ClickHouse/src/Functions/h3kRing.cpp
2020-11-17 16:24:45 +03:00

119 lines
3.7 KiB
C++

#if !defined(ARCADIA_BUILD)
# include "config_functions.h"
#endif
#if USE_H3
#include <vector>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnsNumber.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/IDataType.h>
#include <Functions/FunctionFactory.h>
#include <Functions/IFunction.h>
#include <Common/typeid_cast.h>
#include <ext/range.h>
#include <h3api.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int PARAMETER_OUT_OF_BOUND;
}
namespace
{
class FunctionH3KRing : public IFunction
{
public:
static constexpr auto name = "h3kRing";
static FunctionPtr create(const Context &) { return std::make_shared<FunctionH3KRing>(); }
std::string getName() const override { return name; }
size_t getNumberOfArguments() const override { return 2; }
bool useDefaultImplementationForConstants() const override { return true; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
const auto * arg = arguments[0].get();
if (!WhichDataType(arg).isUInt64())
throw Exception(
"Illegal type " + arg->getName() + " of argument " + std::to_string(1) + " of function " + getName() + ". Must be UInt64",
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
arg = arguments[1].get();
if (!isInteger(arg))
throw Exception(
"Illegal type " + arg->getName() + " of argument " + std::to_string(2) + " of function " + getName() + ". Must be integer",
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt64>());
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
const auto * col_hindex = arguments[0].column.get();
const auto * col_k = arguments[1].column.get();
auto dst = ColumnArray::create(ColumnUInt64::create());
auto & dst_data = dst->getData();
auto & dst_offsets = dst->getOffsets();
dst_offsets.resize(input_rows_count);
auto current_offset = 0;
std::vector<H3Index> hindex_vec;
for (const auto row : ext::range(0, input_rows_count))
{
const H3Index origin_hindex = col_hindex->getUInt(row);
const int k = col_k->getInt(row);
/// Overflow is possible. The function maxKringSize does not check for overflow.
/// The calculation is similar to square of k but several times more.
/// Let's use huge underestimation as the safe bound. We should not allow to generate too large arrays nevertheless.
constexpr auto max_k = 10000;
if (k > max_k)
throw Exception(ErrorCodes::PARAMETER_OUT_OF_BOUND, "Too large 'k' argument for {} function, maximum {}", getName(), max_k);
if (k < 0)
throw Exception(ErrorCodes::PARAMETER_OUT_OF_BOUND, "Argument 'k' for {} function must be non negative", getName());
const auto vec_size = maxKringSize(k);
hindex_vec.resize(vec_size);
kRing(origin_hindex, k, hindex_vec.data());
dst_data.reserve(dst_data.size() + vec_size);
for (auto hindex : hindex_vec)
{
if (hindex != 0)
{
++current_offset;
dst_data.insert(hindex);
}
}
dst_offsets[row] = current_offset;
}
return dst;
}
};
}
void registerFunctionH3KRing(FunctionFactory & factory)
{
factory.registerFunction<FunctionH3KRing>();
}
}
#endif