Bug 779917 - Implement CSS.supports(). r=dbaron f=bz

dom/bindings/Bindings.conf

@@ -144,6 +144,10 @@ DOMInterfaces = {
     'resultNotAddRefed': [ 'item' ]
 },
 
+'CSS': {
+    'concrete': False,
+},
+
 'CSS2Properties': {
   'nativeType': 'nsDOMCSSDeclaration'
 },

dom/webidl/CSS.webidl

@@ -0,0 +1,20 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://dev.w3.org/csswg/css3-conditional/
+ *
+ * Copyright © 2012 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C
+ * liability, trademark and document use rules apply.
+ */
+
+[PrefControlled]
+interface CSS {
+  [Throws, Pref="layout.css.supports-rule.enabled"]
+  static boolean supports(DOMString property, DOMString value);
+
+  [Throws, Pref="layout.css.supports-rule.enabled"]
+  static boolean supports(DOMString conditionText);
+};

dom/webidl/WebIDL.mk

@@ -21,6 +21,7 @@ webidl_files = \
   Blob.webidl \
   CanvasRenderingContext2D.webidl \
   ClientRectList.webidl \
+  CSS.webidl \
   CSSPrimitiveValue.webidl \
   CSSStyleDeclaration.webidl \
   CSSValue.webidl \

layout/style/CSS.cpp

@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* DOM object holding utility CSS functions */
+
+#include "CSS.h"
+
+#include "nsCSSParser.h"
+#include "nsGlobalWindow.h"
+#include "nsIDOMDocument.h"
+#include "nsIDocument.h"
+#include "nsIPrincipal.h"
+#include "nsIURI.h"
+
+namespace mozilla {
+namespace dom {
+
+struct SupportsParsingInfo
+{
+  nsIURI* mDocURI;
+  nsIURI* mBaseURI;
+  nsIPrincipal* mPrincipal;
+};
+
+static nsresult
+GetParsingInfo(nsISupports* aGlobal,
+               SupportsParsingInfo& aInfo)
+{
+  nsGlobalWindow* win = nsGlobalWindow::FromSupports(aGlobal);
+  nsCOMPtr<nsIDocument> doc = win->GetDoc();
+  if (!doc) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aInfo.mDocURI = nsCOMPtr<nsIURI>(doc->GetDocumentURI());
+  aInfo.mBaseURI = nsCOMPtr<nsIURI>(doc->GetBaseURI());
+  aInfo.mPrincipal = win->GetPrincipal();
+  return NS_OK;
+}
+
+/* static */ bool
+CSS::Supports(nsISupports* aGlobal,
+              const nsAString& aProperty,
+              const nsAString& aValue,
+              ErrorResult& aRv)
+{
+  nsCSSParser parser;
+  SupportsParsingInfo info;
+
+  nsresult rv = GetParsingInfo(aGlobal, info);
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return false;
+  }
+
+  return parser.EvaluateSupportsDeclaration(aProperty, aValue, info.mDocURI,
+                                            info.mBaseURI, info.mPrincipal);
+}
+
+/* static */ bool
+CSS::Supports(nsISupports* aGlobal,
+              const nsAString& aCondition,
+              ErrorResult& aRv)
+{
+  nsCSSParser parser;
+  SupportsParsingInfo info;
+
+  nsresult rv = GetParsingInfo(aGlobal, info);
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return false;
+  }
+
+  return parser.EvaluateSupportsCondition(aCondition, info.mDocURI,
+                                          info.mBaseURI, info.mPrincipal);
+}
+
+} // dom
+} // mozilla

layout/style/CSS.h

@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* DOM object holding utility CSS functions */
+
+#ifndef mozilla_dom_CSS_h_
+#define mozilla_dom_CSS_h_
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/Preferences.h"
+
+namespace mozilla {
+namespace dom {
+
+class CSS {
+private:
+  CSS() MOZ_DELETE;
+
+public:
+  static bool Supports(nsISupports* aGlobal,
+                       const nsAString& aProperty,
+                       const nsAString& aValue,
+                       ErrorResult& aRv);
+
+  static bool Supports(nsISupports* aGlobal,
+                       const nsAString& aDeclaration,
+                       ErrorResult& aRv);
+
+  static bool PrefEnabled()
+  {
+    return Preferences::GetBool("layout.css.supports-rule.enabled");
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_CSS_h_

