SourcePro® API Reference Guide

 
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RWFileManager Class Reference

Allocates and deallocates storage in a disk file, much like a "freestore" manager. More...

#include <rw/filemgr.h>

Inheritance diagram for RWFileManager:
RWFile

Public Member Functions

 RWFileManager (const char *filename, const char *mode=rwnil)
 
 ~RWFileManager ()
 
RWoffset allocate (RWspace s)
 
void deallocate (RWoffset t)
 
RWoffset endData () const
 
RWoffset start () const
 
- Public Member Functions inherited from RWFile
 RWFile (const char *filename, const char *mode=0, bool large_file=false)
 
 ~RWFile ()
 
const char * Access () const
 
void ClearErr ()
 
RWoffset CurOffset () const
 
RWoffset64 CurOffset64 () const
 
bool Eof () const
 
bool eof () const
 
bool Erase ()
 
bool Error () const
 
bool Exists () const
 
bool Flush ()
 
const char * GetName () const
 
FILE * GetStream () const
 
bool good () const
 
bool IsEmpty () const
 
bool isValid () const
 
bool Read (bool &i)
 
bool Read (bool *i, size_t n, size_t *count=0)
 
bool Read (char &c)
 
bool Read (char *i, size_t n, int delim, size_t *count=0)
 
bool Read (char *i, size_t n, size_t *count=0)
 
bool Read (char *string)
 
bool Read (double &s)
 
bool Read (double *i, size_t n, size_t *count=0)
 
bool Read (float &f)
 
bool Read (float *i, size_t n, size_t *count=0)
 
bool Read (int &i)
 
bool Read (int *i, size_t n, size_t *count=0)
 
bool Read (long &i)
 
bool Read (long *i, size_t n, size_t *count=0)
 
bool Read (long double &d)
 
bool Read (long double *i, size_t n, size_t *count=0)
 
bool Read (long long &i)
 
bool Read (long long *i, size_t n, size_t *count=0)
 
bool Read (short &i)
 
bool Read (short *i, size_t n, size_t *count=0)
 
bool Read (unsigned char &c)
 
bool Read (unsigned char *c, size_t n, size_t *count=0)
 
bool Read (unsigned int &i)
 
bool Read (unsigned int *i, size_t n, size_t *count=0)
 
bool Read (unsigned long &i)
 
bool Read (unsigned long *i, size_t n, size_t *count=0)
 
bool Read (unsigned long long &i)
 
bool Read (unsigned long long *i, size_t n, size_t *count=0)
 
bool Read (unsigned short &i)
 
bool Read (unsigned short *i, size_t n, size_t *count=0)
 
bool Read (wchar_t &w)
 
bool Read (wchar_t *i, size_t n, size_t *count=0)
 
bool SeekTo (RWoffset offset)
 
bool SeekTo64 (RWoffset64 offset)
 
bool SeekToBegin ()
 
bool SeekToEnd ()
 
bool Write (bool i)
 
bool Write (char i)
 
bool Write (const bool *i, size_t count)
 
bool Write (const char *string)
 
bool Write (const char *string, size_t)
 
bool Write (const double *i, size_t count)
 
bool Write (const float *i, size_t count)
 
bool Write (const int *i, size_t count)
 
bool Write (const long *i, size_t count)
 
bool Write (const long double *i, size_t count)
 
bool Write (const long long *i, size_t count)
 
bool Write (const short *i, size_t count)
 
bool Write (const unsigned char *c, size_t N)
 
bool Write (const unsigned int *i, size_t N)
 
bool Write (const unsigned long *i, size_t N)
 
bool Write (const unsigned long long *i, size_t count)
 
bool Write (const unsigned short *i, size_t N)
 
bool Write (const wchar_t *i, size_t count)
 
bool Write (double d)
 
bool Write (float f)
 
bool Write (int i)
 
bool Write (long double d)
 
bool Write (long i)
 
bool Write (long long i)
 
bool Write (short i)
 
bool Write (unsigned char i)
 
bool Write (unsigned int i)
 
bool Write (unsigned long i)
 
bool Write (unsigned long long i)
 
bool Write (unsigned short i)
 
bool Write (wchar_t i)
 

Additional Inherited Members

- Static Public Member Functions inherited from RWFile
static bool Exists (const char *filename)
 
static bool Exists (const char *filename, int mode)
 

Detailed Description

Class RWFileManager allocates and deallocates storage in a disk file, much like a "freestore" manager. It does this by maintaining a linked list of free space within the file.

Note
Class RWFileManager inherits class RWFile as a public base class; hence all the public member functions of RWFile are visible to RWFileManager. They are not listed here.

If a file is managed by an RWFileManager, then reading or writing to unallocated space in the file has undefined results. In particular, overwriting the end of allocated space is a common problem which usually results in corrupted data. One way to encounter this problem is to use binaryStoreSize() to discover the amount of space needed to store an RWCollection. For most purposes, the storage size of an RWCollection is found using the RWCollectable method recursiveStoreSize().

Synopsis
typedef long RWoffset;
typedef unsigned long RWspace; // (typically)
#include <rw/filemgr.h>
RWFileManager f("file.dat");
Allocates and deallocates storage in a disk file, much like a "freestore" manager.
Definition filemgr.h:66
unspecified_type RWoffset
Definition compat.h:506
Persistence
None

Constructor & Destructor Documentation

◆ RWFileManager()

RWFileManager::RWFileManager ( const char * filename,
const char * mode = rwnil )

Constructs an RWFileManager for the file with path name filename using mode mode. The mode is as given by the C Standard Library function fopen(). If mode is zero (the default), then the constructor attempts to open an existing file with the given filename for update (mode "rb+"). If this is not possible, then it attempts to create a new file with the given filename (mode "wb+"). If the file exists and is not empty, then the constructor assumes it contains an existing file manager; other contents cause the function to throw an exception of type RWExternalErr. If no file exists or if an existing file is empty, then the constructor attempts to create the file (if necessary) and initialize it with a new file manager. The resultant object should be checked for validity using function isValid(). RWFileErr is a possible exception that could be thrown.

◆ ~RWFileManager()

RWFileManager::~RWFileManager ( )

Empty Destructor.

Member Function Documentation

◆ allocate()

RWoffset RWFileManager::allocate ( RWspace s)

Allocates s bytes of storage in the file. Returns the offset to the start of the storage location. The very first allocation for the file is considered "special" and can be returned at any later time by the function start(). RWFileErr is a possible exception that could be thrown.

◆ deallocate()

void RWFileManager::deallocate ( RWoffset t)

Deallocates (frees) the storage space starting at offset t. This space must have been previously allocated by a call to allocate(). The very first allocation ever made in the file is considered "special" and cannot be deallocated. RWFileErr is a possible exception that could be thrown.

◆ endData()

RWoffset RWFileManager::endData ( ) const
inline

Returns an offset just past the end of the file.

◆ start()

RWoffset RWFileManager::start ( ) const
inline

Returns the offset of the first space ever allocated for data in this file. If no space has ever been allocated, returns RWNIL. This is typically used to "get started" and find the rest of the data in the file.

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