be/src/vec/functions/function_soundex.cpp

// Licensed to the Apache Software Foundation (ASF) under one
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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
//
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// software distributed under the License is distributed on an
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include <cctype>

#include "common/status.h"
#include "vec/columns/column_string.h"
#include "vec/data_types/data_type_string.h"
#include "vec/functions/function.h"
#include "vec/functions/simple_function_factory.h"

namespace doris::vectorized {
#include "common/compile_check_begin.h"

class FunctionSoundex : public IFunction {
public:
    static constexpr auto name = "soundex";

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

    String get_name() const override { return name; }

    size_t get_number_of_arguments() const override { return 1; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {
        return std::make_shared<DataTypeString>();
    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                        uint32_t result, size_t input_rows_count) const override {
        const ColumnPtr col_ptr = block.get_by_position(arguments[0]).column;

        auto res_column = ColumnString::create();
        res_column->reserve(input_rows_count);
        auto& res_data = res_column->get_chars();
        auto& res_offsets = res_column->get_offsets();
        res_data.reserve(input_rows_count * CODE_SIZE);
        res_offsets.resize(input_rows_count);
        for (size_t i = 0; i < input_rows_count; ++i) {
            StringRef ref = col_ptr->get_data_at(i);
            RETURN_IF_ERROR(calculate_soundex_and_insert(ref, res_data, res_offsets, i));
        }

        block.replace_by_position(result, std::move(res_column));
        return Status::OK();
    }

private:
    Status calculate_soundex_and_insert(const StringRef& ref, ColumnString::Chars& chars,
                                        ColumnString::Offsets& offsets, const size_t row) const {
        uint32_t row_start = (row == 0) ? 0 : offsets[row - 1];
        uint32_t expect_end = row_start + CODE_SIZE;

        if (ref.size == 0) {
            offsets[row] = row_start;
            return Status::OK();
        }

        char pre_code = '\0';
        for (size_t i = 0; i < ref.size; ++i) {
            auto c = static_cast<unsigned char>(ref.data[i]);

            if (c > 0x7f) {
                return Status::InvalidArgument("soundex only supports ASCII, but got: {}",
                                               ref.data[i]);
            }
            if (!std::isalpha(c)) {
                continue;
            }

            c = static_cast<char>(std::toupper(c));
            if (chars.size() == row_start) {
                chars.push_back(c);
                pre_code = (SOUNDEX_TABLE[c - 'A'] == 'N') ? '\0' : SOUNDEX_TABLE[c - 'A'];
            } else if (char code = SOUNDEX_TABLE[c - 'A']; code != 'N') {
                if (code != 'V' && code != pre_code) {
                    chars.push_back(code);
                    if (chars.size() == expect_end) {
                        offsets[row] = static_cast<ColumnString::Offset>(chars.size());
                        return Status::OK();
                    }
                }

                pre_code = code;
            }
        }

        while (chars.size() != row_start && chars.size() < expect_end) {
            chars.push_back('0');
        }
        offsets[row] = static_cast<ColumnString::Offset>(chars.size());

        return Status::OK();
    }

    /** 1. If a vowel (A, E, I, O, U) separates two consonants that have the same soundex code
     *  the consonant to the right of the vowel is coded. Here we use 'V' to represent vowels.
     *  eg : **Tymczak** is coded as T-522 (T, 5 for the M, 2 for the C, Z ignored , 2 for the K). 
     *  Since the vowel "A" separates the Z and K, the K is coded.
     *
     *  2. If "H" or "W" separate two consonants that have the same soundex code, the consonant to the right of the vowel is NOT coded.
     *  Here we use 'N' to represent these two characters.
     *  eg : **Ashcraft** is coded A-261 (A, 2 for the S, C ignored, 6 for the R, 1 for the F). It is not coded A-226.
     */
    static constexpr char SOUNDEX_TABLE[26] = {'V', '1', '2', '3', 'V', '1', '2', 'N', 'V',
                                               '2', '2', '4', '5', '5', 'V', '1', '2', '6',
                                               '2', '3', 'V', '1', 'N', '2', 'V', '2'};

    static constexpr uint8_t CODE_SIZE = 4;
};

void register_function_soundex(SimpleFunctionFactory& factory) {
    factory.register_function<FunctionSoundex>();
}

#include "common/compile_check_end.h"
} // namespace doris::vectorized