Category : C++ Source Code
Archive   : CCL110JE.ZIP
Filename : EXAMPLE3.CPP

//--------------------------------------------------------------------------
//
// EXAMPLE3.CPP: example program 3 for DOS coroutine library.
// Copyright (c) J.English 1993.
// Author's address: [email protected]
//
// Permission is granted to use copy and distribute the
// information contained in this file provided that this
// copyright notice is retained intact and that any software
// or other document incorporating this file or parts thereof
// makes the source code for the library of which this file
// is a part freely available.
//
//--------------------------------------------------------------------------

#include
#include
#include "coroutine.h"

#define ESC 0x1B // code for the ESC key

//--------------------------------------------------------------------------
//
// Class Example3.
//
// This is a coroutine which displays a series of messages. It
// illustrates how "terminate" can be used as well as the use of
// "wait" in a coroutine destructor.
//
class Example3 : public Coroutine
{
public:
Example3 (int n) { num = n; }
~Example3 ();

protected:
virtual void main (); // code to be executed by coroutine

private:
int num; // coroutine identification number
};

static int quit = 0; // flag to request coroutine termination

//--------------------------------------------------------------------------
//
// Example3::~Example3.
//
// The coroutine class destructor. Note how "wait" is called at the
// beginning of the destructor to ensure the coroutine has terminated
// before any other finalisation is done.
//
Example3::~Example3 ()
{
wait ();
cout << "\nCoroutine E" << num << " finished\n";
}

//--------------------------------------------------------------------------
//
// Example3::main.
//
// This is the code executed by each instance of class Example3.
// It displays a startup message, executes a loop (pausing each
// time) until the main program sets the "quit" flag, and then
// displays a termination message before exiting.
//
void Example3::main ()
{
cout << "\nCoroutine E" << num << " started\n";

while (!quit)
{ cout << num << " ";
pause ();
}
}

//--------------------------------------------------------------------------
//
// The main program.
//
// This creates three instances of class Example3, starts them
// running and then waits until ESC is pressed. It then sets
// the "quit" flag to signal the coroutines to terminate before
// exiting. If 1, 2 or 3 is pressed, the corresponding coroutine
// is immediately terminated. Note that the loop which waits for
// a key to be pressed calls "pause" each time to allow the coroutines
// to execute, and that it uses bioskey(1) (test if a key has been
// pressed) rather than just bioskey(0) which would wait for a key
// to be pressed and would not allow the coroutines to run between
// keypresses.
//
void main ()
{
Example3 e1 (1), e2 (2), e3 (3);

//--- announce startup
cout << "Press ESC to exit, 1 or 2 or 3 to terminate the corresponding\n"
<< "coroutine. Press any key to start.\n";
bioskey (0);

//--- start the coroutines running
if (!e1.run ())
cout << "Couldn't start e1\n";
if (!e2.run ())
cout << "Couldn't start e2\n";
if (!e3.run ())
cout << "Couldn't start e3\n";

//--- wait for a suitable key to be pressed
for (;;)
{ while (bioskey (1) == 0)
Example3::pause ();
switch (bioskey (0) & 0xFF)
{
case ESC:
quit = 1;
return;
case '1':
e1.terminate ();
break;
case '2':
e2.terminate ();
break;
case '3':
e3.terminate ();
break;
}
}
} //--- destructors called here: wait for coroutines to finish, then exit