// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// 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.

#ifndef DORIS_ITOKEN_EXTRACTOR_H

#define DORIS_ITOKEN_EXTRACTOR_H

#include <stddef.h>

#include <string>

#include "storage/index/bloom_filter/bloom_filter.h"

namespace doris {

/// Interface for string parsers.

struct ITokenExtractor {

    virtual ~ITokenExtractor() = default;

    /// Fast inplace implementation for regular use.

    /// Gets string (data ptr and len) and start position for extracting next token (state of extractor).

    /// Returns false if parsing is finished, otherwise returns true.

    virtual bool next_in_string(const char* data, size_t length, size_t* __restrict pos,

                                size_t* __restrict token_start,

                                size_t* __restrict token_length) const = 0;

    /// Special implementation for creating bloom filter for LIKE function.

    /// It skips unescaped `%` and `_` and supports escaping symbols, but it is less lightweight.

    virtual bool next_in_string_like(const char* data, size_t length, size_t* pos,

                                     std::string& out) const = 0;

    virtual void string_to_bloom_filter(const char* data, size_t length,

                                        segment_v2::BloomFilter& bloom_filter) const = 0;

    virtual bool string_like_to_bloom_filter(const char* data, size_t length,

                                             segment_v2::BloomFilter& bloom_filter) const = 0;

};

template <typename Derived>

class ITokenExtractorHelper : public ITokenExtractor {

public:

    void string_to_bloom_filter(const char* data, size_t length,

                                segment_v2::BloomFilter& bloom_filter) const override {

        size_t cur = 0;

        size_t token_start = 0;

        size_t token_len = 0;

        while (cur < length && static_cast<const Derived*>(this)->next_in_string(

                                       data, length, &cur, &token_start, &token_len)) {

            bloom_filter.add_bytes(data + token_start, token_len);

        }

    }

    bool string_like_to_bloom_filter(const char* data, size_t length,

                                     segment_v2::BloomFilter& bloom_filter) const override {

        size_t cur = 0;

        bool added = false;

        std::string token;

        while (cur < length &&

               static_cast<const Derived*>(this)->next_in_string_like(data, length, &cur, token)) {

            bloom_filter.add_bytes(token.data(), token.size());

            added = true;

        }

        return added;

    }

};

/// Parser extracting all ngrams from string.

struct NgramTokenExtractor final : public ITokenExtractorHelper<NgramTokenExtractor> {

public:

    explicit NgramTokenExtractor(size_t n_) : n(n_) {}

    bool next_in_string(const char* data, size_t length, size_t* __restrict pos,

                        size_t* __restrict token_start,

                        size_t* __restrict token_length) const override;

    bool next_in_string_like(const char* data, size_t length, size_t* pos,

                             std::string& token) const override;

private:

    size_t n;

};

} // namespace doris

#endif //DORIS_ITOKEN_EXTRACTOR_H