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// distributed with this work for additional information

// regarding copyright ownership. The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License. You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied. See the License for the

// specific language governing permissions and limitations

// under the License.

#include <algorithm>

#include <vector>

#include "common/status.h"

#include "core/column/column_nullable.h"

#include "core/column/column_string.h"

#include "core/data_type/data_type_number.h"

#include "core/string_ref.h"

#include "exprs/function/simple_function_factory.h"

#include "util/simd/vstring_function.h"

namespace doris {

class FunctionHammingDistance : public IFunction {

public:

using ResultDataType = DataTypeInt64;

using ResultPaddedPODArray = PaddedPODArray<Int64>;

using ResultColumnType = ColumnVector<ResultDataType::PType>;

static constexpr auto name = "hamming_distance";

static FunctionPtr create() { return std::make_shared<FunctionHammingDistance>(); }

String get_name() const override { return name; }

size_t get_number_of_arguments() const override { return 2; }

DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

const bool has_nullable = std::ranges::any_of(

arguments, [](const DataTypePtr& type) { return type->is_nullable(); });

if (has_nullable) {

return make_nullable(std::make_shared<ResultDataType>());

}

return std::make_shared<ResultDataType>();

}

bool use_default_implementation_for_nulls() const override { return false; }

Status execute_impl(FunctionContext* /*context*/, Block& block, const ColumnNumbers& arguments,

uint32_t result, size_t input_rows_count) const override {

const auto& [left_col, left_const] =

unpack_if_const(block.get_by_position(arguments[0]).column);

const auto& [right_col, right_const] =

unpack_if_const(block.get_by_position(arguments[1]).column);

const auto* left_nullable = check_and_get_column<ColumnNullable>(left_col.get());

const auto* right_nullable = check_and_get_column<ColumnNullable>(right_col.get());

const IColumn* left_nested =

left_nullable ? &left_nullable->get_nested_column() : left_col.get();

const IColumn* right_nested =

right_nullable ? &right_nullable->get_nested_column() : right_col.get();

const auto* left_str_col = assert_cast<const ColumnString*>(left_nested);

const auto* right_str_col = assert_cast<const ColumnString*>(right_nested);

auto res_col = ResultColumnType::create(input_rows_count);

auto& res_data = res_col->get_data();

const NullMap* left_null_map =

left_nullable ? &left_nullable->get_null_map_data() : nullptr;

const NullMap* right_null_map =

right_nullable ? &right_nullable->get_null_map_data() : nullptr;

const bool has_nullable = left_null_map != nullptr || right_null_map != nullptr;

if (!has_nullable) {

if (left_const) {

RETURN_IF_ERROR(scalar_vector(left_str_col->get_data_at(0).trim_tail_padding_zero(),

*right_str_col, res_data));

} else if (right_const) {

RETURN_IF_ERROR(vector_scalar(

*left_str_col, right_str_col->get_data_at(0).trim_tail_padding_zero(),

res_data));

} else {

RETURN_IF_ERROR(vector_vector(*left_str_col, *right_str_col, res_data));

}

block.replace_by_position(result, std::move(res_col));

return Status::OK();

}

auto null_col = ColumnUInt8::create(input_rows_count, 0);

auto& null_map = null_col->get_data();

if (left_const) {

if (left_null_map && (*left_null_map)[0]) {

std::fill(null_map.begin(), null_map.end(), 1);

block.replace_by_position(

result, ColumnNullable::create(std::move(res_col), std::move(null_col)));

return Status::OK();

}

const auto left = left_str_col->get_data_at(0).trim_tail_padding_zero();

RETURN_IF_ERROR(scalar_vector_nullable(left, *right_str_col, right_null_map, res_data,

null_map));

} else if (right_const) {

if (right_null_map && (*right_null_map)[0]) {

std::fill(null_map.begin(), null_map.end(), 1);

block.replace_by_position(

result, ColumnNullable::create(std::move(res_col), std::move(null_col)));

return Status::OK();

