Add support for attribute change callbacks in AXNodeData.

ui/accessibility/ax_tree.cc

 // Copyright 2013 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 "ui/accessibility/ax_tree.h"
 
 #include <stddef.h>
 
 #include <set>
 
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "ui/accessibility/ax_node.h"
 
 namespace ui {
 
 namespace {
 
 std::string TreeToStringHelper(AXNode* node, int indent) {
   std::string result = std::string(2 * indent, ' ');
   result += node->data().ToString() + "\n";
   for (int i = 0; i < node->child_count(); ++i)
     result += TreeToStringHelper(node->ChildAtIndex(i), indent + 1);
   return result;
 }
 
+template <typename K, typename V>
+bool KeyValuePairsKeysMatch(std::vector<std::pair<K, V>> pairs1,
+                            std::vector<std::pair<K, V>> pairs2) {
+  if (pairs1.size() != pairs2.size())
+    return false;
+  for (size_t i = 0; i < pairs1.size(); ++i) {
+    if (pairs1[i].first != pairs2[i].first)
+      return false;
+  }
+  return true;
+}
+
+template <typename K, typename V>
+std::map<K, V> MapFromKeyValuePairs(std::vector<std::pair<K, V>> pairs) {
+  std::map<K, V> result;
+  for (size_t i = 0; i < pairs.size(); ++i)
+    result[pairs[i].first] = pairs[i].second;
+  return result;
+}
+
 }  // namespace
 
 // Intermediate state to keep track of during a tree update.
 struct AXTreeUpdateState {
   AXTreeUpdateState() : new_root(nullptr) {}
   // Returns whether this update changes |node|.
   bool HasChangedNode(const AXNode* node) {
     return changed_node_ids.find(node->id()) != changed_node_ids.end();
   }
 
@@ skipping 184 matching lines @@
   // This method updates one node in the tree based on serialized data
   // received in an AXTreeUpdate. See AXTreeUpdate for pre and post
   // conditions.
 
   // Look up the node by id. If it's not found, then either the root
   // of the tree is being swapped, or we're out of sync with the source
   // and this is a serious error.
   AXNode* node = GetFromId(src.id);
   if (node) {
     update_state->pending_nodes.erase(node);
-    if (delegate_ &&
-        update_state->new_nodes.find(node) == update_state->new_nodes.end())
-      delegate_->OnNodeDataWillChange(this, node->data(), src);
+    if (update_state->new_nodes.find(node) == update_state->new_nodes.end())
+      CallNodeChangeCallbacks(node, src);
     node->SetData(src);
   } else {
     if (!is_new_root) {
       error_ = base::StringPrintf(
           "%d is not in the tree and not the new root", src.id);
       return false;
     }
 
     update_state->new_root = CreateNode(NULL, src.id, 0, update_state);
     node = update_state->new_root;
@@ skipping 40 matching lines @@
     // DestroySubtree.
     AXNode* old_root = root_;
     root_ = node;
     if (old_root && old_root != node)
       DestroySubtree(old_root, update_state);
   }
 
   return success;
 }
 
+void AXTree::CallNodeChangeCallbacks(AXNode* node, const AXNodeData& new_data) {
+  if (!delegate_)
+    return;
+
+  const AXNodeData& old_data = node->data();
+  delegate_->OnNodeDataWillChange(this, old_data, new_data);
+
+  if (old_data.role != new_data.role)
+    delegate_->OnRoleChanged(this, node, old_data.role, new_data.role);
+
+  if (old_data.state != new_data.state) {
+    for (int i = AX_STATE_NONE + 1; i <= AX_STATE_LAST; ++i) {
+      AXState state = static_cast<AXState>(i);
+      if (old_data.HasStateFlag(state) != new_data.HasStateFlag(state)) {
+        delegate_->OnStateChanged(this, node, state,
+                                  new_data.HasStateFlag(state));
+      }
+    }
+  }
+
+  const auto& old_strings = old_data.string_attributes;
+  const auto& new_strings = new_data.string_attributes;
+  if (KeyValuePairsKeysMatch(old_strings, new_strings)) {
+    for (size_t i = 0; i < old_strings.size(); ++i) {
+      if (old_strings[i].second != new_strings[i].second) {
+        delegate_->OnStringAttributeChanged(this, node, old_strings[i].first,

[aboxhall, 2017/03/09 00:46:06]

Can we fix this duplication somehow? Something something templated method and
function pointers? Not worth it?

