iobase.h

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/*
BSD 3-Clause License
 
Copyright (c) 2022, Stable Cloud Computing, Inc.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 
3. Neither the name of the copyright holder nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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*/
#ifndef _SCC_UTIL_IOBASE_H
#define _SCC_UTIL_IOBASE_H
 
#include <memory>
 
namespace scc::util
{
 
struct Reader
{
    virtual ~Reader() {}
    virtual size_t read(void*, size_t) = 0;
};
 
struct PipelineReader : public Reader
{
    virtual ~PipelineReader() {}
    virtual void read_reset(const std::shared_ptr<Reader>&) = 0;
    virtual std::shared_ptr<Reader> read_shared() const = 0;
};
 
struct Writer
{
    virtual ~Writer() {}
    virtual size_t write(const void*, size_t) = 0;
};
 
struct PipelineWriter : public Writer
{
    virtual ~PipelineWriter() {}
    virtual void write_reset(const std::shared_ptr<Writer>&) = 0;
    virtual std::shared_ptr<Writer> write_shared() const = 0;
};
 
struct FlowThroughPipelineReader : public PipelineReader
{
    std::shared_ptr<Reader> reader;
 
    FlowThroughPipelineReader() : reader(nullptr) {}
    FlowThroughPipelineReader(const std::shared_ptr<Reader>& r) : reader(r) {}
    virtual ~FlowThroughPipelineReader() {}
    virtual size_t read(void* loc, size_t len)
    {
        if (reader)     return reader->read(loc, len);
        else            return 0;
    }
    virtual void read_reset(const std::shared_ptr<Reader>& r)
    {
        reader = r;
    }
    virtual std::shared_ptr<Reader> read_shared() const { return reader; };
};
 
struct FlowThroughPipelineWriter : public PipelineWriter
{
    std::shared_ptr<Writer> writer;
 
    FlowThroughPipelineWriter() : writer(nullptr) {}
    FlowThroughPipelineWriter(const std::shared_ptr<Writer>& w) : writer(w) {}
    virtual ~FlowThroughPipelineWriter() {}
    virtual size_t write(const void* loc, size_t len)
    {
        if (writer)     return writer->write(loc, len);
        else            return 0;
    }
    virtual void write_reset(const std::shared_ptr<Writer>& w)
    {
        writer = w;
    }
    virtual std::shared_ptr<Writer> write_shared() const { return writer; };
};
}
 
#endif