My instances can interpret the byte-encoded Smalltalk instruction set. They maintain a program counter (pc) for streaming through CompiledMethods. My subclasses are Contexts, which inherit this capability. They store the return pointer in the instance variable sender, and the current position in their method in the instance variable pc. For other users, sender can hold a method to be similarly interpreted. The unclean re-use of sender to hold the method was to avoid a trivial subclass for the stand-alone scanning function.

	private
	interpretExtension:in:for: method:pc:

	scanning
	addSelectorTo: followingByte method nextByte pc scanFor: skipBackBeforeJump thirdByte

	testing
	willJumpIfFalse willJumpIfTrue willReallySend willReturn willSend willStore willStorePop

	instance creation
	on:

	decoding	top
	interpretJump
	interpretNextInstructionFor: Send to the argument, client, a message that specifies the type of the next instruction.

	private	top
	interpretExtension:in:for:
	method:pc:

	scanning	top
	addSelectorTo: If this instruction is a send, add its selector to set.
	followingByte Answer the next bytecode.
	method Answer the compiled method that supplies the receiver's bytecodes.
	nextByte Answer the next bytecode.
	pc Answer the index of the next bytecode.
	scanFor: Answer the index of the first bytecode for which scanBlock answer true when supplied with that bytecode.
	skipBackBeforeJump Assuming that the receiver is positioned jast after a jump, skip back one or two bytes, depending on the size of the previous jump instruction.
	thirdByte Answer the next bytecode.

	testing	top
	willJumpIfFalse Answer whether the next bytecode is a jump-if-false.
	willJumpIfTrue Answer whether the next bytecode is a jump-if-true.
	willReallySend Answer whether the next bytecode is a real message-send, not blockCopy:.
	willReturn Answer whether the next bytecode is a return.
	willSend Answer whether the next bytecode is a message-send.
	willStore Answer whether the next bytecode is a store or store-pop
	willStorePop Answer whether the next bytecode is a store-pop.

	class initialization	top
	initialize Initialize an array of special constants returned by single-bytecode returns.

	instance creation	top
	on: Answer an instance of me on the argument, method.