dylon / ruby-jison

Ruby, Jison Compiler

ruby-jison

Ruby, Jison Compiler

Jison is Your friendly JavaScript parser generator!

require 'jison'
javascript_text = Jison.parse File.read('/path/to/grammar.js.jison')

Prerequesites

1. You must have the jison, npm module installed and on your $PATH, and it must be executable by your application.

npm install jison

To accomplish this brutal task, you will probably need to add npm to your $PATH. To execute it, you may even need node.js, but that's not for me to judge -- I'll let every man decide for himself.

Note that if you receive an exception, like

Errno::ENOENT: No such file or directory - jison
        from /usr/lib/ruby/2.0.0/open3.rb:211:in `spawn'
        from /usr/lib/ruby/2.0.0/open3.rb:211:in `popen_run'
        from /usr/lib/ruby/2.0.0/open3.rb:99:in `popen3'
        from /usr/lib/ruby/2.0.0/open3.rb:279:in `capture3'
        ...

then you probably do not have the jison, npm module installed or it is not on your $PATH.

Operations

Jison.parse

Accepts a string representing a Jison grammar, and returns another string representing its JavaScript equivalent.

require 'jison'

begin
  # `grammar` is a string consisting of a Jison grammar
  javascript_text = Jison.parse(grammar)

  # do something with javascript_text
rescue Jison::ExecutionError => error
  $stderr.puts "jison command terminated with exit code #{error.exit_code}"
  $stderr.puts "#{error.message}\n  #{error.backtrace.join("\n  ")}"
rescue Errno::ENOENT => error
  $stderr.puts "#{error.message}\n  #{error.backtrace.join("\n  ")}"
  cmd = error.message[/\b\w+$/, 0]
  $stdout.puts "Please be sure #{cmd} is installed and on your $PATH"
end

Jison.version

Returns an instance of Jison::Version containing the major, minor and micro versions of the jison on your $PATH. Jison::Version implements Comparable and may be compared against other Jison::Versions, Strings and Fixnums.

require 'jison'

version = Jison.version
version.class #-> Jison::Version
version.to_s #-> "0.4.13"

version.major #-> 0
version.minor #-> 4
version.micro #-> 13

version == version #-> true

version < Jison::Version.new(1,0,0) #-> true
version > Jison::Version.from_string '0.1.0' #-> true
version > Jison::Version.new(1) #-> false

version.between?(0,1) #-> true
version.between?(1,2) #-> false
version.between?('0.1', '0.5') #-> true