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STKPOP
Description
Pop a snapshot from the top of the “stack of stacks” onto the current stack. Current stack contents will be overwritten and lost, and the snapshot will be removed from the “stack of stacks”.
Stack Diagram
Input Stack | Output Stack | |
---|---|---|
… | → | O… |
N Levels | → | M Levels |
Support for inclusion in symbolic expressions |
Support for parallel list processing |
Affected by flags |
Compatibility
This command is new in newRPL, does not exist in userRPL.
Usage
The following program:
« 123 456 789 STKPUSH CLEAR 999 STKPOP »
the numbers 123, 456, 789 will appear on the stack, while the 999 is lost when STKPOP
restores the snapshot.
Related Commands
Command | Short Description | |
---|---|---|
CLEAR | Remove all objects from the stack | |
DEPTH | Get the current stack depth | |
DROP | Remove an object from the stack | |
DROP2 | Remove two objects form the stack | |
DROPN | Remove N objects from the stack | |
DUP | Duplicate an object on the stack | |
DUP2 | Duplicate two objects on the stack | |
DUPDUP | Duplicate the same object twice on the stack | |
DUPN | Duplicate a group of N objects | |
NDUPN | Replicate one object N times and return N | |
NIP | Remove object at level 2 on the stack | |
OVER | Duplicate object at level 2 on the stack | |
PICK | Duplicate object at position N on the stack | |
PICK3 | Duplicate object at level 3 on the stack | |
ROLL | Move object at level N to level 1 | |
ROLLD | Move object from level 1 to level N | |
ROT | Move object from level 3 to level 1 | |
SWAP | Exchange objects in levels 1 and 2 | |
UNPICK | Move object from level 1 to level N. | |
UNROT | Move object from level 1 to level 3 | |
IFT | Evaluate objects on the stack conditionally | |
IFTE | Evaluate objects on the stack conditionally | |
STKPUSH | Push a snapshot of the current stack on the undo stack | NEW |
STKPOP | Pop a stack snapshot from the undo stack | NEW |
STKDROP | Drop a snapshot from the undo stack | NEW |
STKPICK | Copy snapshot in level N to the current stack | NEW |
STKDEPTH | Get the depth of the undo stack | NEW |