1#pragma once
2
3#include <Columns/ColumnConst.h>
4#include <Columns/ColumnString.h>
5#include <Columns/ColumnVector.h>
6#include <DataTypes/DataTypesNumber.h>
7#include <Functions/FunctionHelpers.h>
8#include <Functions/IFunctionImpl.h>
9
10namespace DB
11{
12/** Calculate similarity metrics:
13 *
14 * ngramDistance(haystack, needle) - calculate n-gram distance between haystack and needle.
15 * Returns float number from 0 to 1 - the closer to zero, the more strings are similar to each other.
16 * Also support CaseInsensitive and UTF8 formats.
17 * ngramDistanceCaseInsensitive(haystack, needle)
18 * ngramDistanceUTF8(haystack, needle)
19 * ngramDistanceCaseInsensitiveUTF8(haystack, needle)
20 */
21
22namespace ErrorCodes
23{
24 extern const int ILLEGAL_TYPE_OF_ARGUMENT;
25 extern const int ILLEGAL_COLUMN;
26 extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
27 extern const int TOO_LARGE_STRING_SIZE;
28}
29
30template <typename Impl, typename Name>
31class FunctionsStringSimilarity : public IFunction
32{
33public:
34 static constexpr auto name = Name::name;
35
36 static FunctionPtr create(const Context &) { return std::make_shared<FunctionsStringSimilarity>(); }
37
38 String getName() const override { return name; }
39
40 size_t getNumberOfArguments() const override { return 2; }
41
42 DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
43 {
44 if (!isString(arguments[0]))
45 throw Exception(
46 "Illegal type " + arguments[0]->getName() + " of argument of function " + getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
47
48 if (!isString(arguments[1]))
49 throw Exception(
50 "Illegal type " + arguments[1]->getName() + " of argument of function " + getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
51
52 return std::make_shared<DataTypeNumber<typename Impl::ResultType>>();
53 }
54
55 void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
56 {
57 using ResultType = typename Impl::ResultType;
58
59 const ColumnPtr & column_haystack = block.getByPosition(arguments[0]).column;
60 const ColumnPtr & column_needle = block.getByPosition(arguments[1]).column;
61
62 const ColumnConst * col_haystack_const = typeid_cast<const ColumnConst *>(&*column_haystack);
63 const ColumnConst * col_needle_const = typeid_cast<const ColumnConst *>(&*column_needle);
64
65 if (col_haystack_const && col_needle_const)
66 {
67 ResultType res{};
68 const String & needle = col_needle_const->getValue<String>();
69 if (needle.size() > Impl::max_string_size)
70 {
71 throw Exception(
72 "String size of needle is too big for function " + getName() + ". Should be at most "
73 + std::to_string(Impl::max_string_size),
74 ErrorCodes::TOO_LARGE_STRING_SIZE);
75 }
76 Impl::constant_constant(col_haystack_const->getValue<String>(), needle, res);
77 block.getByPosition(result).column
78 = block.getByPosition(result).type->createColumnConst(col_haystack_const->size(), toField(res));
79 return;
80 }
81
82 auto col_res = ColumnVector<ResultType>::create();
83
84 typename ColumnVector<ResultType>::Container & vec_res = col_res->getData();
85 vec_res.resize(column_haystack->size());
86
87 const ColumnString * col_haystack_vector = checkAndGetColumn<ColumnString>(&*column_haystack);
88 const ColumnString * col_needle_vector = checkAndGetColumn<ColumnString>(&*column_needle);
89
90 if (col_haystack_vector && col_needle_const)
91 {
92 const String & needle = col_needle_const->getValue<String>();
93 if (needle.size() > Impl::max_string_size)
94 {
95 throw Exception(
96 "String size of needle is too big for function " + getName() + ". Should be at most "
97 + std::to_string(Impl::max_string_size),
98 ErrorCodes::TOO_LARGE_STRING_SIZE);
99 }
100 Impl::vector_constant(col_haystack_vector->getChars(), col_haystack_vector->getOffsets(), needle, vec_res);
101 }
102 else if (col_haystack_vector && col_needle_vector)
103 {
104 Impl::vector_vector(
105 col_haystack_vector->getChars(),
106 col_haystack_vector->getOffsets(),
107 col_needle_vector->getChars(),
108 col_needle_vector->getOffsets(),
109 vec_res);
110 }
111 else if (col_haystack_const && col_needle_vector)
112 {
113 const String & haystack = col_haystack_const->getValue<String>();
114 if (haystack.size() > Impl::max_string_size)
115 {
116 throw Exception(
117 "String size of haystack is too big for function " + getName() + ". Should be at most "
118 + std::to_string(Impl::max_string_size),
119 ErrorCodes::TOO_LARGE_STRING_SIZE);
120 }
121 Impl::constant_vector(haystack, col_needle_vector->getChars(), col_needle_vector->getOffsets(), vec_res);
122 }
123 else
124 {
125 throw Exception(
126 "Illegal columns " + block.getByPosition(arguments[0]).column->getName() + " and "
127 + block.getByPosition(arguments[1]).column->getName() + " of arguments of function " + getName(),
128 ErrorCodes::ILLEGAL_COLUMN);
129 }
130
131 block.getByPosition(result).column = std::move(col_res);
132 }
133};
134
135}
136