Rename lib/dokuwiki to vendors/dokuwiki

1 files changed, 1066 insertions, 0 deletions

diff --git a/vendors/dokuwiki/inc/DifferenceEngine.php b/vendors/dokuwiki/inc/DifferenceEngine.php
new file mode 100644
index 000000000..e28826c1f
--- /dev/null
+++ b/vendors/dokuwiki/inc/DifferenceEngine.php
@@ -0,0 +1,1066 @@
+<?php
+/**
+ * A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
+ *
+ * Additions by Axel Boldt for MediaWiki
+ *
+ * @copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
+ * @license  You may copy this code freely under the conditions of the GPL.
+ */
+define('USE_ASSERTS', function_exists('assert'));
+
+class _DiffOp {
+  var $type;
+  var $orig;
+  var $closing;
+
+  function reverse() {
+    trigger_error("pure virtual", E_USER_ERROR);
+  }
+
+  function norig() {
+    return $this->orig ? sizeof($this->orig) : 0;
+  }
+
+  function nclosing() {
+    return $this->closing ? sizeof($this->closing) : 0;
+  }
+}
+
+class _DiffOp_Copy extends _DiffOp {
+  var $type = 'copy';
+
+  function _DiffOp_Copy ($orig, $closing = false) {
+    if (!is_array($closing))
+      $closing = $orig;
+    $this->orig = $orig;
+    $this->closing = $closing;
+  }
+
+  function reverse() {
+    return new _DiffOp_Copy($this->closing, $this->orig);
+  }
+}
+
+class _DiffOp_Delete extends _DiffOp {
+  var $type = 'delete';
+
+  function _DiffOp_Delete ($lines) {
+    $this->orig = $lines;
+    $this->closing = false;
+  }
+
+  function reverse() {
+    return new _DiffOp_Add($this->orig);
+  }
+}
+
+class _DiffOp_Add extends _DiffOp {
+  var $type = 'add';
+
+  function _DiffOp_Add ($lines) {
+    $this->closing = $lines;
+    $this->orig = false;
+  }
+
+  function reverse() {
+    return new _DiffOp_Delete($this->closing);
+  }
+}
+
+class _DiffOp_Change extends _DiffOp {
+  var $type = 'change';
+
+  function _DiffOp_Change ($orig, $closing) {
+    $this->orig = $orig;
+    $this->closing = $closing;
+  }
+
+  function reverse() {
+    return new _DiffOp_Change($this->closing, $this->orig);
+  }
+}
+
+
+/**
+ * Class used internally by Diff to actually compute the diffs.
+ *
+ * The algorithm used here is mostly lifted from the perl module
+ * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
+ *   http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
+ *
+ * More ideas are taken from:
+ *   http://www.ics.uci.edu/~eppstein/161/960229.html
+ *
+ * Some ideas are (and a bit of code) are from from analyze.c, from GNU
+ * diffutils-2.7, which can be found at:
+ *   ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
+ *
+ * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
+ * are my own.
+ *
+ * @author Geoffrey T. Dairiki
+ * @access private
+ */
+class _DiffEngine
+{
+  function diff ($from_lines, $to_lines) {
+    $n_from = sizeof($from_lines);
+    $n_to = sizeof($to_lines);
+
+    $this->xchanged = $this->ychanged = array();
+    $this->xv = $this->yv = array();
+    $this->xind = $this->yind = array();
+    unset($this->seq);
+    unset($this->in_seq);
+    unset($this->lcs);
+
+    // Skip leading common lines.
+    for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
+      if ($from_lines[$skip] != $to_lines[$skip])
+        break;
+      $this->xchanged[$skip] = $this->ychanged[$skip] = false;
+    }
+    // Skip trailing common lines.
+    $xi = $n_from; $yi = $n_to;
+    for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
+      if ($from_lines[$xi] != $to_lines[$yi])
+        break;
+      $this->xchanged[$xi] = $this->ychanged[$yi] = false;
+    }
+
+    // Ignore lines which do not exist in both files.
