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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_ACCESSIBILITY_AX_TREE_SOURCE_CHECKER_H_
#define UI_ACCESSIBILITY_AX_TREE_SOURCE_CHECKER_H_
#include <map>
#include "base/memory/raw_ptr.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "ui/accessibility/ax_tree_source.h"
namespace ui {
template <typename AXSourceNode>
class AXTreeSourceChecker {
public:
explicit AXTreeSourceChecker(AXTreeSource<AXSourceNode>* tree);
AXTreeSourceChecker(const AXTreeSourceChecker&) = delete;
AXTreeSourceChecker& operator=(const AXTreeSourceChecker&) = delete;
~AXTreeSourceChecker();
// Returns true if everything reachable from the root of the tree is
// consistent in its parent/child connections, and returns the error
// as a string.
bool CheckAndGetErrorString(std::string* error_string);
private:
bool Check(AXSourceNode node, std::string indent, std::string* output);
std::string NodeToString(AXSourceNode node);
raw_ptr<AXTreeSource<AXSourceNode>> tree_;
std::map<AXNodeID, AXNodeID> node_id_to_parent_id_map_;
};
template <typename AXSourceNode>
AXTreeSourceChecker<AXSourceNode>::AXTreeSourceChecker(
AXTreeSource<AXSourceNode>* tree)
: tree_(tree) {}
template <typename AXSourceNode>
AXTreeSourceChecker<AXSourceNode>::~AXTreeSourceChecker() = default;
template <typename AXSourceNode>
bool AXTreeSourceChecker<AXSourceNode>::CheckAndGetErrorString(
std::string* error_string) {
node_id_to_parent_id_map_.clear();
AXSourceNode root = tree_->GetRoot();
if (!root) {
*error_string = "Root is not present.";
return false;
}
AXNodeID root_id = tree_->GetId(root);
node_id_to_parent_id_map_[root_id] = kInvalidAXNodeID;
return Check(root, "", error_string);
}
template <typename AXSourceNode>
std::string AXTreeSourceChecker<AXSourceNode>::NodeToString(AXSourceNode node) {
AXNodeData node_data;
tree_->SerializeNode(node, &node_data);
tree_->CacheChildrenIfNeeded(node);
auto num_children = tree_->GetChildCount(node);
std::string children_str;
if (num_children == 0) {
children_str = "(no children)";
} else {
for (size_t i = 0; i < num_children; i++) {
auto* child = tree_->ChildAt(node, i);
AXNodeID child_id = child ? tree_->GetId(child) : kInvalidAXNodeID;
if (i == 0)
children_str += "child_ids=" + base::NumberToString(child_id);
else
children_str += "," + base::NumberToString(child_id);
}
}
tree_->ClearChildCache(node);
AXNodeID parent_id = tree_->GetParent(node)
? tree_->GetId(tree_->GetParent(node))
: kInvalidAXNodeID;
return base::StringPrintf("%s %s parent_id=%d", node_data.ToString().c_str(),
children_str.c_str(), parent_id);
}
template <typename AXSourceNode>
bool AXTreeSourceChecker<AXSourceNode>::Check(AXSourceNode node,
std::string indent,
std::string* output) {
*output += indent + NodeToString(node);
AXNodeID node_id = tree_->GetId(node);
if (node_id <= kInvalidAXNodeID) {
std::string msg = base::StringPrintf(
"Got a node with id %d, but all node IDs should be >= 1:\n%s\n",
node_id, NodeToString(node).c_str());
*output = msg + *output;
return false;
}
// Check parent.
AXNodeID expected_parent_id = node_id_to_parent_id_map_[node_id];
AXSourceNode parent = tree_->GetParent(node);
if (expected_parent_id == kInvalidAXNodeID) {
if (parent) {
std::string msg = base::StringPrintf(
"Node %d is the root, so its parent should be invalid, but we "
"got a node with id %d.\n"
"Node: %s\n"
"Parent: %s\n",
node_id, tree_->GetId(parent), NodeToString(node).c_str(),
NodeToString(parent).c_str());
*output = msg + *output;
return false;
}
} else {
if (!parent) {
std::string msg = base::StringPrintf(
"Node %d is not the root, but its parent was invalid:\n%s\n", node_id,
NodeToString(node).c_str());
*output = msg + *output;
return false;
}
AXNodeID parent_id = tree_->GetId(parent);
if (parent_id != expected_parent_id) {
AXSourceNode expected_parent = tree_->EnsureGetFromId(expected_parent_id);
std::string msg = base::StringPrintf(
"Expected node %d to have a parent of %d, but found a parent of %d.\n"
"Node: %s\n"
"Parent: %s\n"
"Expected parent: %s\n",
node_id, expected_parent_id, parent_id, NodeToString(node).c_str(),
NodeToString(parent).c_str(), NodeToString(expected_parent).c_str());
*output = msg + *output;
return false;
}
}
// Check children.
tree_->CacheChildrenIfNeeded(node);
auto num_children = tree_->GetChildCount(node);
for (size_t i = 0; i < num_children; i++) {
auto* child = tree_->ChildAt(node, i);
if (!child) {
continue;
}
AXNodeID child_id = tree_->GetId(child);
if (node_id_to_parent_id_map_.find(child_id) !=
node_id_to_parent_id_map_.end()) {
*output += "\n" + indent + " ";
AXNodeData child_data;
tree_->SerializeNode(child, &child_data);
*output += child_data.ToString() + "\n";
std::string msg = base::StringPrintf(
"Node %d has a child with ID %d, but we've previously seen a node "
"with that ID, with a parent of %d.\n"
"Node: %s",
node_id, child_id, node_id_to_parent_id_map_[child_id],
NodeToString(node).c_str());
*output = msg + *output;
tree_->ClearChildCache(node);
return false;
}
node_id_to_parent_id_map_[child_id] = node_id;
}
*output += "\n";
for (size_t i = 0; i < num_children; i++) {
auto* child = tree_->ChildAt(node, i);
if (!child) {
continue;
}
if (!Check(child, indent + " ", output)) {
tree_->ClearChildCache(node);
return false;
}
}
tree_->ClearChildCache(node);
return true;
}
} // namespace ui
#endif // UI_ACCESSIBILITY_AX_TREE_SOURCE_CHECKER_H_
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