/*
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* Copyright (C) 2018 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 "utils/sentencepiece/double_array_trie.h"
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#include "utils/base/logging.h"
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namespace libtextclassifier3 {
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bool DoubleArrayTrie::GatherPrefixMatches(
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StringPiece input, const std::function<void(TrieMatch)>& update_fn) const {
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uint32 pos = 0;
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if (nodes_length_ == 0) {
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TC3_LOG(WARNING) << "Trie is empty. Skipping.";
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return true;
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}
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pos = offset(0);
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for (int i = 0; i < input.size(); i++) {
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if (input[i] == 0) {
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break;
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}
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pos ^= static_cast<unsigned char>(input[i]);
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// We exhausted the trie, no more matches possible.
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if (pos < 0 || pos >= nodes_length_) {
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break;
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}
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if (label(pos) != input[i]) {
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break;
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}
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const bool node_has_leaf = has_leaf(pos);
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pos ^= offset(pos);
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if (pos < 0 || pos > nodes_length_) {
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TC3_LOG(ERROR) << "Out-of-bounds trie search position.";
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return false;
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}
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if (node_has_leaf) {
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update_fn(TrieMatch(/*id=*/value(pos), /*match_length=*/i + 1));
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}
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}
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return true;
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}
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bool DoubleArrayTrie::FindAllPrefixMatches(
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StringPiece input, std::vector<TrieMatch>* matches) const {
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return GatherPrefixMatches(
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input, [matches](const TrieMatch match) { matches->push_back(match); });
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}
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bool DoubleArrayTrie::LongestPrefixMatch(StringPiece input,
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TrieMatch* longest_match) const {
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*longest_match = TrieMatch();
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return GatherPrefixMatches(input, [longest_match](const TrieMatch match) {
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*longest_match = match;
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});
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}
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} // namespace libtextclassifier3
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