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// Copyright 2018 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.
#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_ACCESSIBILITY_AX_POSITION_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_ACCESSIBILITY_AX_POSITION_H_
#include <base/logging.h>
#include <base/optional.h>
#include <stdint.h>
#include <ostream>
#include "third_party/blink/renderer/core/editing/forward.h"
#include "third_party/blink/renderer/core/editing/text_affinity.h"
#include "third_party/blink/renderer/modules/modules_export.h"
#include "third_party/blink/renderer/platform/heap/persistent.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
namespace blink {
class AXObject;
// When converting to a DOM position from an |AXPosition| and the corresponding
// DOM position is invalid or doesn't exist, determines how to adjust the
// |AXPosition| in order to make it valid.
enum class AXPositionAdjustmentBehavior { kMoveLeft, kMoveRight };
// Describes a position in the Blink accessibility tree.
// A position is either anchored to before or after a child object inside a
// container object, or is anchored to a character inside a text object.
class MODULES_EXPORT AXPosition final {
DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
public:
static const AXPosition CreatePositionBeforeObject(const AXObject& child);
static const AXPosition CreatePositionAfterObject(const AXObject& child);
static const AXPosition CreateFirstPositionInObject(
const AXObject& container);
static const AXPosition CreateLastPositionInObject(const AXObject& container);
static const AXPosition CreatePositionInTextObject(
const AXObject& container,
int offset,
TextAffinity = TextAffinity::kDownstream);
static const AXPosition FromPosition(const Position&);
static const AXPosition FromPosition(const PositionWithAffinity&);
AXPosition(const AXPosition&) = default;
AXPosition& operator=(const AXPosition&) = default;
~AXPosition() = default;
const AXObject* ContainerObject() const { return container_object_; }
const AXObject* ObjectAfterPosition() const;
int ChildIndex() const;
int TextOffset() const;
TextAffinity Affinity() const { return affinity_; }
// Verifies if the anchor is present and if it's set to a live object with a
// connected node.
bool IsValid() const;
// Returns whether this is a position anchored to a character inside a text
// object.
bool IsTextPosition() const;
const AXPosition CreateNextPosition() const;
const AXPosition CreatePreviousPosition() const;
const PositionWithAffinity ToPositionWithAffinity(
const AXPositionAdjustmentBehavior =
AXPositionAdjustmentBehavior::kMoveLeft) const;
private:
AXPosition();
explicit AXPosition(const AXObject& container);
// The |AXObject| in which the position is present.
// Only valid during a single document lifecycle hence no need to maintain a
// strong reference to it.
WeakPersistent<const AXObject> container_object_;
// If the position is anchored to before or after an object, the number of
// child objects in |container_object_| that come before the position.
// If this is a text position, the number of characters in the canonical text
// of |container_object_| before the position. The canonical text is the DOM
// node's text but with, e.g., whitespace collapsed and any transformations
// applied.
base::Optional<int> text_offset_or_child_index_;
// When the same character offset could correspond to two possible caret
// positions, upstream means it's on the previous line rather than the next
// line.
TextAffinity affinity_;
#if DCHECK_IS_ON()
// TODO(ax-dev): Use layout tree version in place of DOM and style versions.
uint64_t dom_tree_version_;
uint64_t style_version_;
#endif
// For access to our constructor for use when creating empty AX selections.
// There is no sense in creating empty positions in other circomstances so we
// disallow it.
friend class AXSelection;
};
MODULES_EXPORT bool operator==(const AXPosition&, const AXPosition&);
MODULES_EXPORT bool operator!=(const AXPosition&, const AXPosition&);
MODULES_EXPORT bool operator<(const AXPosition&, const AXPosition&);
MODULES_EXPORT bool operator<=(const AXPosition&, const AXPosition&);
MODULES_EXPORT bool operator>(const AXPosition&, const AXPosition&);
MODULES_EXPORT bool operator>=(const AXPosition&, const AXPosition&);
MODULES_EXPORT std::ostream& operator<<(std::ostream&, const AXPosition&);
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_MODULES_ACCESSIBILITY_AX_POSITION_H_
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