clear() and prevention of resizing for same size

Foundation/include/Poco/Buffer.h

@@ -112,6 +112,12 @@ public:
 		return _size;
 	}
 	
+	void clear()
+		/// Sets the contents of the bufer to zero.
+	{
+		std::memset(_ptr, 0, _size * sizeof(T));
+	}
+
 	void resize(std::size_t newSize, bool preserve = false)
 		/// Resizes the buffer. If preserve is true, the contents
 		/// of the buffer is preserved. If the newSize is smaller
@@ -122,6 +128,7 @@ public:
 	{
 		if (preserve) 
 		{
+			if (_size == newSize) return;
 			Buffer tmp;
 			tmp = *this;
 			recreate(newSize);
@@ -129,6 +136,11 @@ public:
 			std::memcpy(_ptr, tmp._ptr, size * sizeof(T));
 			return;
 		}
+		else if (_size == newSize) 
+		{
+			clear();
+			return;
+		}
 
 		recreate(newSize);
 	}
@@ -148,6 +160,12 @@ public:
 		append(buf.begin(), buf.size());
 	}
 
+	std::size_t elementSize() const
+		/// Returns the size of the buffer element.
+	{
+		return sizeof(T);
+	}
+
 	std::size_t byteCount() const
 		/// Returns the total length of the buffer in bytes.
 	{
@@ -201,6 +219,8 @@ public:
 private:
 
 	void recreate(std::size_t newSize)
+	{
+		if (newSize != _size)
 		{
 			delete [] _ptr;
 			if (0 == newSize)
@@ -210,6 +230,7 @@ private:
 
 			_size = newSize;
 		}
+	}
 
 	std::size_t _size;
 	T*          _ptr;

Foundation/testsuite/src/CoreTest.cpp

@@ -216,6 +216,11 @@ void CoreTest::testBuffer()
 	for (int j = 0; i < s; ++i, ++j)
 		assert (b1[i] == j);
  
+	b1.clear();
+	pi = b1.begin();
+	for (; pi != b1.end(); ++pi)
+		assert (*pi == 0);
+
 	b1.resize(0);
 	assert (b1.isEmpty());