[CSS Grid Layout] Implementation of the grid shorthand.

Source/core/css/parser/CSSPropertyParser.cpp

Index: Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/Source/core/css/parser/CSSPropertyParser.cpp b/Source/core/css/parser/CSSPropertyParser.cpp
index c0d17bd4ad78bab38671880c93af5ec3819fdbea..85015b2e9275e88e4f76746ee1f1948795c219b3 100644
--- a/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/Source/core/css/parser/CSSPropertyParser.cpp
@@ -1277,6 +1277,11 @@ bool CSSPropertyParser::parseValue(CSSPropertyID propId, bool important)
             return false;
         return parseGridTemplateShorthand(important);
 
+    case CSSPropertyGrid:
+        if (!RuntimeEnabledFeatures::cssGridLayoutEnabled())
+            return false;
+        return parseGridShorthand(important);
+
     case CSSPropertyWebkitMarginCollapse: {
         if (num == 1) {
             ShorthandScope scope(this, CSSPropertyWebkitMarginCollapse);
@@ -3599,6 +3604,62 @@ bool CSSPropertyParser::parseGridTemplateShorthand(bool important)
     return parseGridTemplateRowsAndAreas(columnsValue, important);
 }
 
+bool CSSPropertyParser::parseGridShorthand(bool important)
+{
+    ShorthandScope scope(this, CSSPropertyGrid);
+    const StylePropertyShorthand& shorthand = shorthandForProperty(CSSPropertyGrid);
+    ASSERT_UNUSED(shorthand, shorthand.length() == 4);

[Julien - ping for review, 2014/04/03 21:14:30]

Can't we just do:

ASSERT(shorthandForProperty(CSSPropertyGrid).lenght() == 4);

[jfernandez, 2014/04/04 15:09:35]

Done.

+
+    // 1- <grid-template>
+    if (parseGridTemplateShorthand(important)) {
+        // Default values for the implicit grid properties.
+        addProperty(CSSPropertyGridAutoFlow, cssValuePool().createIdentifierValue(CSSValueNone), important);
+        addProperty(CSSPropertyGridAutoColumns, cssValuePool().createIdentifierValue(CSSValueAuto), important);
+        addProperty(CSSPropertyGridAutoRows, cssValuePool().createIdentifierValue(CSSValueAuto), important);
+        return true;
+    }
+
+    // Need to rewind parsing to explore the alternative syntax of this shorthand.
+    m_valueList->setCurrentIndex(0);
+
+    // 2- <grid-auto-flow> [ <grid-auto-columns> [ / <grid-auto-rows> ]? ]
+    CSSValueID id = m_valueList->current()->id;
+    if (id != CSSValueRow && id != CSSValueColumn && id != CSSValueNone)
+        return false;
+
+    RefPtrWillBeRawPtr<CSSValue> autoFlowValue = cssValuePool().createIdentifierValue(id);
+    RefPtrWillBeRawPtr<CSSValue> autoColumnsValue = cssValuePool().createIdentifierValue(CSSValueAuto);

[Julien - ping for review, 2014/04/03 21:14:30]

I would rather leave both auto*Value to nullptr and initialize them in the
'else' branches below (if (m_valueList->next())).

Also the specification prose mentions to set them up to the *initial* value, for
which we have a keyword: CSSValueInitial.

[jfernandez, 2014/04/04 15:09:35]

Done.
Well, I think what is has to be done is to use the
"createExplicitInitialValue()" method to set the corresponding "initial" values
for each property; right ? 

+    RefPtrWillBeRawPtr<CSSValue> autoRowsValue = nullptr;
+
+    if (m_valueList->next()) {
+        autoColumnsValue = parseGridTrackSize(*m_valueList);
+        if (!autoColumnsValue)
+            return false;
+        if (m_valueList->current()) {
+            if (!(isForwardSlashOperator(m_valueList->current()) && m_valueList->next()))

[Julien - ping for review, 2014/04/03 21:14:30]

Let's avoid !(... && ...) by expanding it.

[jfernandez, 2014/04/04 15:09:35]

Done.

+                return false;
+            autoRowsValue = parseGridTrackSize(*m_valueList);
+            if (!autoRowsValue)
+                return false;
+        }
+        if (m_valueList->current())
+            return false;
+    }
+    addProperty(CSSPropertyGridAutoFlow, autoFlowValue, important);
+    addProperty(CSSPropertyGridAutoColumns, autoColumnsValue, important);
+    if (autoRowsValue)
+        addProperty(CSSPropertyGridAutoRows, autoRowsValue, important);
+    else
+        addProperty(CSSPropertyGridAutoRows, autoColumnsValue, important);
+
+    // Default values for the explicit grid properties.

[Julien - ping for review, 2014/04/03 21:14:30]

You should quote the specification here or give a more precise comment as this
looks really suspicious until you read the specification prose.

[jfernandez, 2014/04/04 15:09:35]

Done.

+    addProperty(CSSPropertyGridTemplateColumns, cssValuePool().createIdentifierValue(CSSValueNone), important);
+    addProperty(CSSPropertyGridTemplateRows, cssValuePool().createIdentifierValue(CSSValueNone), important);
+    addProperty(CSSPropertyGridTemplateAreas, cssValuePool().createIdentifierValue(CSSValueNone), important);
+
+    return true;
+}
+
 bool CSSPropertyParser::parseGridAreaShorthand(bool important)
 {
     ASSERT(RuntimeEnabledFeatures::cssGridLayoutEnabled());