Perl不匹配正则表达式？

Question

I'm trying to remove all the comments in a bunch of SGF files, and have come up with the following perl command:

perl -pi -e 's/P?C\[(?:[^\]\\]++|\\.)*+\]//gm' *.sgf

I'm trying to match and remove a C or PC followed by a left bracket, then characters that aren't right brackets (if they are they have to be escaped with a \\ ) and then a right bracket.

I'm trying to match the following examples:

C[HelloBot9 [-\\]: GTP Engine for HelloBot9 (white): HelloBot version 0.6.26.08]

PC[IA [-\]: GTP Engine for IA (black): GNU Go version 3.7.11
]

C[person [-\\]: \\\\\\]]

C[AyaMC [3k\]: GTP Engine for AyaMC (black): Aya version 6.61 : If you pass, AyaMC 
will pass. When AyaMC does not, please remove all dead stones.]

And some examples that shouldn't be matched:

XYZ[Other stuff \\]]

C[stuff\\]

PC[stuff\\\\\\]

The regex works in several online regex testers (including a few that state they are perl regex testers), but for some reason doesn't work on the command line. Help is appreciated.

Answer 1

You need to run perl with -0777 option to make sure that contents spanning across lines and matching the pattern can be found. So, using perl -0777pi -e instead of perl -pi -e will solve the issue.

I would also suggest optimizing the pattern a bit by unrolling the alternation group, thus, making matching process "linear":

s/P?C\[[^]\\]*(?:\\.[^]\\]*+)*]//sg

Note that if PC should be matched as a whole word, add \\b before P .

Pattern details :

• P?C\\[ - either PC[ or C[ literal char sequence
• [^]\\\\]* - zero or more chars other than \\ and ]
• (?:\\\\.[^]\\\\]*+)* - zero or more sequences of:
  • \\\\. - a literal \\ and then any char ( . )
  • [^]\\\\]*+ - 0+ chars other than ] and \\ (matched possessively, no backtracking into the pattern)
• ] - a literal ] symbol (note it does not have to be escaped outside the character class to denote a literal closing bracket)