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|
use std::str;
use crate::find_byte::find_byte;
use crate::re_bytes;
use crate::re_unicode;
pub fn expand_str(
caps: &re_unicode::Captures<'_>,
mut replacement: &str,
dst: &mut String,
) {
while !replacement.is_empty() {
match find_byte(b'$', replacement.as_bytes()) {
None => break,
Some(i) => {
dst.push_str(&replacement[..i]);
replacement = &replacement[i..];
}
}
if replacement.as_bytes().get(1).map_or(false, |&b| b == b'$') {
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) => {
dst.push_str(caps.get(i).map(|m| m.as_str()).unwrap_or(""));
}
Ref::Named(name) => {
dst.push_str(
caps.name(name).map(|m| m.as_str()).unwrap_or(""),
);
}
}
}
dst.push_str(replacement);
}
pub fn expand_bytes(
caps: &re_bytes::Captures<'_>,
mut replacement: &[u8],
dst: &mut Vec<u8>,
) {
while !replacement.is_empty() {
match find_byte(b'$', replacement) {
None => break,
Some(i) => {
dst.extend(&replacement[..i]);
replacement = &replacement[i..];
}
}
if replacement.get(1).map_or(false, |&b| b == b'$') {
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) => {
dst.extend(caps.get(i).map(|m| m.as_bytes()).unwrap_or(b""));
}
Ref::Named(name) => {
dst.extend(
caps.name(name).map(|m| m.as_bytes()).unwrap_or(b""),
);
}
}
}
dst.extend(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`, `${foo}`.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum Ref<'a> {
Named(&'a str),
Number(usize),
}
impl<'a> From<&'a str> for Ref<'a> {
fn from(x: &'a str) -> Ref<'a> {
Ref::Named(x)
}
}
impl From<usize> for Ref<'static> {
fn from(x: usize) -> Ref<'static> {
Ref::Number(x)
}
}
/// Parses a possible reference to a capture group name in the given text,
/// starting at the beginning of `replacement`.
///
/// If no such valid reference could be found, None is returned.
fn find_cap_ref(replacement: &[u8]) -> Option<CaptureRef<'_>> {
let mut i = 0;
let rep: &[u8] = replacement;
if rep.len() <= 1 || rep[0] != b'$' {
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 =
str::from_utf8(&rep[i..cap_end]).expect("valid UTF-8 capture name");
Some(CaptureRef {
cap: match cap.parse::<u32>() {
Ok(i) => Ref::Number(i as usize),
Err(_) => Ref::Named(cap),
},
end: cap_end,
})
}
fn find_cap_ref_braced(rep: &[u8], mut i: usize) -> Option<CaptureRef<'_>> {
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 str::from_utf8(&rep[start..i]) {
Err(_) => return None,
Ok(cap) => cap,
};
Some(CaptureRef {
cap: match cap.parse::<u32>() {
Ok(i) => Ref::Number(i as usize),
Err(_) => Ref::Named(cap),
},
end: i + 1,
})
}
/// Returns true if and only if the given byte is allowed in a capture name.
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 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));
}
|