+    for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
+      $xhash[$from_lines[$xi]] = 1;
+    for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
+      $line = $to_lines[$yi];
+      if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
+        continue;
+      $yhash[$line] = 1;
+      $this->yv[] = $line;
+      $this->yind[] = $yi;
+    }
+    for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
+      $line = $from_lines[$xi];
+      if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
+        continue;
+      $this->xv[] = $line;
+      $this->xind[] = $xi;
+    }
+
+    // Find the LCS.
+    $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
+
+    // Merge edits when possible
+    $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
+    $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
+
+    // Compute the edit operations.
+    $edits = array();
+    $xi = $yi = 0;
+    while ($xi < $n_from || $yi < $n_to) {
+      USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
+      USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
+
+      // Skip matching "snake".
+      $copy = array();
+      while ( $xi < $n_from && $yi < $n_to
+          && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
+        $copy[] = $from_lines[$xi++];
+        ++$yi;
+      }
+      if ($copy)
+        $edits[] = new _DiffOp_Copy($copy);
+
+      // Find deletes & adds.
+      $delete = array();
+      while ($xi < $n_from && $this->xchanged[$xi])
+        $delete[] = $from_lines[$xi++];
+
+      $add = array();
+      while ($yi < $n_to && $this->ychanged[$yi])
+        $add[] = $to_lines[$yi++];
+
+      if ($delete && $add)
+        $edits[] = new _DiffOp_Change($delete, $add);
+      elseif ($delete)
+        $edits[] = new _DiffOp_Delete($delete);
+      elseif ($add)
+        $edits[] = new _DiffOp_Add($add);
+    }
+    return $edits;
+  }
+
+
+  /**
+   * Divide the Largest Common Subsequence (LCS) of the sequences
+   * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
+   * sized segments.
+   *
+   * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
+   * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
+   * sub sequences.  The first sub-sequence is contained in [X0, X1),
+   * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
+   * that (X0, Y0) == (XOFF, YOFF) and
+   * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
+   *
+   * This function assumes that the first lines of the specified portions
+   * of the two files do not match, and likewise that the last lines do not
+   * match.  The caller must trim matching lines from the beginning and end
+   * of the portions it is going to specify.
+   */
+  function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
+  $flip = false;
+
+  if ($xlim - $xoff > $ylim - $yoff) {
+    // Things seems faster (I'm not sure I understand why)
+      // when the shortest sequence in X.
+      $flip = true;
+    list ($xoff, $xlim, $yoff, $ylim)
+    = array( $yoff, $ylim, $xoff, $xlim);
+    }
+
+  if ($flip)
+    for ($i = $ylim - 1; $i >= $yoff; $i--)
+    $ymatches[$this->xv[$i]][] = $i;
+  else
+    for ($i = $ylim - 1; $i >= $yoff; $i--)
+    $ymatches[$this->yv[$i]][] = $i;
+
+  $this->lcs = 0;
+  $this->seq[0]= $yoff - 1;
+  $this->in_seq = array();
+  $ymids[0] = array();
+
+  $numer = $xlim - $xoff + $nchunks - 1;
+  $x = $xoff;
+  for ($chunk = 0; $chunk < $nchunks; $chunk++) {
+    if ($chunk > 0)
+    for ($i = 0; $i <= $this->lcs; $i++)
+      $ymids[$i][$chunk-1] = $this->seq[$i];
+
+    $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
+    for ( ; $x < $x1; $x++) {
+        $line = $flip ? $this->yv[$x] : $this->xv[$x];
+        if (empty($ymatches[$line]))
+      continue;
+    $matches = $ymatches[$line];
+        reset($matches);
+    while (list ($junk, $y) = each($matches))
+      if (empty($this->in_seq[$y])) {
+      $k = $this->_lcs_pos($y);
+      USE_ASSERTS && assert($k > 0);
+      $ymids[$k] = $ymids[$k-1];
+      break;
+          }
+    while (list ($junk, $y) = each($matches)) {
+      if ($y > $this->seq[$k-1]) {
+      USE_ASSERTS && assert($y < $this->seq[$k]);
+      // Optimization: this is a common case:
+      //  next match is just replacing previous match.
