Trait Replacer
pub trait Replacer {
// Required method
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut Vec<u8>);
// Provided methods
fn no_expansion<'r>(&'r mut self) -> Option<Cow<'r, [u8]>> { ... }
fn by_ref<'r>(&'r mut self) -> ReplacerRef<'r, Self> { ... }
}Expand description
A trait for types that can be used to replace matches in a haystack.
In general, users of this crate shouldn’t need to implement this trait,
since implementations are already provided for &[u8] along with other
variants of byte string types, as well as FnMut(&Captures) -> Vec<u8> (or
any FnMut(&Captures) -> T where T: AsRef<[u8]>). Those cover most use
cases, but callers can implement this trait directly if necessary.
§Example
This example shows a basic implementation of the Replacer trait. This can
be done much more simply using the replacement byte string interpolation
support (e.g., $first $last), but this approach avoids needing to parse
the replacement byte string at all.
use regex::bytes::{Captures, Regex, Replacer};
struct NameSwapper;
impl Replacer for NameSwapper {
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut Vec<u8>) {
dst.extend_from_slice(&caps["first"]);
dst.extend_from_slice(b" ");
dst.extend_from_slice(&caps["last"]);
}
}
let re = Regex::new(r"(?<last>[^,\s]+),\s+(?<first>\S+)").unwrap();
let result = re.replace(b"Springsteen, Bruce", NameSwapper);
assert_eq!(result, &b"Bruce Springsteen"[..]);Required Methods§
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut Vec<u8>)
fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut Vec<u8>)
Appends possibly empty data 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.extend_from_slice(&caps[0]).
Provided Methods§
fn no_expansion<'r>(&'r mut self) -> Option<Cow<'r, [u8]>>
fn no_expansion<'r>(&'r mut self) -> Option<Cow<'r, [u8]>>
Return a fixed unchanging replacement byte 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 a replacement routine
such as Regex::replace_all.
fn by_ref<'r>(&'r mut self) -> ReplacerRef<'r, Self>
fn by_ref<'r>(&'r mut self) -> ReplacerRef<'r, Self>
Returns a type that implements Replacer, but 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 regex::bytes::{Regex, Replacer};
fn replace_all_twice<R: Replacer>(
re: Regex,
src: &[u8],
mut rep: R,
) -> Vec<u8> {
let dst = re.replace_all(src, rep.by_ref());
let dst = re.replace_all(&dst, rep.by_ref());
dst.into_owned()
}