adding code files

labs/05_vectors/vec.h

@@ -0,0 +1,142 @@
+#ifndef Vec_h_
+#define Vec_h_
+// Simple implementation of the vector class, revised from Koenig and Moo.  This 
+// class is implemented using a dynamically allocated array (of templated type T).  
+// We ensure that that m_size is always <= m_alloc and when a push_back or resize 
+// call would violate this condition, the data is copied to a larger array.
+
+template <class T> class Vec {
+
+public:   
+  // TYPEDEFS
+  typedef T* iterator;
+  typedef const T* const_iterator;
+  typedef unsigned int size_type;
+
+  // CONSTRUCTORS, ASSIGNMNENT OPERATOR, & DESTRUCTOR
+  Vec() { this->create(); }
+  Vec(size_type n, const T& t = T()) { this->create(n, t); }
+  Vec(const Vec& v) { copy(v); }
+  Vec& operator=(const Vec& v); 
+  ~Vec() { delete [] m_data; }
+
+  // MEMBER FUNCTIONS AND OTHER OPERATORS
+  T& operator[] (size_type i) { return m_data[i]; }
+  const T& operator[] (size_type i) const { return m_data[i]; }
+  void push_back(const T& t);
+  iterator erase(iterator p);
+  void resize(size_type n, const T& fill_in_value = T());
+  void clear() { delete [] m_data;  create(); }
+  bool empty() const { return m_size == 0; }
+  size_type size() const { return m_size; }
+
+  // ITERATOR OPERATIONS
+  iterator begin() { return m_data; }
+  const_iterator begin() const { return m_data; }
+  iterator end() { return m_data + m_size; }
+  const_iterator end() const { return m_data + m_size; }
+
+private:  
+  // PRIVATE MEMBER FUNCTIONS
+  void create();
+  void create(size_type n, const T& val);
+  void copy(const Vec<T>& v); 
+
+  // REPRESENTATION
+  T* m_data;         // Pointer to first location in the allocated array
+  size_type m_size;  // Number of elements stored in the vector
+  size_type m_alloc; // Number of array locations allocated,  m_size <= m_alloc
+};
+
+// Create an empty vector (null pointers everywhere).
+template <class T>  void Vec<T>::create() {
+  m_data = NULL;
+  m_size = m_alloc = 0;  // No memory allocated yet
+}
+
+// Create a vector with size n, each location having the given value
+template <class T> void Vec<T>::create(size_type n, const T& val) {
+  m_data = new T[n];
+  m_size = m_alloc = n;
+  for (T* p = m_data; p != m_data + m_size; ++p)
+    *p = val;
+}
+
+// Assign one vector to another, avoiding duplicate copying.
+template <class T> Vec<T>& Vec<T>::operator=(const Vec<T>& v) {
+  if (this != &v) {
+    delete [] m_data;
+    this -> copy(v);
+  }
+  return *this;
+}
+
+// Create the vector as a copy of the given vector. 
+template <class T> void Vec<T>::copy(const Vec<T>& v) {
+  this->m_alloc = v.m_alloc;
+  this->m_size = v.m_size;
+  this->m_data = new T[this->m_alloc];
+  
+  // Copy the data
+  for (size_type i = 0; i < this->m_size; ++i)
+    this -> m_data[ i ] = v.m_data[ i ];
+}
+
+// Add an element to the end, resize if necesssary. 
+template <class T> void Vec<T>::push_back(const T& val) {
+  if (m_size == m_alloc) { 
+    // Allocate a larger array, and copy the old values
+
+    // Calculate the new allocation.  Make sure it is at least one.
+    m_alloc *= 2;
+    if (m_alloc < 1) m_alloc = 1;
+    
+    // Allocate and copy the old array
+    T* new_data = new T[ m_alloc ];
+    for (size_type i=0; i<m_size; ++i)
+      new_data[i] = m_data[i];
+    
+    // Delete the old array and reset the pointers
+    delete [] m_data;
+    m_data = new_data;
+  }
+
+  // Add the value at the last location and increment the bound
+  m_data[m_size] = val;
+  ++ m_size;
+}
+
+// Shift each entry of the array after the iterator. Return the iterator, 
+// which will have the same value, but point to a different element.
+template <class T> typename Vec<T>::iterator Vec<T>::erase(iterator p) {
+  // remember iterator and T* are equivalent
+  for (iterator q = p; q < m_data+m_size-1; ++q)
+    *q = *(q+1);
+  m_size --;
+  return p;
+}
+
+// If n is less than or equal to the current size, just change the size.  If n is 
+// greater than the current size, the new slots must be filled in with the given value. 
+// Re-allocation should occur only if necessary.  push_back should not be used.
+template <class T> void Vec<T>::resize(size_type n, const T& fill_in_value) {
+  if (n <= m_size)
+    m_size = n;
+  else {
+    // If necessary, allocate new space and copy the old values
+    if (n > m_alloc) {
+      m_alloc = n;
+      T* new_data = new T[m_alloc];
+      for (size_type i=0; i<m_size; ++i)
+	new_data[i] = m_data[i];
+      delete [] m_data;
+      m_data = new_data;
+    }
+    
+    // Now fill in the remaining values and assign the final size.
+    for (size_type i = m_size; i<n; ++i)
+      m_data[i] = fill_in_value;
+    m_size = n;
+  }
+}
+#endif