+      $this->in_seq[$this->seq[$k]] = false;
+      $this->seq[$k] = $y;
+      $this->in_seq[$y] = 1;
+          }
+      else if (empty($this->in_seq[$y])) {
+      $k = $this->_lcs_pos($y);
+      USE_ASSERTS && assert($k > 0);
+      $ymids[$k] = $ymids[$k-1];
+          }
+        }
+      }
+    }
+
+  $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
+  $ymid = $ymids[$this->lcs];
+  for ($n = 0; $n < $nchunks - 1; $n++) {
+    $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
+    $y1 = $ymid[$n] + 1;
+    $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
+    }
+  $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
+
+  return array($this->lcs, $seps);
+  }
+
+  function _lcs_pos ($ypos) {
+  $end = $this->lcs;
+  if ($end == 0 || $ypos > $this->seq[$end]) {
+    $this->seq[++$this->lcs] = $ypos;
+    $this->in_seq[$ypos] = 1;
+    return $this->lcs;
+    }
+
+  $beg = 1;
+  while ($beg < $end) {
+    $mid = (int)(($beg + $end) / 2);
+    if ( $ypos > $this->seq[$mid] )
+    $beg = $mid + 1;
+    else
+    $end = $mid;
+    }
+
+  USE_ASSERTS && assert($ypos != $this->seq[$end]);
+
+  $this->in_seq[$this->seq[$end]] = false;
+  $this->seq[$end] = $ypos;
+  $this->in_seq[$ypos] = 1;
+  return $end;
+  }
+
+  /**
+   * Find LCS of two sequences.
+   *
+   * The results are recorded in the vectors $this->{x,y}changed[], by
+   * storing a 1 in the element for each line that is an insertion
+   * or deletion (ie. is not in the LCS).
+   *
+   * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
+   *
+   * Note that XLIM, YLIM are exclusive bounds.
+   * All line numbers are origin-0 and discarded lines are not counted.
+   */
+  function _compareseq ($xoff, $xlim, $yoff, $ylim) {
+  // Slide down the bottom initial diagonal.
+  while ($xoff < $xlim && $yoff < $ylim
+         && $this->xv[$xoff] == $this->yv[$yoff]) {
+    ++$xoff;
+    ++$yoff;
+    }
+
+  // Slide up the top initial diagonal.
+  while ($xlim > $xoff && $ylim > $yoff
+         && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
+    --$xlim;
+    --$ylim;
+    }
+
+  if ($xoff == $xlim || $yoff == $ylim)
+    $lcs = 0;
+  else {
+    // This is ad hoc but seems to work well.
+    //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
+    //$nchunks = max(2,min(8,(int)$nchunks));
+    $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
+    list ($lcs, $seps)
+    = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
+    }
+
+  if ($lcs == 0) {
+    // X and Y sequences have no common subsequence:
+    // mark all changed.
+    while ($yoff < $ylim)
+    $this->ychanged[$this->yind[$yoff++]] = 1;
+    while ($xoff < $xlim)
+    $this->xchanged[$this->xind[$xoff++]] = 1;
+    }
+  else {
+    // Use the partitions to split this problem into subproblems.
+    reset($seps);
+    $pt1 = $seps[0];
+    while ($pt2 = next($seps)) {
+    $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
+    $pt1 = $pt2;
+      }
+    }
+  }
+
+  /**
+   * Adjust inserts/deletes of identical lines to join changes
+   * as much as possible.
+   *
+   * We do something when a run of changed lines include a
+   * line at one end and has an excluded, identical line at the other.
+   * We are free to choose which identical line is included.
+   * `compareseq' usually chooses the one at the beginning,
+   * but usually it is cleaner to consider the following identical line
+   * to be the "change".