}

RETURN_IF_ERROR(vector_scalar_nullable(

*left_str_col, right_str_col->get_data_at(0).trim_tail_padding_zero(),

left_null_map, res_data, null_map));

} else {

for (size_t i = 0; i < input_rows_count; ++i) {

const bool left_is_null = left_null_map && (*left_null_map)[i];

const bool right_is_null = right_null_map && (*right_null_map)[i];

if (left_is_null || right_is_null) {

null_map[i] = 1;

res_data[i] = 0;

continue;

}

RETURN_IF_ERROR(hamming_distance(

left_str_col->get_data_at(i).trim_tail_padding_zero(),

right_str_col->get_data_at(i).trim_tail_padding_zero(), res_data[i], i));

}

}

block.replace_by_position(result,

ColumnNullable::create(std::move(res_col), std::move(null_col)));

return Status::OK();

}

private:

static Status vector_vector(const ColumnString& lcol, const ColumnString& rcol,

ResultPaddedPODArray& res) {

DCHECK_EQ(lcol.size(), rcol.size());

const size_t size = lcol.size();

res.resize(size);

std::vector<size_t> left_offsets;

std::vector<size_t> right_offsets;

for (size_t i = 0; i < size; ++i) {

const auto left = lcol.get_data_at(i).trim_tail_padding_zero();

const auto right = rcol.get_data_at(i).trim_tail_padding_zero();

RETURN_IF_ERROR(hamming_distance_with_offsets(

left, left_offsets, false, simd::VStringFunctions::is_ascii(left), right,

right_offsets, false, simd::VStringFunctions::is_ascii(right), res[i], i));

}

return Status::OK();

}

static Status vector_scalar(const ColumnString& lcol, const StringRef& rdata,

ResultPaddedPODArray& res) {

const size_t size = lcol.size();

res.resize(size);

const bool right_ascii = simd::VStringFunctions::is_ascii(rdata);

std::vector<size_t> right_offsets;

simd::VStringFunctions::get_utf8_char_offsets(rdata, right_offsets);

std::vector<size_t> left_offsets;

for (size_t i = 0; i < size; ++i) {

const auto left = lcol.get_data_at(i).trim_tail_padding_zero();

RETURN_IF_ERROR(hamming_distance_with_offsets(

left, left_offsets, false, simd::VStringFunctions::is_ascii(left), rdata,

right_offsets, true, right_ascii, res[i], i));

}

return Status::OK();

}

static Status scalar_vector(const StringRef& ldata, const ColumnString& rcol,

ResultPaddedPODArray& res) {

const size_t size = rcol.size();

res.resize(size);

const bool left_ascii = simd::VStringFunctions::is_ascii(ldata);

std::vector<size_t> left_offsets;

simd::VStringFunctions::get_utf8_char_offsets(ldata, left_offsets);

std::vector<size_t> right_offsets;

for (size_t i = 0; i < size; ++i) {

const auto right = rcol.get_data_at(i).trim_tail_padding_zero();

RETURN_IF_ERROR(hamming_distance_with_offsets(

ldata, left_offsets, true, left_ascii, right, right_offsets, false,

simd::VStringFunctions::is_ascii(right), res[i], i));

}

return Status::OK();

}

static Status vector_scalar_nullable(const ColumnString& lcol, const StringRef& rdata,

const NullMap* left_null_map, ResultPaddedPODArray& res,

NullMap& null_map) {

const size_t size = lcol.size();

res.resize(size);

const bool right_ascii = simd::VStringFunctions::is_ascii(rdata);

std::vector<size_t> right_offsets;

simd::VStringFunctions::get_utf8_char_offsets(rdata, right_offsets);

std::vector<size_t> left_offsets;

for (size_t i = 0; i < size; ++i) {

if (left_null_map && (*left_null_map)[i]) {

null_map[i] = 1;

res[i] = 0;

continue;

}

const auto left = lcol.get_data_at(i).trim_tail_padding_zero();

