[asterisk-dev] [Code Review] Add stack-like functions for manipulating comma-separated lists in the dialplan

[Terry Wilson]

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http://reviewboard.digium.com/r/230/
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Review request for Asterisk Developers.


Summary
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Currently there exists the ARRAY() dialplan function for setting multiple variables to the values in a comma-separated list.  This is only useful if the size of the list is known beforehand.  This patch adds the functions SHIFT(), POP(), and PUSH() for dealing with comma-separated lists of unknown length.  PUSH() and POP() add and remove a value to the end of the list (top of the stack), while SHIFT() removes a value from the front of a list.

I originally found a need for this when working on my calendaring branch.  I needed to be able to return a list of attendees to the dialplan and to be able to iterate over them.  As an example, I can now do something like:
exten => s,1,Set(attendees=${EVENT_ATTENDEES()})
exten => s,n,While($[${SET(attendee=${SHIFT(attendees)})}])
exten => s,n,NoOp(Attendee is ${attendee})
exten => s,n,EndWhile

instead of having to mess with using CUT(), maintaining a count for the offset, etc.  From what I can tell perl, python, and php all consider push and pop to operate on the "right-hand" side of a list.


Diffs
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  /trunk/funcs/func_strings.c 189273 

Diff: http://reviewboard.digium.com/r/230/diff


Testing
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I've tested most of the cases I can think of, like pushing to non-existent variables, pushing multiple values, shift and pop with a variable with a single or multiple entries, etc.


Thanks,

Terry