+global\_DiffEngine::diff()

Complexity

Conditions	31
Paths	> 20000

Size

Total Lines	86
Code Lines	61

Duplication

Lines	0
Ratio	0 %

<?php
    function diff($from_lines, $to_lines) {

It is generally recommended to explicitly declare the visibility for methods.

        $n_from = count($from_lines);
        $n_to = count($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;

$xhash was never initialized. Although not strictly required by PHP, it is generally a good practice to add $xhash = array(); before regardless.

        for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
            $line = $to_lines[$yi];
            if (($this->ychanged[$yi] = empty($xhash[$line])))
                continue;
            $yhash[$line] = 1;

$yhash was never initialized. Although not strictly required by PHP, it is generally a good practice to add $yhash = array(); before regardless.

            $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.
        $this->_compareseq(0, count($this->xv), 0, count($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)

The expression $copy of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new _DiffOp_Copy($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)

The expression $delete of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

The expression $add of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new _DiffOp_Change($delete, $add);
            elseif ($delete)

The expression $delete of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new _DiffOp_Delete($delete);
            elseif ($add)

The expression $add of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new _DiffOp_Add($add);
        }
        return $edits;
    }