113 lines
2.6 KiB
C++
113 lines
2.6 KiB
C++
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// memory_file.hpp
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// Copyright (c) 2012 Ben Hanson (http://www.benhanson.net/)
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// Inspired by http://en.wikibooks.org/wiki/Optimizing_C%2B%2B/General_optimization_techniques/Input/Output#Memory-mapped_file
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file licence_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef LEXERTL_MEMORY_FILE_H
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#define LEXERTL_MEMORY_FILE_H
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#ifdef __unix__
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#elif defined _WIN32
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#include <windows.h>
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#endif
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// Only files small enough to fit into memory are supported.
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namespace lexertl
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{
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template<typename CharT>
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class basic_memory_file
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{
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public:
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basic_memory_file (const char *pathname_) :
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_data (0),
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_size (0)
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{
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#ifdef __unix__
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_fh = ::open (pathname_, O_RDONLY);
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if (_fh > -1)
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{
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struct stat sbuf_;
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if (::fstat (_fh, &sbuf_) > -1)
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{
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_data = static_cast<const CharT *>
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(::mmap (0, sbuf_.st_size, PROT_READ, MAP_SHARED, _fh, 0));
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if (_data == MAP_FAILED)
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{
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_data = 0;
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}
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else
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{
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_size = sbuf_.st_size;
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}
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}
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}
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#elif defined _WIN32
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_fh = ::CreateFileA (pathname_, GENERIC_READ, FILE_SHARE_READ, 0,
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OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
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_fmh = 0;
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if (_fh != INVALID_HANDLE_VALUE)
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{
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_fmh = ::CreateFileMapping (_fh, 0, PAGE_READONLY, 0, 0, 0);
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if (_fmh != 0)
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{
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_data = static_cast<CharT *>(::MapViewOfFile
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(_fmh, FILE_MAP_READ, 0, 0, 0));
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if (_data) _size = ::GetFileSize(_fh, 0);
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}
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}
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#endif
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}
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~basic_memory_file ()
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{
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#if defined(__unix__)
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::munmap(const_cast<CharT *>(_data), _size);
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::close(_fh);
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#elif defined(_WIN32)
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::UnmapViewOfFile(_data);
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::CloseHandle(_fmh);
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::CloseHandle(_fh);
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#endif
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}
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const CharT *data () const
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{
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return _data;
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}
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std::size_t size () const
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{
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return _size;
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}
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private:
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const CharT *_data;
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std::size_t _size;
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#ifdef __unix__
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int _fh;
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#elif defined _WIN32
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HANDLE _fh;
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HANDLE _fmh;
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#else
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#error Only Posix or Windows are supported.
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#endif
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};
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typedef basic_memory_file<char> memory_file;
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typedef basic_memory_file<wchar_t> wmemory_file;
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}
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#endif
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