Class: RLTK::Lexer

Inherits:
Object
  • Object
show all
Defined in:
lib/rltk/lexer.rb

Overview

The Lexer class may be sub-classed to produce new lexers. These lexers have a lot of features, and are described in the main documentation.

Direct Known Subclasses

RLTK::Lexers::Calculator, RLTK::Lexers::EBNF

Defined Under Namespace

Classes: Environment, LexerCore, Rule

Class Method Summary (collapse)

Class Method Details

+ (Object) inherited(klass)

Called when the Lexer class is sub-classed, this method adds a LexerCore to the new class, and installs some needed class and instance methods.



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# File 'lib/rltk/lexer.rb', line 44

def Lexer.inherited(klass)
	klass.class_exec do
		@core = LexerCore.new
		
		# Returns this class's LexerCore object.
		def self.core
			@core
		end
		
		# Lexes the given string using a newly instantiated
		# environment.
		def self.lex(str)
			@core.lex(str, self::Environment.new(@core.start_state))
		end
		
		# Lexes the contents of the given file using a newly
		# instantiated environment.
		def self.lex_file(file_name)
			@core.lex_file(file_name, self::Environment.new(@core.start_state))
		end
		
		# Routes method calls to the new subclass to the LexerCore
		# object.
		def self.method_missing(method, *args, &proc)
			@core.send(method, *args, &proc)
		end
		
		# Instantiates a new lexer and creates an environment to be
		# used for subsequent calls.
		def initialize
			@env = self.class::Environment.new(self.class.core.start_state)
		end
		
		# Returns the environment used by an instantiated lexer.
		def env
			@env
		end
		
		# Lexes a string using the encapsulated environment.
		def lex(string)
			self.class.core.lex(string, @env)
		end
		
		# Lexes a file using the encapsulated environment.
		def lex_file(file_name)
			self.class.core.lex_file(file_name, @env)
		end
	end
end