be/src/storage/index/inverted/token_stream.h

Source
// 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.

#pragma once

#include <unicode/utext.h>
#include <unicode/utf8.h>

#include <algorithm>
#include <cstddef>
#include <memory>
#include <span>
#include <string_view>
#include <utility>

#include "CLucene.h"
#include "CLucene/analysis/AnalysisHeader.h"
#include "common/cast_set.h"
#include "storage/index/inverted/util/reader.h"

using namespace lucene::analysis;

namespace doris::segment_v2::inverted_index {

class DorisTokenizer;
using TokenizerPtr = std::shared_ptr<DorisTokenizer>;

using TokenStreamPtr = std::shared_ptr<TokenStream>;

// Reused analyzers keep ordinary scratch across values; one oversized value must not pin its
// capacity for the rest of the writer lifetime.
constexpr size_t ANALYZER_SCRATCH_HIGH_WATER_BYTES = 64 * 1024;

// Longest prefix of text that fits in max_bytes without splitting a rune, and its rune count.
inline std::pair<size_t, size_t> utf8_prefix_at_most(std::string_view text, size_t max_bytes) {
    const auto length = static_cast<int32_t>(text.size());
    const auto limit = static_cast<int32_t>(std::min(text.size(), max_bytes));
    int32_t offset = 0;
    size_t rune_count = 0;
    while (offset < length) {
        int32_t next = offset;
        U8_FWD_1(text, next, length);
        if (next > limit) {
            break;
        }
        offset = next;
        ++rune_count;
    }
    return {static_cast<size_t>(offset), rune_count};
}

template <typename Container>
void release_oversized_scratch(Container& container) {
    if (container.capacity() * sizeof(typename Container::value_type) >
        ANALYZER_SCRATCH_HIGH_WATER_BYTES) {
        Container().swap(container);
    }
}

/**
 * All custom tokenizers and token_filters must use the following functions 
 * to set token information. Using these unified set methods helps avoid 
 * unnecessary data copying.
 * 
 * Note: Must not mix with other set methods
 */
class DorisTokenStream {
public:
    DorisTokenStream() = default;
    virtual ~DorisTokenStream() = default;

    void set(Token* t, const std::string_view& term, int32_t pos = 1) {
        t->setTextNoCopy(term.data(), cast_set<int32_t>(term.size()));
        t->setPositionIncrement(pos);
    }

    void set_text(Token* t, const std::string_view& term) {
        t->setTextNoCopy(term.data(), cast_set<int32_t>(term.size()));
    }

    int32_t get_position_increment(Token* t) { return t->getPositionIncrement(); }
    void set_position_increment(Token* t, int32_t pos) { t->setPositionIncrement(pos); }

    // Return each rune's original relative byte start followed by the token's final byte end.
    virtual std::span<const int32_t> get_source_byte_offsets() const { return {}; }

    // Return separate rune ends when removed delimiters leave gaps between adjacent runes.
    virtual std::span<const int32_t> get_source_byte_end_offsets() const { return {}; }

    // Return a conservative relative source span when exact rune boundaries are unavailable.
    virtual bool get_conservative_source_byte_span(int32_t& start, int32_t& end) const {
        return false;
    }

    // Enable source-boundary tracking only for streams with a downstream consumer.
    virtual void set_source_byte_offsets_enabled(bool enabled) {}
};

class TokenStreamWrapper : public TokenStream {
public:
    explicit TokenStreamWrapper(std::shared_ptr<TokenStream> ts) : _impl(std::move(ts)) {}
    ~TokenStreamWrapper() override = default;

    Token* next(Token* token) override { return _impl->next(token); }
    void close() override { _impl->close(); }
    void reset() override { _impl->reset(); }

private:
    std::shared_ptr<TokenStream> _impl;
};

class TokenStreamComponents {
public:
    TokenStreamComponents(TokenizerPtr tokenizer, TokenStreamPtr result)
            : _source(std::move(tokenizer)), _sink(std::move(result)) {}

    void set_reader(const ReaderPtr& reader);
    TokenStreamPtr get_token_stream();
    TokenizerPtr get_source();

private:
    TokenizerPtr _source;
    TokenStreamPtr _sink;
};
using TokenStreamComponentsPtr = std::shared_ptr<TokenStreamComponents>;

}; // namespace doris::segment_v2::inverted_index

Coverage Report

Created: 2026-10-09 18:00