+   *
+   * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
+   */
+  function _shift_boundaries ($lines, &$changed, $other_changed) {
+  $i = 0;
+  $j = 0;
+
+  USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
+  $len = sizeof($lines);
+  $other_len = sizeof($other_changed);
+
+  while (1) {
+    /*
+     * Scan forwards to find beginning of another run of changes.
+     * Also keep track of the corresponding point in the other file.
+     *
+     * Throughout this code, $i and $j are adjusted together so that
+     * the first $i elements of $changed and the first $j elements
+     * of $other_changed both contain the same number of zeros
+     * (unchanged lines).
+     * Furthermore, $j is always kept so that $j == $other_len or
+     * $other_changed[$j] == false.
+     */
+    while ($j < $other_len && $other_changed[$j])
+    $j++;
+
+    while ($i < $len && ! $changed[$i]) {
+    USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
+    $i++; $j++;
+    while ($j < $other_len && $other_changed[$j])
+      $j++;
+      }
+
+    if ($i == $len)
+    break;
+
+    $start = $i;
+
+    // Find the end of this run of changes.
+    while (++$i < $len && $changed[$i])
+    continue;
+
+    do {
+    /*
+     * Record the length of this run of changes, so that
+     * we can later determine whether the run has grown.
+     */
+    $runlength = $i - $start;
+
+    /*
+     * Move the changed region back, so long as the
+     * previous unchanged line matches the last changed one.
+     * This merges with previous changed regions.
+     */
+    while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
+      $changed[--$start] = 1;
+      $changed[--$i] = false;
+      while ($start > 0 && $changed[$start - 1])
+      $start--;
+      USE_ASSERTS && assert('$j > 0');
+      while ($other_changed[--$j])
+      continue;
+      USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
+        }
+
+    /*
+     * Set CORRESPONDING to the end of the changed run, at the last
+     * point where it corresponds to a changed run in the other file.
+     * CORRESPONDING == LEN means no such point has been found.
+     */
+    $corresponding = $j < $other_len ? $i : $len;
+
+    /*
+     * Move the changed region forward, so long as the
+     * first changed line matches the following unchanged one.
+     * This merges with following changed regions.
+     * Do this second, so that if there are no merges,
+     * the changed region is moved forward as far as possible.
+     */
+    while ($i < $len && $lines[$start] == $lines[$i]) {
+      $changed[$start++] = false;
+      $changed[$i++] = 1;
+      while ($i < $len && $changed[$i])
+      $i++;
+
+      USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
+      $j++;
+      if ($j < $other_len && $other_changed[$j]) {
+      $corresponding = $i;
+      while ($j < $other_len && $other_changed[$j])
+        $j++;
+          }
+        }
+      } while ($runlength != $i - $start);
+
+    /*
+     * If possible, move the fully-merged run of changes
+     * back to a corresponding run in the other file.
+     */
+    while ($corresponding < $i) {
+    $changed[--$start] = 1;
+    $changed[--$i] = 0;
+    USE_ASSERTS && assert('$j > 0');
+    while ($other_changed[--$j])
+      continue;
+    USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
+      }
+    }
+  }
+}
+
+/**
+ * Class representing a 'diff' between two sequences of strings.
+ */
+class Diff
+{
+  var $edits;
+
+  /**
+   * Constructor.
+   * Computes diff between sequences of strings.
+   *
+   * @param $from_lines array An array of strings.
+   *      (Typically these are lines from a file.)
+   * @param $to_lines array An array of strings.
+   */
+  function Diff($from_lines, $to_lines) {
+    $eng = new _DiffEngine;
+    $this->edits = $eng->diff($from_lines, $to_lines);
+    //$this->_check($from_lines, $to_lines);
+  }
+
+  /**
+   * Compute reversed Diff.
+   *
+   * SYNOPSIS:
+   *
+   *  $diff = new Diff($lines1, $lines2);
+   *  $rev = $diff->reverse();
+   * @return object A Diff object representing the inverse of the
+   *          original diff.
+   */
+  function reverse () {
+  $rev = $this;
+    $rev->edits = array();
+    foreach ($this->edits as $edit) {
+      $rev->edits[] = $edit->reverse();
+    }
+  return $rev;
+  }
+
+  /**
+   * Check for empty diff.
+   *
+   * @return bool True iff two sequences were identical.
+   */
+  function isEmpty () {
+    foreach ($this->edits as $edit) {
+      if ($edit->type != 'copy')
+        return false;
+    }
+    return true;
+  }
+
+  /**
+   * Compute the length of the Longest Common Subsequence (LCS).
+   *
+   * This is mostly for diagnostic purposed.
+   *
+   * @return int The length of the LCS.
+   */
+  function lcs () {
+  $lcs = 0;
+    foreach ($this->edits as $edit) {
+      if ($edit->type == 'copy')
+        $lcs += sizeof($edit->orig);
+    }
+  return $lcs;
+  }
+
+  /**
+   * Get the original set of lines.
+   *
+   * This reconstructs the $from_lines parameter passed to the
+   * constructor.
+   *
+   * @return array The original sequence of strings.
+   */
+  function orig() {
+    $lines = array();
+
+    foreach ($this->edits as $edit) {
+      if ($edit->orig)
+        array_splice($lines, sizeof($lines), 0, $edit->orig);
+    }
+    return $lines;
+  }
+
+  /**
+   * Get the closing set of lines.
+   *
+   * This reconstructs the $to_lines parameter passed to the
+   * constructor.
+   *
+   * @return array The sequence of strings.
+   */
+  function closing() {
+    $lines = array();
+
+    foreach ($this->edits as $edit) {
+      if ($edit->closing)
+        array_splice($lines, sizeof($lines), 0, $edit->closing);
+    }
+    return $lines;
+  }
+
+  /**
+   * Check a Diff for validity.
+   *
+   * This is here only for debugging purposes.
+   */
+  function _check ($from_lines, $to_lines) {
+    if (serialize($from_lines) != serialize($this->orig()))
+      trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
+    if (serialize($to_lines) != serialize($this->closing()))
+      trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
+
+    $rev = $this->reverse();
+    if (serialize($to_lines) != serialize($rev->orig()))
+      trigger_error("Reversed original doesn't match", E_USER_ERROR);
+    if (serialize($from_lines) != serialize($rev->closing()))
+      trigger_error("Reversed closing doesn't match", E_USER_ERROR);
+
+
+    $prevtype = 'none';
+    foreach ($this->edits as $edit) {
+      if ( $prevtype == $edit->type )
+        trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
+      $prevtype = $edit->type;
+    }
+
+    $lcs = $this->lcs();
+    trigger_error("Diff okay: LCS = $lcs", E_USER_NOTICE);
+  }
+}
+
+/**
+ * FIXME: bad name.
+ */
+class MappedDiff
+extends Diff
+{
+  /**
+   * Constructor.
+   *
+   * Computes diff between sequences of strings.
+   *
+   * This can be used to compute things like
+   * case-insensitve diffs, or diffs which ignore
+   * changes in white-space.
+   *
+   * @param $from_lines array An array of strings.
+   *  (Typically these are lines from a file.)
+   *
+   * @param $to_lines array An array of strings.
+   *
+   * @param $mapped_from_lines array This array should
+   *  have the same size number of elements as $from_lines.
+   *  The elements in $mapped_from_lines and
+   *  $mapped_to_lines are what is actually compared
+   *  when computing the diff.
+   *
+   * @param $mapped_to_lines array This array should
+   *  have the same number of elements as $to_lines.
