minetest/src/util/stream.h
paradust7 0704ca0550
Make logging cost free when there is no output target (#12247)
The logging streams now do almost no work when there is no output target for them.

For example, if LL_VERBOSE has no output targets, then `verbosestream << x` will return a StreamProxy with a null target. Any further `<<` operations applied to it will do nothing.
2022-05-04 20:55:01 +02:00

71 lines
1.8 KiB
C++

/*
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>
#include <functional>
template<int BufferLength, typename Emitter = std::function<void(const std::string &)> >
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(buffer, buffer_index));
buffer_index = 0;
} else {
buffer[buffer_index++] = c;
if (buffer_index >= BufferLength) {
m_emitter(std::string(buffer, buffer_index));
buffer_index = 0;
}
}
}
std::streamsize xsputn(const char *s, std::streamsize n) {
for (int 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;
}
};