pstash.cpp

Think in C++文中代码实现

// File from page 471 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
// on bulletin boards, internet nodes, shareware disks and 
// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: PSTASH.CPP -- Pointer stash definitions
#include "..\11\pstash.h"
#include <iostream.h>
#include <string.h> // Mem functions

int pstash::add(void* element) {
  const InflateSize = 10;
  if(next >= quantity)
    inflate(InflateSize);
  storage[next++] = element;
  return(next - 1); // Index number
}

// Operator overloading replacement for fetch
void* pstash::operator[](int index) const {
  if(index >= next || index < 0)
    return 0;  // Out of bounds
  // Produce pointer to desired element:
  return storage[index];
}

void pstash::inflate(int increase) {
  const psz = sizeof(void*);
  // realloc() is cleaner than this:
  void** st = new void*[quantity + increase];
  memset(st, 0, (quantity + increase) * psz);
  memcpy(st, storage, quantity * psz);
  quantity += increase;
  delete storage; // Old storage
  storage = st; // Point to new memory
}