ClickHouse/src/Functions/extractAllGroups.h
2022-08-19 09:56:59 +00:00

261 lines
10 KiB
C++

#pragma once
#include <Columns/ColumnArray.h>
#include <Columns/ColumnConst.h>
#include <Columns/ColumnString.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeString.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/IFunction.h>
#include <Functions/Regexps.h>
#include <Interpreters/Context.h>
#include <Core/Settings.h>
#include <memory>
#include <string>
#include <vector>
#include <Core/iostream_debug_helpers.h>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
extern const int TOO_LARGE_ARRAY_SIZE;
}
enum class ExtractAllGroupsResultKind
{
VERTICAL,
HORIZONTAL
};
/** Match all groups of given input string with given re, return array of arrays of matches.
*
* Depending on `Impl::Kind`, result is either grouped by group id (Horizontal) or in order of appearance (Vertical):
*
* SELECT extractAllGroupsVertical('abc=111, def=222, ghi=333', '("[^"]+"|\\w+)=("[^"]+"|\\w+)')
* =>
* [['abc', '111'], ['def', '222'], ['ghi', '333']]
*
* SELECT extractAllGroupsHorizontal('abc=111, def=222, ghi=333', '("[^"]+"|\\w+)=("[^"]+"|\\w+)')
* =>
* [['abc', 'def', 'ghi'], ['111', '222', '333']
*/
template <typename Impl>
class FunctionExtractAllGroups : public IFunction
{
ContextPtr context;
public:
static constexpr auto Kind = Impl::Kind;
static constexpr auto name = Impl::Name;
explicit FunctionExtractAllGroups(ContextPtr context_)
: context(context_)
{}
static FunctionPtr create(ContextPtr context) { return std::make_shared<FunctionExtractAllGroups>(context); }
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 true; }
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);
/// Two-dimensional array of strings, each `row` of top array represents matching groups.
return std::make_shared<DataTypeArray>(std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>()));
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
static const auto MAX_GROUPS_COUNT = 128;
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("Length of 'needle' argument must be greater than 0.", ErrorCodes::BAD_ARGUMENTS);
using StringPiece = typename Regexps::Regexp::StringPieceType;
const Regexps::Regexp holder = Regexps::createRegexp<false, false, false>(needle);
const auto & regexp = holder.getRE2();
if (!regexp)
throw Exception("There are no groups in regexp: " + needle, ErrorCodes::BAD_ARGUMENTS);
const size_t groups_count = regexp->NumberOfCapturingGroups();
if (!groups_count)
throw Exception("There are no groups in regexp: " + needle, ErrorCodes::BAD_ARGUMENTS);
if (groups_count > MAX_GROUPS_COUNT - 1)
throw Exception("Too many groups in regexp: " + std::to_string(groups_count)
+ ", max: " + std::to_string(MAX_GROUPS_COUNT - 1),
ErrorCodes::BAD_ARGUMENTS);
// Including 0-group, which is the whole regexp.
PODArrayWithStackMemory<StringPiece, MAX_GROUPS_COUNT> matched_groups(groups_count + 1);
ColumnArray::ColumnOffsets::MutablePtr root_offsets_col = ColumnArray::ColumnOffsets::create();
ColumnArray::ColumnOffsets::MutablePtr nested_offsets_col = ColumnArray::ColumnOffsets::create();
ColumnString::MutablePtr data_col = ColumnString::create();
auto & root_offsets_data = root_offsets_col->getData();
auto & nested_offsets_data = nested_offsets_col->getData();
ColumnArray::Offset current_root_offset = 0;
ColumnArray::Offset current_nested_offset = 0;
if constexpr (Kind == ExtractAllGroupsResultKind::VERTICAL)
{
root_offsets_data.resize(input_rows_count);
for (size_t i = 0; i < input_rows_count; ++i)
{
std::string_view current_row = column_haystack->getDataAt(i).toView();
// Extract all non-intersecting matches from haystack except group #0.
