fancy_regex/replacer.rs
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use alloc::borrow::Cow;
use alloc::string::String;
use crate::Captures;
/// Replacer describes types that can be used to replace matches in a string.
///
/// In general, users of this crate shouldn't need to implement this trait,
/// since implementations are already provided for `&str` along with other
/// variants of string types and `FnMut(&Captures) -> String` (or any
/// `FnMut(&Captures) -> T` where `T: AsRef<str>`), which covers most use cases.
pub trait Replacer {
/// Appends text to `dst` to replace the current match.
///
/// The current match is represented by `caps`, which is guaranteed to
/// have a match at capture group `0`.
///
/// For example, a no-op replacement would be
/// `dst.push_str(caps.get(0).unwrap().as_str())`.
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String);
/// Return a fixed unchanging replacement string.
///
/// When doing replacements, if access to `Captures` is not needed (e.g.,
/// the replacement byte string does not need `$` expansion), then it can
/// be beneficial to avoid finding sub-captures.
///
/// In general, this is called once for every call to `replacen`.
fn no_expansion(&mut self) -> Option<Cow<str>> {
None
}
/// Return a `Replacer` that borrows and wraps this `Replacer`.
///
/// This is useful when you want to take a generic `Replacer` (which might
/// not be cloneable) and use it without consuming it, so it can be used
/// more than once.
///
/// # Example
///
/// ```
/// use fancy_regex::{Regex, Replacer};
///
/// fn replace_all_twice<R: Replacer>(
/// re: Regex,
/// src: &str,
/// mut rep: R,
/// ) -> String {
/// let dst = re.replace_all(src, rep.by_ref());
/// let dst = re.replace_all(&dst, rep.by_ref());
/// dst.into_owned()
/// }
/// ```
fn by_ref(&mut self) -> ReplacerRef<Self> {
ReplacerRef(self)
}
}
/// By-reference adaptor for a `Replacer`
///
/// Returned by [`Replacer::by_ref`](trait.Replacer.html#method.by_ref).
#[derive(Debug)]
pub struct ReplacerRef<'a, R: ?Sized>(&'a mut R);
impl<'a, R: Replacer + ?Sized + 'a> Replacer for ReplacerRef<'a, R> {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
self.0.replace_append(caps, dst)
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
self.0.no_expansion()
}
}
impl<'a> Replacer for &'a str {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
caps.expand(*self, dst);
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
no_expansion(self)
}
}
impl<'a> Replacer for &'a String {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
self.as_str().replace_append(caps, dst)
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
no_expansion(self)
}
}
impl Replacer for String {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
self.as_str().replace_append(caps, dst)
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
no_expansion(self)
}
}
impl<'a> Replacer for Cow<'a, str> {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
self.as_ref().replace_append(caps, dst)
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
no_expansion(self)
}
}
impl<'a> Replacer for &'a Cow<'a, str> {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
self.as_ref().replace_append(caps, dst)
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
no_expansion(self)
}
}
fn no_expansion<T: AsRef<str>>(t: &T) -> Option<Cow<'_, str>> {
let s = t.as_ref();
if s.contains('$') {
None
} else {
Some(Cow::Borrowed(s))
}
}
impl<F, T> Replacer for F
where
F: FnMut(&Captures<'_>) -> T,
T: AsRef<str>,
{
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String) {
dst.push_str((*self)(caps).as_ref());
}
}
/// `NoExpand` indicates literal string replacement.
///
/// It can be used with `replace` and `replace_all` to do a literal string
/// replacement without expanding `$name` to their corresponding capture
/// groups. This can be both convenient (to avoid escaping `$`, for example)
/// and performant (since capture groups don't need to be found).
///
/// `'t` is the lifetime of the literal text.
#[derive(Clone, Debug)]
pub struct NoExpand<'t>(pub &'t str);
impl<'t> Replacer for NoExpand<'t> {
fn replace_append(&mut self, _: &Captures<'_>, dst: &mut String) {
dst.push_str(self.0);
}
fn no_expansion(&mut self) -> Option<Cow<'_, str>> {
Some(Cow::Borrowed(self.0))
}
}