1#include <DataTypes/DataTypeDateTime.h>
2#include <DataTypes/DataTypeDateTime64.h>
3
4#include <Core/Field.h>
5
6#include <Functions/IFunctionImpl.h>
7#include <Functions/FunctionFactory.h>
8#include <Functions/extractTimeZoneFromFunctionArguments.h>
9
10#include <IO/WriteHelpers.h>
11#include <Common/assert_cast.h>
12
13
14namespace DB
15{
16
17namespace ErrorCodes
18{
19 extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
20 extern const int ILLEGAL_TYPE_OF_ARGUMENT;
21}
22
23/// Just changes time zone information for data type. The calculation is free.
24class FunctionToTimeZone : public IFunction
25{
26public:
27 static constexpr auto name = "toTimeZone";
28 static FunctionPtr create(const Context &) { return std::make_shared<FunctionToTimeZone>(); }
29
30 String getName() const override
31 {
32 return name;
33 }
34
35 size_t getNumberOfArguments() const override { return 2; }
36
37 DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
38 {
39 if (arguments.size() != 2)
40 throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
41 + toString(arguments.size()) + ", should be 2",
42 ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
43
44 const auto which_type = WhichDataType(arguments[0].type);
45 if (!which_type.isDateTime() && !which_type.isDateTime64())
46 throw Exception{"Illegal type " + arguments[0].type->getName() + " of argument of function " + getName() +
47 ". Should be DateTime or DateTime64", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
48
49 String time_zone_name = extractTimeZoneNameFromFunctionArguments(arguments, 1, 0);
50 if (which_type.isDateTime())
51 return std::make_shared<DataTypeDateTime>(time_zone_name);
52
53 const auto * date_time64 = assert_cast<const DataTypeDateTime64 *>(arguments[0].type.get());
54 return std::make_shared<DataTypeDateTime64>(date_time64->getScale(), time_zone_name);
55 }
56
57 void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
58 {
59 block.getByPosition(result).column = block.getByPosition(arguments[0]).column;
60 }
61};
62
63void registerFunctionToTimeZone(FunctionFactory & factory)
64{
65 factory.registerFunction<FunctionToTimeZone>();
66}
67
68}
69