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Contents
# frozen_string_literal: true
require_relative 'parse_tree_builder'
require_relative '../ptree/non_terminal_node'
require_relative '../ptree/terminal_node'
require_relative '../ptree/parse_tree'
module Rley # This module is used as a namespace
module ParseRep # This module is used as a namespace
# The purpose of a CSTBuilder is to build piece by piece a CST
# (Concrete Syntax Tree) from a sequence of input tokens and
# visit events produced by walking over a GFGParsing object.
# Uses the Builder GoF pattern.
# The Builder pattern creates a complex object
# (say, a parse tree) from simpler objects (terminal and non-terminal
# nodes) and using a step by step approach.
class CSTBuilder < ParseTreeBuilder
protected
# Method to override
# Create a parse tree object with given
# node as root node.
def create_tree(aRootNode)
return Rley::PTree::ParseTree.new(aRootNode)
end
# Method to override
# Factory method for creating a node object for the given
# input token.
# @param _terminal [Terminal] Terminal symbol associated with the token
# @param aTokenPosition [Integer] Position of token in the input stream
# @param aToken [Token] The input token
def new_leaf_node(_production, _terminal, aTokenPosition, aToken)
PTree::TerminalNode.new(aToken, aTokenPosition)
end
# Method to override.
# Factory method for creating a parent node object.
# @param aProduction [Production] Production rule
# @param aRange [Range] Range of tokens matched by the rule
# @param _tokens [Array] The input tokens
# @param theChildren [Array] Children nodes (one per rhs symbol)
def new_parent_node(aProduction, aRange, _tokens, theChildren)
node = Rley::PTree::NonTerminalNode.new(aProduction.lhs, aRange)
theChildren&.reverse_each { |child| node.add_subnode(child) }
node
end
end # class
end # module
end # module
# End of file
Version data entries
11 entries across 11 versions & 1 rubygems