Re: Stack overflow in regexp matcher

[Barry Margolin]

In article <8u-dncYjy6Q3iLTWnZ2dnUVZ8nKdnZ2d@posted.visi>,
 "akaiser@visi.com" <akaiser@visi.com> wrote:

> A function of mine gets "Stack overflow in regexp matcher" on a certain 
> file using the regexp
> 
>      "^< \\(.+].+=|\\)"
> 
> The file is a single line of about 73000 characters, but the regexp matches 
> ending at character 56.
> 
> Is this a bug?  And if not, why not?
> 
> djc

The problem is that + is greedy, so this has to scan the entire line 
looking for the last "]", then see if there's an "=" somewhere later.  
If it can't find an "=" it has to back up to the previous "]" and search 
again, and so on.  If there are lots of "]" characters, this has to save 
the state of each of them in the matching stack.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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