zstd_streambuf.h

/*******************************************************************************
 * Copyright 2026 MINRES Technologies GmbH
 *
 * Licensed 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 _UTIL_ZSTD_STREAMBUF_H_
#define _UTIL_ZSTD_STREAMBUF_H_
 
#include <cctype>
#include <climits>
#include <iostream>
#include <string>
#include <sys/stat.h>
#include <vector>
#include <zstd.h>
 
namespace util {
// ============================================================
// ZSTD
// ============================================================
 
class zstd_streambuf : public std::streambuf {
public:
    explicit zstd_streambuf(const std::string& path);
 
    ~zstd_streambuf() override;
 
protected:
    int_type underflow() override;
 
private:
    FILE* file_;
    ZSTD_DCtx* dctx_;
    std::vector<char> buffer_;
    std::vector<char> inbuf_;
};
 
class zstd_stream : public std::istream {
public:
    zstd_stream() = delete;
    explicit zstd_stream(const std::string& path)
    : std::istream(&buf_)
    , buf_(path) {
        rdbuf(&buf_);
    }
 
private:
    zstd_streambuf buf_;
};
 
} // namespace util
#endif // _UTIL_ZSTD_STREAMBUF_H_