[WIP] Add support for CSSValue-> CSSLengthValue and CSSTranslation

third_party/WebKit/Source/core/css/cssom/CSSTranslation.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/cssom/CSSTranslation.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/css/CSSPrimitiveValue.h"
 
 namespace blink {
 
 CSSTranslation* CSSTranslation::create(CSSLengthValue* x, CSSLengthValue* y, CSSLengthValue* z, ExceptionState& exceptionState)
 {
     if (z->containsPercent()) {
         exceptionState.throwTypeError("CSSTranslation does not support z CSSLengthValue with percent units");
         return nullptr;
     }
     return new CSSTranslation(x, y, z);
 }
 
+CSSTranslation* CSSTranslation::fromCSSValue(const CSSValue& value)
+{
+    if (!value.isFunctionValue())
+        return nullptr;
+
+    const CSSFunctionValue& cssFunctionValue = toCSSFunctionValue(value);
+    if (cssFunctionValue.length() < 2)
+        return nullptr;
+
+    CSSLengthValue* x = CSSLengthValue::fromCSSValue(*cssFunctionValue.item(0));
+    CSSLengthValue* y = CSSLengthValue::fromCSSValue(*cssFunctionValue.item(1));
+    if (!x || !y)
+        return nullptr;
+
+    if (cssFunctionValue.functionType() == CSSValueTranslate) {
+        if (cssFunctionValue.length() != 2)
+            return nullptr;
+        return CSSTranslation::create(x, y);
+    }
+
+    if (cssFunctionValue.functionType() == CSSValueTranslate3d) {
+        if (cssFunctionValue.length() != 3)
+            return nullptr;
+        CSSLengthValue* z = CSSLengthValue::fromCSSValue(*cssFunctionValue.item(2));
+        if (!z || z->containsPercent())
+            return nullptr;
+        return new CSSTranslation(x, y, z);
+    }
+    return nullptr;
+}
+
 CSSFunctionValue* CSSTranslation::toCSSValue() const
 {
     CSSFunctionValue* result = CSSFunctionValue::create(is2D() ? CSSValueTranslate : CSSValueTranslate3d);
     result->append(m_x->toCSSValue());
     result->append(m_y->toCSSValue());
     if (!is2D())
         result->append(m_z->toCSSValue());
     return result;
 }
 
 } // namespace blink