1.5.1 CodeString

A CodeString looks rather like a list. It sprouts all the list-emulation methods __getitem__, __len__, __delslice__, index, etc, along with some extra bits.

The main point of the class is to keep jumps under control. You can add or remove opcodes as you like and jumps that aren't directly involved are unaffected. What happens to jumps that target affected opcodes is detailed in the method descriptions below.

CodeString ([cs])

Initialize the codestring with code from cs, if supplied. Otherwise create an empty codestring. cs can be any code-y object, i.e. a codestring, code object, function or method.

disassemble (codestring)

I'm not sure this function is well named or necessary. Nevertheless, it initializes the CodeString from codestring, splitting it into bytecodes, creating the opcode objects and resolving jumps.

add_label (label)

Add label to the CodeString's list of labels.

find_labels (index)

Return a list of labels that point to the indexth opcode.

assembles ()

Return a string that represents the CodeString's present state.

The list methods all do what you would expect them to; the descriptions only mention what happens to labels that point at affected blocks.

__getitem__ (index)

__setitem__ (index,value)

Labels pointing to the replaced opcode are directed at the freshly inserted opcode.

__delitem__ (index)

Labels targeting the deleted item are directed to the following opcode, unless it's the last, in which case they are directed to what has become the last opcode.

__getslice__ (lo,hi)

__setslice__ (lo,hi,values)

Labels pointing into the block being stomped on are redirected to the start of the block being inserted. If there are labels pointing into the block being stomped on, rather than at it's start, a warning is printed, because that is a bit dodgy.

__delslice__ (lo,hi)

Labels that point into the block being stomped on get attached to what immediately follows the block, unless the end is being deleted, then they are attached to what is now the last opcode.

__len__ ()

append (value)

extend (list)

remove (x)

Behaves like __delitem__, i.e. labels targeting the deleted item are directed to the following opcode, unless it's the last, in which case they are directed to what has become the last opcode.

index (x)

As mentioned in the overview, funky acquisition stuff means that opcodes you think should actually be the same object may well not be. However opcodes define a __cmp__ method that performs logical is style matching, so the method behaves how you would expect it to.

opcodes

The list of opcodes. Probably best not to access this directly.

byte2op

A dictionary mapping byte offsets into indices into the opcodes list. Only valid from construction until the first mutation of the code string, so again probably best left alone.

labels

A list of labels that point to bits of the codestring.

code

The EditableCode that the code is part of.