[dmazzoni, 2017/03/10 23:40:25]

Figured it out!

What do you think? It's about 90% better, far less duplication,
but about 25% more "magic". :)

+                                            old_strings[i].second,
+                                            new_strings[i].second);
+      }
+    }
+  } else {
+    auto old_string_map = MapFromKeyValuePairs(old_strings);
+    auto new_string_map = MapFromKeyValuePairs(new_strings);
+    for (size_t i = 0; i < old_strings.size(); ++i) {
+      const auto& new_iter = new_string_map.find(old_strings[i].first);
+      if (new_iter == new_string_map.end()) {
+        delegate_->OnStringAttributeChanged(this, node, old_strings[i].first,
+                                            old_strings[i].second, "");
+      }
+    }
+    for (size_t i = 0; i < new_strings.size(); ++i) {
+      const auto& old_iter = old_string_map.find(new_strings[i].first);
+      if (old_iter == old_string_map.end()) {
+        delegate_->OnStringAttributeChanged(this, node, new_strings[i].first,
+                                            "", new_strings[i].second);
+      } else if (old_iter->second != new_strings[i].second) {
+        delegate_->OnStringAttributeChanged(this, node, new_strings[i].first,
+                                            old_iter->second,
+                                            new_strings[i].second);
+      }
+    }
+  }
+
+  const auto& old_bools = old_data.bool_attributes;
+  const auto& new_bools = new_data.bool_attributes;
+  if (KeyValuePairsKeysMatch(old_bools, new_bools)) {
+    for (size_t i = 0; i < old_bools.size(); ++i) {
+      if (old_bools[i].second != new_bools[i].second) {
+        delegate_->OnBoolAttributeChanged(this, node, old_bools[i].first,
+                                          new_bools[i].second);
+      }
+    }
+  } else {
+    auto old_bool_map = MapFromKeyValuePairs(old_bools);
+    auto new_bool_map = MapFromKeyValuePairs(new_bools);
+    for (size_t i = 0; i < old_bools.size(); ++i) {
+      const auto& new_iter = new_bool_map.find(old_bools[i].first);
+      if (old_bools[i].second && new_iter == new_bool_map.end()) {
+        delegate_->OnBoolAttributeChanged(this, node, old_bools[i].first,
+                                          false);
+      }
+    }
+    for (size_t i = 0; i < new_bools.size(); ++i) {
+      const auto& old_iter = old_bool_map.find(new_bools[i].first);
+      if (old_iter == old_bool_map.end()) {
+        if (new_bools[i].second) {
+          delegate_->OnBoolAttributeChanged(this, node, new_bools[i].first,
+                                            new_bools[i].second);
+        }
+      } else if (old_iter->second != new_bools[i].second) {
+        delegate_->OnBoolAttributeChanged(this, node, new_bools[i].first,
+                                          new_bools[i].second);
+      }
+    }
+  }
+
+  const auto& old_floats = old_data.float_attributes;
+  const auto& new_floats = new_data.float_attributes;
+  if (KeyValuePairsKeysMatch(old_floats, new_floats)) {
+    for (size_t i = 0; i < old_floats.size(); ++i) {
+      if (old_floats[i].second != new_floats[i].second) {
+        delegate_->OnFloatAttributeChanged(this, node, old_floats[i].first,
+                                           old_floats[i].second,
+                                           new_floats[i].second);
+      }
+    }
+  } else {
+    auto old_float_map = MapFromKeyValuePairs(old_floats);
+    auto new_float_map = MapFromKeyValuePairs(new_floats);
+    for (size_t i = 0; i < old_floats.size(); ++i) {
+      const auto& new_iter = new_float_map.find(old_floats[i].first);
+      if (new_iter == new_float_map.end()) {
+        delegate_->OnFloatAttributeChanged(this, node, old_floats[i].first,
+                                           old_floats[i].second, 0.0);
+      }
+    }
+    for (size_t i = 0; i < new_floats.size(); ++i) {
+      const auto& old_iter = old_float_map.find(new_floats[i].first);
+      if (old_iter == old_float_map.end()) {
+        delegate_->OnFloatAttributeChanged(this, node, new_floats[i].first, 0.0,
+                                           new_floats[i].second);
