resize and reserve

Author: evvic

vector/include/vector.hpp

@@ -19,6 +19,69 @@ class vector {
         delete[] m_data; // free memory in destructor
     }
 
+    /**
+     *  @brief  Set the capacity of the vector.
+     *  @param  new_capacity The new capacity for the vector.
+     *  @return void.
+     */
+    void reserve(const std::size_t new_capacity) {
+        // reserve only affects capacity not size
+        // therefore a reserving an amount smaller than size will be ignored
+
+        if (new_capacity > m_capacity) {
+            reallocate(new_capacity);
+        }
+    }
+
+    /**
+     *  @brief  Set the size of the vector.
+     *  @param  new_size The new size for the vector.
+     *  @return void.
+     */
+    void resize(const std::size_t new_size) {
+        // resize affects size and capacity
+        // therefore a resizing an amount smaller than size will shrink the vector
+
+        // reserve more space if needed
+        if (new_size > m_capacity) reallocate(new_size);
+
+        // shrink if needed
+        for (std::size_t i = new_size; i < m_size; ++i) {
+            m_data[i].~T(); // call destructor explicitly
+        }
+
+        // if growing, initialize new elements with default constructor
+        for (std::size_t i = m_size; i < new_size; ++i) {
+            new (&m_data[i]) T();
+        }
+        
+        m_size = new_size;
+    }
+
+    /**
+     *  @brief  Set the size of the vector.
+     *  @param  new_size The new size for the vector.
+     *  @param  val The value to initialize new elements with.
+     *  @return void.
+     */
+    void resize(const std::size_t new_size, const T& val) {
+
+        // reserve more space if needed
+        if (new_size > m_capacity) reallocate(new_size);
+
+        // shrink if needed
+        for (std::size_t i = new_size; i < m_size; ++i) {
+            m_data[i].~T(); // call destructor explicitly
+        }
+
+        // if growing, initialize new elements with val
+        for (std::size_t i = m_size; i < new_size; ++i) {
+            new (&m_data[i]) T(val);
+        }
+        
+        m_size = new_size;
+    }
+
     /**
      *  @brief  Add an element to the end of the vector.
      *  @param  value  The value to add to the end of the vector.
@@ -121,6 +184,8 @@ class vector {
      */
     void reallocate(std::size_t new_capacity) {
 
+        // reserc
+
         // TODO: handle reallocation for shrinking
         if (new_capacity <= m_size) {
             m_size = new_capacity;

vector/tests/vector_test.cpp

@@ -210,3 +210,59 @@ TEST_F(VectorTest, PopBack) {
 
     EXPECT_EQ(vals.size(), 1);
 }
+
+TEST_F(VectorTest, ReserveTest) {
+    std2::vector<Point3D> points;
+    
+    // Add 100 points
+    for(int i = 0; i < 100; i++) {
+        points.push_back(Point3D(i, i, i));
+    }
+    
+    std::cout << "Before reserve: size=" << points.size() << std::endl;
+              
+    points.reserve(50);
+    
+    std::cout << "After reserve(50): size=" << points.size() << std::endl;
+
+    EXPECT_EQ(points.size(), 100);
+}
+
+TEST_F(VectorTest, ResizeTest) {
+    std2::vector<Point3D> points;
+    
+    // First reserve space for 200
+    points.reserve(200);
+    
+    // Add 100 points
+    for(int i = 0; i < 100; i++) {
+        points.push_back(Point3D(i, i, i));
+    }
+    
+    std::cout << "Initial state: size=" << points.size() << std::endl;
+              
+    // Now resize to 50
+    points.resize(50);
+    
+    std::cout << "After resize(50): size=" << points.size() << std::endl;
+
+    // Now resize to 100
+    points.resize(100, Point3D(1.0f, 1.0f, 1.0f));
+    
+    std::cout << "After resize(100): size=" << points.size() << std::endl;
+
+}
+
+TEST_F(VectorTest, ResizeWithValue) {
+    std2::vector<Point3D> points;
+    
+    // Resize to 3 elements, all with value (1,1,1)
+    points.resize(3, Point3D(1.0f));
+    
+    EXPECT_EQ(points.size(), 3);
+    for(size_t i = 0; i < points.size(); ++i) {
+        EXPECT_EQ(points[i].x, 1.0f);
+        EXPECT_EQ(points[i].y, 1.0f);
+        EXPECT_EQ(points[i].z, 1.0f);
+    }
+}