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Re^4: Elegant way to split into sequences of identical chars?

by xdg (Monsignor)
on Nov 30, 2005 at 21:14 UTC ( #513117=note: print w/replies, xml ) Need Help??


in reply to Re^3: Elegant way to split into sequences of identical chars?
in thread Elegant way to split into sequences of identical chars?

Great suggestion! I forgot about regex debug mode. It looks like whatever the code in (??{ code }) evaluates to is compiled into a regex (if it isn't one already) and then that regex is applied in a separate scope from the rest of the regex -- so it has its own match variables and so on. I wouldn't have expected that given the documentation in perlre.

In the debug output, the telltales appear to be "Entering embedded..." and "restoring...", as seen below.

Entering embedded `(.)\1*' Setting an EVAL scope, savestack=31 0 <> <xx556xx> | 1: OPEN1 0 <> <xx556xx> | 3: REG_ANY 1 <x> <x556xx> | 4: CLOSE1 1 <x> <x556xx> | 6: CURLYX[1] {0,32767} 1 <x> <x556xx> | 10: WHILEM[1/1] 0 out of 0..32767 cc=140fafc Setting an EVAL scope, savestack=37 1 <x> <x556xx> | 8: REF1 2 <xx> <556xx> | 10: WHILEM[1/1] 1 out of 0..32767 cc=140fafc Setting an EVAL scope, savestack=43 2 <xx> <556xx> | 8: REF1 failed... failed, try continuation... 2 <xx> <556xx> | 11: NOTHING 2 <xx> <556xx> | 12: END Setting an EVAL scope, savestack=47 restoring \1 to -1(0)..1(no) restoring \1..\1 to undef

-xdg

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