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Hammer is a parsing library. Like many modern parsing libraries, it provides a parser combinator interface for writing grammars as inline domain-specific languages, but Hammer also provides a variety of parsing backends. It's also bit-oriented rather than character-oriented, making it ideal for parsing binary data such as images, network packets, audio, and executables.

Hammer is written in C, but will provide bindings for other languages. If you don't see a language you're interested in on the list, just ask.

Hammer currently builds under Linux and OS X. (Windows is coming.)

Build Status Features

  • Bit-oriented -- grammars can include single-bit flags or multi-bit constructs that span character boundaries, with no hassle
  • Thread-safe, reentrant
  • Benchmarking for parsing backends -- determine empirically which backend will be most time-efficient for your grammar
  • Parsing backends:
    • Packrat parsing
    • LL(k)
    • GLR
    • LALR
    • Regular expressions
  • Language bindings:
    • C++
    • Java (not currently building; give us a few days)
    • Python
    • Ruby
    • Perl
    • Go
    • PHP
    • .NET



Optional Dependencies

  • pkg-config (for scons test)
  • glib-2.0 (>= 2.29) (for scons test)
  • glib-2.0-dev (for scons test)
  • swig (for Python/Perl/PHP bindings; Perl requires >= 2.0.8; Python 3.x requires >= 3.0.0)
  • python2.7-dev (for Python 2 bindings)
  • python3-dev (>= 3.5) (for Python 3 bindings)
  • a JDK (for Java bindings)
  • a working phpenv configuration (for PHP bindings)
  • Ruby >= 1.9.3 and bundler, for the Ruby bindings
  • mono-devel and mono-mcs (>= 3.0.6) (for .NET bindings)
  • nunit (for testing .NET bindings)

To build, type scons. To run the built-in test suite, type scons test. For a debug build, add --variant=debug.

To build bindings, pass a "bindings" argument to scons, e.g. scons bindings=python. scons bindings=python test will build Python bindings and run tests for both C and Python. --variant=debug is valid here too. You can build more than one set of bindings at a time; just separate them with commas, e.g. scons bindings=python,perl.

For Java, if jni.h and jni_md.h aren't already somewhere on your include path, prepend C_INCLUDE_PATH=/path/to/jdk/include to that.

To make Hammer available system-wide, use scons install. This places include files in /usr/local/include/hammer and library files in /usr/local/lib by default; to install elsewhere, add a prefix=<destination> argument, e.g. scons install prefix=$HOME. A suitable bindings= argument will install bindings in whatever place your system thinks is appropriate.


Just #include <hammer/hammer.h> (also #include <hammer/glue.h> if you plan to use any of the convenience macros) and link with -lhammer.

If you've installed Hammer system-wide, you can use pkg-config in the usual way.

To learn about hammer check


The examples/ directory contains some simple examples, currently including:

Known Issues

The Python bindings work with Python 2.7, and Python 3.5+.

The requirement for SWIG >= 2.0.8 for Perl bindings is due to a known bug in SWIG. ppa:dns/irc has backports of SWIG 2.0.8 for Ubuntu versions 10.04-12.10; you can also build SWIG from source.

The .NET bindings are for Mono 3.0.6 and greater. If you're on a Debian-based distro that only provides Mono 2 (e.g., Ubuntu 12.04), there are backports for 3.0.x, and a 3.2.x PPA maintained by the Mono team.


Please join us at #hammer on if you have any questions or just want to talk about parsing.


You can also email us at


Parser combinators for binary formats, in C. Yes, in C. What? Don't look at me like that.







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  • C 64.3%
  • Python 9.3%
  • Ruby 6.4%
  • C# 4.3%
  • PHP 4.2%
  • C++ 3.4%
  • Other 8.1%