https://bugs.exim.org/show_bug.cgi?id=1679
Bug ID: 1679
Summary: Ability to explicitly specify what to capture (feature
request)
Product: PCRE
Version: N/A
Hardware: All
OS: All
Status: NEW
Severity: wishlist
Priority: medium
Component: Code
Assignee: ph10@???
Reporter: henrik.hank@???
CC: pcre-dev@???
Hello,
it would be very helpful to be able to explicitly specify what the group being
in should capture. You should be able to specify original and other capture
strings when specifying what to capture for a group. The modified capture
string would be available for the replacement string. I'm unsure whether
following groups in the regular expression should see the original or the
modified capture string.
This feature is useful when doing find-and-replace according to a list--let me
put it like this--with two columns. I.e., replace A with B, C with D and E with
F. How else would you want to accomplish this than speciying the replacements
in the regular expression? So, I think, it's appropriate.
I tried to use existing features with Perl--with semi-satisfying results. This
Perl script does the job:
> print (("apple, cherry, lemon" =~ s/
> \bapple\b
> (*MARK:pear)
> |
> \bcherry\b
> (*MARK:strawberry)
> |
> \blemon\b
> (*MARK:lime)
> /$REGMARK/xgr) . "\n");
Output:
> pear, strawberry, lime
This also works:
> print (("a1a" =~ s/
> \d
> (*MARK:()
> /$REGMARK/xgr) . "\n");
This doesn't work:
> print (("a1a" =~ s/
> \d
> (*MARK:\))
> /$REGMARK/xgr) . "\n");
POSSIBLE SYNTAX
Subject string:
> apple, cherry, lemon
Regular expression with replacement syntax:
> (?x)
> \bapple\b
> (*CAPTURE:
> $0\ \(pear\)
> )
> |
> \bcherry\b
> (*CAPTURE:
> $0\ \(strawberry\)
> )
> |
> \blemon\b
> (*CAPTURE:
> $0\ \(lime\)
> )
Regular expression with consistent syntax:
> (?x)
> \bapple\b
> (*CAPTURE:
> \g{0}\ \(pear\)
> )
> |
> \bcherry\b
> (*CAPTURE:
> \g{0}\ \(strawberry\)
> )
> |
> \blemon\b
> (*CAPTURE:
> \g{0}\ \(lime\)
> )
Replacement string:
> $0
Result:
> apple (pear), cherry (strawberry), lemon (lime)
Are there any doubts/objections/contradictions?
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