Unprefix CSS Variables

Source/core/css/CSSParser.cpp

Index: Source/core/css/CSSParser.cpp
diff --git a/Source/core/css/CSSParser.cpp b/Source/core/css/CSSParser.cpp
index 55a9e4322866c1dc94513a3efd76dfe92a78700e..048571e643864d2f58f74d00f72f681fb76f1523 100644
--- a/Source/core/css/CSSParser.cpp
+++ b/Source/core/css/CSSParser.cpp
@@ -3063,7 +3063,7 @@ void CSSParser::storeVariableDeclaration(const CSSParserString& name, PassOwnPtr
     if (!value)
         return;
 
-    static const unsigned prefixLength = sizeof("-webkit-var-") - 1;
+    static const unsigned prefixLength = sizeof("var-") - 1;
 
     ASSERT(name.length() > prefixLength);
     AtomicString variableName = name.atomicSubstring(prefixLength, name.length() - prefixLength);
@@ -9796,6 +9796,10 @@ inline bool CSSParser::detectFunctionTypeToken(int length)
             m_token = CUEFUNCTION;
             return true;
         }
+        if (RuntimeEnabledFeatures::cssVariablesEnabled() && isASCIIAlphaCaselessEqual(name[0], 'v') && isASCIIAlphaCaselessEqual(name[1], 'a') && isASCIIAlphaCaselessEqual(name[2], 'r')) {

[Mike Lawther (Google), 2013/05/29 04:54:13]

This is a job for a new patch, but this looks like it would work with eg "VaR"?
The spec text currently says: "The "var-" prefix must be written in
lower-case.".

[alancutter (OOO until 2018), 2013/05/29 06:41:51]

I was unsure whether I should tackle that in this patch or not. I decided it
would be prudent to keep the case sensitivity of var as a separate patch.

[Mike Lawther (Google), 2013/05/29 08:23:00]

I agree - post a new patch for this.

+            m_token = VARFUNCTION;
+            return true;
+        }
         return false;
 
     case 4:
@@ -9992,8 +9996,6 @@ inline void CSSParser::detectDashToken(int length)
             m_token = MINFUNCTION;
         else if (isASCIIAlphaCaselessEqual(name[10], 'x') && isEqualToCSSIdentifier(name + 1, "webkit-ma"))
             m_token = MAXFUNCTION;
-        else if (RuntimeEnabledFeatures::cssVariablesEnabled() && isASCIIAlphaCaselessEqual(name[10], 'r') && isEqualToCSSIdentifier(name + 1, "webkit-va"))
-            m_token = VARFUNCTION;
     } else if (length == 12 && isEqualToCSSIdentifier(name + 1, "webkit-calc"))
         m_token = CALCFUNCTION;
     else if (length == 19 && isEqualToCSSIdentifier(name + 1, "webkit-distributed"))
@@ -10244,16 +10246,16 @@ inline void CSSParser::detectSupportsToken(int length)
 }
 
 template <typename CharacterType>
-inline bool CSSParser::detectCSSVariablesToken(int length)
+inline void CSSParser::detectCSSVariableDeclarationToken(int length)
 {
-    ASSERT(tokenStart<CharacterType>()[0] == '-');
-    if (length < sizeof("-webkit-var-*") - 1)
-        return false;
+    static const unsigned prefixLength = sizeof("var-") - 1;
+    if (length <= prefixLength)
+        return;
     CharacterType* name = tokenStart<CharacterType>();
-    return name[11] == '-' && isIdentifierStartAfterDash(name + 12) && isEqualToCSSIdentifier(name + 1, "webkit-var");
+    if (name[3] == '-' && isIdentifierStartAfterDash(name + 4) && isEqualToCSSIdentifier(name, "var"))

[Mike Lawther (Google), 2013/05/29 04:54:13]

You can get rid of these magic numbers with something like
static const char* token = "var";
const unsigned tokenLength = sizeof(token) - 1;
const unsigned prefixLength = tokenLength + (sizeof("-") - 1);

Now you can replace '3' with 'tokenLength', and replace '4' with 'prefixLength'.

[alancutter (OOO until 2018), 2013/05/29 06:41:51]

I would prefer to have the entire "var-" as a string for searchability.
The token is really the entire thing rather than just the "var" bit. It's hard
to label that as anything other than prefixWithoutDash.
Would it be okay to just have:

ASSERT(prefixLength > 0)
if (name[prefixLength - 1] == '-' && ...

?

[Mike Lawther (Google), 2013/05/29 08:23:00]

Can you make that a COMPILE_ASSERT? No need to have a runtime check for what is
a compile time problem :)

+        m_token = VAR_DEFINITION;
 }
 
-
 template <typename SrcCharacterType>
 int CSSParser::realLex(void* yylvalWithoutType)
 {
@@ -10351,6 +10353,8 @@ restartAfterComment:
                     }
                 }
             }
+        } else if (UNLIKELY(RuntimeEnabledFeatures::cssVariablesEnabled())) {
+            detectCSSVariableDeclarationToken<SrcCharacterType>(result - tokenStart<SrcCharacterType>());
         }
         break;
 
@@ -10437,9 +10441,7 @@ restartAfterComment:
             parseIdentifier(result, resultString, hasEscape);
             m_token = IDENT;
 
-            if (RuntimeEnabledFeatures::cssVariablesEnabled() && detectCSSVariablesToken<SrcCharacterType>(result - tokenStart<SrcCharacterType>()))
-                m_token = VAR_DEFINITION;
-            else if (*currentCharacter<SrcCharacterType>() == '(') {
+            if (*currentCharacter<SrcCharacterType>() == '(') {
                 m_token = FUNCTION;
                 if (!hasEscape)
                     detectDashToken<SrcCharacterType>(result - tokenStart<SrcCharacterType>());