RETURN_IF_ERROR(hamming_distance_with_offsets(

left, left_offsets, false, simd::VStringFunctions::is_ascii(left), rdata,

right_offsets, true, right_ascii, res[i], i));

}

return Status::OK();

}

static Status scalar_vector_nullable(const StringRef& ldata, const ColumnString& rcol,

const NullMap* right_null_map, ResultPaddedPODArray& res,

NullMap& null_map) {

const size_t size = rcol.size();

res.resize(size);

const bool left_ascii = simd::VStringFunctions::is_ascii(ldata);

std::vector<size_t> left_offsets;

simd::VStringFunctions::get_utf8_char_offsets(ldata, left_offsets);

std::vector<size_t> right_offsets;

for (size_t i = 0; i < size; ++i) {

if (right_null_map && (*right_null_map)[i]) {

null_map[i] = 1;

res[i] = 0;

continue;

}

const auto right = rcol.get_data_at(i).trim_tail_padding_zero();

RETURN_IF_ERROR(hamming_distance_with_offsets(

ldata, left_offsets, true, left_ascii, right, right_offsets, false,

simd::VStringFunctions::is_ascii(right), res[i], i));

}

return Status::OK();

}

static Status hamming_distance_ascii(const StringRef& left, const StringRef& right,

Int64& result, size_t row) {

if (left.size != right.size) {

return Status::InvalidArgument(

"hamming_distance requires strings of the same length at row {}", row);

}

Int64 distance = 0;

for (size_t i = 0; i < left.size; ++i) {

distance += static_cast<Int64>(left.data[i] != right.data[i]);

}

result = distance;

return Status::OK();

}

static Status hamming_distance_utf8(const StringRef& left,

const std::vector<size_t>& left_offsets,

const StringRef& right,

const std::vector<size_t>& right_offsets, Int64& result,

size_t row) {

if (left_offsets.size() != right_offsets.size()) {

return Status::InvalidArgument(

"hamming_distance requires strings of the same length at row {}", row);

}

Int64 distance = 0;

const size_t len = left_offsets.size();

for (size_t i = 0; i + 1 < len; ++i) {

const size_t left_off = left_offsets[i];

const size_t left_next = left_offsets[i + 1];

const size_t right_off = right_offsets[i];

const size_t right_next = right_offsets[i + 1];

distance += static_cast<Int64>(!simd::VStringFunctions::utf8_char_equal(

left, left_off, left_next, right, right_off, right_next));

}

if (len > 0) {

const size_t left_off = left_offsets[len - 1];

const size_t right_off = right_offsets[len - 1];

distance += static_cast<Int64>(!simd::VStringFunctions::utf8_char_equal(

left, left_off, left.size, right, right_off, right.size));

}

result = distance;

return Status::OK();

}

static Status hamming_distance_with_offsets(

const StringRef& left, std::vector<size_t>& left_offsets, bool left_offsets_ready,

bool left_ascii, const StringRef& right, std::vector<size_t>& right_offsets,

bool right_offsets_ready, bool right_ascii, Int64& result, size_t row) {

if (left_ascii && right_ascii) {

return hamming_distance_ascii(left, right, result, row);

}

if (!left_offsets_ready) {

simd::VStringFunctions::get_utf8_char_offsets(left, left_offsets);

}

if (!right_offsets_ready) {

simd::VStringFunctions::get_utf8_char_offsets(right, right_offsets);

}

return hamming_distance_utf8(left, left_offsets, right, right_offsets, result, row);

}

static Status hamming_distance(const StringRef& left, const StringRef& right, Int64& result,

size_t row) {

std::vector<size_t> left_offsets;

std::vector<size_t> right_offsets;

return hamming_distance_with_offsets(

left, left_offsets, false, simd::VStringFunctions::is_ascii(left), right,

right_offsets, false, simd::VStringFunctions::is_ascii(right), result, row);

}

};

void register_function_hamming_distance(SimpleFunctionFactory& factory) {

factory.register_function<FunctionHammingDistance>();

}

} // namespace doris