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Versions: 6
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Contents
#
# Copyright (c) 2018-present, Blue Marble Payroll, LLC
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
#
module Logicality
module Lexer
class RegexpLexer
include Grammar
class << self
def invalid_pattern
"#{pattern}|(\\s*)"
end
def invalid_regexp
Regexp.new(invalid_pattern)
end
def pattern
Grammar.constants.map { |c| Grammar.const_get(c).source }
.join('|')
end
def regexp
Regexp.new(pattern)
end
end
attr_reader :expression
def initialize(expression)
raise ArgumentError, 'Expression is required' unless expression && expression.to_s.length > 0
@expression = expression.to_s
if invalid_matches.length > 0
raise ArgumentError, "Invalid syntax: #{invalid_matches}"
end
reset
end
def next_token
return nil if index > matches.length - 1
increment
scan_array = matches[index]
return nil unless scan_array
tokens = scan_array.map.with_index do |value, index|
const = Grammar.constants[index]
value ? Token.new(const, value) : nil
end.compact
if tokens.length > 1
raise ArgumentError, "Too many tokens found for: #{scan_array}"
elsif tokens.length == 0
raise ArgumentError, "Cannot tokenize: #{scan_array}"
end
tokens.first
end
def reset
@index = -1
self
end
private
attr_reader :index
def increment
@index += 1
nil
end
def invalid_matches
@invalid_matches ||= expression.gsub(self.class.invalid_regexp, '')
end
def matches
@matches ||= expression.scan(self.class.regexp)
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems