includes/diffengine/Engine/xdiff.php
author Dan Fuhry <dan@enanocms.org>
Tue, 12 Jul 2011 22:37:21 -0400
changeset 344 0fa28c5aabe9
parent 1 fe660c52c48f
permissions -rw-r--r--
Release prep 1.0.6pl4
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<?php
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/**
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 * Class used internally by Diff to actually compute the diffs.  This class
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 * uses the xdiff PECL package (http://pecl.php.net/package/xdiff) to compute
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 * the differences between the two input arrays.
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 *
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 * @author  Jon Parise <jon@horde.org>
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 * @package Text_Diff
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 *
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 * @access private
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 */
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class Text_Diff_Engine_xdiff {
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    function diff($from_lines, $to_lines)
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    {
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        array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
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        array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
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        /* Convert the two input arrays into strings for xdiff processing. */
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        $from_string = implode("\n", $from_lines);
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        $to_string = implode("\n", $to_lines);
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        /* Diff the two strings and convert the result to an array. */
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        $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));
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        $diff = explode("\n", $diff);
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        /* Walk through the diff one line at a time.  We build the $edits
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         * array of diff operations by reading the first character of the
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         * xdiff output (which is in the "unified diff" format).
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         *
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         * Note that we don't have enough information to detect "changed"
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         * lines using this approach, so we can't add Text_Diff_Op_changed
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         * instances to the $edits array.  The result is still perfectly
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         * valid, albeit a little less descriptive and efficient. */
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        $edits = array();
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        foreach ($diff as $line) {
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            switch ($line[0]) {
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            case ' ':
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                $edits[] = &new Text_Diff_Op_copy(array(substr($line, 1)));
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                break;
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            case '+':
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                $edits[] = &new Text_Diff_Op_add(array(substr($line, 1)));
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                break;
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            case '-':
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                $edits[] = &new Text_Diff_Op_delete(array(substr($line, 1)));
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                break;
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            }
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        }
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        return $edits;
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    }
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}