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©Copyright 1996 Rogue Wave Software
RWAuditStreamBufferstreambuf
#include <rw/auditbuf.h>
#include <iostream.h> RWAuditStreamBuffer buf(arguments) ostream os(&buf); // may be used for ostreams istream is(&buf); // or istreams of any kind
Class RWAuditStreamBuffer is used to construct a stream, after which the RWAuditStreamBuffer instance will count all the bytes that pass through the stream. If constructed with a function pointer, RWAuditStreamBuffer will call that function with each byte that passes through the stream. The counting capacity provides for streams the equivalent of the RWCollectable method recursiveStoreSize() which is only available for RWFile.
None
#include <rw/auditbuf.h>
#include <rw/bstream.h>
#include <rw/pstream.h>
#include <iostream.h>
int main() {
RWCollectable ct;
fillCollectable(); // make a collection, somehow
RWAuditStreamBuffer bcounter, pcounter;
RWbostream bcount(&bcounter); //ctor takes streambuf pointer
RWpostream pcount(&pcounter);
//_
bcount << ct;
pcount << ct;
cout << "We just counted " << bcounter
<< " bytes from an RWbostream." << endl;
cout << "We just counted " << pcounter
<< " bytes from an RWpostream." << endl;
return 0;
}
RWAuditStreamBuffer may be used as the streambuf for any stream, including those derived from RWvostream or RWvistream, strstream, ifstream, ofstream, etc.
typedef void (*RWauditFunction)(unsigned char, void*);
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 conter to be manipulated by RWAuditFunction.
RWAuditStreamBuffer(RWauditFunction=0, void*=0);
Constructs a new RWAuditStreamBuffer that may be used only to examine and count every byte that passes into an ostream that has the RWAuditStreamBuffer instance as its streambuf. It will not forward the bytes to any stream, nor accept bytes from a stream. The second argument to the constructor allows you to supply storage for the byte count. It is optional.
RWAuditStreamBuffer(istream&, RWauditFunction=0, void*=0);
Constructs a new RWAuditStreamBuffer that passes bytes from the istream on which it is constructed to the istream that has the RWAuditStreamBuffer instance as its streambuf. A typical use would be to count or examine the bytes being input from a file through a stream derived from RWvistream. The second argument to the constructor allows you to supply storage for the byte count. It is optional.
RWAuditStreamBuffer(iostream&, RWauditFunction=0, void*=0);
Constructs a new RWAuditStreamBuffer that passes bytes to and from the iostream on which it is constructed to and from the istream that has the RWAuditStreamBuffer instance as its 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 second argument to the constructor allows you to supply storage for the byte count. It is optional.
RWAuditStreamBuffer(ostream&, RWauditFunction=0, void*=0);
Constructs a new RWAuditStreamBuffer that passes bytes into the ostream on which it is constructed from the ostream that has the RWAuditStreamBuffer instance as its streambuf. A typical use would be to count or examine the bytes being output to a file through a stream derived from RWvostream. The second argument to the constructor allows you to supply storage for the byte count. It is optional.
RWAuditStreamBuffer(streambuf*, RWauditFunction=0, void*=0);
Constructs a new RWAuditStreamBuffer that passes bytes into the ostream on which it is constructed from the ostream that has the RWAuditStreamBuffer instance as its streambuf. A typical use would be to count or examine the bytes being output to a file through a stream derived from RWvostream. The second argument to the constructor allows you to supply storage for the byte count. It is optional.
virtual ~RWAuditStreamBuffer();
We have provided an empty destructor since some compilers complain if there is no virtual destructor for a class that has virtual methods.
operator unsigned long();
Provides the count of bytes seen so far.
unsigned long reset(unsigned long value = 0);
Resets the count of bytes seen so far. Returns the current count.
#include <iostream.h>
#include <fstream.h>
#include <rw/auditbuf.h>
#include <rw/pstream.h>
#include <rw/cstring.h>
void doCrc (unsigned char c, void* x) {
*(unsigned char*)x ^= c;
}
int main() {
if(1) { // just a block to control variable lifetime
unsigned char check = '\0';
// create an output stream
ofstream op("crc.pst");
// create an RWAuditStreamBuffer that will do CRC
RWAuditStreamBuffer crcb(op,doCrc,&check);
// create an RWpostream to put the data through.
RWpostream p(&crcb);
// now send some random stuff to the stream
p << RWCString("The value of Tools.h++ is at least ");
p << (int)4;
p << RWCString(" times that of the next best library!\n") ;
p << RWCString("Pi is about ") << (double)3.14159 << '.';
// finally, save the sum on the stream itself.
p << (unsigned int)check; // alters check, _after_ saving it...
// just for fun, print out some statistics:
cout << "We just saved " << crcb
<< " bytes of data to the file." << endl;
cout << "The checksum for those bytes was " <<check << endl;
} // end of block
// now read the data back in, checking to see if it survived.
unsigned char check = '\0';
// create an instream
ifstream ip("crc.pst");
// create an RWAuditStreamBuffer that will do CRC
RWAuditStreamBuffer crcb(ip,doCrc,&check);
// create an RWpistream to interpret the bytes
RWpistream p(&crcb);
RWCString first, mid1, mid2;
int value;
double pi;
char pnc;
unsigned int savedCRC;
unsigned char matchCRC;
// read in the data. Don\'t read the checksum yet!
p >> first >> value >> mid1 >> mid2 >> pi >> pnc;
// save the checksum
matchCRC = check;
// Now it is safe to alter the running checksum by reading in
// the one saved in the file.
p >> savedCRC;
if(savedCRC != matchCRC) {
cout << "Checksum error. Saved CRC: " << savedCRC
<< " built CRC: " << matchCRC << dec << endl;
}
else {
cout << "The message was: " << endl;
cout << first << value << mid1 << mid2 << pi << pnc << endl;
}
// just for fun, print out some statistics:
cout << "We just read " << crcb
<< " bytes of data from the file." << endl;
cout << "The checksum was " << matchCRC << flush;
cout << " and the saved checksum was " << savedCRC << endl;
return 0;
}
