stash2.cpp

Think in C++ 第二版源码

//: C06:Stash2.cpp {O}
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Constructors & destructors
#include "Stash2.h"
#include <iostream>
#include <cassert>
using namespace std;
const int increment = 100;

Stash::Stash(int sz) {
  size = sz;
  quantity = 0;
  storage = 0;
  next = 0;
}

int Stash::add(void* element) {
  if(next >= quantity) // Enough space left?
    inflate(increment);
  // Copy element into storage,
  // starting at next empty space:
  int startBytes = next * size;
  unsigned char* e = (unsigned char*)element;
  for(int i = 0; i < size; i++)
    storage[startBytes + i] = e[i];
  next++;
  return(next - 1); // Index number
}

void* Stash::fetch(int index) {
  assert(0 <= index && index < next);
  // Produce pointer to desired element:
  return &(storage[index * size]);
}

int Stash::count() {
  return next; // Number of elements in CStash
}

void Stash::inflate(int increase) {
  assert(increase > 0);
  int newQuantity = quantity + increase;
  int newBytes = newQuantity * size;
  int oldBytes = quantity * size;
  unsigned char* b = new unsigned char[newBytes];
  for(int i = 0; i < oldBytes; i++)
    b[i] = storage[i]; // Copy old to new
  delete [](storage); // Old storage
  storage = b; // Point to new memory
  quantity = newQuantity;
}

Stash::~Stash() {
  if(storage != 0) {
   cout << "freeing storage" << endl;
   delete []storage;
  }
} ///:~