Re: Using a regex to catch interpreters

I see three problems:

1)The [^>] in (?=[^>]*\n) can match newlines.

2) ">" isn't allowed anywhere on the ">>>" line (after the ">>>"). Is that intentional?

3) The second negative lookahead is currently anchored to the character right after the ">>>", not to the start of the next line.

Fixes:

s/
   (?<!^>>[^>])
   ^>>>
   (?=
      [^\n]*\n      # <-- removed < and added first \n
      (?!^>>[^>])   # <-- moved into (?=...)
   )
/PYTHON_PROMPT/xmg;
[download]

Updated

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Re^2: Using a regex to catch interpreters by ikegami (Patriarch) on Jul 06, 2005 at 06:52 UTC
Also, the above (like your original) won't work if anything appears after "`>>`" on the previous line (including spaces). For example, `>> text >>> text` [download] gets changed to `>> text PYTHON_PROMPT text` [download] Is that how it should be? Fixing this isn't easy, and it might be impossible without `$1` Update: Well, the following doesn't use `$1`. However, I don't know about effeciency (since I don't have another solution with which to compare). It works, though, which is more than I can say for my attempts that did use `$1`. Read more... (658 Bytes) `{ foreach ($_) { if (/\G (?= >>> )/xgc) { # Substitution supressed by following ">>". redo if /\G >>> [^\n]* \n (?= >> (?!>) ) /xcg; # Do substitution. s/\G >>>/PYTHON_PROMPT/xcg; # Go process next line. /\G [^\n]* \n /xcg; redo; } # Substitution prevented by preceeding ">>" /\G >> (?!>) [^\n]* \n >>> [^\n]* \n /xcg && redo; # ^^^^^ optional due to statement order. # Go process next line. m/\G [^\n]* \n /xcg && redo; } print; print("==========\n"); }` [download]	[reply] [d/l] [select]

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Re^2: Using a regex to catch interpreters
by ikegami (Patriarch) on Jul 06, 2005 at 06:52 UTC

Also, the above (like your original) won't work if anything appears after ">>" on the previous line (including spaces). For example,

>> text
>>> text
[download]

gets changed to

>> text
PYTHON_PROMPT text
[download]

Is that how it should be? Fixing this isn't easy, and it might be impossible without $1

Update: Well, the following doesn't use $1. However, I don't know about effeciency (since I don't have another solution with which to compare). It works, though, which is more than I can say for my attempts that did use $1.

Read more... (658 Bytes)

{
   foreach ($_) {
      if (/\G (?= >>> )/xgc) {
         # Substitution supressed by following ">>".
         redo if /\G >>> [^\n]* \n (?= >> (?!>) ) /xcg;

         # Do substitution.
         s/\G >>>/PYTHON_PROMPT/xcg;

         # Go process next line.
         /\G [^\n]* \n /xcg;
         redo;
      }

      # Substitution prevented by preceeding ">>"
      /\G >> (?!>) [^\n]* \n >>> [^\n]* \n /xcg && redo;
           # ^^^^^ optional due to statement order.

      # Go process next line.
      m/\G [^\n]* \n /xcg && redo;
   }

   print;
   print("==========\n");
}
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