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Access re2 library using cffi

Project description

# cffi_re2
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cffi_re2 is a cffi-based high-level Python binding for Google's [re2]( library.

### Installation

Before installing cffi_re2, you will need to install re2. On Ubuntu/Debian you can do that using

sudo apt-get install libre2-dev

Else, you can simply install the current version from the git repository:

git clone
make test
sudo make install

See the [re2 repository]( for further information.

After installing re2, you can install cffi_re2:

pip install cffi_re2
or from a local copy:
sudo python install

*cffi_re2* is fully compatbile with both *Python3.x* as well as [*PyPy*]( (including *PyPy3*).

You can run the unit tests using:
sudo python test

### Using cffi_re2

*cffi_re2* is mostly compatible to the *re* module from the Python standard library and exposes the same interface. In almost all cases you can use the same source code for both libraries. The flags in `cffi_re2` are exactly the same as those in `re`, so you can e.g. use `re.IGNORECASE` in `cffi_re2.compile` and vice versa.

One way to use *cffi_re2* is:

import cffi_re2 as re

Note however, that, due to the design of the [*RE2*]( library, some syntax elements like zero-width lookaheads or lookbehinds are [not supported](

When using those syntax elements, the backend reports a syntax error when calling `cffi_re2.compile`, for example:

ValueError: invalid perl operator: (?<

One workaround is to convert your regex into a group-capturing form and select the appropriate group later. For larger sets of complex regular expressions, this is often not feasible, however.

In this case, it is recommended to use a hybrid approach, i.e. falling back to *re* if *cffi_re2* fails to compile an expression.

import re
import cffi_re2

def compileRegex(rgx, flags=0):
return cffi_re2.compile(rgx, flags)
except ValueError:
return re.compile(rgx, flags)

Note that in the current implementation there are still several known and unknown incompatibilities between *cffi_re2* and *re*. If you encounter issues, please report them as a bug.

### Benchmarks

### About

*cffi_re2* was originally developed by [Liang Zhaohao]( Many new features and improvements were contributed by [Uli Köhler](

The library is licensed under the MIT license (see LICENSE file).

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