"IMAP" Instruction remap extension

Fingerprint ID:0x494d4150

New in version 0.5-rc2.

This fingerprint, from RC/Funge-98, implements the commands remapping other commands. It provides the following commands:

C : —

Clears all command mappings.

M : newcmd oldcmd —

Makes the oldcmd does behave like the newcmd. newcmd itself is not affected.

O : cmd —

Restores the command cmd to the original function.

There are many options regarding to this fingerprint, due to a freedom allowed by the specification. PyFunge uses the following rules:

• Any command can be remapped. For example, you can set next cell to be executed to -42 and remap command -42 to z so IP won’t reflect. Of course, even you remap some command to the space it will take one tick.
• PyFunge does not support chained remapping, so M command always look up newcmd from the original command list. In the other words, if you remap v as ^ and ^ as v it won’t cause an infinite loop and rather swaps two commands. Despite that PyFunge’s structure makes the chained remap easier than non-chained remap, PyFunge sticks to this behavior since it prohibits an infinite loop.
• There is a distinction between actual commands and remappings: if ( and ) changes command mapping, it will change actual commands and won’t touch remappings. But after they are executed the original remapping will be restored. For example assuming X is remapped to Y, X command in the new fingerprint won’t affect both X and Y mappings, and Y will affect both X and Y.
• Even after IMAP fingerprint is unloaded, the mapping will be retained and could be changed after IMAP fingerprint is reloaded then.