h1. Neotoma

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h2. About

Neotoma is a packrat parser-generator for Erlang for Parsing Expression Grammars (PEGs). It consists of a parsing-combinator library with memoization routines, a parser for PEGs, and a utility to generate parsers from PEGs. It is inspired by treetop, a Ruby library with similar aims, and parsec, the parser-combinator library for Haskell.

Neotoma is licensed under the MIT License (see LICENSE).

h2. Features

Simple, declarative parsers generated from even simpler grammars.

Fully integrated, single-pass lexical and syntactic analysis (a feature of PEGs).

Packrat-style memoization, boasting parse-time bound linearly to the input size (at the expense of memory usage).

In-place semantic analysis/transformation, supporting single-pass end-to-end in some applications.

Erlang code-generation for the lexical/syntactic analysis piece, with the option of semantic analysis/transformation inline, or in a separate module.

Line/column number tracking for easy resolution of parsing errors.

h2. Installation

Clone the repository from github: <notextile><pre><code>$ git clone git://github.com/seancribbs/neotoma.git</code></pre></notextile>

Symlink or copy the cloned repository to somewhere in your Erlang code path. $ERLANG_HOME/lib is best.

Build the source: <notextile><pre><code>$ make</code></pre></notextile>

h2. Usage

After making sure the library is in your code path, fire up an Erlang shell.

To generate a parser from a PEG, use @neotoma:file/1,2@ (more detailed documentation pending). For PEG examples, see the @extra/@ directory in the repository.

<notextile><pre><code>1> neotoma:file("extra/arithmetic.peg").</code></pre></notextile>

This will place @arithmetic.erl@ in the same directory as the @.peg@ file by default.

h2. Contributing

Please send pull-requests to 'seancribbs' on github. When submitting a patch, eunit tests are strongly encouraged.