+   */
+  function MappedDiff($from_lines, $to_lines,
+            $mapped_from_lines, $mapped_to_lines) {
+
+    assert(sizeof($from_lines) == sizeof($mapped_from_lines));
+    assert(sizeof($to_lines) == sizeof($mapped_to_lines));
+
+    $this->Diff($mapped_from_lines, $mapped_to_lines);
+
+    $xi = $yi = 0;
+    for ($i = 0; $i < sizeof($this->edits); $i++) {
+      $orig = &$this->edits[$i]->orig;
+      if (is_array($orig)) {
+        $orig = array_slice($from_lines, $xi, sizeof($orig));
+        $xi += sizeof($orig);
+      }
+
+      $closing = &$this->edits[$i]->closing;
+      if (is_array($closing)) {
+        $closing = array_slice($to_lines, $yi, sizeof($closing));
+        $yi += sizeof($closing);
+      }
+    }
+  }
+}
+
+/**
+ * A class to format Diffs
+ *
+ * This class formats the diff in classic diff format.
+ * It is intended that this class be customized via inheritance,
+ * to obtain fancier outputs.
+ */
+class DiffFormatter
+{
+  /**
+   * Number of leading context "lines" to preserve.
+   *
+   * This should be left at zero for this class, but subclasses
+   * may want to set this to other values.
+   */
+  var $leading_context_lines = 0;
+
+  /**
+   * Number of trailing context "lines" to preserve.
+   *
+   * This should be left at zero for this class, but subclasses
+   * may want to set this to other values.
+   */
+  var $trailing_context_lines = 0;
+
+  /**
+   * Format a diff.
+   *
+   * @param $diff object A Diff object.
+   * @return string The formatted output.
+   */
+  function format($diff) {
+
+    $xi = $yi = 1;
+    $block = false;
+    $context = array();
+
+    $nlead = $this->leading_context_lines;
+    $ntrail = $this->trailing_context_lines;
+
+    $this->_start_diff();
+
+    foreach ($diff->edits as $edit) {
+      if ($edit->type == 'copy') {
+        if (is_array($block)) {
+          if (sizeof($edit->orig) <= $nlead + $ntrail) {
+            $block[] = $edit;
+          }
+          else{
+            if ($ntrail) {
+              $context = array_slice($edit->orig, 0, $ntrail);
+              $block[] = new _DiffOp_Copy($context);
+            }
+            $this->_block($x0, $ntrail + $xi - $x0,
+                    $y0, $ntrail + $yi - $y0,
+                    $block);
+            $block = false;
+          }
+        }
+        $context = $edit->orig;
+      }
+      else {
+        if (! is_array($block)) {
+          $context = array_slice($context, sizeof($context) - $nlead);
+          $x0 = $xi - sizeof($context);
+          $y0 = $yi - sizeof($context);
+          $block = array();
+          if ($context)
+            $block[] = new _DiffOp_Copy($context);
+        }
+        $block[] = $edit;
+      }
+
+      if ($edit->orig)
+        $xi += sizeof($edit->orig);
+      if ($edit->closing)
+        $yi += sizeof($edit->closing);
+    }
+
+    if (is_array($block))
+      $this->_block($x0, $xi - $x0,
+              $y0, $yi - $y0,
+              $block);
+
+    return $this->_end_diff();
+  }
+
+  function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
+    $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
+    foreach ($edits as $edit) {
+      if ($edit->type == 'copy')
+        $this->_context($edit->orig);
+      elseif ($edit->type == 'add')
+        $this->_added($edit->closing);
+      elseif ($edit->type == 'delete')
+        $this->_deleted($edit->orig);
+      elseif ($edit->type == 'change')
+        $this->_changed($edit->orig, $edit->closing);
+      else
+        trigger_error("Unknown edit type", E_USER_ERROR);
+    }
+    $this->_end_block();
+  }
+
+  function _start_diff() {
+    ob_start();
+  }
+
+  function _end_diff() {
+    $val = ob_get_contents();
+    ob_end_clean();
+    return $val;
+  }
+
+  function _block_header($xbeg, $xlen, $ybeg, $ylen) {
+    if ($xlen > 1)
+      $xbeg .= "," . ($xbeg + $xlen - 1);
+    if ($ylen > 1)
+      $ybeg .= "," . ($ybeg + $ylen - 1);
+
+    return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
+  }
+
+  function _start_block($header) {
+    echo $header;
+  }
+
+  function _end_block() {
+  }
+
+  function _lines($lines, $prefix = ' ') {
+    foreach ($lines as $line)
+      echo "$prefix $line\n";
+  }
+
+  function _context($lines) {
+    $this->_lines($lines);
+  }
+
+  function _added($lines) {
+    $this->_lines($lines, ">");
+  }
+  function _deleted($lines) {
+    $this->_lines($lines, "<");
+  }
+
+  function _changed($orig, $closing) {
+    $this->_deleted($orig);
+    echo "---\n";
+    $this->_added($closing);
+  }
+}
+
+
+/**
+ *  Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
+ *
+ */
+
+define('NBSP', "\xC2\xA0");     // utf-8 non-breaking space.
