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#include <Columns/ColumnString.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnConst.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeString.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/Regexps.h>
#include <memory>
#include <string>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
}
namespace
{
/** Match all groups of given input string with given re, return array of arrays of matches.
*
* SELECT extractGroups('hello abc=111 world', '("[^"]+"|\\w+)=("[^"]+"|\\w+)')
* should produce:
* ['abc', '111']
*/
class FunctionExtractGroups : public IFunction
{
public:
static constexpr auto name = "extractGroups";
static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionExtractGroups>(); }
String getName() const override { return name; }
size_t getNumberOfArguments() const override { return 2; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return true; }
bool useDefaultImplementationForConstants() const override { return false; }
ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
{
FunctionArgumentDescriptors args{
{"haystack", &isStringOrFixedString<IDataType>, nullptr, "const String or const FixedString"},
{"needle", &isStringOrFixedString<IDataType>, isColumnConst, "const String or const FixedString"},
};
validateFunctionArgumentTypes(*this, arguments, args);
return std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>());
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
const ColumnPtr column_haystack = arguments[0].column;
const ColumnPtr column_needle = arguments[1].column;
const auto needle = typeid_cast<const ColumnConst &>(*column_needle).getValue<String>();
if (needle.empty())
throw Exception(ErrorCodes::BAD_ARGUMENTS, "{} length of 'needle' argument must be greater than 0.", getName());
const Regexps::Regexp regexp = Regexps::createRegexp<false, false, false>(needle);
const auto & re2 = regexp.getRE2();
if (!re2)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "There are no groups in regexp: {}", needle);
const size_t groups_count = re2->NumberOfCapturingGroups();
if (!groups_count)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "There are no groups in regexp: {}", needle);
// Including 0-group, which is the whole regexp.
PODArrayWithStackMemory<std::string_view, 128> matched_groups(groups_count + 1);
ColumnArray::ColumnOffsets::MutablePtr offsets_col = ColumnArray::ColumnOffsets::create();
ColumnString::MutablePtr data_col = ColumnString::create();
auto & offsets_data = offsets_col->getData();
offsets_data.resize(input_rows_count);
ColumnArray::Offset current_offset = 0;
for (size_t i = 0; i < input_rows_count; ++i)
{
std::string_view current_row = column_haystack->getDataAt(i).toView();
if (re2->Match({current_row.data(), current_row.size()},
0, current_row.size(), re2_st::RE2::UNANCHORED, matched_groups.data(),
static_cast<int>(matched_groups.size())))
{
// 1 is to exclude group #0 which is whole re match.
for (size_t group = 1; group <= groups_count; ++group)
data_col->insertData(matched_groups[group].data(), matched_groups[group].size());
current_offset += groups_count;
}
offsets_data[i] = current_offset;
}
return ColumnArray::create(std::move(data_col), std::move(offsets_col));
}
};
}
REGISTER_FUNCTION(ExtractGroups)
{
factory.registerFunction<FunctionExtractGroups>();
}
}
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