layout/style/Makefile.in

@@ -43,7 +43,7 @@ EXPORTS		= \
 		nsCSSValue.h \
 		nsDOMCSSAttrDeclaration.h \
 		nsDOMCSSDeclaration.h \
-	 nsDOMCSSRGBColor.h \
+		nsDOMCSSRGBColor.h \
 		nsDOMMediaQueryList.h \
 		nsICSSDeclaration.h \
 		nsICSSLoaderObserver.h \
@@ -83,11 +83,13 @@ EXPORTS_mozilla/css = \
 		$(NULL)
 
 EXPORTS_mozilla/dom = \
-  CSSValue.h \
-  $(null)
+		CSS.h \
+		CSSValue.h \
+		$(NULL)
 
 CPPSRCS		= \
 		AnimationCommon.cpp \
+		CSS.cpp \
 		nsCSSAnonBoxes.cpp \
 		nsCSSDataBlock.cpp \
 		Declaration.cpp \
@@ -140,6 +142,7 @@ include $(topsrcdir)/ipc/chromium/chromium-config.mk
 
 LOCAL_INCLUDES	+= \
 		-I$(srcdir)/../base \
+		-I$(topsrcdir)/dom/base \
 		-I$(srcdir)/../generic \
 		-I$(srcdir)/../xul/base/src \
 		-I$(srcdir)/../../content/base/src \

layout/style/nsCSSParser.cpp

@@ -229,6 +229,17 @@ public:
                                    uint32_t aLineNumber, // for error reporting
                                    InfallibleTArray<float>& aSelectorList);
 
+  bool EvaluateSupportsDeclaration(const nsAString& aProperty,
+                                   const nsAString& aValue,
+                                   nsIURI* aDocURL,
+                                   nsIURI* aBaseURL,
+                                   nsIPrincipal* aDocPrincipal);
+
+  bool EvaluateSupportsCondition(const nsAString& aCondition,
+                                 nsIURI* aDocURL,
+                                 nsIURI* aBaseURL,
+                                 nsIPrincipal* aDocPrincipal);
+
 protected:
   class nsAutoParseCompoundProperty;
   friend class nsAutoParseCompoundProperty;
@@ -299,7 +310,7 @@ protected:
   class nsAutoSuppressErrors {
     public:
       nsAutoSuppressErrors(CSSParserImpl* aParser,
-                           bool aSuppressErrors)
+                           bool aSuppressErrors = true)
         : mParser(aParser),
           mOriginalValue(aParser->mSuppressErrors)
       {
@@ -1350,6 +1361,55 @@ CSSParserImpl::ParseKeyframeSelectorString(const nsSubstring& aSelectorString,
   return success;
 }
 
