Add a public Blink function to canonicalize and restrict the type of CSS selectors.

public/web/WebSelector.h

Index: public/web/WebSelector.h
diff --git a/public/web/WebSelector.h b/public/web/WebSelector.h
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+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebSelector_h
+#define WebSelector_h
+
+namespace WebKit {
+
+class WebString;
+
+struct WebSelectorRestriction {

[abarth-chromium, 2013/08/28 06:29:37]

What's the point of this class?  Why not just declare the enum in the WebKit
namespace and pass that directly to canonicalizeSelector?

[Jeffrey Yasskin, 2013/08/28 17:55:14]

I was thinking that we may want more restrictions in the future (e.g.
single-selector vs list, only certain kinds of simple selectors), and it'll be
better to express those in a struct than in a mask type or in multiple
parameters, but I guess we can change the canonicalizeSelector() signature when
that happens. I've switched to a raw enum.

Should the enum's name be WebKit::SelectorType or WebKit::WebSelectorType? And
if WebSelectorType, should the enumerators be WebSelectorTypeComplex, etc.?

+    // Defaults to no restrictions.
+    WebSelectorRestriction();

[abarth-chromium, 2013/08/28 06:29:37]

WEBKIT_EXPORT  <--- needed for the component build

[Jeffrey Yasskin, 2013/08/28 17:55:14]

Argh, thanks. I wish the tests lived outside libwebkit.so so they'd catch things
like this.

+
+    // Terminology from http://dev.w3.org/csswg/selectors4/#structure.
+    enum SelectorType {
+        Complex,

[abarth-chromium, 2013/08/28 06:29:37]

Complex -> SelectorTypeComplex

[Jeffrey Yasskin, 2013/08/28 17:55:14]

Done.

+        Compound,

[abarth-chromium, 2013/08/28 06:29:37]

Compound -> SelectorTypeCompound

[Jeffrey Yasskin, 2013/08/28 17:55:14]

Done.

+        // Not yet implemented:
+        // Simple,
+    };
+
+    // If the selector is a list, this restriction applies to each selector within the list.
+    SelectorType type;
+};
+
+// Returns the value that would be returned from CSSStyleRule.selectorText in the CSSOM for a rule with this selector, if the selector is valid and matches the restrictions.
+// Returns "" for an invalid selector or a selector that doesn't match the restrictions.
+// The canonical form is not guaranteed to stay the same over time.
+WebString canonicalizeSelector(WebString selector, WebSelectorRestriction = WebSelectorRestriction());

[abarth-chromium, 2013/08/28 06:29:37]

EXPORT_WEBKIT

[Jeffrey Yasskin, 2013/08/28 17:55:14]

Done.

+
+} // namespace WebKit
+
+#endif