free_mutant/lib/mutant/mutator/node/if_statement.rb

module Mutant
  class Mutator
    class Node
      # Mutator for Rubinius::AST::If nodes
      class IfStatement < self

        handle(Rubinius::AST::If)

      private

        # Emit mutations on Rubinius::AST::If nodes
        #
        # @return [undefined]
        #
        # @api private
        #
        def dispatch
          emit_condition_mutants
          emit_if_branch_mutants
          emit_else_branch_mutants
          emit_inverted_condition 
          emit_deleted_if_branch
          emit_deleted_else_branch
        end

        # Emit inverted condition
        #
        # Especially the same like swap branches but more universal as it also 
        # covers the case there is no else branch
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_inverted_condition
          emit_self(invert(condition), if_branch, else_branch)
        end

        # Emit deleted else branch
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_deleted_else_branch
          emit_self(condition, if_branch, nil)
        end

        # Emit deleted if branch
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_deleted_if_branch
          body = else_branch
          return unless body
          emit_self(condition, else_branch, nil)
        end

        # Return ast that returns inverted boolean value
        #
        # @param [Rubinius::Node::AST] node
        #
        # @return [Rubinius::Node::AST]
        #
        # @api private
        #
        # Using :'!' instead of :! since syntax highlighting in vim does not 
        # capture literal symbol.
        #
        def invert(node)
          if Helper.on_18?
            return new(Rubinius::AST::Not, node)
          end

          new_send(node,:'!')
        end

        # Emit mutants of condition
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_condition_mutants
          Mutator.each(condition) do |mutant|
            emit_self(mutant, if_branch, else_branch)
          end
        end

        # Emit if body mutations
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_if_branch_mutants
          Mutator.each(if_branch) do |mutant|
            emit_self(condition, mutant, else_branch)
          end
        end

        # Emit else body mutations
        #
        # @return [undefined]
        #
        # @api private
        #
        def emit_else_branch_mutants
          body = else_branch
          return unless body
          Mutator.each(body) do |mutant|
            emit_self(condition, if_branch, mutant)
          end
        end

        # Return if_branch of node
        #
        # @return [Rubinius::AST::Node]
        #
        # @api private
        #
        def if_branch
          node.body
        end

        # Return condition of node
        #
        # @return [Rubinius::AST::Node]
        #
        # @api private
        #
        def condition
          node.condition
        end

        # Return else body of node
        #
        # @return [Rubinius::AST::Node]
        #
        # @api private
        #
        def else_branch
          node.else
        end
      end
    end
  end
end