in reply to Using a regex to catch interpreters

The following assumes the entire text in a single scalar, and leaves lines starting with four >'s alone as well. 
s/^>>>(?!>)(?![^\n]*\n>>(?!>))/PYTHON_PROMPT/gm;

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Also, I'd prefer to avoid $1 if possible, for performance reasons.
That's a strange remark. You're willing to use regexes, and even Perl, but not $1, "for performance reasons". Apparently, performance is very important to you. In that case, you ought to use C - what you want to do isn't too hard in C.

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Re^2: Using a regex to catch interpreters
by eastcoastcoder (Sexton) on Jul 06, 2005 at 14:53 UTC
    Clarification: 
    
>>> etc
>>> etc
>>> etc

should be converted to
PYTHON_PROMPT etc
PYTHON_PROMPT etc
PYTHON_PROMPT etc

while
>>> etc
>>> etc
>> etc
should not.

So, those read aheads / arrays / etc won't work, will they?

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    Also, re not using $1 for performance - it's not so much that I mind for this regex, it's that I'm under the impression that once you use $1 once, perl needs to track it for every regex in the entire program... which I don't want to slow down. Is there a way to tell Perl to only turn on $1 here, but no where else...

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[d/l]
      it's that I'm under the impression that once you use $1 once, perl needs to track it for every regex in the entire program...

      You're thinking of $&, $` and $'. They are always set by all regexps when they are used anywhere in the program.

      $1 .. $9 are always set by every regexps that succeeds. When a given regexp has no corresponding capture, they are set to undefined. No attention is payed to whether $1 .. $9 are used anywhere.

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[d/l]
[select]
      Speaking of test, here's some code I wrote to do basic testing 
      use Test::Simple tests => 7;

sub cpi
{
# the converter goes here
}

$a =
'>> no snake here
>>> or here

I agree';

$b =
'>> and neither should this
>>> be understood snakily
>>> because it is a nested quote
>> yes I know it is not really named after a snake
';

$c =
'>>
>>>no snake
>>>no snake
';

$d=
'>>> still no snake seen
>> right!
';

$snakea =
'>>> i = j
';

$snakeb =
'>>> i = j + 1
>>> q

is good code';

$snakec = 
'>> does this work right?
lets see:
>>> i = test(func)
';

ok (cpi($a) eq $a);
ok (cpi($b) eq $b);
ok (cpi($c) eq $c);
ok (cpi($d) eq $d);

ok (cpi($snakea) eq 
'PYTHON_PROMPT_PROTECTED i = j
');
ok (cpi($snakeb) eq
'PYTHON_PROMPT_PROTECTED i = j + 1
PYTHON_PROMPT_PROTECTED q

is good code');
ok(cpi($snakec) eq
'>> does this work right?
lets see:
PYTHON_PROMPT_PROTECTED i = test(func)
');

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[d/l]
Re^2: Using a regex to catch interpreters
by eastcoastcoder (Sexton) on Jul 07, 2005 at 17:30 UTC
    Please see my test cases below - your code failed 6 out of 7!
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