RWAuditStreamBuffer Class Reference
[Virtual Streams]

Constructs a stream and audits the bytes that pass through it. More...

#include <rw/auditbuf.h>

List of all members.

Public Member Functions
	RWAuditStreamBuffer (RWauditFunction=0, void *=0)
	RWAuditStreamBuffer (std::istream &, RWauditFunction=0, void *=0)
	RWAuditStreamBuffer (std::iostream &, RWauditFunction=0, void *=0)
	RWAuditStreamBuffer (std::ostream &, RWauditFunction=0, void *=0)
	RWAuditStreamBuffer (std::streambuf *, RWauditFunction=0, void *=0)
virtual	~RWAuditStreamBuffer ()
	operator unsigned long ()
unsigned long	reset (unsigned long val=0ul)
Related Functions
(Note that these are not member functions.)
typedef void(*	RWauditFunction )(unsigned char, void *)

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Detailed Description

Class RWAuditStreamBuffer is used to construct a stream, after which the RWAuditStreamBuffer instance counts all the bytes that pass through the stream. If constructed with a function pointer, RWAuditStreamBuffer calls that function with each byte that passes through the stream. The counting capacity provides for streams the equivalent of the method RWCollectable::recursiveStoreSize(), which is only available for RWFile.

Synopsis

 #include <rw/auditbuf.h>
 #include <iostream>
 RWAuditStreamBuffer buf(arguments)
 std::ostream os(&buf); // may be used for ostreams
 std::istream is(&buf); // or istreams of any kind

Examples

 #include <rw/bstream.h>
 #include <rw/pstream.h>
 #include <rw/auditbuf.h>

 #include <rw/collint.h>  // for RWCollectableInt
 #include <rw/collstr.h>  // for RWCollectableString
 #include <rw/dlistcol.h> // for RWDlistCollectables

 #include <iostream>

 int main ()
 {
     RWCollectableInt i(7);
     RWCollectableString s("Hello!\n");

     RWDlistCollectables ct;

     // Construct a collection
     ct.append(&i);
     ct.append(&s);
     ct.prepend(&ct);

     RWAuditStreamBuffer bcounter, pcounter;

     RWbostream bcount(&bcounter); // ctor takes streambuf pointer
     RWpostream pcount(&pcounter);


     bcount << ct;
     pcount << ct;

     std::cout << "We just counted " << bcounter
               << " bytes from an RWbostream.\n";
     std::cout << "We just counted " << pcounter
               << " bytes from an RWpostream." << std::endl;

     return 0;
 }

Program output:

 We just counted 43 bytes from an RWbostream.
 We just counted 52 bytes from an RWpostream.

Related Classes

RWAuditStreamBuffer may be used as the std::streambuf for any stream, including those derived from RWvostream or RWvistream, std::strstream, std::ifstream, std::ofstream, etc.

Persistence

None

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Constructor & Destructor Documentation

RWAuditStreamBuffer::RWAuditStreamBuffer	(	RWauditFunction	= 0,
		void *	= 0
	)

Constructs a new RWAuditStreamBuffer that may be used only to examine and count every byte that passes into an std::ostream that has the RWAuditStreamBuffer instance as its std::streambuf. It does not forward the bytes to any stream, nor accept bytes from a stream. The second parameter to the constructor allows you to supply storage for the byte count. It is optional.

RWAuditStreamBuffer::RWAuditStreamBuffer	(	std::istream &	,
		RWauditFunction	= 0,
		void *	= 0
	)

Constructs a new RWAuditStreamBuffer that passes bytes from the std::istream on which it is constructed to the std::istream that has the RWAuditStreamBuffer instance as its std::streambuf. A typical use would be to count or examine the bytes being input from a file through a stream derived from RWvistream. The third parameter to the constructor allows you to supply storage for the byte count. It is optional.

RWAuditStreamBuffer::RWAuditStreamBuffer	(	std::iostream &	,
		RWauditFunction	= 0,
		void *	= 0
	)

Constructs a new RWAuditStreamBuffer that passes bytes to and from the std::iostream on which it is constructed to and from the std::istream that has the RWAuditStreamBuffer instance as its std::streambuf. A typical use would be to count or examine the bytes being transferred to and from a file used to store and retrieve changing data. The third parameter to the constructor allows you to supply storage for the byte count. It is optional.

RWAuditStreamBuffer::RWAuditStreamBuffer	(	std::ostream &	,
		RWauditFunction	= 0,
		void *	= 0
	)

Constructs a new RWAuditStreamBuffer that passes bytes into the std::ostream on which it is constructed from the std::ostream that has the RWAuditStreamBuffer instance as its std::streambuf. A typical use would be to count or examine the bytes being output to a file through a stream derived from RWvostream. The third parameter to the constructor allows you to supply storage for the byte count. It is optional.

RWAuditStreamBuffer::RWAuditStreamBuffer	(	std::streambuf *	,
		RWauditFunction	= 0,
		void *	= 0
	)

Constructs a new RWAuditStreamBuffer that passes bytes into the std::ostream on which it is constructed from the std::ostream that has the RWAuditStreamBuffer instance as its std::streambuf. A typical use would be to count or examine the bytes being output to a file through a stream derived from RWvostream. The third parameter to the constructor allows you to supply storage for the byte count. It is optional.

virtual RWAuditStreamBuffer::~RWAuditStreamBuffer

(

)

[virtual]

We have provided an empty destructor since some compilers complain if there is no virtual destructor for a class that has virtual methods.

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Member Function Documentation

RWAuditStreamBuffer::operator unsigned long

(

)

[inline]

Provides the count of bytes seen so far.

unsigned long RWAuditStreamBuffer::reset

(

unsigned long

val = 0ul

)

[inline]

Resets the count of bytes seen so far. Returns the current count.

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Friends And Related Function Documentation

typedef void(* RWauditFunction)(unsigned char, void *) [related]

If you wish to do more than count each character handled by the buffer, you may provide an RWauditFunction to the constructor. The first parameter to this function is a byte provided by the stream. The second parameter is the address of the counter to be manipulated by RWAuditFunction.