1.1 --- a/algs4-c++/src/Queue.cpp	Tue Jun 23 12:28:03 2015 -0500
     1.2 +++ b/algs4-c++/src/Queue.cpp	Tue Jun 23 14:52:17 2015 -0500
     1.3 @@ -25,6 +25,13 @@
     1.4          std::cout << *iter << std::endl;
     1.5          }
     1.6  
     1.7 +    Queue<long> q2( queue );
     1.8 +    std::cout << "Copied queue to q2.  q2 has " << q2.size() << " entries." << std::endl;
     1.9 +    for ( auto iter = q2.begin(); iter != q2.end(); ++iter ) {
    1.10 +        std::cout << *iter << std::endl;
    1.11 +        }
    1.12 +
    1.13 +
    1.14      std::cout << "Dequeuing entries..." << std::endl;
    1.15  
    1.16      while ( ! queue.is_empty() ) {
    1.17 @@ -34,5 +41,9 @@
    1.18  
    1.19      std::cout << "Queue has " << queue.size() << " entries." << std::endl;
    1.20  
    1.21 +
    1.22 +    // Silently empty q2 to avoid the assertion in the destructor.
    1.23 +    while ( ! q2.is_empty() )
    1.24 +        q2.dequeue();
    1.25      }
    1.26  

     2.1 --- a/algs4-c++/src/Queue.hpp	Tue Jun 23 12:28:03 2015 -0500
     2.2 +++ b/algs4-c++/src/Queue.hpp	Tue Jun 23 14:52:17 2015 -0500
     2.3 @@ -5,6 +5,7 @@
     2.4  
     2.5  #include <cstddef>
     2.6  #include <cassert>
     2.7 +#include <iterator>
     2.8  
     2.9  template <typename T>
    2.10  class Queue {
    2.11 @@ -21,9 +22,7 @@
    2.12  public:
    2.13  
    2.14      ////////////////////////////////////
    2.15 -    class iterator;
    2.16 -    friend class iterator;
    2.17 -    class iterator {
    2.18 +    class iterator : public std::iterator<std::forward_iterator_tag, T> {
    2.19  
    2.20      public:
    2.21  
    2.22 @@ -42,9 +41,31 @@
    2.23  
    2.24      ////////////////////////////////////
    2.25  
    2.26 +    class const_iterator : public std::iterator<std::forward_iterator_tag, T> {
    2.27 +
    2.28 +    public:
    2.29 +
    2.30 +        const_iterator( const Node *c );
    2.31 +
    2.32 +        const_iterator& operator++();
    2.33 +        const_iterator operator++(int);
    2.34 +
    2.35 +        const T operator*();
    2.36 +        bool operator!=( typename Queue<T>::const_iterator );
    2.37 +
    2.38 +    private:
    2.39 +
    2.40 +        const Node *curr;
    2.41 +        };
    2.42 +
    2.43 +    ////////////////////////////////////
    2.44 +
    2.45      Queue( void );
    2.46      ~Queue( void );
    2.47  
    2.48 +    // 1.3.41 Copy constructor.
    2.49 +    Queue( const Queue<T> &q );
    2.50 +
    2.51      void enqueue( T &item );
    2.52      T dequeue( void );
    2.53  
    2.54 @@ -53,6 +74,8 @@
    2.55  
    2.56      iterator begin( void );
    2.57      iterator end( void );
    2.58 +    const_iterator begin( void ) const;
    2.59 +    const_iterator end( void ) const;
    2.60  
    2.61  
    2.62  private:
    2.63 @@ -71,6 +94,19 @@
    2.64      last (nullptr)
    2.65      {
    2.66      }
    2.67 +
    2.68 +// 1.3.41
    2.69 +template <typename T>
    2.70 +Queue<T>::Queue( const Queue<T> &q ) :
    2.71 +    N (0),
    2.72 +    first (nullptr),
    2.73 +    last (nullptr)
    2.74 +    {
    2.75 +    for ( auto it = q.begin(); it != q.end(); ++it ) {
    2.76 +        T item = *it;    
    2.77 +        this->enqueue( item );
    2.78 +        }
    2.79 +    }
    2.80      
    2.81  template <typename T>
    2.82  Queue<T>::~Queue( void ) {
    2.83 @@ -136,6 +172,16 @@
    2.84      return Queue<T>::iterator( nullptr );
    2.85      }
    2.86  
    2.87 +template <typename T>
    2.88 +typename Queue<T>::const_iterator Queue<T>::begin( void ) const {
    2.89 +    return Queue<T>::const_iterator( first );
    2.90 +    }
    2.91 +
    2.92 +template <typename T>
    2.93 +typename Queue<T>::const_iterator Queue<T>::end( void ) const {
    2.94 +    return Queue<T>::const_iterator( nullptr );
    2.95 +    }
    2.96 +
    2.97  
    2.98  ////////////////////////////////////////////////////////////////////////////////
    2.99  
   2.100 @@ -173,6 +219,42 @@
   2.101      return this->curr != other.curr;
   2.102      }
   2.103  
   2.104 +////////////////////////////////////////////////////////////////////////////////
   2.105 +
   2.106 +template <typename T>
   2.107 +Queue<T>::const_iterator::const_iterator( const Node *c ) :
   2.108 +    curr (c)
   2.109 +    {
   2.110 +    }
   2.111 +
   2.112 +template <typename T>
   2.113 +typename Queue<T>::const_iterator & Queue<T>::const_iterator::operator++() {
   2.114 +    if ( this->curr != nullptr ) {
   2.115 +        this->curr = this->curr->next;
   2.116 +        }
   2.117 +    return *this;
   2.118 +    }
   2.119 +
   2.120 +template <typename T>
   2.121 +typename Queue<T>::const_iterator Queue<T>::const_iterator::operator++( int ) {
   2.122 +    auto t = Queue<T>::const_iterator( *this );
   2.123 +
   2.124 +    if ( this->curr != nullptr ) {
   2.125 +        this->curr = this->curr->next;
   2.126 +        }
   2.127 +    return t;
   2.128 +    }
   2.129 +
   2.130 +template <typename T>
   2.131 +const T Queue<T>::const_iterator::operator*() {
   2.132 +    return this->curr->item;
   2.133 +    }
   2.134 +
   2.135 +template <typename T>
   2.136 +bool Queue<T>::const_iterator::operator!=( typename Queue<T>::const_iterator other ) {
   2.137 +    return this->curr != other.curr;
   2.138 +    }
   2.139 +
   2.140  
   2.141  #endif
   2.142