1 files changed, 89 insertions, 0 deletions
diff --git a/tools/aapt2/DominatorTree.cpp b/tools/aapt2/DominatorTree.cpp
new file mode 100644
index 000000000000..29587a8b39a7
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+++ b/tools/aapt2/DominatorTree.cpp
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ConfigDescription.h"
+#include "DominatorTree.h"
+
+#include <algorithm>
+
+namespace aapt {
+
+DominatorTree::DominatorTree(
+        const std::vector<std::unique_ptr<ResourceConfigValue>>& configs) {
+    for (const auto& config : configs) {
+        mProductRoots[config->product].tryAddChild(
+                util::make_unique<Node>(config.get(), nullptr));
+    }
+}
+
+void DominatorTree::accept(Visitor* visitor) {
+    for (auto& entry : mProductRoots) {
+        visitor->visitTree(entry.first, &entry.second);
+    }
+}
+
+bool DominatorTree::Node::tryAddChild(std::unique_ptr<Node> newChild) {
+    assert(newChild->mValue && "cannot add a root or empty node as a child");
+    if (mValue && !dominates(newChild.get())) {
+        // This is not the root and the child dominates us.
+        return false;
+    }
+    return addChild(std::move(newChild));
+}
+
+bool DominatorTree::Node::addChild(std::unique_ptr<Node> newChild) {
+    bool hasDominatedChildren = false;
+    // Demote children dominated by the new config.
+    for (auto& child : mChildren) {
+        if (newChild->dominates(child.get())) {
+            child->mParent = newChild.get();
+            newChild->mChildren.push_back(std::move(child));
+            child = {};
+            hasDominatedChildren = true;
+        }
+    }
+    // Remove dominated children.
+    if (hasDominatedChildren) {
+        mChildren.erase(std::remove_if(mChildren.begin(), mChildren.end(),
+                [](const std::unique_ptr<Node>& child) -> bool {
+            return child == nullptr;
+        }), mChildren.end());
+    }
+    // Add the new config to a child if a child dominates the new config.
+    for (auto& child : mChildren) {
+        if (child->dominates(newChild.get())) {
+            child->addChild(std::move(newChild));
+            return true;
+        }
+    }
+    // The new config is not dominated by a child, so add it here.
+    newChild->mParent = this;
+    mChildren.push_back(std::move(newChild));
+    return true;
+}
+
+bool DominatorTree::Node::dominates(const Node* other) const {
+    // Check root node dominations.
+    if (other->isRootNode()) {
+        return isRootNode();
+    } else if (isRootNode()) {
+        return true;
+    }
+    // Neither node is a root node; compare the configurations.
+    return mValue->config.dominates(other->mValue->config);
+}
+
+} // namespace aapt