blob: d2552e2ca995c9831ee5555101f644cff1fcd388 [file] [log] [blame]
<?php if (!defined('PmWiki')) exit();
Copyright 2003,2004 Nils Knappmeier (
Copyright 2004 Patrick R. Michaud (
This file is part of PmWiki; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version. See pmwiki.php for full details.
This file implements a diff function in native PHP. It is based
upon the PHPDiffEngine code written by Nils Knappmeier, who in turn
had used Daniel Unterberger's diff
( as the basis for his code.
Pm's revision of Nils' code simply attempts to streamline it
for speed (eliminate function calls and unnecessary string ops)
and place everything into a single file.
## PHPDiff returns the differences between $old and $new, formatted
## in the standard diff(1) output format.
function PHPDiff($old,$new)
# split the source text into arrays of lines
$t1 = explode("\n",$old);
if ($x>'') $t1[]="$x\n\\ No newline at end of file";
$t2 = explode("\n",$new);
if ($x>'') $t2[]="$x\n\\ No newline at end of file";
# build a reverse-index array using the line as key and line number as value
# don't store blank lines, so they won't be targets of the shortest distance
# search
foreach($t1 as $i=>$x) if ($x>'') $r1[$x][]=$i;
foreach($t2 as $i=>$x) if ($x>'') $r2[$x][]=$i;
$a1=0; $a2=0; # start at beginning of each list
# walk this loop until we reach the end of one of the lists
while ($a1<count($t1) && $a2<count($t2)) {
# if we have a common element, save it and go to the next
if ($t1[$a1]==$t2[$a2]) { $actions[]=4; $a1++; $a2++; continue; }
# otherwise, find the shortest move (Manhattan-distance) from the
# current location
$best1=count($t1); $best2=count($t2);
$s1=$a1; $s2=$a2;
while(($s1+$s2-$a1-$a2) < ($best1+$best2-$a1-$a2)) {
foreach((array)@$r1[$t2[$s2]] as $n)
if ($n>=$s1) { $d=$n; break; }
if ($d>=$s1 && ($d+$s2-$a1-$a2)<($best1+$best2-$a1-$a2))
{ $best1=$d; $best2=$s2; }
foreach((array)@$r2[$t1[$s1]] as $n)
if ($n>=$s2) { $d=$n; break; }
if ($d>=$s2 && ($s1+$d-$a1-$a2)<($best1+$best2-$a1-$a2))
{ $best1=$s1; $best2=$d; }
$s1++; $s2++;
while ($a1<$best1) { $actions[]=1; $a1++; } # deleted elements
while ($a2<$best2) { $actions[]=2; $a2++; } # added elements
# we've reached the end of one list, now walk to the end of the other
while($a1<count($t1)) { $actions[]=1; $a1++; } # deleted elements
while($a2<count($t2)) { $actions[]=2; $a2++; } # added elements
# and this marks our ending point
# now, let's follow the path we just took and report the added/deleted
# elements into $out.
$op = 0;
$x0=$x1=0; $y0=$y1=0;
$out = array();
foreach($actions as $act) {
if ($act==1) { $op|=$act; $x1++; continue; }
if ($act==2) { $op|=$act; $y1++; continue; }
if ($op>0) {
$xstr = ($x1==($x0+1)) ? $x1 : ($x0+1).",$x1";
$ystr = ($y1==($y0+1)) ? $y1 : ($y0+1).",$y1";
if ($op==1) $out[] = "{$xstr}d{$y1}";
elseif ($op==3) $out[] = "{$xstr}c{$ystr}";
while ($x0<$x1) { $out[] = '< '.$t1[$x0]; $x0++; } # deleted elems
if ($op==2) $out[] = "{$x1}a{$ystr}";
elseif ($op==3) $out[] = '---';
while ($y0<$y1) { $out[] = '> '.$t2[$y0]; $y0++; } # added elems
$x1++; $x0=$x1;
$y1++; $y0=$y1;
$out[] = '';
return join("\n",$out);
$DiffFunction = 'PHPDiff';