Class: RLTK::Lexer::Environment

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

Overview

All actions passed to LexerCore.rule are evaluated inside an instance of the Environment class or its subclass (which must have the same name). This class provides functions for manipulating lexer state and flags.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(start_state, match = nil) ⇒ Environment

Instantiates a new Environment object.

Parameters:

  • start_state (Symbol) —

    Lexer’s start state.

  • match (Match) (defaults to: nil) —

    Match object for matching text.



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# File 'lib/rltk/lexer.rb', line 261

def initialize(start_state, match = nil)
	@state	= [start_state]
	@match	= match
	@flags	= Array.new
end

Instance Attribute Details

#flags ⇒ Array<Symbol> (readonly)

Returns Flags currently set in this environment.

Returns:

  • (Array<Symbol>) —

    Flags currently set in this environment.



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# File 'lib/rltk/lexer.rb', line 252

def flags
  @flags
end

#match ⇒ Match

Returns Match object generated by a rule’s regular expression.

Returns:

  • (Match) —

    Match object generated by a rule’s regular expression.



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# File 'lib/rltk/lexer.rb', line 255

def match
  @match
end

Instance Method Details

#clear_flags ⇒ void

This method returns an undefined value.

Unsets all flags in the current environment.



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# File 'lib/rltk/lexer.rb', line 340

def clear_flags
	@flags = Array.new

	nil
end

#pop_state ⇒ void

This method returns an undefined value.

Pops a state from the state stack.



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# File 'lib/rltk/lexer.rb', line 282

def pop_state
	@state.pop

	nil
end

#push_state(state) ⇒ void

This method returns an undefined value.

Pushes a new state onto the state stack.



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# File 'lib/rltk/lexer.rb', line 291

def push_state(state)
	@state << state

	nil
end

#rule_exec(match, txt, &block) ⇒ Object

This function will instance_exec a block for a rule after setting the match value.

Parameters:

  • match (Match) —

    Match object for matching text.

  • txt (String) —

    Text of matching string.

  • block (Proc) —

    Block for matched rule.



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# File 'lib/rltk/lexer.rb', line 273

def rule_exec(match, txt, &block)
	self.match = match

	self.instance_exec(txt, &block)
end

#set_flag(flag) ⇒ void

This method returns an undefined value.

Sets a flag in the current environment.

Parameters:

  • flag (Symbol) —

    Flag to set as enabled.



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# File 'lib/rltk/lexer.rb', line 318

def set_flag(flag)
	if not @flags.include?(flag)
		@flags << flag
	end

	nil
end

#set_state(state) ⇒ void

This method returns an undefined value.

Sets the value on the top of the state stack.

Parameters:

  • state (Symbol) —

    New state for the lexing environment.



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# File 'lib/rltk/lexer.rb', line 302

def set_state(state)
	@state[-1] = state

	nil
end

#state ⇒ Symbol

Returns Current state of the lexing environment.

Returns:

  • (Symbol) —

    Current state of the lexing environment.



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# File 'lib/rltk/lexer.rb', line 309

def state
	@state.last
end

#unset_flag(flag) ⇒ void

This method returns an undefined value.

Unsets a flag in the current environment.

Parameters:

  • flag (Symbol) —

    Flag to unset.



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# File 'lib/rltk/lexer.rb', line 331

def unset_flag(flag)
	@flags.delete(flag)

	nil
end