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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 2019-2025, Ben Burton *
* For further details contact Ben Burton (bab@debian.org). *
* *
* This program is free software; you can redistribute it and/or *
* modify it under the terms of the GNU General Public License as *
* published by the Free Software Foundation; either version 2 of the *
* License, or (at your option) any later version. *
* *
* As an exception, when this program is distributed through (i) the *
* App Store by Apple Inc.; (ii) the Mac App Store by Apple Inc.; or *
* (iii) Google Play by Google Inc., then that store may impose any *
* digital rights management, device limits and/or redistribution *
* restrictions that are required by its terms of service. *
* *
* 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 *
* General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program. If not, see <https://www.gnu.org/licenses/>. *
* *
**************************************************************************/
#include <cstring>
#include "utilities/memstream.h"
namespace regina {
std::streamsize mem_streambuf::xsgetn(char* s, std::streamsize n) {
if (current_ + n > end_)
n = end_ - current_;
std::memcpy(s, current_, n);
current_ += n;
return n;
}
mem_streambuf::pos_type mem_streambuf::seekpos(
pos_type pos, std::ios_base::openmode which) {
if ((which & std::ios_base::in) && begin_ + pos <= end_) {
current_ = begin_ + pos;
return pos;
} else
return pos_type(off_type(-1));
}
mem_streambuf::pos_type mem_streambuf::seekoff(off_type off,
std::ios_base::seekdir /* dir */, std::ios_base::openmode which) {
if (! (which & std::ios_base::in))
return pos_type(off_type(-1));
if (off == std::ios_base::beg) {
if (off >= 0 && begin_ + off <= end_) {
current_ = begin_ + off;
return off;
}
} else if (off == std::ios_base::cur) {
if (current_ + off >= begin_ && current_ + off <= end_) {
current_ += off;
return (current_ - begin_);
}
} else if (off == std::ios_base::end) {
if (off <= 0 && end_ + off >= begin_) {
current_ = end_ + off;
return (current_ - begin_);
}
}
return pos_type(off_type(-1));
}
} // namespace regina
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