# matchers
Regular expression matching on Rust streams.
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## Overview
The [`regex`] crate implements regular expression matching on strings and byte
arrays. However, in order to match the output of implementations of `fmt::Debug`
and `fmt::Display`, or by any code which writes to an instance of `fmt::Write`
or `io::Write`, it is necessary to first allocate a buffer, write to that
buffer, and then match the buffer against a regex.
In cases where it is not necessary to extract substrings, but only to test whether
or not output matches a regex, it is not strictly necessary to allocate and
write this output to a buffer. This crate provides a simple interface on top of
the lower-level [`regex-automata`] library that implements `fmt::Write` and
`io::Write` for regex patterns. This may be used to test whether streaming
output matches a pattern without buffering that output.
Users who need to extract substrings based on a pattern or who already have
buffered data should probably use the [`regex`] crate instead.
[`regex`]: https://crates.io/crates/regex
[`regex-automata`]: https://crates.io/crates/regex-automata