Implementation of CSS3 nav-up/down/left/right properties from CSS3 UI.

Source/core/css/parser/CSSPropertyParser.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 1049 matching lines @@
             validPrimitive = true;
         else {
             RefPtrWillBeRawPtr<CSSValue> val = parseFilter();
             if (val) {
                 addProperty(propId, val, important);
                 return true;
             }
             return false;
         }
         break;
+    case CSSPropertyNavDown: // auto | <id> [ current | root | <target-name> ] | inherit
+    case CSSPropertyNavLeft:
+    case CSSPropertyNavRight:
+    case CSSPropertyNavUp:
+        if (id == CSSValueAuto) {
+            validPrimitive = true;
+        } else if (value) {

[Timothy Loh, 2014/10/01 13:14:54]

value is never null here.

I would move this logic into a separate function (something like
PassRefPtrWillBeRawPtr<CSSValue> parseNav(), which returns nullptr if it fails
to parse). Then this branch would just be "parsedValue = parseNav()".

+            if (value->unit != CSSPrimitiveValue::CSS_PARSER_IDSEL && value->unit != CSSPrimitiveValue::CSS_PARSER_HEXCOLOR)
+                return false;
+            String selectorText = "#";
+            selectorText.append(value->string);
+
+            RefPtrWillBeRawPtr<CSSPrimitiveValue> idSel = cssValuePool().createValue(selectorText, CSSPrimitiveValue::CSS_STRING);
+            value = m_valueList->next();
+            RefPtrWillBeRawPtr<CSSPrimitiveValue> target;
+            if (value) {
+                if (value->unit == CSSPrimitiveValue::CSS_IDENT) {
+                    target = parseValidPrimitive(value->id, value);

[Timothy Loh, 2014/10/01 13:14:53]

Don't you want to check if the id is CSSValueCurrent or CSSValueRoot?

+                } else if (value->unit == CSSPrimitiveValue::CSS_STRING) {
+                    if (value->string.startsWithIgnoringCase("_"))
+                        return false;
+                    target = cssValuePool().createValue(value->string, CSSPrimitiveValue::CSS_STRING);
+                }

[Timothy Loh, 2014/10/01 13:14:53]

You'll want to call m_valueList->next() here to indicate you've consumed the
current token. The code outside the huge switch checks there are no trailing
tokens.

+            } else {
+                target = cssValuePool().createValue(CSSValueCurrent);
+            }
+
+            RefPtrWillBeRawPtr<CSSValueList> propertyValue = CSSValueList::createSpaceSeparated();
+            propertyValue->append(idSel);
+            propertyValue->append(target);
+            addProperty(propId, propertyValue, important);

[Timothy Loh, 2014/10/01 13:14:54]

Don't addProperty, just break after setting parsedValue.

+            return true;
+        }
+        break;
     case CSSPropertyFlex: {
         ShorthandScope scope(this, propId);
         if (id == CSSValueNone) {
             addProperty(CSSPropertyFlexGrow, cssValuePool().createValue(0, CSSPrimitiveValue::CSS_NUMBER), important);
             addProperty(CSSPropertyFlexShrink, cssValuePool().createValue(0, CSSPrimitiveValue::CSS_NUMBER), important);
             addProperty(CSSPropertyFlexBasis, cssValuePool().createIdentifierValue(CSSValueAuto), important);
             return true;
         }
         return parseFlex(m_valueList, important);
     }
@@ skipping 7094 matching lines @@
         parsedValues->append(CSSPrimitiveValue::createIdentifier(CSSValueFill));
     if (!seenStroke)
         parsedValues->append(CSSPrimitiveValue::createIdentifier(CSSValueStroke));
     if (!seenMarkers)
         parsedValues->append(CSSPrimitiveValue::createIdentifier(CSSValueMarkers));
 
     return parsedValues.release();
 }
 
 } // namespace blink