/********************************************************************************

* *

* This file is part of IfcOpenShell. *

* *

* IfcOpenShell is free software: you can redistribute it and/or modify *

* it under the terms of the Lesser GNU General Public License as published by *

* the Free Software Foundation, either version 3.0 of the License, or *

* (at your option) any later version. *

* *

* IfcOpenShell 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 *

* Lesser GNU General Public License for more details. *

* *

* You should have received a copy of the Lesser GNU General Public License *

* along with this program. If not, see <http://www.gnu.org/licenses/>. *

* *

********************************************************************************/

/********************************************************************************

* *

* Reads a file in chunks of BUF_SIZE and provides functions to access its *

* contents randomly and character by character *

* *

********************************************************************************/

#ifndef IFCSPFSTREAM_H

#define IFCSPFSTREAM_H

#include <fstream>

#include <string>

// As of IfcOpenShell version 0.3.0 the paging functionality, which

// loads a file on disk into multiple chunks, has been disabled.

// It proved to be an inefficient way of working with large files,

// as often these did not facilitate to be parsed in a sequential

// manner efficiently. To enable the paging functionality uncomment

// the following statement.

// #define BUF_SIZE (8 * 1024 * 1024)

namespace IfcParse {

/// The IfcSpfStream class represents a ISO 10303-21 IFC-SPF file in memory.

/// The file is interpreted as a sequence of tokens which are lazily

/// interpreted only when requested. If the size of the file is

/// larger than BUF_SIZE, the file is split into seperate pages, of

/// which only one is simultaneously kept in memory, for files

/// that define their entities not in a sequential nature, this is

/// detrimental for the performance of the parser.

class IfcSpfStream {

private:

FILE* stream;

char* buffer;

unsigned int ptr;

unsigned int len;

void ReadBuffer(bool inc=true);

#ifdef BUF_SIZE

unsigned int offset;

bool paging;

#endif

public:

bool valid;

bool eof;

unsigned int size;

IfcSpfStream(const std::string& fn);

IfcSpfStream(std::istream& f, int len);

IfcSpfStream(void* data, int len);

/// Returns the character at the cursor

char Peek();

/// Returns the character at specified offset

char Read(unsigned int offset);

/// Increment the file cursor and reads new page if necessary

void Inc();

void Close();

/// Moves the file cursor to an arbitrary offset in the file

void Seek(unsigned int offset);

/// Returns the cursor position

unsigned int Tell();

};

}

#endif