Module: Filigree::Visitable

Defined in:
lib/filigree/visitor.rb

Overview

This module provides a default implementation of three common traversal patterns: pre-order, post-order, and in-order (level-order). The including class must implement the ‘children` function.

Instance Method Summary collapse

Instance Method Details

#visit(visitor, method = :preorder) ⇒ Boolean

Visit this object with the provided visitor in pre-, post-, or in-order traversal.

Parameters:

  • visitor (Visitor) —

    Visitor to call

  • method (:preorder, :inorder, :postorder, :downup) (defaults to: :preorder) —

    How to visit

Returns:

  • (Boolean) —

    If a pattern matched or not



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# File 'lib/filigree/visitor.rb', line 237

def visit(visitor, method = :preorder)
	case method
	when :preorder
		res = (visitor.visit(self) != MatchError)
		children.flatten.compact.inject(false) { |mod, child| child.visit(visitor, :preorder) || mod } || res

	when :inorder
		mod   = false
		nodes = [self]

		# Not all Ruby implementations support modifying arrays while
		# you are iterating over them.
		while node = nodes.shift
			nodes += node.children.flatten.compact
			mod = visitor.visit(node) || mod
		end

		mod

	when :postorder
		res = children.flatten.compact.inject(false) { |mod, child| child.visit(visitor, :postorder) || mod }
		(visitor.visit(self) != MatchError) || res

	when :downup
		res = (visitor.visit(self) != MatchError)
		res = children.flatten.compact.inject(false) { |mod, child| child.visit(visitor, :downup) || mod } || res
		(visitor.visit(self) != MatchError) || res
	end
end