1 | #include <Functions/IFunctionImpl.h> |
2 | #include <Functions/FunctionHelpers.h> |
3 | #include <Functions/FunctionFactory.h> |
4 | #include <DataTypes/DataTypesNumber.h> |
5 | #include <DataTypes/DataTypeNullable.h> |
6 | #include <DataTypes/getLeastSupertype.h> |
7 | #include <Core/ColumnNumbers.h> |
8 | #include <Columns/ColumnNullable.h> |
9 | |
10 | |
11 | namespace DB |
12 | { |
13 | |
14 | /// Implements the function ifNull which takes 2 arguments and returns |
15 | /// the value of the 1st argument if it is not null. Otherwise it returns |
16 | /// the value of the 2nd argument. |
17 | class FunctionIfNull : public IFunction |
18 | { |
19 | public: |
20 | static constexpr auto name = "ifNull" ; |
21 | |
22 | FunctionIfNull(const Context & context_) : context(context_) {} |
23 | |
24 | static FunctionPtr create(const Context & context) |
25 | { |
26 | return std::make_shared<FunctionIfNull>(context); |
27 | } |
28 | |
29 | std::string getName() const override |
30 | { |
31 | return name; |
32 | } |
33 | |
34 | size_t getNumberOfArguments() const override { return 2; } |
35 | bool useDefaultImplementationForNulls() const override { return false; } |
36 | bool useDefaultImplementationForConstants() const override { return true; } |
37 | ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const override { return {0}; } |
38 | |
39 | DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override |
40 | { |
41 | if (arguments[0]->onlyNull()) |
42 | return arguments[1]; |
43 | |
44 | if (!arguments[0]->isNullable()) |
45 | return arguments[0]; |
46 | |
47 | return getLeastSupertype({removeNullable(arguments[0]), arguments[1]}); |
48 | } |
49 | |
50 | void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override |
51 | { |
52 | /// Always null. |
53 | if (block.getByPosition(arguments[0]).type->onlyNull()) |
54 | { |
55 | block.getByPosition(result).column = block.getByPosition(arguments[1]).column; |
56 | return; |
57 | } |
58 | |
59 | /// Could not contain nulls, so nullIf makes no sense. |
60 | if (!block.getByPosition(arguments[0]).type->isNullable()) |
61 | { |
62 | block.getByPosition(result).column = block.getByPosition(arguments[0]).column; |
63 | return; |
64 | } |
65 | |
66 | /// ifNull(col1, col2) == if(isNotNull(col1), assumeNotNull(col1), col2) |
67 | |
68 | Block temp_block = block; |
69 | |
70 | size_t is_not_null_pos = temp_block.columns(); |
71 | temp_block.insert({nullptr, std::make_shared<DataTypeUInt8>(), "" }); |
72 | size_t assume_not_null_pos = temp_block.columns(); |
73 | temp_block.insert({nullptr, removeNullable(block.getByPosition(arguments[0]).type), "" }); |
74 | |
75 | auto is_not_null = FunctionFactory::instance().get("isNotNull" , context)->build( |
76 | {temp_block.getByPosition(arguments[0])}); |
77 | |
78 | auto assume_not_null = FunctionFactory::instance().get("assumeNotNull" , context)->build( |
79 | {temp_block.getByPosition(arguments[0])}); |
80 | |
81 | auto func_if = FunctionFactory::instance().get("if" , context)->build( |
82 | {temp_block.getByPosition(is_not_null_pos), temp_block.getByPosition(assume_not_null_pos), temp_block.getByPosition(arguments[1])}); |
83 | |
84 | is_not_null->execute(temp_block, {arguments[0]}, is_not_null_pos, input_rows_count); |
85 | assume_not_null->execute(temp_block, {arguments[0]}, assume_not_null_pos, input_rows_count); |
86 | func_if->execute(temp_block, {is_not_null_pos, assume_not_null_pos, arguments[1]}, result, input_rows_count); |
87 | |
88 | block.getByPosition(result).column = std::move(temp_block.getByPosition(result).column); |
89 | } |
90 | |
91 | private: |
92 | const Context & context; |
93 | }; |
94 | |
95 | |
96 | void registerFunctionIfNull(FunctionFactory & factory) |
97 | { |
98 | factory.registerFunction<FunctionIfNull>(FunctionFactory::CaseInsensitive); |
99 | } |
100 | |
101 | } |
102 | |