Google RE2 Python Bindings

1.1.20251105 · active · verified Thu Apr 09

google-re2 provides Python bindings for Google's high-performance RE2 C++ regular expression library. It offers a fast and secure alternative to Python's built-in `re` module, designed for linear-time execution, but with a more restricted feature set. The library maintains a frequent release cadence, often monthly, reflecting updates to the underlying C++ library.

Warnings

gotcha `re2` is NOT a full drop-in replacement for Python's `re` module. It intentionally omits advanced features like backreferences, lookarounds, and some complex Unicode properties for performance and security reasons. Patterns using these features will raise `re2.error: invalid perl_re`.
Fix: Review and rewrite regex patterns to avoid unsupported features. Consult RE2's C++ syntax documentation for supported features. For patterns requiring full PCRE compatibility, consider `re` or `regex` libraries.
gotcha Installation may require a C++ compiler (e.g., GCC, Clang, MSVC) and RE2 C++ library headers if pre-built wheels are not available for your specific Python version and operating system. This can complicate deployment in environments without build tools.
Fix: Ensure your environment has a C++ compiler and the necessary RE2 C++ development files. On Debian/Ubuntu: `sudo apt-get install build-essential libre2-dev`. On Fedora: `sudo dnf install @development-tools re2-devel`. On Windows, install Visual C++ Build Tools.
gotcha While `re2` supports UTF-8, its interpretation of certain character classes (e.g., `\b` for word boundaries, `\w` for word characters) can differ from Python's `re` module, especially with non-ASCII or complex Unicode text. This can lead to unexpected matching behavior.
Fix: Thoroughly test patterns with diverse Unicode inputs. Explicitly use Unicode character properties (e.g., `\p{L}` for letters) where supported if fine-grained Unicode control is needed.

Install

pip install google-re2 Install stable version

Imports

re2
```
import re2
```
The PyPI package `google-re2` exposes its functionality via the `re2` module name.

Quickstart

This example demonstrates basic usage of the `re2` module, including compiling patterns, searching, finding all matches, and performing substitutions. The API largely mirrors Python's built-in `re` module for common operations.

import re2

# Compile a regex pattern
pattern = re2.compile(r'hello (\w+)')

# Search for a match
match = pattern.search('hello world')
if match:
    print(f"Found: {match.group(0)}")
    print(f"Captured: {match.group(1)}")

# Find all occurrences
text = 'hello python, hello universe'
all_matches = re2.findall(r'hello (\w+)', text)
print(f"All matches: {all_matches}")

# Replace text
replaced_text = re2.sub(r'hello', 'hi', text)
print(f"Replaced text: {replaced_text}")

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