106 lines
3.6 KiB
C++
106 lines
3.6 KiB
C++
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//
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// Copyright (C) 2017 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#include "trie_builder.h"
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#include <android-base/strings.h>
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using android::base::Split;
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namespace android {
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namespace properties {
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TrieBuilder::TrieBuilder(const std::string& default_context, const std::string& default_type)
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: builder_root_("root") {
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auto* context_pointer = StringPointerFromContainer(default_context, &contexts_);
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builder_root_.set_context(context_pointer);
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auto* type_pointer = StringPointerFromContainer(default_type, &types_);
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builder_root_.set_type(type_pointer);
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}
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bool TrieBuilder::AddToTrie(const std::string& name, const std::string& context,
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const std::string& type, bool exact, std::string* error) {
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auto* context_pointer = StringPointerFromContainer(context, &contexts_);
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auto* type_pointer = StringPointerFromContainer(type, &types_);
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return AddToTrie(name, context_pointer, type_pointer, exact, error);
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}
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bool TrieBuilder::AddToTrie(const std::string& name, const std::string* context,
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const std::string* type, bool exact, std::string* error) {
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TrieBuilderNode* current_node = &builder_root_;
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auto name_pieces = Split(name, ".");
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bool ends_with_dot = false;
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if (name_pieces.back().empty()) {
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ends_with_dot = true;
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name_pieces.pop_back();
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}
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// Move us to the final node that we care about, adding incremental nodes if necessary.
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while (name_pieces.size() > 1) {
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auto child = current_node->FindChild(name_pieces.front());
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if (child == nullptr) {
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child = current_node->AddChild(name_pieces.front());
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}
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if (child == nullptr) {
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*error = "Unable to allocate Trie node";
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return false;
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}
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current_node = child;
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name_pieces.erase(name_pieces.begin());
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}
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// Store our context based on what type of match it is.
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if (exact) {
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if (!current_node->AddExactMatchContext(name_pieces.front(), context, type)) {
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*error = "Duplicate exact match detected for '" + name + "'";
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return false;
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}
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} else if (!ends_with_dot) {
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if (!current_node->AddPrefixContext(name_pieces.front(), context, type)) {
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*error = "Duplicate prefix match detected for '" + name + "'";
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return false;
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}
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} else {
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auto child = current_node->FindChild(name_pieces.front());
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if (child == nullptr) {
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child = current_node->AddChild(name_pieces.front());
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}
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if (child == nullptr) {
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*error = "Unable to allocate Trie node";
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return false;
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}
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if (child->context() != nullptr || child->type() != nullptr) {
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*error = "Duplicate prefix match detected for '" + name + "'";
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return false;
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}
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child->set_context(context);
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child->set_type(type);
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}
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return true;
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}
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const std::string* TrieBuilder::StringPointerFromContainer(const std::string& string,
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std::set<std::string>* container) {
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// Get a pointer to the string in a given set, such that we only ever serialize each string once.
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auto [iterator, _] = container->emplace(string);
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return &(*iterator);
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}
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} // namespace properties
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} // namespace android
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