doris/be/src/vec/functions/like.h

// 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
//
// 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.

#pragma once

#include <functional>
#include <memory>

#include "runtime/string_search.hpp"
#include "runtime/string_value.h"
#include "vec/columns/column_const.h"
#include "vec/columns/column_set.h"
#include "vec/columns/columns_number.h"
#include "vec/data_types/data_type_nullable.h"
#include "vec/data_types/data_type_number.h"
#include "vec/exprs/vexpr.h"
#include "vec/functions/function.h"
#include "vec/functions/simple_function_factory.h"

namespace doris::vectorized {

// TODO: replace with std::string_view when `LikeSearchState.substring_pattern` can
// construct from std::string_view.
struct LikeSearchState {
    char escape_char;

    /// Holds the string the StringValue points to and is set any time StringValue is
    /// used.
    std::string search_string;

    /// Used for LIKE predicates if the pattern is a constant argument, and is either a
    /// constant string or has a constant string at the beginning or end of the pattern.
    /// This will be set in order to check for that pattern in the corresponding part of
    /// the string.
    doris::StringValue search_string_sv;

    /// Used for LIKE predicates if the pattern is a constant argument and has a constant
    /// string in the middle of it. This will be use in order to check for the substring
    /// in the value.
    doris::StringSearch substring_pattern;

    /// Used for RLIKE and REGEXP predicates if the pattern is a constant argument.
    std::unique_ptr<re2::RE2> regex;

    LikeSearchState() : escape_char('\\') {}

    void set_search_string(const std::string& search_string_arg) {
        search_string = search_string_arg;
        search_string_sv = StringValue(search_string);
        substring_pattern = StringSearch(&search_string_sv);
    }
};

using LikeFn = std::function<doris::Status(LikeSearchState* state, const StringValue&,
                                            const StringValue&, unsigned char*)>;

struct LikeState {
    LikeSearchState search_state;
    LikeFn function;
};

class FunctionLikeBase : public IFunction {
public:
    size_t get_number_of_arguments() const override { return 2; }

    DataTypePtr get_return_type_impl(const DataTypes& /*arguments*/) const override {
        return std::make_shared<DataTypeUInt8>();
    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                        size_t result, size_t /*input_rows_count*/) override;

    Status close(FunctionContext* context, FunctionContext::FunctionStateScope scope) override;
protected:
    Status vector_vector(const ColumnString::Chars& values,
                         const ColumnString::Offsets& value_offsets,
                         const ColumnString::Chars& patterns,
                         const ColumnString::Offsets& pattern_offsets,
                         ColumnUInt8::Container& result, const LikeFn& function,
                         LikeSearchState* search_state);

    static Status constant_starts_with_fn(LikeSearchState* state, const StringValue& val,
                                          const StringValue& pattern, unsigned char* result);

    static Status constant_ends_with_fn(LikeSearchState* state, const StringValue& val,
                                        const StringValue& pattern, unsigned char* result);

    static Status constant_equals_fn(LikeSearchState* state, const StringValue& val,
                                     const StringValue& pattern, unsigned char* result);

    static Status constant_substring_fn(LikeSearchState* state, const StringValue& val,
                                        const StringValue& pattern, unsigned char* result);
};

class FunctionLike : public FunctionLikeBase {
public:
    static constexpr auto name = "like";

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

    String get_name() const override { return name; }

    Status prepare(FunctionContext* context, FunctionContext::FunctionStateScope scope) override;
private:
    static Status like_fn(LikeSearchState* state, const StringValue& val,
                          const StringValue& pattern, unsigned char* result);

    static Status constant_regex_full_fn(LikeSearchState* state, const StringValue& val,
                                         const StringValue& pattern, unsigned char* result);

    static void convert_like_pattern(LikeSearchState* state, const std::string& pattern,
                                     std::string* re_pattern);

    static void remove_escape_character(std::string* search_string);
};

class FunctionRegexp : public FunctionLikeBase {
public:
    static constexpr auto name = "regexp";

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

    String get_name() const override { return name; }

    Status prepare(FunctionContext* context, FunctionContext::FunctionStateScope scope) override;
private:
    static Status regexp_fn(LikeSearchState* state, const StringValue& val,
                            const StringValue& pattern, unsigned char* result);

    static Status constant_regex_partial_fn(LikeSearchState* state, const StringValue& val,
                                            const StringValue& pattern, unsigned char* result);
};

void register_function_like(SimpleFunctionFactory& factory) {
    factory.register_function<FunctionLike>();
}

void register_function_regexp(SimpleFunctionFactory& factory) {
    factory.register_function<FunctionRegexp>();
}
} // namespace doris::vectorized