Improved parse error handling for CSSMQ.

Source/core/css/CSSParser.h

Index: Source/core/css/CSSParser.h
diff --git a/Source/core/css/CSSParser.h b/Source/core/css/CSSParser.h
index a28c3f6250f51e649bd0fc39d6955bbfe76675af..99d1d108773dc57be0c382759ffb0f8a7bc26342 100644
--- a/Source/core/css/CSSParser.h
+++ b/Source/core/css/CSSParser.h
@@ -3,6 +3,7 @@
  * Copyright (C) 2004, 2005, 2006, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 - 2010  Torch Mobile (Beijing) Co. Ltd. All rights reserved.
+ * Copyright (C) 2013 Opera Software ASA. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -67,6 +68,68 @@ class WebKitCSSArrayFunctionValue;
 class WebKitCSSMixFunctionValue;
 class WebKitCSSShaderValue;
 
+// Keep track of matching parentheses using a stack of opening brackets.
+// Needed for correct error recovery.
+class BracketStack {
+public:
+    inline void push(int bracket) { m_stack.append(bracket); }
+
+    inline void pop(int bracket)
+    {
+        if (m_stack.size() > 0) {
+            switch (bracket) {
+            case '}':
+                if (m_stack.last() == '{')
+                    m_stack.removeLast();
+                break;
+            case ')':
+                if (m_stack.last() == '(')
+                    m_stack.removeLast();
+                break;
+            case ']':
+                if (m_stack.last() == '[')
+                    m_stack.removeLast();
+                break;
+            default:
+                ASSERT_NOT_REACHED();
+                break;
+            }
+        }
+    }
+
+    inline int pop()
+    {
+        if (!m_stack.size())
+            return 0;
+
+        int ret = 0;
+        switch (top()) {
+        case '{':
+            ret = '}';
+            break;
+        case '(':
+            ret = ')';
+            break;
+        case '[':
+            ret = ']';
+            break;
+        default:
+            ASSERT_NOT_REACHED();
+            break;
+        }
+        m_stack.removeLast();
+        return ret;
+    }
+
+    int top() const { return m_stack.last(); }
+
+    inline size_t level() const { return m_stack.size(); }
+
+private:
+    // Make room for 16 levels deep nesting of parentheses initially.
+    Vector<int, 16> m_stack;
+};
+
 class CSSParser {
     friend inline int cssyylex(void*, CSSParser*);
 
@@ -405,6 +468,12 @@ public:
     PassRefPtr<CSSPrimitiveValue> createPrimitiveStringValue(CSSParserValue*);
     PassRefPtr<CSSPrimitiveValue> createPrimitiveVariableNameValue(CSSParserValue*);
 
+    // Store block level.
+    void markMediaListStart();
+
+    // Error token reached while parsing a media_query, synchronized at current token.
+    MediaQuery* recoverMediaQuery();
+
     static KURL completeURL(const CSSParserContext&, const String& url);
 
     Location currentLocation();
@@ -553,6 +622,18 @@ private:
     bool m_inViewport;
 #endif
 
+    enum ReEmissionState {
+        DontEmit,
+        ReEmit,
+        DidReEmit
+    };
+
+    inline void markCurrentTokenForReEmission();
+
+    ReEmissionState m_reEmissionState;
+    BracketStack m_brackets;
+    size_t m_storedBlockLevel;
+
     int (CSSParser::*m_lexFunc)(void*);
 
     Vector<RefPtr<StyleRuleBase> > m_parsedRules;
@@ -705,6 +786,18 @@ inline int cssyylex(void* yylval, CSSParser* parser)
     return parser->lex(yylval);
 }
 
+inline void CSSParser::markCurrentTokenForReEmission()
+{
+    // Sanity check.
+    // Re-emitting a token which has just been re-emitted may cause an infinite
+    // loop. Also, marking a token for re-emit twice also doesn't make sense.
+    ASSERT(m_reEmissionState == DontEmit);
+
+    // Make sure we don't enter an infinite loop if the assert triggers.
+    if (m_reEmissionState == DontEmit)
+        m_reEmissionState = ReEmit;
+}
+
 } // namespace WebCore
 
 #endif // CSSParser_h