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module CodeRay
module Scanners
class Scanner
# A WordList is a Hash with some additional features.
# It is intended to be used for keyword recognition.
#
# WordList is highly optimized to be used in Scanners,
# typically to decide whether a given ident is a keyword.
#
# Example:
#
# # define word arrays
# RESERVED_WORDS = %w[
# asm break case continue default do else
# ...
# ]
#
# PREDEFINED_TYPES = %w[
# int long short char void
# ...
# ]
#
# PREDEFINED_CONSTANTS = %w[
# EOF NULL ...
# ]
#
# # make a WordList
# IDENT_KIND = Scanner::WordList.new(:ident).
# add(RESERVED_WORDS, :reserved).
# add(PREDEFINED_TYPES, :pre_type).
# add(PREDEFINED_CONSTANTS, :pre_constant)
#
# ...
#
# def scan_tokens tokens, options
# ...
#
# elsif match = scan(/ [A-Za-z_][A-Za-z_0-9]* /x)
# # use it
# kind = IDENT_KIND[match]
# ...
#
class WordList < Hash
# Creates a new WordList with +default+ as default value.
# case_mode controls how keys are compared;
# :case_match is faster.
def initialize default = false, case_mode = :case_match
@case_ignore =
case case_mode
when :case_match then false
when :case_ignore then true
else raise ArgumentError,
":case_ignore or :case_match expected, but #{case_mode} given"
end
if @case_ignore
super() do |h, k|
h[k] = h.fetch k.downcase, default
end
else
super default
end
end
# Checks if a word is included.
def include? word
self[word] if @case_ignore
has_key? word
end
# Add words to the list and associate them with
# +kind+.
def add words, kind = true
words.each do |word|
self[mind_case(word)] = kind
end
self
end
alias words keys
# Returns whether key comparing is done case insensitive.
def case_ignore?
@case_mode
end
private
# helper method for key
def mind_case word
if @case_ignore
word.downcase
else
word.dup
end
end
end
end
end
end
# vim:sw=2:ts=2:noet:tw=78
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