Erase now returns old value

Author: JCash

src/jc/cpp/ringbuffer.h

@@ -77,8 +77,8 @@ class RingBuffer
     void        PushUnchecked(const T& item);
     /// Removes (and returns) the first inserted item from the ring buffer. Asserts if the buffer is empty
     T           Pop();
-    /// Removes the element at logical index (0-based) and keeps order
-    void        Erase(uint32_t index);
+    /// Removes the element at logical index (0-based), keeps order, returns old value
+    T           Erase(uint32_t index);
 
     T&          operator[] (size_t i)           { assert(i < Size()); return m_Buffer[(m_Tail + i) % m_Max]; }
     const T&    operator[] (size_t i) const     { assert(i < Size()); return m_Buffer[(m_Tail + i) % m_Max]; }
@@ -195,14 +195,17 @@ T RingBuffer<T>::Pop()
 }
 
 template <typename T>
-void RingBuffer<T>::Erase(uint32_t index)
+T RingBuffer<T>::Erase(uint32_t index)
 {
     uint32_t size = Size();
     assert(index < size);
 
     // Compute physical index of the element to erase
     uint32_t pos = (m_Tail + index) % m_Max;
 
+    // Store old value to return
+    T old_value = m_Buffer[pos];
+
     // Shift elements left from pos towards head to preserve order
     // Stop when the next index equals m_Head (the logical end)
     while (true)
@@ -225,6 +228,8 @@ void RingBuffer<T>::Erase(uint32_t index)
         --m_Head;
     }
     m_Full = 0;
+
+    return old_value;
 }
 
 

test/ringbuffer.cpp

@@ -411,7 +411,8 @@ TEST(RingBufferTest, Erase_Contiguous_Middle)
     jc::RingBuffer<int> rb(8);
     for (int i = 0; i < 6; ++i) rb.Push(i); // 0..5
 
-    rb.Erase(2); // remove '2'
+    int removed = rb.Erase(2); // remove '2'
+    ASSERT_EQ(2, removed);
     ASSERT_EQ(5u, rb.Size());
     const int expected1[5] = {0,1,3,4,5};
     for (uint32_t i = 0; i < 5; ++i)
@@ -427,7 +428,8 @@ TEST(RingBufferTest, Erase_Wrapped_Middle)
     for (int i = 0; i < 5; ++i) rb.Pop();   // -> [5,6,7]
     for (int i = 8; i < 12; ++i) rb.Push(i); // wrap -> [5,6,7,8,9,10,11]
 
-    rb.Erase(3); // remove '8'
+    int removed2 = rb.Erase(3); // remove '8'
+    ASSERT_EQ(8, removed2);
 
     ASSERT_EQ(6u, rb.Size());
     const int expected2[6] = {5,6,7,9,10,11};
@@ -448,7 +450,8 @@ TEST(RingBufferTest, Erase_HeadZero_TailPositive)
     ASSERT_EQ(0u, rb.Head());
     ASSERT_EQ(4u, rb.Tail());
 
-    rb.Erase(1); // remove '5'
+    int removed3 = rb.Erase(1); // remove '5'
+    ASSERT_EQ(5, removed3);
 
     ASSERT_EQ(5u, rb.Size());
     const int expected3[5] = {4,6,7,8,9};