tweak regexp engine debugging output #23978
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(This commit makes no practical changes in behaviour except for
debugging output.)
Currently, one of the regex engine stack states is EVAL_postponed_AB.
When executing something like /(??{'A'})B/ where A and represent
general subpatterns, the engine executes the eval code, which returns
the string 'A', which is compiled into a subpattern. Then the engine
pushes an EVAL_postponed_AB state and runs the subpattern until it
reaches an END op. Then it pushes *another* EVAL_postponed_AB state and
runs the B part of the pattern until the final END. Then before
returning success, it pops EVAL_postponed_AB off the stack (twice),
executing any cleanup required. Similarly during failure, the
EVAL_postponed_AB_fail action will be executed once or twice (depending
on whether it failed during A or B).
This commit splits that state into two,
EVAL_postponed_A
EVAL_postponed_B
The first is pushed before running A, the second before running B.
The actions currently remain the same and share the same code; i.e. this
commit just does the equivalent of:
- case EVAL_postponed_AB:
+ case EVAL_postponed_A:
+ case EVAL_postponed_B:
... cleanup code ....
But it makes the code easier to understand, makes debugging output
clearer, and will allow in future for the cleanup behaviours to differ
between A and B.
This commit also fixes up a few debugging messages and code comments
which were still referring to 'EVAL_AB', which was renamed to
EVAL_postponed_AB some years ago.
khwilliamson
approved these changes
Dec 2, 2025
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khwilliamson
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khwilliamson
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2nd commit message doesn't make sense When executing something like /(??{'A'})B/ where A and represent
Otherwise lgtm
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These two commits contain minor improvements to the debugging output produced by the regex engine.