+
+class _HWLDF_WordAccumulator {
+  function _HWLDF_WordAccumulator () {
+    $this->_lines = array();
+    $this->_line = '';
+    $this->_group = '';
+    $this->_tag = '';
+  }
+
+  function _flushGroup ($new_tag) {
+    if ($this->_group !== '') {
+    if ($this->_tag == 'mark')
+      $this->_line .= '<strong>'.$this->_group.'</strong>';
+    else
+    $this->_line .= $this->_group;
+  }
+    $this->_group = '';
+    $this->_tag = $new_tag;
+  }
+
+  function _flushLine ($new_tag) {
+    $this->_flushGroup($new_tag);
+    if ($this->_line != '')
+      $this->_lines[] = $this->_line;
+    $this->_line = '';
+  }
+
+  function addWords ($words, $tag = '') {
+    if ($tag != $this->_tag)
+      $this->_flushGroup($tag);
+
+    foreach ($words as $word) {
+      // new-line should only come as first char of word.
+      if ($word == '')
+        continue;
+      if ($word[0] == "\n") {
+        $this->_group .= NBSP;
+        $this->_flushLine($tag);
+        $word = substr($word, 1);
+      }
+      assert(!strstr($word, "\n"));
+      $this->_group .= $word;
+    }
+  }
+
+  function getLines() {
+    $this->_flushLine('~done');
+    return $this->_lines;
+  }
+}
+
+class WordLevelDiff extends MappedDiff
+{
+  function WordLevelDiff ($orig_lines, $closing_lines) {
+    list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
+    list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
+
+
+    $this->MappedDiff($orig_words, $closing_words,
+              $orig_stripped, $closing_stripped);
+  }
+
+  function _split($lines) {
+    // FIXME: fix POSIX char class.
+#    if (!preg_match_all('/ ( [^\S\n]+ | [[:alnum:]]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
+    if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
+              implode("\n", $lines),
+              $m)) {
+      return array(array(''), array(''));
+    }
+    return array($m[0], $m[1]);
+  }
+
+  function orig () {
+    $orig = new _HWLDF_WordAccumulator;
+
+    foreach ($this->edits as $edit) {
+      if ($edit->type == 'copy')
+        $orig->addWords($edit->orig);
+      elseif ($edit->orig)
+        $orig->addWords($edit->orig, 'mark');
+    }
+    return $orig->getLines();
+  }
+
+  function closing () {
+    $closing = new _HWLDF_WordAccumulator;
+
+    foreach ($this->edits as $edit) {
+      if ($edit->type == 'copy')
+        $closing->addWords($edit->closing);
+      elseif ($edit->closing)
+        $closing->addWords($edit->closing, 'mark');
+    }
+    return $closing->getLines();
+  }
+}
+
+/**
+ * "Unified" diff formatter.
+ *
+ * This class formats the diff in classic "unified diff" format.
