<?php



require_once 'Text/Diff.php';



/**

 * A class for computing three way diffs.

 *

 * $Horde: framework/Text_Diff/Diff3.php,v 1.4 2005/07/03 05:10:11 selsky Exp $

 *

 * @package Text_Diff

 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>

 */

class Text_Diff3 extends Text_Diff {



    /**

     * Conflict counter.

     *

     * @var integer

     */

    var $_conflictingBlocks = 0;



    /**

     * Computes diff between 3 sequences of strings.

     *

     * @param array $orig    The original lines to use.

     * @param array $final1  The first version to compare to.

     * @param array $final2  The second version to compare to.

     */

    function Text_Diff3($orig, $final1, $final2)

    {

        if (extension_loaded('xdiff')) {

            $engine = &new Text_Diff_Engine_xdiff();

        } else {

            $engine = &new Text_Diff_Engine_native();

        }



        $this->_edits = $this->_diff3($engine->diff($orig, $final1),

                                      $engine->diff($orig, $final2));

    }



    function mergedOutput($label1 = false, $label2 = false)

    {

        $lines = array();

        foreach ($this->_edits as $edit) {

            if ($edit->isConflict()) {

                /* FIXME: this should probably be moved somewhere else. */

                $lines = array_merge($lines,

                                     array('<<<<<<<' . ($label1 ? ' ' . $label1 : '')),

                                     $edit->final1,

                                     array("======="),

                                     $edit->final2,

                                     array('>>>>>>>' . ($label2 ? ' ' . $label2 : '')));

                $this->_conflictingBlocks++;

            } else {

                $lines = array_merge($lines, $edit->merged());

            }

        }



        return $lines;

    }



    /**

     * @access private

     */

    function _diff3($edits1, $edits2)

    {

        $edits = array();

        $bb = &new Text_Diff3_BlockBuilder();



        $e1 = current($edits1);

        $e2 = current($edits2);

        while ($e1 || $e2) {

            if ($e1 && $e2 && is_a($e1, 'Text_Diff_Op_copy') && is_a($e2, 'Text_Diff_Op_copy')) {

                /* We have copy blocks from both diffs. This is the (only)

                 * time we want to emit a diff3 copy block.  Flush current

                 * diff3 diff block, if any. */

                if ($edit = $bb->finish()) {

                    $edits[] = $edit;

                }



                $ncopy = min($e1->norig(), $e2->norig());

                assert($ncopy > 0);

                $edits[] = &new Text_Diff3_Op_copy(array_slice($e1->orig, 0, $ncopy));



                if ($e1->norig() > $ncopy) {

                    array_splice($e1->orig, 0, $ncopy);

                    array_splice($e1->final, 0, $ncopy);

                } else {

                    $e1 = next($edits1);

                }



                if ($e2->norig() > $ncopy) {

                    array_splice($e2->orig, 0, $ncopy);

                    array_splice($e2->final, 0, $ncopy);

                } else {

                    $e2 = next($edits2);

                }

            } else {

                if ($e1 && $e2) {

                    if ($e1->orig && $e2->orig) {

                        $norig = min($e1->norig(), $e2->norig());

                        $orig = array_splice($e1->orig, 0, $norig);

                        array_splice($e2->orig, 0, $norig);

                        $bb->input($orig);

                    }



                    if (is_a($e1, 'Text_Diff_Op_copy')) {

                        $bb->out1(array_splice($e1->final, 0, $norig));

                    }



                    if (is_a($e2, 'Text_Diff_Op_copy')) {

                        $bb->out2(array_splice($e2->final, 0, $norig));

                    }

                }



                if ($e1 && ! $e1->orig) {

                    $bb->out1($e1->final);

                    $e1 = next($edits1);

                }

                if ($e2 && ! $e2->orig) {

                    $bb->out2($e2->final);

                    $e2 = next($edits2);

                }

            }

        }



        if ($edit = $bb->finish()) {

            $edits[] = $edit;

        }



        return $edits;

    }



}



/**

 * @package Text_Diff

 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>

 *

 * @access private

 */

class Text_Diff3_Op {



    function Text_Diff3_Op($orig = false, $final1 = false, $final2 = false)

    {

        $this->orig = $orig ? $orig : array();

        $this->final1 = $final1 ? $final1 : array();

        $this->final2 = $final2 ? $final2 : array();

    }



    function merged()

    {

        if (!isset($this->_merged)) {

            if ($this->final1 === $this->final2) {

                $this->_merged = &$this->final1;

            } elseif ($this->final1 === $this->orig) {

                $this->_merged = &$this->final2;

            } elseif ($this->final2 === $this->orig) {

                $this->_merged = &$this->final1;

            } else {

                $this->_merged = false;

            }

        }



        return $this->_merged;

    }



    function isConflict()

    {

        return $this->merged() === false;

    }



}



/**

 * @package Text_Diff

 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>

 *

 * @access private

 */

class Text_Diff3_Op_copy extends Text_Diff3_Op {



    function Text_Diff3_Op_Copy($lines = false)

    {

        $this->orig = $lines ? $lines : array();

        $this->final1 = &$this->orig;

        $this->final2 = &$this->orig;

    }



    function merged()

    {

        return $this->orig;

    }



    function isConflict()

    {

        return false;

    }



}



/**

 * @package Text_Diff

 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>

 *

 * @access private

 */

class Text_Diff3_BlockBuilder {



    function Text_Diff3_BlockBuilder()

    {

        $this->_init();

    }



    function input($lines)

    {

        if ($lines) {

            $this->_append($this->orig, $lines);

        }

    }



    function out1($lines)

    {

        if ($lines) {

            $this->_append($this->final1, $lines);

        }

    }



    function out2($lines)

    {

        if ($lines) {

            $this->_append($this->final2, $lines);

        }

    }



    function isEmpty()

    {

        return !$this->orig && !$this->final1 && !$this->final2;

    }



    function finish()

    {

        if ($this->isEmpty()) {

            return false;

        } else {

            $edit = &new Text_Diff3_Op($this->orig, $this->final1, $this->final2);

            $this->_init();

            return $edit;

        }

    }



    function _init()

    {

        $this->orig = $this->final1 = $this->final2 = array();

    }



    function _append(&$array, $lines)

    {

        array_splice($array, sizeof($array), 0, $lines);

    }



}