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icecream.cpp
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C/C++ Source or Header
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1998-02-09
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7KB
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263 lines
#include "stlexam.h"
#pragma hdrstop
/**************************************************************************
*
* icecream.cpp - priority queue example program. Section 11.3.1
*
* $Id: icecream.cpp,v 1.16 1996/09/03 22:26:40 smithey Exp $
*
***************************************************************************
*
* (c) Copyright 1994, 1995 Rogue Wave Software, Inc.
* ALL RIGHTS RESERVED *
* The software and information contained herein are proprietary to, and
* comprise valuable trade secrets of, Rogue Wave Software, Inc., which
* intends to preserve as trade secrets such software and information.
* This software is furnished pursuant to a written license agreement and
* may be used, copied, transmitted, and stored only in accordance with
* the terms of such license and with the inclusion of the above copyright
* notice. This software and information or any other copies thereof may
* not be provided or otherwise made available to any other person.
*
* Notwithstanding any other lease or license that may pertain to, or
* accompany the delivery of, this computer software and information, the
* rights of the Government regarding its use, reproduction and disclosure
* are as set forth in Section 52.227-19 of the FARS Computer
* Software-Restricted Rights clause.
*
* Use, duplication, or disclosure by the Government is subject to
* restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in
* Technical Data and Computer Software clause at DFARS 252.227-7013.
* Contractor/Manufacturer is Rogue Wave Software, Inc.,
* P.O. Box 2328, Corvallis, Oregon 97339.
*
* This computer software and information is distributed with "restricted
* rights." Use, duplication or disclosure is subject to restrictions as
* set forth in NASA FAR SUP 18-52.227-79 (April 1985) "Commercial
* Computer Software-Restricted Rights (April 1985)." If the Clause at
* 18-52.227-74 "Rights in Data General" is specified in the contract,
* then the "Alternate III" clause applies.
*
**************************************************************************/
#ifndef _RWSTD_HEADER_REQUIRES_HPP
#include <vector>
#include <queue>
#else
#include <vector.hpp>
#include <queue.hpp>
#endif
#ifdef _RW_STD_IOSTREAM
#include <iostream>
#else
#include <iostream.h>
#endif
#ifndef _RWSTD_NO_NAMESPACE
using namespace std;
#endif
//
// Execution event in a descrete event driven simulation.
//
class event
{
public:
//
// Construct sets time of event.
//
event (unsigned int t) : time(t) { };
//
// Time is a public data field.
//
const unsigned int time;
//
// Execute event my invoking this method.
//
virtual void processEvent() = 0;
};
//
// Needed by some compilers.
//
inline void __destroy (event **) {}
struct eventComparison
{
bool operator () (const event * left, const event * right)
{ return left->time > right->time; }
};
//
// Framework for discrete event-driven simulations.
//
class simulation
{
public:
simulation () : eventQueue(), time(0) {}
void run ();
unsigned int time;
void scheduleEvent (event * newEvent) { eventQueue.push(newEvent); }
protected:
priority_queue<event*, vector<event *,allocator<event*> >, eventComparison > eventQueue;
};
void simulation::run ()
{
while (! eventQueue.empty())
{
event * nextEvent = eventQueue.top();
eventQueue.pop();
time = nextEvent->time;
nextEvent->processEvent();
delete nextEvent;
}
}
//
// Ice cream store simulation.
//
class storeSimulation : public simulation
{
public:
storeSimulation() : freeChairs(35), profit(0.0), simulation() { }
bool canSeat (unsigned int numberOfPeople);
void order (unsigned int numberOfScoops);
void leave (unsigned int numberOfPeople);
//
// Data fields.
//
unsigned int freeChairs;
double profit;
} theSimulation;
class arriveEvent : public event
{
public:
arriveEvent (unsigned int time, unsigned int groupSize)
: event(time), size(groupSize) { }
virtual void processEvent();
private:
unsigned int size;
};
class orderEvent : public event
{
public:
orderEvent (unsigned int time, unsigned int groupSize)
: event(time), size(groupSize) { }
virtual void processEvent();
private:
unsigned int size;
};
class leaveEvent : public event
{
public:
leaveEvent (unsigned int time, unsigned int groupSize)
: event(time), size(groupSize) { }
virtual void processEvent();
private:
unsigned int size;
};
//
// Return random integer between 0 and n.
//
int irand (int n) { return (rand()/10) % n; }
void arriveEvent::processEvent ()
{
if (theSimulation.canSeat(size))
theSimulation.scheduleEvent(new orderEvent(time + 1 + irand(4), size));
}
void orderEvent::processEvent ()
{
//
// Each person orders some number of scoops.
//
for (int i = 0; i < size; i++)
theSimulation.order(1 + irand(4));
//
// Then we schedule the leave event.
//
theSimulation.scheduleEvent(new leaveEvent(time + 1 + irand(10), size));
}
void leaveEvent::processEvent () { theSimulation.leave(size); }
//
// If sufficient room then seat customers.
//
bool storeSimulation::canSeat (unsigned int numberOfPeople)
{
cout << "Time: " << time;
cout << " group of " << numberOfPeople << " customers arrives";
if (numberOfPeople < freeChairs)
{
cout << " is seated" << endl;
freeChairs -= numberOfPeople;
return true;
}
else
{
cout << " no room, they leave" << endl;
return false;
}
}
//
// Service icecream, compute profits.
//
void storeSimulation::order (unsigned int numberOfScoops)
{
cout << "Time: " << time;
cout << " serviced order for " << numberOfScoops << endl;
profit += 0.35 * numberOfScoops;
}
//
// People leave, free up chairs.
//
void storeSimulation::leave (unsigned int numberOfPeople)
{
cout << "Time: " << time;
cout << " group of size " << numberOfPeople << " leaves" << endl;
freeChairs += numberOfPeople;
}
int main ()
{
cout << "Ice Cream Store simulation from Chapter 9" << endl;
//
// Load queue with some number of initial events.
//
unsigned int t = 0;
while (t < 20)
{
t += irand(6);
cout << "pumping queue with event " << t << endl;
theSimulation.scheduleEvent(new arriveEvent(t, 1 + irand(4)));
}
//
// Run the simulation.
//
theSimulation.run();
cout << "Total profits " << theSimulation.profit << endl;
cout << "End of ice cream store simulation" << endl;
return 0;
}