1 files changed, 188 insertions, 0 deletions
diff --git a/third_party/rust/time-macros/src/helpers/string.rs b/third_party/rust/time-macros/src/helpers/string.rs
new file mode 100644
index 0000000000..6b478f60dc
--- /dev/null
+++ b/third_party/rust/time-macros/src/helpers/string.rs
@@ -0,0 +1,188 @@
+use std::ops::{Index, RangeFrom};
+
+use proc_macro::Span;
+
+use crate::Error;
+
+pub(crate) fn parse(token: &proc_macro::Literal) -> Result<(Span, Vec<u8>), Error> {
+    let span = token.span();
+    let repr = token.to_string();
+
+    match repr.as_bytes() {
+        [b'"', ..] => Ok((span, parse_lit_str_cooked(&repr[1..]))),
+        [b'b', b'"', rest @ ..] => Ok((span, parse_lit_byte_str_cooked(rest))),
+        [b'r', rest @ ..] | [b'b', b'r', rest @ ..] => Ok((span, parse_lit_str_raw(rest))),
+        _ => Err(Error::ExpectedString {
+            span_start: Some(span),
+            span_end: Some(span),
+        }),
+    }
+}
+
+fn byte(s: impl AsRef<[u8]>, idx: usize) -> u8 {
+    s.as_ref().get(idx).copied().unwrap_or_default()
+}
+
+fn parse_lit_str_cooked(mut s: &str) -> Vec<u8> {
+    let mut content = String::new();
+    'outer: loop {
+        let ch = match byte(s, 0) {
+            b'"' => break,
+            b'\\' => {
+                let b = byte(s, 1);
+                s = &s[2..];
+                match b {
+                    b'x' => {
+                        let (byte, rest) = backslash_x(s);
+                        s = rest;
+                        char::from_u32(u32::from(byte)).expect("byte was just validated")
+                    }
+                    b'u' => {
+                        let (chr, rest) = backslash_u(s);
+                        s = rest;
+                        chr
+                    }
+                    b'n' => '\n',
+                    b'r' => '\r',
+                    b't' => '\t',
+                    b'\\' => '\\',
+                    b'0' => '\0',
+                    b'\'' => '\'',
+                    b'"' => '"',
+                    b'\r' | b'\n' => loop {
+                        let ch = s.chars().next().unwrap_or_default();
+                        if ch.is_whitespace() {
+                            s = &s[ch.len_utf8()..];
+                        } else {
+                            continue 'outer;
+                        }
+                    },
+                    _ => bug!("invalid escape"),
+                }
+            }
+            b'\r' => {
+                // bare CR not permitted
+                s = &s[2..];
+                '\n'
+            }
+            _ => {
+                let ch = s.chars().next().unwrap_or_default();
+                s = &s[ch.len_utf8()..];
+                ch
+            }
+        };
+        content.push(ch);
+    }
+
+    content.into_bytes()
+}
+
+fn parse_lit_str_raw(s: &[u8]) -> Vec<u8> {
+    let mut pounds = 0;
+    while byte(s, pounds) == b'#' {
+        pounds += 1;
+    }
+    let close = s
+        .iter()
+        .rposition(|&b| b == b'"')
+        .expect("had a string without trailing \"");
+
+    s[pounds + 1..close].to_owned()
+}
+
+fn parse_lit_byte_str_cooked(mut v: &[u8]) -> Vec<u8> {
+    let mut out = Vec::new();
+    'outer: loop {
+        let byte = match byte(v, 0) {
+            b'"' => break,
+            b'\\' => {
+                let b = byte(v, 1);
+                v = &v[2..];
+                match b {
+                    b'x' => {
+                        let (byte, rest) = backslash_x(v);
+                        v = rest;
+                        byte
+                    }
+                    b'n' => b'\n',
+                    b'r' => b'\r',
+                    b't' => b'\t',
+                    b'\\' => b'\\',
+                    b'0' => b'\0',
+                    b'\'' => b'\'',
+                    b'"' => b'"',
+                    b'\r' | b'\n' => loop {
+                        let byte = byte(v, 0);
+                        let ch = char::from_u32(u32::from(byte)).expect("invalid byte");
+                        if ch.is_whitespace() {
+                            v = &v[1..];
+                        } else {
+                            continue 'outer;
+                        }
+                    },
+                    _ => bug!("invalid escape"),
+                }
+            }
+            b'\r' => {
+                // bare CR not permitted
+                v = &v[2..];
+                b'\n'
+            }
+            b => {
+                v = &v[1..];
+                b
+            }
+        };
+        out.push(byte);
+    }
+
+    out
+}
+
+fn backslash_x<S>(s: &S) -> (u8, &S)
+where
+    S: Index<RangeFrom<usize>, Output = S> + AsRef<[u8]> + ?Sized,
+{
+    let mut ch = 0;
+    let b0 = byte(s, 0);
+    let b1 = byte(s, 1);
+    ch += 0x10 * (b0 - b'0');
+    ch += match b1 {
+        b'0'..=b'9' => b1 - b'0',
+        b'a'..=b'f' => 10 + (b1 - b'a'),
+        b'A'..=b'F' => 10 + (b1 - b'A'),
+        _ => bug!("invalid hex escape"),
+    };
+    (ch, &s[2..])
+}
+
+fn backslash_u(mut s: &str) -> (char, &str) {
+    s = &s[1..];
+
+    let mut ch = 0;
+    let mut digits = 0;
+    loop {
+        let b = byte(s, 0);
+        let digit = match b {
+            b'0'..=b'9' => b - b'0',
+            b'a'..=b'f' => 10 + b - b'a',
+            b'A'..=b'F' => 10 + b - b'A',
+            b'_' if digits > 0 => {
+                s = &s[1..];
+                continue;
+            }
+            b'}' if digits != 0 => break,
+            _ => bug!("invalid unicode escape"),
+        };
+        ch *= 0x10;
+        ch += u32::from(digit);
+        digits += 1;
+        s = &s[1..];
+    }
+    s = &s[1..];
+
+    (
+        char::from_u32(ch).expect("invalid unicode escape passed by compiler"),
+        s,
+    )
+}