Function matcherFromTokens

2.0.3/Sizzle.js:1694–1751

(tokens)

        }

        function matcherFromTokens(tokens) {
            var checkContext, matcher, j,
                len = tokens.length,
                leadingRelative = Expr.relative[tokens[0].type],
                implicitRelative = leadingRelative || Expr.relative[" "],
                i = leadingRelative ? 1 : 0,

                // The foundational matcher ensures that elements are reachable from top-level context(s)
                matchContext = addCombinator(function(elem) {
                    return elem === checkContext;
                }, implicitRelative, true),
                matchAnyContext = addCombinator(function(elem) {
                    return indexOf.call(checkContext, elem) > -1;
                }, implicitRelative, true),
                matchers = [
                    function(elem, context, xml) {
                        return (!leadingRelative && (xml || context !== outermostContext)) || (
                            (checkContext = context).nodeType ?
                            matchContext(elem, context, xml) :
                            matchAnyContext(elem, context, xml));
                    }
                ];

            for (; i < len; i++) {
                if ((matcher = Expr.relative[tokens[i].type])) {
                    matchers = [addCombinator(elementMatcher(matchers), matcher)];
                } else {
                    matcher = Expr.filter[tokens[i].type].apply(null, tokens[i].matches);

                    // Return special upon seeing a positional matcher
                    if (matcher[expando]) {
                        // Find the next relative operator (if any) for proper handling
                        j = ++i;
                        for (; j < len; j++) {
                            if (Expr.relative[tokens[j].type]) {
                                break;
                            }
                        }
                        return setMatcher(
                            i > 1 && elementMatcher(matchers),
                            i > 1 && toSelector(
                                // If the preceding token was a descendant combinator, insert an implicit any-element `*`
                                tokens.slice(0, i - 1).concat({
                                    value: tokens[i - 2].type === " " ? "*" : ""
                                })
                            ).replace(rtrim, "$1"),
                            matcher,
                            i < j && matcherFromTokens(tokens.slice(i, j)),
                            j < len && matcherFromTokens((tokens = tokens.slice(j))),
                            j < len && toSelector(tokens)
                        );
                    }
                    matchers.push(matcher);
                }
            }

            return elementMatcher(matchers);
        }