+bool
+CSSParserImpl::EvaluateSupportsDeclaration(const nsAString& aProperty,
+                                           const nsAString& aValue,
+                                           nsIURI* aDocURL,
+                                           nsIURI* aBaseURL,
+                                           nsIPrincipal* aDocPrincipal)
+{
+  nsCSSProperty propID = nsCSSProps::LookupProperty(aProperty,
+                                                    nsCSSProps::eEnabled);
+  if (propID == eCSSProperty_UNKNOWN) {
+    return false;
+  }
+
+  nsCSSScanner scanner(aValue, 0);
+  css::ErrorReporter reporter(scanner, mSheet, mChildLoader, aDocURL);
+  InitScanner(scanner, reporter, aDocURL, aBaseURL, aDocPrincipal);
+  nsAutoSuppressErrors suppressErrors(this);
+
+  bool parsedOK = ParseProperty(propID) && !GetToken(true);
+
+  CLEAR_ERROR();
+  ReleaseScanner();
+
+  mTempData.ClearProperty(propID);
+  mTempData.AssertInitialState();
+
+  return parsedOK;
+}
+
+bool
+CSSParserImpl::EvaluateSupportsCondition(const nsAString& aDeclaration,
+                                         nsIURI* aDocURL,
+                                         nsIURI* aBaseURL,
+                                         nsIPrincipal* aDocPrincipal)
+{
+  nsCSSScanner scanner(aDeclaration, 0);
+  css::ErrorReporter reporter(scanner, mSheet, mChildLoader, aDocURL);
+  InitScanner(scanner, reporter, aDocURL, aBaseURL, aDocPrincipal);
+  nsAutoSuppressErrors suppressErrors(this);
+
+  bool conditionMet;
+  bool parsedOK = ParseSupportsCondition(conditionMet) && !GetToken(true);
+
+  CLEAR_ERROR();
+  ReleaseScanner();
+
+  return parsedOK && conditionMet;
+}
+
 //----------------------------------------------------------------------
 
 bool
@@ -10214,3 +10274,25 @@ nsCSSParser::ParseKeyframeSelectorString(const nsSubstring& aSelectorString,
     ParseKeyframeSelectorString(aSelectorString, aURI, aLineNumber,
                                 aSelectorList);
 }
+
+bool
+nsCSSParser::EvaluateSupportsDeclaration(const nsAString& aProperty,
+                                         const nsAString& aValue,
+                                         nsIURI* aDocURL,
+                                         nsIURI* aBaseURL,
+                                         nsIPrincipal* aDocPrincipal)
+{
+  return static_cast<CSSParserImpl*>(mImpl)->
+    EvaluateSupportsDeclaration(aProperty, aValue, aDocURL, aBaseURL,
+                                aDocPrincipal);
+}
+
+bool
+nsCSSParser::EvaluateSupportsCondition(const nsAString& aCondition,
+                                       nsIURI* aDocURL,
+                                       nsIURI* aBaseURL,
+                                       nsIPrincipal* aDocPrincipal)
+{
+  return static_cast<CSSParserImpl*>(mImpl)->
+    EvaluateSupportsCondition(aCondition, aDocURL, aBaseURL, aDocPrincipal);
+}

layout/style/nsCSSParser.h

@@ -180,6 +180,25 @@ public:
                                    uint32_t           aLineNumber,
                                    InfallibleTArray<float>& aSelectorList);
 
+  /**
+   * Parse a property and value and return whether the property/value pair
+   * is supported.
+   */
+  bool EvaluateSupportsDeclaration(const nsAString& aProperty,
+                                   const nsAString& aValue,
+                                   nsIURI* aDocURL,
+                                   nsIURI* aBaseURL,
+                                   nsIPrincipal* aDocPrincipal);
+
+  /**
+   * Parse an @supports condition and returns the result of evaluating the
+   * condition.
+   */
+  bool EvaluateSupportsCondition(const nsAString& aCondition,
+                                 nsIURI* aDocURL,
+                                 nsIURI* aBaseURL,
+                                 nsIPrincipal* aDocPrincipal);
+
 protected:
   // This is a CSSParserImpl*, but if we expose that type name in this
   // header, we can't put the type definition (in nsCSSParser.cpp) in

layout/style/test/Makefile.in

@@ -98,6 +98,7 @@ MOCHITEST_FILES =	test_acid3_test46.html \
 		test_default_computed_style.html \
 		test_css_cross_domain.html \
 		test_css_eof_handling.html \
+		test_css_supports.html \
 		test_default_bidi_css.html \
 		test_descriptor_storage.html \
 		test_descriptor_syntax_errors.html \

