compositor-worker: Introduce CompositorProxy.

Source/core/dom/CompositorProxy.cpp

+// Copyright 2015 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 "config.h"
+#include "core/dom/CompositorProxy.h"
+
+#include "bindings/core/v8/ExceptionMessages.h"
+#include "bindings/core/v8/ExceptionState.h"
+#include "core/dom/DOMNodeIds.h"
+#include "core/dom/ExecutionContext.h"
+
+namespace blink {
+
+struct AttributeFlagMapping {
+    const char* name;
+    unsigned length;
+    CompositorProxy::Attributes attribute;
+};
+
+static AttributeFlagMapping allowedAttributes[] = {
+    { "opacity", 7, CompositorProxy::Attributes::OPACITY },
+    { "scrollleft", 10, CompositorProxy::Attributes::SCROLL_LEFT },
+    { "scrolltop", 9, CompositorProxy::Attributes::SCROLL_TOP },
+    { "touch", 5, CompositorProxy::Attributes::TOUCH },
+    { "transform", 8, CompositorProxy::Attributes::TRANSFORM },
+};
+
+static bool CompareAttributeName(const AttributeFlagMapping& attribute, StringImpl* attributeLower)
+{
+    ASSERT(attributeLower->is8Bit());
+    return memcmp(attribute.name, attributeLower->characters8(), std::min(attribute.length, attributeLower->length())) < 0;
+}
+
+static CompositorProxy::Attributes attributeFlagForName(const String& attributeName)
+{
+    CompositorProxy::Attributes attributeFlag = CompositorProxy::Attributes::NONE;
+    const String attributeLower = attributeName.lower();
+    const AttributeFlagMapping* start = allowedAttributes;
+    const AttributeFlagMapping* end = allowedAttributes + WTF_ARRAY_LENGTH(allowedAttributes);
+    if (attributeLower.impl()->is8Bit()) {
+        const AttributeFlagMapping* match = std::lower_bound(start, end, attributeLower.impl(), CompareAttributeName);
+        if (match != end)
+            attributeFlag = match->attribute;
+    }
+    return attributeFlag;
+}
+
+static uint32_t attributesBitfieldFromNames(const Vector<String>& attributeArray)
+{
+    uint32_t attributesBitfield = 0;
+    for (const auto& attribute : attributeArray) {
+        attributesBitfield |= static_cast<uint32_t>(attributeFlagForName(attribute));
+    }
+    return attributesBitfield;
+}
+
+#if ENABLE(ASSERT)
+static bool sanityCheckAttributeFlags(uint32_t attributeFlags)
+{
+    uint32_t sanityCheckAttributes = attributeFlags;
+    for (unsigned i = 0; i < arraysize(allowedAttributes); ++i) {
+        sanityCheckAttributes &= ~static_cast<uint32_t>(allowedAttributes[i].attribute);
+    }
+    return !sanityCheckAttributes;
+}
+#endif
+
+CompositorProxy* CompositorProxy::create(ExecutionContext* context, Element* element, const Vector<String>& attributeArray, ExceptionState& exceptionState)
+{
+    if (!context->isDocument()) {
+        exceptionState.throwTypeError(ExceptionMessages::failedToConstruct("CompositorProxy", "Can only be created from the main context."));
+        exceptionState.throwIfNeeded();
+        return nullptr;
+    }
+
+    return new CompositorProxy(*element, attributeArray);
+}
+
+CompositorProxy* CompositorProxy::create(uint64_t elementId, uint32_t attributeFlags)
+{
+    return new CompositorProxy(elementId, attributeFlags);
+}
+
+CompositorProxy::CompositorProxy(Element& element, const Vector<String>& attributeArray)
+    : m_elementId(DOMNodeIds::idForNode(&element))
+    , m_bitfieldsSupported(attributesBitfieldFromNames(attributeArray))
+{
+    ASSERT(isMainThread());
+    ASSERT(m_bitfieldsSupported);
+    ASSERT(sanityCheckAttributeFlags(m_bitfieldsSupported));
+}
+
+CompositorProxy::CompositorProxy(uint64_t elementId, uint32_t attributeFlags)
+    : m_elementId(elementId)
+    , m_bitfieldsSupported(attributeFlags)
+{
+    ASSERT(!isMainThread());
+    ASSERT(sanityCheckAttributeFlags(m_bitfieldsSupported));
+}
+
+CompositorProxy::~CompositorProxy()
+{
+}
+
+bool CompositorProxy::supports(const String& attributeName) const
+{
+    return !!(m_bitfieldsSupported & static_cast<uint32_t>(attributeFlagForName(attributeName)));
+}
+
+} // namespace blink