+      } else if (old_iter->second != new_floats[i].second) {
+        delegate_->OnFloatAttributeChanged(this, node, new_floats[i].first,
+                                           old_iter->second,
+                                           new_floats[i].second);
+      }
+    }
+  }
+
+  const auto& old_ints = old_data.int_attributes;
+  const auto& new_ints = new_data.int_attributes;
+  if (KeyValuePairsKeysMatch(old_ints, new_ints)) {
+    for (size_t i = 0; i < old_ints.size(); ++i) {
+      if (old_ints[i].second != new_ints[i].second) {
+        delegate_->OnIntAttributeChanged(this, node, old_ints[i].first,
+                                         old_ints[i].second,
+                                         new_ints[i].second);
+      }
+    }
+  } else {
+    auto old_int_map = MapFromKeyValuePairs(old_ints);
+    auto new_int_map = MapFromKeyValuePairs(new_ints);
+    for (size_t i = 0; i < old_ints.size(); ++i) {
+      const auto& new_iter = new_int_map.find(old_ints[i].first);
+      if (new_iter == new_int_map.end()) {
+        delegate_->OnIntAttributeChanged(this, node, old_ints[i].first,
+                                         old_ints[i].second, 0);
+      }
+    }
+    for (size_t i = 0; i < new_ints.size(); ++i) {
+      const auto& old_iter = old_int_map.find(new_ints[i].first);
+      if (old_iter == old_int_map.end()) {
+        delegate_->OnIntAttributeChanged(this, node, new_ints[i].first, 0,
+                                         new_ints[i].second);
+      } else if (old_iter->second != new_ints[i].second) {
+        delegate_->OnIntAttributeChanged(this, node, new_ints[i].first,
+                                         old_iter->second, new_ints[i].second);
+      }
+    }
+  }
+
+  const auto& old_intlists = old_data.intlist_attributes;
+  const auto& new_intlists = new_data.intlist_attributes;
+  if (KeyValuePairsKeysMatch(old_intlists, new_intlists)) {
+    for (size_t i = 0; i < old_intlists.size(); ++i) {
+      if (old_intlists[i].second != new_intlists[i].second) {
+        delegate_->OnIntListAttributeChanged(this, node, old_intlists[i].first,
+                                             old_intlists[i].second,
+                                             new_intlists[i].second);
+      }
+    }
+  } else {
+    auto old_intlist_map = MapFromKeyValuePairs(old_intlists);
+    auto new_intlist_map = MapFromKeyValuePairs(new_intlists);
+    for (size_t i = 0; i < old_intlists.size(); ++i) {
+      const auto& new_iter = new_intlist_map.find(old_intlists[i].first);
+      if (new_iter == new_intlist_map.end()) {
+        delegate_->OnIntListAttributeChanged(this, node, old_intlists[i].first,
+                                             old_intlists[i].second,
+                                             std::vector<int32_t>());
+      }
+    }
+    for (size_t i = 0; i < new_intlists.size(); ++i) {
+      const auto& old_iter = old_intlist_map.find(new_intlists[i].first);
+      if (old_iter == old_intlist_map.end()) {
+        delegate_->OnIntListAttributeChanged(this, node, new_intlists[i].first,
+                                             std::vector<int32_t>(),
+                                             new_intlists[i].second);
+      } else if (old_iter->second != new_intlists[i].second) {
+        delegate_->OnIntListAttributeChanged(this, node, new_intlists[i].first,
+                                             old_iter->second,
+                                             new_intlists[i].second);
+      }
+    }
+  }
+}
+
 void AXTree::DestroySubtree(AXNode* node,
                             AXTreeUpdateState* update_state) {
   DCHECK(update_state);
   if (delegate_) {
     if (!update_state->HasChangedNode(node))
       delegate_->OnSubtreeWillBeDeleted(this, node);
     else
       delegate_->OnSubtreeWillBeReparented(this, node);
   }
   DestroyNodeAndSubtree(node, update_state);
@@ skipping 71 matching lines @@
       update_state->pending_nodes.insert(child);
       update_state->new_nodes.insert(child);
     }
     new_children->push_back(child);
   }
 
   return success;
 }
 
 }  // namespace ui