Implements CSSPropertyAPI for the clip property.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIClip.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/properties/CSSPropertyAPIClip.h"
+
+#include "core/css/CSSQuadValue.h"
+#include "core/css/CSSValueList.h"
+#include "core/css/parser/CSSParserTokenRange.h"
+#include "core/css/parser/CSSPropertyParser.h"
+#include "core/css/parser/CSSPropertyParserHelpers.h"
+
+namespace blink {
+
+static CSSValue* consumeClipComponent(CSSParserTokenRange& range,

[meade_UTC10, 2017/01/05 04:10:22]

You could make this helper method more private by putting it into an anonymous
namespace (instead of making it static).

+                                      CSSParserMode cssParserMode) {
+  if (range.peek().id() == CSSValueAuto)
+    return CSSPropertyParserHelpers::consumeIdent(range);
+  return CSSPropertyParserHelpers::consumeLength(
+      range, cssParserMode, ValueRangeAll,
+      CSSPropertyParserHelpers::UnitlessQuirk::Allow);
+}
+
+const CSSValue* CSSPropertyAPIClip::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext& context) {
+  if (range.peek().id() == CSSValueAuto)
+    return CSSPropertyParserHelpers::consumeIdent(range);
+
+  if (range.peek().functionId() != CSSValueRect)
+    return nullptr;
+
+  CSSParserTokenRange args = CSSPropertyParserHelpers::consumeFunction(range);
+  // rect(t, r, b, l) || rect(t r b l)
+  CSSValue* top = consumeClipComponent(args, context.mode());
+  if (!top)
+    return nullptr;
+  bool needsComma =
+      CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args);
+  CSSValue* right = consumeClipComponent(args, context.mode());
+  if (!right ||
+      (needsComma &&
+       !CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args)))
+    return nullptr;
+  CSSValue* bottom = consumeClipComponent(args, context.mode());
+  if (!bottom ||
+      (needsComma &&
+       !CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args)))
+    return nullptr;
+  CSSValue* left = consumeClipComponent(args, context.mode());
+  if (!left || !args.atEnd())
+    return nullptr;
+  return CSSQuadValue::create(top, right, bottom, left,
+                              CSSQuadValue::SerializeAsRect);
+}
+
+}  // namespace blink