Change HTMLTokenizer::Attribute::Range.start initial invalid value from 0 -> -1

third_party/WebKit/Source/core/html/parser/HTMLToken.h

Index: third_party/WebKit/Source/core/html/parser/HTMLToken.h
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLToken.h b/third_party/WebKit/Source/core/html/parser/HTMLToken.h
index 679a187e1d1a14bdd36a685985f7846369b99ad0..3f0d7637b4582d308426a33e0a32ee115c88fb7c 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLToken.h
+++ b/third_party/WebKit/Source/core/html/parser/HTMLToken.h
@@ -81,6 +81,32 @@ public:
         class Range {
             DISALLOW_NEW();
         public:
+            static constexpr int kInvalidOffset = -1;
+
+            inline void clear()
+            {
+#if ENABLE(ASSERT)
+                start = kInvalidOffset;
+                end = kInvalidOffset;
+#endif
+            }
+
+            // Check Range instance that is actively being parsed.
+            inline void checkValidStart() const
+            {
+                DCHECK(start != kInvalidOffset);

[Charlie Harrison, 2016/07/06 13:50:37]

nit: Use DCHECK_NE.

+                DCHECK_GE(start, 0);
+            }
+
+            // Check Range instance which finished parse.
+            inline void checkValid() const
+            {
+                checkValidStart();
+                DCHECK(end != kInvalidOffset);

[Charlie Harrison, 2016/07/06 13:50:37]

ditto

+                DCHECK_GE(end, 0);
+                DCHECK_LE(start, end);
+            }
+
             int start;
             int end;
         };
@@ -122,8 +148,8 @@ public:
     void clear()
     {
         m_type = Uninitialized;
+        m_range.clear();
         m_range.start = 0;
-        m_range.end = 0;
         m_baseOffset = 0;
         // Don't call Vector::clear() as that would destroy the
         // alloced VectorBuffer. If the innerHTML'd content has
@@ -314,45 +340,43 @@ public:
         ASSERT(m_type == StartTag || m_type == EndTag);
         m_attributes.grow(m_attributes.size() + 1);
         m_currentAttribute = &m_attributes.last();
-#if ENABLE(ASSERT)
-        m_currentAttribute->mutableNameRange().start = 0;
-        m_currentAttribute->mutableNameRange().end = 0;
-        m_currentAttribute->mutableValueRange().start = 0;
-        m_currentAttribute->mutableValueRange().end = 0;
-#endif
+        m_currentAttribute->mutableNameRange().clear();
+        m_currentAttribute->mutableValueRange().clear();
     }
 
     void beginAttributeName(int offset)
     {
         m_currentAttribute->mutableNameRange().start = offset - m_baseOffset;
+        m_currentAttribute->nameRange().checkValidStart();
     }
 
     void endAttributeName(int offset)
     {
         int index = offset - m_baseOffset;
         m_currentAttribute->mutableNameRange().end = index;
+        m_currentAttribute->nameRange().checkValid();
         m_currentAttribute->mutableValueRange().start = index;
         m_currentAttribute->mutableValueRange().end = index;
     }
 
     void beginAttributeValue(int offset)
     {
+        m_currentAttribute->mutableValueRange().clear();
         m_currentAttribute->mutableValueRange().start = offset - m_baseOffset;
-#if ENABLE(ASSERT)
-        m_currentAttribute->mutableValueRange().end = 0;
-#endif
+        m_currentAttribute->valueRange().checkValidStart();
     }
 
     void endAttributeValue(int offset)
     {
         m_currentAttribute->mutableValueRange().end = offset - m_baseOffset;
+        m_currentAttribute->valueRange().checkValid();
     }
 
     void appendToAttributeName(UChar character)
     {
         ASSERT(character);
         ASSERT(m_type == StartTag || m_type == EndTag);
-        ASSERT(m_currentAttribute->nameRange().start);
+        m_currentAttribute->nameRange().checkValidStart();
         m_currentAttribute->appendToName(character);
     }
 
@@ -360,7 +384,7 @@ public:
     {
         ASSERT(character);
         ASSERT(m_type == StartTag || m_type == EndTag);
-        ASSERT(m_currentAttribute->valueRange().start);
+        m_currentAttribute->valueRange().checkValidStart();
         m_currentAttribute->appendToValue(character);
     }