From 82bedcee8401b6d7eb3bc9dd4294294946498c24 Mon Sep 17 00:00:00 2001
From: Sam Stephenson <sam@37signals.com>
Date: Tue, 24 Jul 2007 20:49:55 +0000
Subject: [PATCH] prototype: Optimize Selector#match and Element#match for
 simple selectors.  Closes #9082.

---
 CHANGELOG               |  2 ++
 src/selector.js         | 58 ++++++++++++++++++++++++++++++++++++++++-
 test/unit/selector.html | 22 +++++++++++++++-
 3 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 3f8b16f..59f5020 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Optimize Selector#match and Element#match for simple selectors.  Closes #9082.  [Andrew Dupont]
+
 * Remove the dependency on Element.ClassNames from Element#addClassName/removeClassName/toggleClassName, and deprecate Element.ClassNames. Closes #9073. [Tobie Langel]
 
 * Make Element#wrap accept a second argument for setting attributes on the wrapper. Allow wrapping elements which are not part of the document. Closes #9071. [Tobie Langel]
diff --git a/src/selector.js b/src/selector.js
index d98d099..3880b1d 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -74,7 +74,39 @@ Selector.prototype = {
   },
   
   match: function(element) {
-    return this.findElements(document).include(element);
+    this.tokens = [];
+
+    var e = this.expression, ps = Selector.patterns, as = Selector.assertions;
+    var le, p, m;
+    
+    while (e && le !== e && (/\S/).test(e)) {
+      le = e;
+      for (var i in ps) {
+        p = ps[i];
+        if (m = e.match(p)) {
+          // use the Selector.assertions methods unless the selector
+          // is too complex.
+          if (as[i]) {
+            this.tokens.push([i, Object.clone(m)]);
+            e = e.replace(m[0], '');
+          } else {
+            // reluctantly do a document-wide search
+            // and look for a match in the array
+            return this.findElements(document).include(element);
+          }
+        }
+      }
+    }
+    
+    var match = true, name, matches;
+    for (var i = 0, token; token = this.tokens[i]; i++) {
+      name = token[0], matches = token[1];
+      if (!Selector.assertions[name](element, matches)) {
+        match = false; break;
+      }
+    }
+    
+    return match;
   },
   
   toString: function() {
@@ -223,6 +255,30 @@ Object.extend(Selector, {
     attr:         /\[((?:[\w-]*:)?[\w-]+)\s*(?:([!^$*~|]?=)\s*((['"])([^\]]*?)\4|([^'"][^\]]*?)))?\]/
   },
   
+  // for Selector.match and Element#match
+  assertions: {
+    tagName: function(element, matches) {
+      return matches[1].toUpperCase() == element.tagName.toUpperCase();
+    },
+
+    className: function(element, matches) {
+      return Element.hasClassName(element, matches[1]);
+    },
+
+    id: function(element, matches) {
+      return element.id === matches[1];
+    },
+
+    attrPresence: function(element, matches) {
+      return Element.hasAttribute(element, matches[1]);
+    },
+
+    attr: function(element, matches) {
+      var nodeValue = Element.readAttribute(element, matches[1]);
+      return Selector.operators[matches[2]](nodeValue, matches[3]);
+    }    
+  },
+  
   handlers: {
     // UTILITY FUNCTIONS
     // joins two collections
diff --git a/test/unit/selector.html b/test/unit/selector.html
index baa6ba2..90a33b6 100644
--- a/test/unit/selector.html
+++ b/test/unit/selector.html
@@ -61,7 +61,7 @@
   </div> <!-- #level1 -->
 
   <div id="dupContainer">
-    <span id="dupL1">
+    <span id="dupL1" class="span_foo span_bar">
       <span id="dupL2">
         <span id="dupL3">
           <span id="dupL4">
@@ -198,6 +198,26 @@
       assertElementMatches(Selector.findElement($('list').descendants(), 'li#item_3'), 'li');
       assertEqual(undefined, Selector.findElement($('list').descendants(), 'em'));
     }},
+    
+    testElementMatch: function() {with(this) {
+      var span = $('dupL1');
+      // tests that should pass
+      assert(span.match('span'));
+      assert(span.match('span#dupL1'));
+      assert(span.match('div > span'), 'child combinator');
+      assert(span.match('#dupContainer span'), 'descendant combinator');      
+      assert(span.match('#dupL1'), 'ID only');
+      assert(span.match('span.span_foo'), 'class name 1');
+      assert(span.match('span.span_bar'), 'class name 2');
+      assert(span.match('span:first-child'), 'first-child pseudoclass');
+      
+      assert(!span.match('span.span_wtf'), 'bogus class name');
+      assert(!span.match('#dupL2'), 'different ID');
+      assert(!span.match('div'), 'different tag name');
+      assert(!span.match('span span'), 'different ancestry');
+      assert(!span.match('span > span'), 'different parent');
+      assert(!span.match('span:nth-child(5)'), 'different pseudoclass');
+    }},
 
     testSelectorWithSpaceInAttributeValue: function() {with(this) {
       assertEnumEqual([$('with_title')], $$('cite[title="hello world!"]'));