Class: TireSwing::Visitor

Inherits:
Object show all
Defined in:
lib/tire_swing/visitor.rb

Overview

Represents a visitor for an AST. See TireSwing::VisitorDefinition more more information.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.visit(node, *args) ⇒ Object

delegates to a new instance of the visitor class



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# File 'lib/tire_swing/visitor.rb', line 20

def visit(node, *args)
  visitor = new
  visitor.visit(node, *args)
end

.visitor_for(node) ⇒ Object

Look up a visitor block for this node



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# File 'lib/tire_swing/visitor.rb', line 26

def visitor_for(node)
  nodes[node.class] or raise "could not find visitor definition for #{node.class}: #{node.inspect}"
end

.visits(*constants, &blk) ⇒ Object

Describe a visitor block for a given node type. If no block is given, an empty lambda is used. The block always takes at least one argument, an instance of the node you’re visiting, as well as any additional arguments if desired.



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# File 'lib/tire_swing/visitor.rb', line 13

def visits(*constants, &blk)
  constants.each do |constant|
    nodes[constant] = (blk || lambda {})
  end
end

Instance Method Details

#visit(node, *args) ⇒ Object

Visit the given node using the visitor mapping defined with .visits. This finds the block to call for the given node and calls it with the node and additional arguments, if any.

Raises an exception if no visitor is found for the given node.



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# File 'lib/tire_swing/visitor.rb', line 44

def visit(node, *args)
  block = self.class.visitor_for(node)
  if args.empty?
    block.call(node)
  else
    block.call(node, *args)
  end
end