move polymer.dart into dart svn

pkg/polymer/lib/src/css_emitters.dart

+// Copyright (c) 2013, 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.
+
+library polymer.src.css_emitters;
+
+import 'package:csslib/visitor.dart' show Visitor, CssPrinter, ElementSelector,
+       UriTerm, Selector, HostDirective, SimpleSelectorSequence, StyleSheet;
+
+import 'info.dart';
+import 'paths.dart' show PathMapper;
+import 'utils.dart';
+
+void rewriteCssUris(PathMapper pathMapper, String cssPath, bool rewriteUrls,
+    StyleSheet styleSheet) {
+  new _UriVisitor(pathMapper, cssPath, rewriteUrls).visitTree(styleSheet);
+}
+
+/** Compute each CSS URI resource relative from the generated CSS file. */
+class _UriVisitor extends Visitor {
+  /**
+   * Relative path from the output css file to the location of the original
+   * css file that contained the URI to each resource.
+   */
+  final String _pathToOriginalCss;
+
+  factory _UriVisitor(PathMapper pathMapper, String cssPath, bool rewriteUrl) {
+    var cssDir = path.dirname(cssPath);
+    var outCssDir = rewriteUrl ? pathMapper.outputDirPath(cssPath)
+        : path.dirname(cssPath);
+    return new _UriVisitor._internal(path.relative(cssDir, from: outCssDir));
+  }
+
+  _UriVisitor._internal(this._pathToOriginalCss);
+
+  void visitUriTerm(UriTerm node) {
+    // Don't touch URIs that have any scheme (http, etc.).
+    var uri = Uri.parse(node.text);
+    if (uri.host != '') return;
+    if (uri.scheme != '' && uri.scheme != 'package') return;
+
+    node.text = pathToUrl(
+        path.normalize(path.join(_pathToOriginalCss, node.text)));
+  }
+}
+
+
+/** Emit the contents of the style tag outside of a component. */
+String emitStyleSheet(StyleSheet ss, FileInfo file) =>
+  (new _CssEmitter(file.components.keys.toSet())
+      ..visitTree(ss, pretty: true)).toString();
+
+/** Emit a component's style tag content emulating scoped css. */
+String emitComponentStyleSheet(StyleSheet ss, String tagName) =>
+    (new _ComponentCssEmitter(tagName)..visitTree(ss, pretty: true)).toString();
+
+String emitOriginalCss(StyleSheet css) =>
+    (new CssPrinter()..visitTree(css)).toString();
+
+/** Only x-tag name element selectors are emitted as [is="x-"]. */
+class _CssEmitter extends CssPrinter {
+  final Set _componentsTag;
+  _CssEmitter(this._componentsTag);
+
+  void visitElementSelector(ElementSelector node) {
+    // If element selector is a component's tag name, then change selector to
+    // find element who's is attribute's the component's name.
+    if (_componentsTag.contains(node.name)) {
+      emit('[is="${node.name}"]');
+      return;
+    }
+    super.visitElementSelector(node);
+  }
+}
+
+/**
+ * Emits a css stylesheet applying rules to emulate scoped css. The rules adjust
+ * element selectors to include the component's tag name.
+ */
+class _ComponentCssEmitter extends CssPrinter {
+  final String _componentTagName;
+  bool _inHostDirective = false;
+  bool _selectorStartInHostDirective = false;
+
+  _ComponentCssEmitter(this._componentTagName);
+
+  /** Is the element selector an x-tag name. */
+  bool _isSelectorElementXTag(Selector node) {
+    if (node.simpleSelectorSequences.length > 0) {
+      var selector = node.simpleSelectorSequences[0].simpleSelector;
+      return selector is ElementSelector && selector.name == _componentTagName;
+    }
+    return false;
+  }
+
+  void visitSelector(Selector node) {
+    // If the selector starts with an x-tag name don't emit it twice.
+    if (!_isSelectorElementXTag(node)) {
+      if (_inHostDirective) {
+        // Style the element that's hosting the component, therefore don't emit
+        // the descendent combinator (first space after the [is="x-..."]).
+        emit('[is="$_componentTagName"]');
+        // Signal that first simpleSelector must be checked.
+        _selectorStartInHostDirective = true;
+      } else {
+        // Emit its scoped as a descendent (space at end).
+        emit('[is="$_componentTagName"] ');
+      }
+    }
+    super.visitSelector(node);
+  }
+
+  /**
+   * If first simple selector of a ruleset in a @host directive is a wildcard
+   * then don't emit the wildcard.
+   */
+  void visitSimpleSelectorSequence(SimpleSelectorSequence node) {
+    if (_selectorStartInHostDirective) {
+      _selectorStartInHostDirective = false;
+      if (node.simpleSelector.isWildcard) {
+        // Skip the wildcard if first item in the sequence.
+        return;
+      }
+      assert(node.isCombinatorNone);
+    }
+
+    super.visitSimpleSelectorSequence(node);
+  }
+
+  void visitElementSelector(ElementSelector node) {
+    // If element selector is the component's tag name, then change selector to
+    // find element who's is attribute is the component's name.
+    if (_componentTagName == node.name) {
+      emit('[is="$_componentTagName"]');
+      return;
+    }
+    super.visitElementSelector(node);
+  }
+
+  /**
+   * If we're polyfilling scoped styles the @host directive is stripped.  Any
+   * ruleset(s) processed in an @host will fixup the first selector.  See
+   * visitSelector and visitSimpleSelectorSequence in this class, they adjust
+   * the selectors so it styles the element hosting the compopnent.
+   */
+  void visitHostDirective(HostDirective node) {
+    _inHostDirective = true;
+    emit('/* @host */');
+    for (var ruleset in node.rulesets) {
+      ruleset.visit(this);
+    }
+    _inHostDirective = false;
+    emit('/* end of @host */\n');
+  }
+}