Lazy Parse CSS

third_party/WebKit/Source/core/css/parser/CSSLazyPropertyParserImpl.h

Index: third_party/WebKit/Source/core/css/parser/CSSLazyPropertyParserImpl.h
diff --git a/third_party/WebKit/Source/core/css/parser/CSSLazyPropertyParserImpl.h b/third_party/WebKit/Source/core/css/parser/CSSLazyPropertyParserImpl.h
new file mode 100644
index 0000000000000000000000000000000000000000..00c04d7d6b8a8a098da164771681b6157883a910
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/parser/CSSLazyPropertyParserImpl.h
@@ -0,0 +1,63 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CSSLazyPropertyParserImpl_h
+#define CSSLazyPropertyParserImpl_h
+
+#include "core/css/CSSSelectorList.h"
+#include "core/css/StylePropertySet.h"
+#include "core/css/parser/CSSParser.h"
+#include "core/css/parser/CSSParserMode.h"
+#include "core/css/parser/CSSParserTokenRange.h"
+#include "core/css/parser/CSSTokenizer.h"
+#include "wtf/Vector.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+// This class helps lazy parsing by retaining necessary state. It should not
+// outlive the StyleSheetContents that initiated the parse, as it retains a raw
+// reference to the UseCounter associated with the style sheet.
+class CSSLazyParsingState
+    : public GarbageCollectedFinalized<CSSLazyParsingState> {
+ public:
+  CSSLazyParsingState(const CSSParserContext&,
+                      std::unique_ptr<Vector<String>> escapedStrings,

[esprehn, 2016/10/24 21:20:21]

There's no reason to pass around a unique_ptr to Vector like this, just pass by
value and use move semantics to move from one place to another.

[Charlie Harrison, 2016/10/25 15:56:55]

timloh had wanted to me only lazily initiate the Vector on the Tokenizer::Scope.
I don't think empty Vectors are very expensive, so I think this change should be
ok.

timloh, please let me know if you disagree.

[Timothy Loh, 2016/10/25 23:47:31]

I think it was already a unique_ptr at that point, I just wanted it to not be
allocated if we weren't using it. Making it a Vector instead of
unique_ptr<Vector> should be good.

+                      const String& sheetText);
+
+  // This should be a copy of the context used in CSSParser::parseSheet.
+  const CSSParserContext& context() { return m_context; }
+
+  bool shouldLazilyParseProperties(const CSSSelectorList&);
+
+  DEFINE_INLINE_TRACE() {}
+
+ private:
+  CSSParserContext m_context;
+  std::unique_ptr<Vector<String>> m_escapedStrings;
+  // Also referenced on the css resource.
+  String m_sheetText;
+};
+
+// This class is responsible for lazily parsing a single CSS declaration list.
+class CSSLazyPropertyParserImpl : public CSSLazyPropertyParser {
+ public:
+  CSSLazyPropertyParserImpl(CSSParserTokenRange block, CSSLazyParsingState*);
+
+  // CSSLazyPropertyParser:
+  StylePropertySet* parseProperties() override;
+
+  DEFINE_INLINE_TRACE() {
+    visitor->trace(m_lazyState);
+    CSSLazyPropertyParser::trace(visitor);
+  }
+
+ private:
+  Vector<CSSParserToken, 0u> m_tokens;

[esprehn, 2016/10/24 21:20:21]

remove 0, the default is zero, no need to specify it.

[Charlie Harrison, 2016/10/25 15:56:55]

Done.

+  Member<CSSLazyParsingState> m_lazyState;
+};
+
+}  // namespace blink
+
+#endif  // CSSLazyPropertyParserImpl_h