const auto * pos = current_row.data();
const auto * end = pos + current_row.size();
while (pos < end
&& regexp->Match({pos, static_cast<size_t>(end - pos)},
0, end - pos, regexp->UNANCHORED, matched_groups.data(), 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());
/// If match is empty - it's technically Ok but we have to shift one character nevertheless
/// to avoid infinite loop.
pos = matched_groups[0].data() + std::max<size_t>(1, matched_groups[0].size());
current_nested_offset += groups_count;
nested_offsets_data.push_back(current_nested_offset);
++current_root_offset;
}
root_offsets_data[i] = current_root_offset;
}
}
else
{
/// Additional limit to fail fast on supposedly incorrect usage.
const auto max_matches_per_row = context->getSettingsRef().regexp_max_matches_per_row;
PODArray<StringPiece, 0> all_matches;
/// Number of times RE matched on each row of haystack column.
PODArray<size_t, 0> number_of_matches_per_row;
/// We expect RE to match multiple times on each row, `* 8` is arbitrary to reduce number of re-allocations.
all_matches.reserve(input_rows_count * groups_count * 8);
number_of_matches_per_row.reserve(input_rows_count);
for (size_t i = 0; i < input_rows_count; ++i)
{
size_t matches_per_row = 0;
const auto & current_row = column_haystack->getDataAt(i);
// Extract all non-intersecting matches from haystack except group #0.
const auto * pos = current_row.data;
const auto * end = pos + current_row.size;
while (pos < end
&& regexp->Match({pos, static_cast<size_t>(end - pos)},
0, end - pos, regexp->UNANCHORED, matched_groups.data(), matched_groups.size()))
{
// 1 is to exclude group #0 which is whole re match.
for (size_t group = 1; group <= groups_count; ++group)
all_matches.push_back(matched_groups[group]);
++matches_per_row;
if (matches_per_row > max_matches_per_row)
throw Exception(ErrorCodes::TOO_LARGE_ARRAY_SIZE,
"Too many matches per row (> {}) in the result of function {}",
max_matches_per_row, getName());
pos = matched_groups[0].data() + std::max<size_t>(1, matched_groups[0].size());
}
number_of_matches_per_row.push_back(matches_per_row);
}
{
size_t total_matched_groups_string_len = 0;
for (const auto & m : all_matches)
total_matched_groups_string_len += m.length();
data_col->reserve(total_matched_groups_string_len);
}
nested_offsets_col->reserve(matched_groups.size());
root_offsets_col->reserve(groups_count);
// Re-arrange `all_matches` from:
// [
// "ROW 0: 1st group 1st match",
// "ROW 0: 2nd group 1st match",
// ...,
// "ROW 0: 1st group 2nd match",
// "ROW 0: 2nd group 2nd match",
// ...,
// "ROW 1: 1st group 1st match",
// ...
// ]
//
// into column of 2D arrays:
// [
// /* all matchig groups from ROW 0 of haystack column */
// ["ROW 0: 1st group 1st match", "ROW 0: 1st group 2nd match", ...],
// ["ROW 0: 2nd group 1st match", "ROW 0: 2nd group 2nd match", ...],
// ...
// ],
// [
// /* all matchig groups from row 1 of haystack column */
// ["ROW 1: 1st group 1st match", ...],
// ...
// ]
size_t row_offset = 0;
for (const auto matches_per_row : number_of_matches_per_row)
{
const size_t next_row_offset = row_offset + matches_per_row * groups_count;
for (size_t group_id = 0; group_id < groups_count; ++group_id)
{
for (size_t i = row_offset + group_id; i < next_row_offset && i < all_matches.size(); i += groups_count)
{
const auto & match = all_matches[i];
data_col->insertData(match.begin(), match.length());
}
nested_offsets_col->insertValue(data_col->size());
}
root_offsets_col->insertValue(nested_offsets_col->size());
row_offset = next_row_offset;
}
}
ColumnArray::MutablePtr nested_array_col = ColumnArray::create(std::move(data_col), std::move(nested_offsets_col));
ColumnArray::MutablePtr root_array_col = ColumnArray::create(std::move(nested_array_col), std::move(root_offsets_col));
return root_array_col;
}
};
}