New CSS parser written in Dart to replace pyparser

utils/css/validate.dart

+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Validate {
+  static int _classNameCheck(var selector, int matches) {
+    if (selector.isCombinatorDescendant() ||
+        (selector.isCombinatorNone() && matches == 0)) {
+      if (matches < 0) {
+        String tooMany = selector.toString();
+        throw new CssSelectorException(
+            'Can not mix Id selector with class selector(s). Id ' +
+            'selector must be singleton too many starting at $tooMany');
+      }
+  
+      return matches + 1;
+    } else {
+      String error = selector.toString();
+      throw new CssSelectorException(
+          'Selectors can not have combinators (>, +, or ~) before $error');
+    }
+  }
+
+  static int _elementIdCheck(var selector, int matches) {
+    if (selector.isCombinatorNone() && matches == 0) {
+      // Perfect just one element id returns matches of -1.
+      return -1;
+    } else if (selector.isCombinatorDescendant()) {
+        String tooMany = selector.toString();
+        throw new CssSelectorException(
+            'Use of Id selector must be singleton starting at $tooMany');
+    } else {
+      String error = selector.toString();
+      throw new CssSelectorException(
+          'Selectors can not have combinators (>, +, or ~) before $error');
+    }
+  }
+
+  // Validate the @{css expression} only .class and #elementId are valid inside
+  // of @{...}.
+  static template(List<lang.Node> selectors, CssWorld cssWorld) {
+    var errorSelector;                  // signal which selector didn't match.
+    bool found = false;                 // signal if a selector is matched.
+    int matches = 0;                    // < 0 IdSelectors, > 0 ClassSelector
+    for (var sels in selectors) {
+      for (var selector in sels.simpleSelectorSequences) {
+        found = false;
+        var simpleSelector = selector.simpleSelector;
+        if (simpleSelector is ClassSelector) {
+          // Any class name starting with an underscore is a private class name
+          // that doesn't have to match the world of known classes.
+          if (!simpleSelector.name.startsWith('_')) {
+            // TODO(terry): For now iterate through all classes look for faster
+            //              mechanism hash map, etc.
+            var className;
+            for (var className in cssWorld.classes) {
+              if (selector.simpleSelector.name == className) {
+                matches = _classNameCheck(selector, matches);
+                found = true;              // .class found.
+                break;
+              }
+              for (var className2 in cssWorld.classes) {
+                print(className2);
+              }
+            }
+
+          } else {
+            // Don't check any class name that is prefixed with an underscore.
+            // However, signal as found and bump up matches; it's a valid class
+            // name.
+            matches = _classNameCheck(selector, matches);
+            found = true;                 // ._class are always okay.
+          }
+        } else if (simpleSelector is IdSelector) {
+          // Any element id starting with an underscore is a private element id
+          // that doesn't have to match the world of known elemtn ids.
+          if (!simpleSelector.name.startsWith('_')) {
+            for (var id in cssWorld.ids) {
+              if (simpleSelector.name == id) {
+                matches = _elementIdCheck(selector, matches);
+                found = true;             // #id found.
+                break;
+              }
+            }
+          } else {
+            // Don't check any element ID that is prefixed with an underscore.
+            // However, signal as found and bump up matches; it's a valid element
+            // ID.
+            matches = _elementIdCheck(selector, matches);
+            found = true;                 // #_id are always okay
+          }
+        } else {
+          String badSelector = simpleSelector.toString();
+          throw new CssSelectorException(
+              'Invalid template selector $badSelector');
+        }
+
+        if (!found) {
+          String unknownName = simpleSelector.toString();
+          throw new CssSelectorException('Unknown selector name $unknownName');
+        }
+      }
+    }
+
+    // Every selector must match.
+    assert((matches >= 0 ? matches : -matches) == selectors.length);
+  }
+}
+