A small PEG based parser library. See the Hacking page in the Wiki as well.
Ruby HTML CSS Shell
Latest commit a80c077 Jan 16, 2017 @kschiess committed on GitHub Merge pull request #170 from aprescott/travis-no-sudo
Use sudo: false for the Travis configuration and update Ruby versions.



Parslet makes developing complex parsers easy. It does so by

* providing the best error reporting possible
* not generating reams of code for you to debug

Parslet takes the long way around to make your job easier. It allows for
incremental language construction. Often, you start out small, implementing
the atoms of your language first; _parslet_ takes pride in making this

Eager to try this out? Please see the associated web site:


  require 'parslet'
  include Parslet

  # parslet parses strings
    parse('foo') # => "foo"@0

  # it matches character sets
  match['abc'].parse('a') # => "a"@0
  match['abc'].parse('b') # => "b"@0
  match['abc'].parse('c') # => "c"@0

  # and it annotates its output
    parse('foo') # => {:important_bit=>"foo"@0}

  # you can construct parsers with just a few lines
  quote = str('"')
  simple_string = quote >> (quote.absent? >> any).repeat >> quote

    parse('"Simple Simple Simple"') # => "\"Simple Simple Simple\""@0

  # or by making a fuss about it 
  class Smalltalk < Parslet::Parser
    root :smalltalk

    rule(:smalltalk) { statements }
    rule(:statements) { 
      # insert smalltalk parser here (outside of the scope of this readme)

  # and then


  * Tools for every part of the parser chain
  * Transformers generate Abstract Syntax Trees
  * Accelerators transform parsers, making them quite a bit faster
  * Pluggable error reporters
  * Graphviz export for your parser
  * Rspec testing support rig
  * Simply Ruby, composable and hackable


This library is intended to work with Ruby variants >= 1.9. I've tested it on 
MRI 1.9, rbx-head, jruby. Please report as a bug if you encounter issues.


Production worthy.

(c) 2010-2016 Kaspar Schiess