# Erlang NIF bindings for the RE2 regex library
[](https://gitlab.com/tuncer/re2erl/pipelines)
## Using re2
The library's API follows the standard Erlang/OTP `re` API as closely as possible
while accounting for the differences in RE2. One notable difference is that
there's no `run/{2,3}` but only `match/{2,3}` as in the C++ API. It would
be easy to add `run/{2,3}`, if that's needed.
## Obtaining re2
### Installation via package manager
To use `re2`, you can add it as a project dependency and let your
package manager of choice handle it:
rebar.config: `{re2, "1.*"}`
erlang.mk: `DEPS = re2`
mix.exs: `{:re2, "~> 1.*"}`
### Installation from source into `$ERL_LIBS`
If you want to make `re2` available globally, you can install it from source
into your Erlang installation by adding it in one of your `$ERL_LIBS` paths.
So, it's either somewhere like `/usr/local/lib/lib/erlang/lib` or `$HOME/.erl`.
You can either download a tagged release from
`https://github.com/tuncer/re2/releases` and extract that or clone the git
repo `https://github.com/tuncer/re2` in the target directory. Once that's
done, cd into the directory and run `rebar compile` or just `make`.
Now, if you start `erl`, you should be able to call functions from the
`re2` module.
```
$ erl
1> code:which(re2).
"/usr/local/lib/erlang/lib/re2/ebin/re2.beam"
2>
```
### Advanced build time options
[RE2](https://github.com/google/re2) is automatically downloaded to `c_src/re2`
by the build script, and lined into the NIF lib. If you prefer to link against
[RE2](https://github.com/google/re2) as found on the system, you can set the
env var `SYSTEM_RE2=1`. If you do that and the library can not be found, it
will fall back to a local copy (`c_src/re2`). Also, if you want to override the
RE2 version that is fetched and built, when not using system RE2, you can do so
by setting `RE2_REV` to a git rev.
Unless otherwise noted, the [RE2](https://github.com/google/re2) source files
are distributed under the BSD-style license found in `c_src/re2/LICENSE`.
