Data Abstraction and Problem Solving with C++
Walls and Mirrors
by Frank M. Carrano
StackP.cpp
Go to the documentation of this file.00001 00017 #include <cstddef> // for NULL 00018 #include <new> // for bad_alloc 00019 #include "StackP.h" // header file 00020 00021 using namespace std; 00022 00023 Stack::Stack() : topPtr(NULL) 00024 { 00025 } // end default constructor 00026 00027 Stack::Stack(const Stack& aStack) 00028 { 00029 if (aStack.topPtr == NULL) 00030 topPtr = NULL; // original list is empty 00031 00032 else 00033 { // copy first node 00034 topPtr = new StackNode; 00035 topPtr->item = aStack.topPtr->item; 00036 00037 // copy rest of list 00038 StackNode *newPtr = topPtr; // new list pointer 00039 for (StackNode *origPtr = aStack.topPtr->next; 00040 origPtr != NULL; 00041 origPtr = origPtr->next) 00042 { newPtr->next = new StackNode; 00043 newPtr = newPtr->next; 00044 newPtr->item = origPtr->item; 00045 } // end for 00046 00047 newPtr->next = NULL; 00048 } // end if 00049 } // end copy constructor 00050 00051 Stack::~Stack() 00052 { 00053 // pop until stack is empty 00054 while (!isEmpty()) 00055 pop(); 00056 // Assertion: topPtr == NULL 00057 } // end destructor 00058 00059 bool Stack::isEmpty() const 00060 { 00061 return topPtr == NULL; 00062 } // end isEmpty 00063 00064 void Stack::push(const StackItemType& newItem) 00065 throw(StackException) 00066 { 00067 // create a new node 00068 try 00069 { 00070 StackNode *newPtr = new StackNode; 00071 00072 // set data portion of new node 00073 newPtr->item = newItem; 00074 00075 // insert the new node 00076 newPtr->next = topPtr; 00077 topPtr = newPtr; 00078 } 00079 catch (bad_alloc e) 00080 { 00081 throw StackException( 00082 "StackException: push cannot allocate memory."); 00083 } // try 00084 } // end push 00085 00086 void Stack::pop() throw(StackException) 00087 { 00088 if (isEmpty()) 00089 throw StackException("StackException: stack empty on pop"); 00090 else 00091 { // stack is not empty; delete top 00092 StackNode *temp = topPtr; 00093 topPtr = topPtr->next; 00094 // return deleted node to system 00095 temp->next = NULL; // safeguard 00096 delete temp; 00097 } // end if 00098 } // end pop 00099 00100 void Stack::pop(StackItemType& stackTop) throw(StackException) 00101 { 00102 if (isEmpty()) 00103 throw StackException("StackException: stack empty on pop"); 00104 else 00105 { // stack is not empty; retrieve and delete top 00106 stackTop = topPtr->item; 00107 StackNode *temp = topPtr; 00108 topPtr = topPtr->next; 00109 00110 // return deleted node to system 00111 temp->next = NULL; // safeguard 00112 delete temp; 00113 } // end if 00114 } // end pop 00115 00116 void Stack::getTop(StackItemType& stackTop) const throw(StackException) 00117 { 00118 if (isEmpty()) 00119 throw StackException("StackException: stack empty on getTop"); 00120 else 00121 // stack is not empty; retrieve top 00122 stackTop = topPtr->item; 00123 } // end getTop 00124 // End of implementation file.
