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// 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.
#ifndef CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_SEARCH_H_
#define CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_SEARCH_H_
#include <string>
#include <vector>
#include "base/macros.h"
#include "content/common/content_export.h"
namespace content {
class BrowserAccessibility;
class BrowserAccessibilityManager;
// A function that returns whether or not a given node matches, given the
// start element of the search as an optional comparator.
typedef bool (*AccessibilityMatchPredicate)(
BrowserAccessibility* start_element,
BrowserAccessibility* this_element);
// This class provides an interface for searching the accessibility tree from
// a given starting node, with a few built-in options and allowing an arbitrary
// number of predicates that can be used to restrict the search.
//
// This class is meant to perform one search. Initialize it, then iterate
// over the matches, and then delete it.
//
// This class stores raw pointers to the matches in the tree! Don't keep this
// object around if the tree is mutating.
class CONTENT_EXPORT OneShotAccessibilityTreeSearch {
public:
enum Direction { FORWARDS, BACKWARDS };
const int UNLIMITED_RESULTS = -1;
OneShotAccessibilityTreeSearch(BrowserAccessibilityManager* tree);
virtual ~OneShotAccessibilityTreeSearch();
//
// Search parameters. All of these are optional.
//
// Sets the node where the search starts. The first potential match will
// be the one immediately following this one. This node will be used as
// the first arguement to any predicates.
void SetStartNode(BrowserAccessibility* start_node);
// Search forwards or backwards in an in-order traversal of the tree.
void SetDirection(Direction direction);
// Set the maximum number of results, or UNLIMITED_RESULTS
// for no limit (default).
void SetResultLimit(int result_limit);
// If true, only searches children of |start_node| and doesn't
// recurse.
void SetImmediateDescendantsOnly(bool immediate_descendants_only);
// If true, only considers nodes that aren't invisible or offscreen.
void SetVisibleOnly(bool visible_only);
// Restricts the matches to only nodes where |text| is found as a
// substring of any of that node's accessible text, including its
// name, description, or value. Case-insensitive.
void SetSearchText(const std::string& text);
// Restricts the matches to only those that satisfy all predicates.
void AddPredicate(AccessibilityMatchPredicate predicate);
//
// Calling either of these executes the search.
//
size_t CountMatches();
BrowserAccessibility* GetMatchAtIndex(size_t index);
private:
void Search();
void SearchByWalkingTree();
void SearchByIteratingOverChildren();
bool Matches(BrowserAccessibility* node);
BrowserAccessibilityManager* tree_;
BrowserAccessibility* start_node_;
Direction direction_;
int result_limit_;
bool immediate_descendants_only_;
bool visible_only_;
std::string search_text_;
std::vector<AccessibilityMatchPredicate> predicates_;
std::vector<BrowserAccessibility*> matches_;
bool did_search_;
DISALLOW_COPY_AND_ASSIGN(OneShotAccessibilityTreeSearch);
};
} // namespace content
#endif // CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_SEARCH_H_
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