61 lines
1.9 KiB
C++
61 lines
1.9 KiB
C++
// Copyright 2023 gRPC authors.
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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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#include "test/core/util/osa_distance.h"
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#include <stdint.h>
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#include <algorithm>
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#include <limits>
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#include <utility>
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#include <vector>
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namespace grpc_core {
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size_t OsaDistance(absl::string_view s1, absl::string_view s2) {
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if (s1.size() > s2.size()) std::swap(s1, s2);
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if (s1.empty()) return static_cast<uint8_t>(s2.size());
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const auto width = s1.size() + 1;
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const auto height = s2.size() + 1;
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std::vector<size_t> matrix(width * height,
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std::numeric_limits<size_t>::max());
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#define MATRIX_CELL(x, y) matrix[(y) * width + (x)]
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MATRIX_CELL(0, 0) = 0;
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for (size_t i = 1; i <= s1.size(); ++i) {
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MATRIX_CELL(i, 0) = i;
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}
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for (size_t j = 1; j <= s2.size(); ++j) {
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MATRIX_CELL(0, j) = j;
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}
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for (size_t i = 1; i <= s1.size(); ++i) {
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for (size_t j = 1; j <= s2.size(); ++j) {
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const size_t cost = s1[i - 1] == s2[j - 1] ? 0 : 1;
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MATRIX_CELL(i, j) = std::min({
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MATRIX_CELL(i - 1, j) + 1, // deletion
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MATRIX_CELL(i, j - 1) + 1, // insertion
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MATRIX_CELL(i - 1, j - 1) + cost // substitution
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});
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if (i > 1 && j > 1 && s1[i - 1] == s2[j - 2] && s1[i - 2] == s2[j - 1]) {
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MATRIX_CELL(i, j) = std::min(
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MATRIX_CELL(i, j), MATRIX_CELL(i - 2, j - 2) + 1); // transposition
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}
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}
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}
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return MATRIX_CELL(s1.size(), s2.size());
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}
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} // namespace grpc_core
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