[Pmwiki-users] PHP Diff Engine
Thu Sep 23 15:45:51 CDT 2004
>Just to recap my previous concerns about PHP-based diff algorithms;
>many PHP installations have limits on the maximum amount of memory
>available for the script to use -- by default this is usually set to
>8 megabytes. So, if we have a diff algorithm that requires a M x N
>table to compare texts of M and N lines, then we can quickly find ourselves
It's been a while since I wrote it, but I think NxM memory is only the
The matching-matrix is not built in this version and in the matrix to
remember to path
back to the source is only filled for the visited nodes. There are some
other optimizations, such that, everything depends on the size the
If you have a 1000 lines page and you change or add 5 lines, you should
Delete 100 lines and replaces them by hundred completely different lines
and you might screw up.
>running out of memory when the texts reach a few hundred lines or so.
>But I'm guessing that's apparently not much of a problem since nobody
>using the PHPDiffEngine seems to have reported it... :)
The version in the cookbook definitly doesn't need so much memory. And
should run in n*log n time. The drawback are sometimes bad results...
The great thing about being the only species that makes
a distinction between right and wrong is that we can
make up the rules for ourselves as we go along.
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