OAG Library (OpenGL) Part 1 - Setting Up the Library for an MFC Application

/** @file FileSystemFilter.h
 *  Implements a filter system to filter calls to Exists() and Open()
 *  in order to improve the sucess rate of file opening ...
 */
#ifndef AI_FILESYSTEMFILTER_H_INC
#define AI_FILESYSTEMFILTER_H_INC

#include "IOSystem.h"
#include "fast_atof.h"
#include "Assert.h"

// ---------------------------------------------------------------------------
/** File system filter  
 */
class FileSystemFilter : public IOSystem
{
public:
	/** Constructor. */
	FileSystemFilter(const std::string& file, IOSystem* old)
		: wrapped  (old)
		, src_file (file)
	{
		ai_assert(NULL != wrapped);

		// Determine base directory
		base = src_file;
		std::string::size_type ss2;
		if (std::string::npos != (ss2 = base.find_last_of("\\/")))	{
			base.erase(ss2,base.length()-ss2);
		}
		else {
			base = "";
		//	return;
		}

		// make sure the directory is terminated properly
		char s;

		if (base.length() == 0) {
			base = ".\\";
		}
		else if ((s = *(base.end()-1)) != '\\' && s != '/')
			base.append("\\");

		//Determine the filename
		filename = GetFileNameFromPath(src_file);

		//DefaultLogger::get()->info("Import root directory is \'" + base + "\'");
	}

	/** Destructor. */
	~FileSystemFilter()
	{
		// haha
	}

	// -------------------------------------------------------------------
	/** Returns the directory separator. */
	char getOsSeparator() const
	{
		return wrapped->getOsSeparator();
	}


	// -------------------------------------------------------------------
	/** Closes the given file and releases all resources associated with it. */
	void Close( IOStream* pFile)
	{
		return wrapped->Close(pFile);
	}

public:
	std::string src_file, base, filename;

private:
	IOSystem* wrapped;

	// -------------------------------------------------------------------
	/** Build a valid path from a given relative or absolute path.
	 */
	void BuildPath (std::string& in) const
	{
		// if we can already access the file, great.
		if (in.length() < 3 || wrapped->Exists(in.c_str())) {
			return;
		}

		// Determine whether this is a relative path. 
		if (in[1] != ':') {
		
			// append base path and try 
			in = base + in;
			if (wrapped->Exists(in.c_str())) {
				return;
			}
		}

		// hopefully the underyling file system has another few tricks to access this file ...
	}
};


#endif //AI_DEFAULTIOSYSTEM_H_INC