stream.h

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/*
Minetest
Copyright (C) 2022 Minetest Authors
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.
 
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
 
#pragma once
 
#include <iostream>
#include <string_view>
#include <functional>
 
template<int BufferLength, typename Emitter = std::function<void(std::string_view)> >
class StringStreamBuffer : public std::streambuf {
public:
        StringStreamBuffer(Emitter emitter) : m_emitter(emitter) {
                buffer_index = 0;
        }
 
        int overflow(int c) {
                push_back(c);
                return c;
        }
 
        void push_back(char c) {
                if (c == '\n' || c == '\r') {
                        if (buffer_index)
                                m_emitter(std::string_view(buffer, buffer_index));
                        buffer_index = 0;
                } else {
                        buffer[buffer_index++] = c;
                        if (buffer_index >= BufferLength) {
                                m_emitter(std::string_view(buffer, buffer_index));
                                buffer_index = 0;
                        }
                }
        }
 
        std::streamsize xsputn(const char *s, std::streamsize n) {
                for (std::streamsize i = 0; i < n; ++i)
                        push_back(s[i]);
                return n;
        }
private:
        Emitter m_emitter;
        char buffer[BufferLength];
        int buffer_index;
};
 
class DummyStreamBuffer : public std::streambuf {
        int overflow(int c) {
                return c;
        }
        std::streamsize xsputn(const char *s, std::streamsize n) {
                return n;
        }
};