Initial skeleton of Accessibility Object Model Phase 1

third_party/WebKit/Source/core/dom/AccessibleNode.cpp

+// Copyright 2017 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/dom/AccessibleNode.h"
+
+#include "core/dom/AXObjectCache.h"
+#include "core/dom/AXUtils.h"
+#include "core/dom/Element.h"
+#include "core/frame/Settings.h"
+
+namespace blink {
+
+AccessibleNode::AccessibleNode(Element* element) : m_element(element) {
+  DCHECK(RuntimeEnabledFeatures::accessibilityObjectModelEnabled());
+}
+
+AccessibleNode::~AccessibleNode() {}
+
+const AtomicString& AccessibleNode::getProperty(
+    AOMStringProperty property) const {
+  if (!m_element)
+    return nullAtom;
+
+  const AtomicString& result = m_stringProperties.at(property);

[esprehn, 2017/03/22 03:40:31]

I'd suggest using a vector instead, you probably won't have that many properties
per thing, and a HashMap is a lot of overhead.

[dmazzoni, 2017/03/23 03:36:40]

The reason I did this was memory. There are 48 properties, corresponding to 48
ARIA attributes, in phase 1, and probably a dozen more by the end of the spec. I
didn't want every AccessibleNode to have space for 48+ values that would be
mostly unused.

Perhaps std::map would be less overhead but more sparse?

In Chromium accessibility code we often use vector<pair<enum, value>>, that's
another option.

+  if (result.isNull())
+    return nullAtom;
+
+  switch (property) {
+    case AOMStringProperty::Role:
+      if (!AXUtils::getInstance()->isValidRoleAttribute(result))

[esprehn, 2017/03/22 03:40:31]

This feels like over abstraction going through a singleton and a virtual call,
what's this for?

[dmazzoni, 2017/03/23 03:36:40]

Removed, we're not doing validation for now.

+        return nullAtom;
+      break;
+    case AOMStringProperty::Label:
+      // No validation needed.
+      break;
+    case AOMStringProperty::None:
+      NOTREACHED();
+      return nullAtom;
+  }
+
+  return result;
+}
+
+String AccessibleNode::role() const {

[esprehn, 2017/03/22 03:40:31]

return AtomicString

[dmazzoni, 2017/03/23 03:36:40]

Done throughout.

+  return getProperty(AOMStringProperty::Role);
+}
+
+void AccessibleNode::setRole(const String& role) {

[esprehn, 2017/03/22 03:40:31]

Take an AtomicString here instead

+  if (!m_element)
+    return;
+
+  m_stringProperties.set(AOMStringProperty::Role, AtomicString(role));
+
+  // TODO(dmazzoni): Make a cleaner API for this rather than pretending
+  // the DOM attribute changed.
+  if (AXObjectCache* cache = m_element->document().axObjectCache())
+    cache->handleAttributeChanged(HTMLNames::roleAttr, m_element);
+}
+
+String AccessibleNode::label() const {

[esprehn, 2017/03/22 03:40:31]

ditto

+  return getProperty(AOMStringProperty::Label);
+}
+
+void AccessibleNode::setLabel(const String& label) {

[esprehn, 2017/03/22 03:40:31]

ditto

+  m_stringProperties.set(AOMStringProperty::Label, AtomicString(label));
+  if (AXObjectCache* cache = m_element->document().axObjectCache())
+    cache->handleAttributeChanged(HTMLNames::aria_labelAttr, m_element);
+}
+
+DEFINE_TRACE(AccessibleNode) {
+  visitor->trace(m_element);
+}
+
+}  // namespace blink