tstash.h

Think in C++文中代码实现

// File from page 592 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).
//////////////////////////////////////////////////

//: TSTASH.H -- PSTASH using templates
#ifndef TSTASH_H_
#define TSTASH_H_
#include <stdlib.h>
#include "..\allege.h"
// More convenient than nesting in tstash:
enum owns { no = 0, yes = 1, Default };
// Declaration required:
template<class Type, int sz> class tstashIter;

template<class Type, int chunksize = 20>
class tstash {
  int quantity;
  int next;
  owns own; // Flag
  void inflate(int increase = chunksize);
protected:
  Type** storage;
public:
  tstash(owns Owns = yes);
  ~tstash();
  int Owns() const { return own; }
  void Owns(owns newOwns) { own = newOwns; }
  int add(Type* element);
  int remove(int index, owns d = Default);
  Type* operator[](int index);
  int count() const { return next; }
  friend class tstashIter<Type, chunksize>;
};

template<class Type, int sz = 20>
class tstashIter {
  tstash<Type, sz>& ts;
  int index;
public:
  tstashIter(tstash<Type, sz>& TS)
    : ts(TS), index(0) {}
  tstashIter(const tstashIter& rv)
    : ts(rv.ts), index(rv.index) {}
  // Jump interator forward or backward:
  void forward(int amount) {
    index += amount;
    if(index >= ts.next) index = ts.next -1;
  }
  void backward(int amount) {
    index -= amount;
    if(index < 0) index = 0;
  }
  // Return value of ++ and -- to be 
  // used inside conditionals:
  int operator++() {
    if(++index >= ts.next) return 0;
    return 1;
  }
  int operator++(int) { return operator++(); }
  int operator--() {
    if(--index < 0) return 0;
    return 1;
  }
  int operator--(int) { return operator--(); }
  operator int() {
    return index >= 0 && index < ts.next;
  }
  Type* operator->() {
    Type* t = ts.storage[index];
    if(t) return t;
    allege(0,"tstashIter::operator->return 0");
    return 0; // To allow inlining
  }
  // Remove the current element:
  int remove(owns d = Default){
    return ts.remove(index, d);
  }
};

template<class Type, int sz>
tstash<Type, sz>::tstash(owns Owns) : own(Owns) {
  quantity = 0;
  storage = 0;
  next = 0;
}

// Destruction of contained objects:
template<class Type, int sz>
tstash<Type, sz>::~tstash() {
  if(!storage) return;
  if(own == yes)
    for(int i = 0; i < count(); i++)
      delete storage[i];
  free(storage);
}

template<class Type, int sz>
int tstash<Type, sz>::add(Type* element) {
  if(next >= quantity)
    inflate();
  storage[next++] = element;
  return(next - 1); // Index number
}

template<class Type, int sz>
int tstash<Type, sz>::remove(int index,owns d){
  if(index >= next || index < 0)
    return 0;
  switch(d) {
    case Default:
      if(own != yes) break;
    case yes:
      delete storage[index];
    case no:
      storage[index] = 0; // Position is empty
  }
  return 1;
}

template<class Type, int sz> inline
Type* tstash<Type, sz>::operator[](int index) {
  // No check in shipping application:
  assert(index >= 0 && index < next);
  return storage[index];
}

template<class Type, int sz>
void tstash<Type, sz>::inflate(int increase) {
  void* v = 
    realloc(storage, (quantity+increase)*sizeof(Type*));
  allegemem(v);  // Was it successful?
  storage = (Type**)v;
  quantity += increase;
}
#endif // TSTASH_H_