("foo", 2)],
+ vec!["", "", "xxx"],
+ "$foo test",
+ "xxx test",
+ );
+
+ interp!(
+ interp9,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test $bar$foo",
+ "test yyyxxx",
+ );
+
+ interp!(
+ interp10,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test $ test",
+ "test $ test",
+ );
+
+ interp!(
+ interp11,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test ${} test",
+ "test test",
+ );
+
+ interp!(
+ interp12,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test ${ } test",
+ "test test",
+ );
+
+ interp!(
+ interp13,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test ${a b} test",
+ "test test",
+ );
+
+ interp!(
+ interp14,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test ${a} test",
+ "test test",
+ );
+
+ // This is a funny case where a braced reference is never closed, but
+ // within the unclosed braced reference, there is an unbraced reference.
+ // In this case, the braced reference is just treated literally and the
+ // unbraced reference is found.
+ interp!(
+ interp15,
+ vec![("bar", 1), ("foo", 2)],
+ vec!["", "yyy", "xxx"],
+ "test ${wat $bar ok",
+ "test ${wat yyy ok",
+ );
+}