17 using DistanceArray = MultiArray<size_t, NoneOwningMultiArray, size_t, size_t>;
31 void initDistanceArray(DistanceArray &distanceArray,
const size_t size1,
const size_t size2)
33 const auto maxDistance(size1 + size2);
34 distanceArray.at(0, 0) = maxDistance;
35 for (
size_t i = 0;
i <= size1; ++
i) {
36 distanceArray.at(
i + 1, 1) =
i;
37 distanceArray.at(
i + 1, 0) = maxDistance;
39 for (
size_t i = 0;
i <= size2; ++
i) {
40 distanceArray.at(1,
i + 1) =
i;
41 distanceArray.at(0,
i + 1) = maxDistance;
47 size_t performDamerauLevenshteinAlgorithm(
48 DistanceArray &distanceArray,
const char *
const str1,
const size_t size1,
const char *
const str2,
const size_t size2)
51 for (
size_t index1 = 1; index1 <= size1; ++index1) {
53 for (
size_t index2 = 1; index2 <= size2; ++index2) {
54 const size_t substitution((str1[index1 - 1] == str2[index2 - 1]) ? 0 : 1);
55 const size_t transposition1(dist1[
static_cast<unsigned char>(str2[index2 - 1])]);
56 const size_t transposition2(dist2);
62 distanceArray.at(index1, index2) + substitution,
63 distanceArray.at(index1 + 1, index2) + 1,
64 distanceArray.at(index1, index2 + 1) + 1,
65 distanceArray.at(transposition1, transposition2) + (index1 - transposition1 - 1) + 1 + (index2 - transposition2 - 1)
69 dist1[
static_cast<int>(str1[index1 - 1])] = index1;
71 return distanceArray.at(size1 + 1, size2 + 1);
75 template <
typename DistanceArray>
76 size_t performDamerauLevenshteinAlgorithmAllocatingOnHeap(
77 DistanceArray &distanceArray,
const char *
const str1,
const size_t size1,
const char *
const str2,
const size_t size2)
79 std::vector<size_t> buffer(distanceArray.totalSize());
80 distanceArray.buffer() = buffer.data();
81 initDistanceArray(distanceArray, size1, size2);
82 return performDamerauLevenshteinAlgorithm(distanceArray, str1, size1, str2, size2);
87 template <
typename DistanceArray>
88 size_t performDamerauLevenshteinAlgorithmAllocatingOnStack(
89 DistanceArray &distanceArray,
const char *
const str1,
const size_t size1,
const char *
const str2,
const size_t size2)
91 size_t buffer[128] = { 0 };
92 distanceArray.buffer() = buffer;
93 initDistanceArray(distanceArray, size1, size2);
94 return performDamerauLevenshteinAlgorithm(distanceArray, str1, size1, str2, size2);
120 auto distanceArray(makeNoneOwningMultiArray<std::size_t>(size1 + 2, size2 + 2));
121 if (distanceArray.totalSize() <= 128) {
122 return performDamerauLevenshteinAlgorithmAllocatingOnStack(distanceArray, str1, size1, str2, size2);
124 return performDamerauLevenshteinAlgorithmAllocatingOnHeap(distanceArray, str1, size1, str2, size2);
Contains all utilities provides by the c++utilities library.
std::size_t computeDamerauLevenshteinDistance(const char *const str1, const size_t size1, const char *const str2, const size_t size2)
Computes Damerau–Levenshtein distance with adjacent transpositions.
constexpr T max(T first, T second)
Returns the greatest of the given items.
constexpr T min(T first, T second)
Returns the smallest of the given items.