antlr-3.4/runtime/Ruby/lib/antlr3/constants.rb

#!/usr/bin/ruby
# encoding: utf-8

=begin LICENSE

[The "BSD licence"]
Copyright (c) 2009-2010 Kyle Yetter
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 1. Redistributions of source code must retain the above copyright
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=end

module ANTLR3
  

=begin rdoc ANTLR3::Constants

A simple module to keep track of the various built-in token types, channels, and
token names used by ANTLR throughout the runtime library.

=end
module Constants
  # built-in token channel IDs
  
  # the channel to which most tokens will be assigned
  DEFAULT = DEFAULT_CHANNEL = DEFAULT_TOKEN_CHANNEL = :default
  
  # the channel for tokens which should not be passed to a parser by a token stream
  HIDDEN  = HIDDEN_CHANNEL  = :hidden
  
  # flag used by recognizers during memoization to
  # represent a previous prediction failure
  MEMO_RULE_FAILED = -2
  
  # flag used by recognizers during memoization to indicate
  # that the rule has not been memoized yet
  MEMO_RULE_UNKNOWN = -1
  
  # built-in token types used internally by ANTLR3
  
  INVALID_TOKEN_TYPE = 0
  
  EOF = -1
  
  
  # Imaginary tree-navigation token type indicating the ascent after moving through the
  # children of a node
  UP = 3
  
  # Imaginary tree-navigation token type indicating a descent into the children of a node
  DOWN = 2
  
  # End of Rule (used internally by DFAs)
  EOR_TOKEN_TYPE = 1
  
  # The smallest possible value of non-builtin ANTLR-generated token types
  MIN_TOKEN_TYPE = 4
  
  # A hash mapping built in token types to their respective names
  # returning a string "<UNKNOWN: #{type}>" for non-builtin token
  # types
  BUILT_IN_TOKEN_NAMES = Hash.new do |h, k|
    "<UNKNOWN: #{ k }>"
  end
  
  BUILT_IN_TOKEN_NAMES.update( 
    0 => "<invalid>".freeze, 1 => "<EOR>".freeze, 
    2 => "<DOWN>".freeze, 3 => "<UP>".freeze, 
    -1 => "<EOF>".freeze
  )
  
  
end

include Constants
end