Leafo\ScssPhp\Compiler::matchExtends PHP Method

    protected function matchExtends($selector, &$out, $from = 0, $initial = true)
    {
        foreach ($selector as $i => $part) {
            if ($i < $from) {
                continue;
            }
            if ($this->matchExtendsSingle($part, $origin)) {
                $after = array_slice($selector, $i + 1);
                $before = array_slice($selector, 0, $i);
                list($before, $nonBreakableBefore) = $this->extractRelationshipFromFragment($before);
                foreach ($origin as $new) {
                    $k = 0;
                    // remove shared parts
                    if ($initial) {
                        while ($k < $i && isset($new[$k]) && $selector[$k] === $new[$k]) {
                            $k++;
                        }
                    }
                    $replacement = [];
                    $tempReplacement = $k > 0 ? array_slice($new, $k) : $new;
                    for ($l = count($tempReplacement) - 1; $l >= 0; $l--) {
                        $slice = $tempReplacement[$l];
                        array_unshift($replacement, $slice);
                        if (!$this->isImmediateRelationshipCombinator(end($slice))) {
                            break;
                        }
                    }
                    $afterBefore = $l != 0 ? array_slice($tempReplacement, 0, $l) : [];
                    // Merge shared direct relationships.
                    $mergedBefore = $this->mergeDirectRelationships($afterBefore, $nonBreakableBefore);
                    $result = array_merge($before, $mergedBefore, $replacement, $after);
                    if ($result === $selector) {
                        continue;
                    }
                    $out[] = $result;
                    // recursively check for more matches
                    $this->matchExtends($result, $out, count($before) + count($mergedBefore), false);
                    // selector sequence merging
                    if (!empty($before) && count($new) > 1) {
                        $sharedParts = $k > 0 ? array_slice($before, 0, $k) : [];
                        $postSharedParts = $k > 0 ? array_slice($before, $k) : $before;
                        list($injectBetweenSharedParts, $nonBreakable2) = $this->extractRelationshipFromFragment($afterBefore);
                        $result2 = array_merge($sharedParts, $injectBetweenSharedParts, $postSharedParts, $nonBreakable2, $nonBreakableBefore, $replacement, $after);
                        $out[] = $result2;
                    }
                }
            }
        }
    }