Class: Rley::SPPF::EpsilonNode

Inherits:

LeafNode

• Object
• SPPFNode
• LeafNode
• Rley::SPPF::EpsilonNode

Defined in:

lib/rley/sppf/epsilon_node.rb

Overview

A leaf node in a parse forest that matches an empty string from the input

Instance Attribute Summary

Attributes inherited from SPPFNode

#range

Instance Method Summary

• #accept(aVisitor) ⇒ Object

  Part of the 'visitee' role in Visitor design pattern.

• #initialize(aPosition) ⇒ EpsilonNode constructor

  aPosition [Integer] is the position of the token in the input stream.

• #to_string(indentation) ⇒ String

  Emit a (formatted) string representation of the node.

Methods inherited from LeafNode

#inspect, #key

Methods inherited from SPPFNode

#origin

Constructor Details

#initialize(aPosition) ⇒ EpsilonNode

aPosition [Integer] is the position of the token in the input stream.

# File 'lib/rley/sppf/epsilon_node.rb', line 11

def initialize(aPosition)
  range = { low: aPosition, high: aPosition }
  super(range)
end

Instance Method Details

#accept(aVisitor) ⇒ Object

Part of the 'visitee' role in Visitor design pattern.

Parameters:

• aVisitor (ParseTreeVisitor) —

  the visitor

# File 'lib/rley/sppf/epsilon_node.rb', line 25

def accept(aVisitor)
  aVisitor.visit_epsilon(self)
end

#to_string(indentation) ⇒ String

Emit a (formatted) string representation of the node. Mainly used for diagnosis/debugging purposes.

Returns:

• (String)

# File 'lib/rley/sppf/epsilon_node.rb', line 19

def to_string(indentation)
  return "_#{range.to_string(indentation)}"
end