The visitor pattern allows functionality to be added to a number of classes
(or in this case one class, Instruction, that can vary in
behavior) without modifying the classes themselves. Additionally, the visitor
pattern simulates double dispatching. For instance visit method of
Instruction calls a particular method of
InstructionVisitor based on the Instruction's opcode.
InstructionVisitor provides an interface for performing actions
based on the instruction type. Classes implementing this interface should not
be able to miss any of the instruction types. This interface was created as
an alternative to having 138 different subtypes of Instruction.
See Also:Instruction.visit See Also:EDU.purdue.cs.bloat.tree.Tree author: Nate Nystrom (author: href="mailto:nystrom@cs.purdue.edu">nystrom@cs.purdue.edu)