+ */
+class UnifiedDiffFormatter extends DiffFormatter
+{
+    function UnifiedDiffFormatter($context_lines = 4) {
+        $this->leading_context_lines = $context_lines;
+        $this->trailing_context_lines = $context_lines;
+    }
+
+    function _block_header($xbeg, $xlen, $ybeg, $ylen) {
+        if ($xlen != 1)
+            $xbeg .= "," . $xlen;
+        if ($ylen != 1)
+            $ybeg .= "," . $ylen;
+        return "@@ -$xbeg +$ybeg @@\n";
+    }
+
+    function _added($lines) {
+        $this->_lines($lines, "+");
+    }
+    function _deleted($lines) {
+        $this->_lines($lines, "-");
+    }
+    function _changed($orig, $final) {
+        $this->_deleted($orig);
+        $this->_added($final);
+    }
+}
+
+/**
+ *  Wikipedia Table style diff formatter.
+ *
+ */
+class TableDiffFormatter extends DiffFormatter
+{
+  function TableDiffFormatter() {
+    $this->leading_context_lines = 2;
+    $this->trailing_context_lines = 2;
+  }
+
+  function _pre($text){
+    $text = htmlspecialchars($text);
+    $text = str_replace('  ',' &nbsp;',$text);
+    if($text{0} == ' ') $text = '&nbsp;'.substr($text,1);
+    return $text;
+  }
+
+  function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
+    global $lang;
+    $l1 = $lang['line'].' '.$xbeg;
+    $l2 = $lang['line'].' '.$ybeg;
+    $r = '<tr><td class="diff-blockheader" colspan="2">'.$l1.":</td>\n" .
+      '<td class="diff-blockheader" colspan="2">'.$l2.":</td></tr>\n";
+    return $r;
+  }
+
+  function _start_block( $header ) {
+    print( $header );
+  }
+
+  function _end_block() {
+  }
+
+  function _lines( $lines, $prefix=' ', $color="white" ) {
+  }
+
+  function addedLine( $line ) {
+    $line = str_replace('  ',' &nbsp;',$line);
+    if($line{0} == ' ') $line = '&nbsp;'.substr($line,1);
+    return '<td>+</td><td class="diff-addedline">' .
+      $line.'</td>';
+  }
+
+  function deletedLine( $line ) {
+    $line = str_replace('  ',' &nbsp;',$line);
+    if($line{0} == ' ') $line = '&nbsp;'.substr($line,1);
+    return '<td>-</td><td class="diff-deletedline">' .
+      $line.'</td>';
+  }
+
+  function emptyLine() {
+    //$line = str_replace('  ','&nbsp; ',$line);
+    return '<td colspan="2">&nbsp;</td>';
+  }
+
+  function contextLine( $line ) {
+    $line = str_replace('  ',' &nbsp;',$line);
+    if($line{0} == ' ') $line = '&nbsp;'.substr($line,1);
+    return '<td> </td><td class="diff-context">'.$line.'</td>';
+  }
+
+  function _added($lines) {
+    foreach ($lines as $line) {
+      print( '<tr>' . $this->emptyLine() .
+        $this->addedLine( $line ) . "</tr>\n" );
+    }
+  }
+
+  function _deleted($lines) {
+    foreach ($lines as $line) {
+      print( '<tr>' . $this->deletedLine( $line ) .
+        $this->emptyLine() . "</tr>\n" );
+    }
+  }
+
+  function _context( $lines ) {
+    foreach ($lines as $line) {
+      print( '<tr>' . $this->contextLine( $line ) .
+        $this->contextLine( $line ) . "</tr>\n" );
+    }
+  }
+
+  function _changed( $orig, $closing ) {
+    $diff = new WordLevelDiff( $orig, $closing );
+    $del = $diff->orig();
+    $add = $diff->closing();
+
+    while ( $line = array_shift( $del ) ) {
+      $aline = array_shift( $add );
+      print( '<tr>' . $this->deletedLine( $line ) .
+        $this->addedLine( $aline ) . "</tr>\n" );
+    }
+    $this->_added( $add ); # If any leftovers
+  }
+}
+
+
+//Setup VIM: ex: et ts=2 enc=utf-8 :