ClickHouse/dbms/src/Functions/IFunction.cpp
2018-02-08 20:18:52 +03:00

252 lines
8.1 KiB
C++

#include <Functions/IFunction.h>
#include <Functions/FunctionHelpers.h>
#include <Columns/ColumnNullable.h>
#include <DataTypes/DataTypeNullable.h>
#include <DataTypes/DataTypeNothing.h>
#include <Columns/ColumnConst.h>
#include <Interpreters/ExpressionActions.h>
#include <Common/typeid_cast.h>
#include <ext/range.h>
#include <ext/collection_cast.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
namespace
{
/** Return ColumnNullable of src, with null map as OR-ed null maps of args columns in blocks.
* Or ColumnConst(ColumnNullable) if the result is always NULL or if the result is constant and always not NULL.
*/
ColumnPtr wrapInNullable(const ColumnPtr & src, Block & block, const ColumnNumbers & args, size_t result)
{
ColumnPtr result_null_map_column;
/// If result is already nullable.
ColumnPtr src_not_nullable = src;
if (src->onlyNull())
return src;
else if (src->isColumnNullable())
{
src_not_nullable = static_cast<const ColumnNullable &>(*src).getNestedColumnPtr();
result_null_map_column = static_cast<const ColumnNullable &>(*src).getNullMapColumnPtr();
}
for (const auto & arg : args)
{
const ColumnWithTypeAndName & elem = block.getByPosition(arg);
if (!elem.type->isNullable())
continue;
/// Const Nullable that are NULL.
if (elem.column->onlyNull())
return block.getByPosition(result).type->createColumnConst(block.rows(), Null());
if (elem.column->isColumnConst())
continue;
if (elem.column->isColumnNullable())
{
const ColumnPtr & null_map_column = static_cast<const ColumnNullable &>(*elem.column).getNullMapColumnPtr();
if (!result_null_map_column)
{
result_null_map_column = null_map_column;
}
else
{
MutableColumnPtr mutable_result_null_map_column = result_null_map_column->mutate();
NullMap & result_null_map = static_cast<ColumnUInt8 &>(*mutable_result_null_map_column).getData();
const NullMap & src_null_map = static_cast<const ColumnUInt8 &>(*null_map_column).getData();
for (size_t i = 0, size = result_null_map.size(); i < size; ++i)
if (src_null_map[i])
result_null_map[i] = 1;
result_null_map_column = std::move(mutable_result_null_map_column);
}
}
}
if (!result_null_map_column)
return makeNullable(src);
if (src_not_nullable->isColumnConst())
return ColumnNullable::create(src_not_nullable->convertToFullColumnIfConst(), result_null_map_column);
else
return ColumnNullable::create(src_not_nullable, result_null_map_column);
}
struct NullPresence
{
bool has_nullable = false;
bool has_null_constant = false;
};
NullPresence getNullPresense(const Block & block, const ColumnNumbers & args)
{
NullPresence res;
for (const auto & arg : args)
{
const auto & elem = block.getByPosition(arg);
if (!res.has_nullable)
res.has_nullable = elem.type->isNullable();
if (!res.has_null_constant)
res.has_null_constant = elem.type->onlyNull();
}
return res;
}
NullPresence getNullPresense(const ColumnsWithTypeAndName & args)
{
NullPresence res;
for (const auto & elem : args)
{
if (!res.has_nullable)
res.has_nullable = elem.type->isNullable();
if (!res.has_null_constant)
res.has_null_constant = elem.type->onlyNull();
}
return res;
}
bool allArgumentsAreConstants(const Block & block, const ColumnNumbers & args)
{
for (auto arg : args)
if (!typeid_cast<const ColumnConst *>(block.getByPosition(arg).column.get()))
return false;
return true;
}
}
bool PreparedFunctionImpl::defaultImplementationForConstantArguments(Block & block, const ColumnNumbers & args, size_t result)
{
if (args.empty() || !useDefaultImplementationForConstants() || !allArgumentsAreConstants(block, args))
return false;
ColumnNumbers arguments_to_remain_constants = getArgumentsThatAreAlwaysConstant();
Block temporary_block;
bool have_converted_columns = false;
size_t arguments_size = args.size();
for (size_t arg_num = 0; arg_num < arguments_size; ++arg_num)
{
const ColumnWithTypeAndName & column = block.getByPosition(args[arg_num]);
if (arguments_to_remain_constants.end() != std::find(arguments_to_remain_constants.begin(), arguments_to_remain_constants.end(), arg_num))
temporary_block.insert(column);
else
{
have_converted_columns = true;
temporary_block.insert({ static_cast<const ColumnConst *>(column.column.get())->getDataColumnPtr(), column.type, column.name });
}
}
/** When using default implementation for constants, the function requires at least one argument
* not in "arguments_to_remain_constants" set. Otherwise we get infinite recursion.
*/
if (!have_converted_columns)
throw Exception("Number of arguments for function " + getName() + " doesn't match: the function requires more arguments",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
temporary_block.insert(block.getByPosition(result));
ColumnNumbers temporary_argument_numbers(arguments_size);
for (size_t i = 0; i < arguments_size; ++i)
temporary_argument_numbers[i] = i;
execute(temporary_block, temporary_argument_numbers, arguments_size);
block.getByPosition(result).column = ColumnConst::create(temporary_block.getByPosition(arguments_size).column, block.rows());
return true;
}
bool PreparedFunctionImpl::defaultImplementationForNulls(Block & block, const ColumnNumbers & args, size_t result)
{
if (args.empty() || !useDefaultImplementationForNulls())
return false;
NullPresence null_presence = getNullPresense(block, args);
if (null_presence.has_null_constant)
{
block.getByPosition(result).column = block.getByPosition(result).type->createColumnConst(block.rows(), Null());
return true;
}
if (null_presence.has_nullable)
{
Block temporary_block = createBlockWithNestedColumns(block, args, result);
execute(temporary_block, args, result);
block.getByPosition(result).column = wrapInNullable(temporary_block.getByPosition(result).column, block, args, result);
return true;
}
return false;
}
void PreparedFunctionImpl::execute(Block & block, const ColumnNumbers & args, size_t result)
{
if (defaultImplementationForConstantArguments(block, args, result))
return;
if (defaultImplementationForNulls(block, args, result))
return;
executeImpl(block, args, result);
}
void FunctionBuilderImpl::checkNumberOfArguments(size_t number_of_arguments) const
{
if (isVariadic())
return;
size_t expected_number_of_arguments = getNumberOfArguments();
if (number_of_arguments != expected_number_of_arguments)
throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
+ toString(number_of_arguments) + ", should be " + toString(expected_number_of_arguments),
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
}
DataTypePtr FunctionBuilderImpl::getReturnType(const ColumnsWithTypeAndName & arguments) const
{
checkNumberOfArguments(arguments.size());
if (!arguments.empty() && useDefaultImplementationForNulls())
{
NullPresence null_presense = getNullPresense(arguments);
if (null_presense.has_null_constant)
{
return makeNullable(std::make_shared<DataTypeNothing>());
}
if (null_presense.has_nullable)
{
Block nested_block = createBlockWithNestedColumns(Block(arguments), ext::collection_cast<ColumnNumbers>(ext::range(0, arguments.size())));
auto return_type = getReturnTypeImpl(ColumnsWithTypeAndName(nested_block.begin(), nested_block.end()));
return makeNullable(return_type);
}
}
return getReturnTypeImpl(arguments);
}
}