layout/style/test/test_css_supports.html

@@ -0,0 +1,134 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=779917
+-->
+<head>
+  <title>Test for Bug 779917</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=779917">Mozilla Bug 779917</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 779917 **/
+
+function runTest()
+{
+  var passingConditions = [
+    "(color: green)",
+    "((color: green))",
+    "(color: green !important)",
+    "(color: rainbow) or (color: green)",
+    "(color: green) or (color: rainbow)",
+    "(color: green) and (color: blue)",
+    "(color: rainbow) or (color: iridescent) or (color: green)",
+    "(color: red) and (color: green) and (color: blue)",
+    "(color:green)",
+    "not (color: rainbow)",
+    "not (not (color: green))",
+    "(unknown:) or (color: green)",
+    "(unknown) or (color: green)",
+    "(font: 16px serif)",
+    "(color:) or (color: green)",
+    "not (@page)",
+    "not ({ something @with [ balanced ] brackets })",
+    "an-extension(of some kind) or (color: green)",
+    "not ()",
+    "( Font:  20px serif ! Important) ",
+    "(color: /* comment */ green)",
+    "(/* comment */ color: green)",
+    "(color: green /* comment */)",
+    "(color: green) /* comment */",
+    "/* comment */ (color: green)",
+    "(color /* comment */: green)",
+    "(color: green) /* unclosed comment",
+    "(color: green",
+    "(((((((color: green",
+    "(font-family: 'Helvetica"
+  ];
+
+  var failingConditions = [
+    "(color: rainbow)",
+    "(color: rainbow) and (color: green)",
+    "(color: blue) and (color: rainbow)",
+    "(color: green) and (color: green) or (color: green)",
+    "(color: green) or (color: green) and (color: green)",
+    "not not (color: green)",
+    "not (color: rainbow) and not (color: iridescent)",
+    "not (color: rainbow) or (color: green)",
+    "(not (color: rainbow) or (color: green))",
+    "(unknown: green)",
+    "not ({ something @with (unbalanced brackets })",
+    "(color: green) or an-extension(that is [unbalanced)",
+    "not(unknown: unknown)",
+    "(color: green) or(color: blue)",
+    "color: green",
+    "(color: green;)",
+    "(font-family: 'Helvetica\n",
+    "(font-family: 'Helvetica\n')",
+    "()",
+    ""
+  ];
+
+  var passingDeclarations = [
+    ["color", "green"],
+    ["color", " green "],
+    ["Color", "Green"],
+    ["color", "green /* comment */"],
+    ["color", "/* comment */ green"],
+    ["color", "green /* unclosed comment"],
+    ["font", "16px serif"],
+    ["font", "16px /* comment */ serif"],
+    ["font", "16px\nserif"],
+    ["color", "\\0067reen"]
+  ];
+
+  var failingDeclarations = [
+    ["color ", "green"],
+    ["color", "rainbow"],
+    ["color", "green green"],
+    ["color", "green !important"],
+    ["\\0063olor", "green"],
+    ["/* comment */color", "green"],
+    ["color/* comment */", "green"],
+    ["font-family", "'Helvetica\n"],
+    ["font-family", "'Helvetica\n'"],
+    ["color", "green;"],
+    ["color", ""],
+    ["unknown", "unknown"],
+    ["", "green"],
+    ["", ""]
+  ];
+
+  passingConditions.forEach(function(aCondition) {
+    is(CSS.supports(aCondition), true, "CSS.supports returns true for passing condition \"" + aCondition + "\"");
+  });
+
+  failingConditions.forEach(function(aCondition) {
+    is(CSS.supports(aCondition), false, "CSS.supports returns false for failing condition \"" + aCondition + "\"");
+  });
+
+  passingDeclarations.forEach(function(aDeclaration) {
+    is(CSS.supports(aDeclaration[0], aDeclaration[1]), true, "CSS.supports returns true for supported declaration \"" + aDeclaration.join(":") + "\"");
+  });
+
+  failingDeclarations.forEach(function(aDeclaration) {
+    is(CSS.supports(aDeclaration[0], aDeclaration[1]), false, "CSS.supports returns false for unsupported declaration \"" + aDeclaration.join(":") + "\"");
+  });
+
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+SpecialPowers.pushPrefEnv({ "set": [["layout.css.supports-rule.enabled", true]] }, runTest);
+</script>
+</pre>
+</body>
+</html>