# HG changeset patch
# User Eris Caffee <discordia@eldalin.com>
# Date 1432950738 18000
# Node ID 438f5608900e9c569b669b5dfa32ab834d5a1ea1
# Parent  3db1a894bbdf8e9488c4bbfd10018c8d1e531a58
Linked list based Stack class.

diff -r 3db1a894bbdf -r 438f5608900e algs4-c++/src/Stack.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/algs4-c++/src/Stack.cpp	Fri May 29 20:52:18 2015 -0500
@@ -0,0 +1,144 @@
+// g++ -D STACK_MAIN -std=c++0x Stack.cpp
+// g++ -D STACK_MAIN -std=c++11 Stack.cpp
+
+
+#include "Stack.hpp"
+
+#include <cassert>
+#include <cstddef>
+
+#include <iostream>
+
+template <typename T>
+Stack<T>::Stack( void ) :
+    N (0),
+    list (nullptr)
+    {
+    }
+    
+template <typename T>
+Stack<T>::~Stack( void ) {
+    assert( N == 0 );  // Catch the potential memory leak.
+    while ( list ) {
+        Node * next = list->next;
+        delete list;
+        list = next;
+        }
+    }
+
+template <typename T>
+void Stack<T>::push( T &item ) {
+    Node * node = new Node();
+    node->item = item;
+    node->next = list;
+    list = node;
+    N++;
+    }
+
+template <typename T>
+T Stack<T>::pop( void ) {
+    assert( N > 0 );
+
+    T item = list->item;
+
+    Node *old = list;
+    list = list->next;
+    delete old;
+    N--;
+
+    return item;
+    }
+
+template <typename T>
+bool Stack<T>::is_empty( void ) {
+    return N == 0;
+    }
+
+template <typename T>
+size_t Stack<T>::size( void ) {
+    return N;
+    }
+
+template <typename T>
+typename Stack<T>::iterator Stack<T>::begin( void ) {
+    return Stack<T>::iterator( list );
+    }
+
+template <typename T>
+typename Stack<T>::iterator Stack<T>::end( void ) {
+    return Stack<T>::iterator( nullptr );
+    }
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <typename T>
+Stack<T>::iterator::iterator( Node *c ) :
+    curr (c)
+    {
+    }
+
+template <typename T>
+typename Stack<T>::iterator & Stack<T>::iterator::operator++() {
+    if ( this->curr != nullptr ) {
+        this->curr = this->curr->next;
+        }
+    return *this;
+    }
+
+template <typename T>
+typename Stack<T>::iterator Stack<T>::iterator::operator++( int ) {
+    auto t = Stack<T>::iterator( *this );
+
+    if ( this->curr != nullptr ) {
+        this->curr = this->curr->next;
+        }
+    return t;
+    }
+
+template <typename T>
+T Stack<T>::iterator::operator*() {
+    return this->curr->item;
+    }
+
+template <typename T>
+bool Stack<T>::iterator::operator!=( typename Stack<T>::iterator other ) {
+    return this->curr != other.curr;
+    }
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+#ifdef STACK_MAIN
+
+#include <iostream>
+
+int main ( int argc, char **argv ) {
+
+    Stack<long> stack;
+
+    long i;
+    while ( ! std::cin.eof() ) {
+        std::cin >> i;
+        if ( std::cin.good() ) 
+            stack.push(i);
+        }
+
+    std::cout << "Stack has " << stack.size() << " entries." << std::endl;
+
+    for ( auto iter = stack.begin(); iter != stack.end(); ++iter ) {
+        std::cout << *iter << std::endl;
+        }
+
+    std::cout << "Popping entries..." << std::endl;
+
+    while ( ! stack.is_empty() ) {
+        i = stack.pop();
+        std::cout << i << std::endl;
+        }
+
+    std::cout << "Stack has " << stack.size() << " entries." << std::endl;
+
+    }
+
+#endif
diff -r 3db1a894bbdf -r 438f5608900e algs4-c++/src/Stack.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/algs4-c++/src/Stack.hpp	Fri May 29 20:52:18 2015 -0500
@@ -0,0 +1,66 @@
+#ifndef STACK_HPP
+#define STACK_HPP
+
+#include <cstddef>
+
+// Linked list based stack after Sedgewick and Wayne, Algorithms 4th ed, Algorithm 1.2
+
+template <typename T>
+class Stack {
+
+public:
+
+    ////////////////////////////////////
+    class Node {
+    public:
+        T item;
+        Node *next;
+        };
+
+
+    ////////////////////////////////////
+    class iterator;
+    friend class iterator;
+    class iterator {
+
+    public:
+
+        iterator( Node *c );
+
+        iterator& operator++();
+        iterator operator++(int);
+
+        T operator*();
+        bool operator!=( typename Stack<T>::iterator );
+
+    private:
+
+        Node *curr;
+        };
+
+    ////////////////////////////////////
+
+    Stack( void );
+    ~Stack( void );
+
+    void push( T &item );
+    T pop( void );
+
+    bool is_empty( void );
+    size_t size( void );
+
+    iterator begin( void );
+    iterator end( void );
+
+private:
+
+    size_t N;
+    Node *list;
+
+    void resize( size_t new_max );
+    };
+
+
+
+#endif
+