From 89ac111853eb4bae2fc358087c4c4657939321c0 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Sat, 15 Mar 2014 23:11:13 +0100
Subject: util/CircularBuffer: add method GetSize()

---
 src/util/CircularBuffer.hxx |  9 +++++++++
 test/TestCircularBuffer.hxx | 10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/util/CircularBuffer.hxx b/src/util/CircularBuffer.hxx
index 67b60e198..0321b91f6 100644
--- a/src/util/CircularBuffer.hxx
+++ b/src/util/CircularBuffer.hxx
@@ -98,6 +98,15 @@ public:
 		return Next(tail) == head;
 	}
 
+	/**
+	 * Returns the number of elements stored in this buffer.
+	 */
+	constexpr size_type GetSize() const {
+		return head <= tail
+			? tail - head
+			: capacity - head + tail;
+	}
+
 	/**
 	 * Prepares writing.  Returns a buffer range which may be written.
 	 * When you are finished, call Append().
diff --git a/test/TestCircularBuffer.hxx b/test/TestCircularBuffer.hxx
index f8fb95418..88b0a9ea8 100644
--- a/test/TestCircularBuffer.hxx
+++ b/test/TestCircularBuffer.hxx
@@ -32,6 +32,7 @@ public:
 		/* [.......X] */
 		CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(size_t(0), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Write().data);
@@ -43,6 +44,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(1), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
@@ -55,6 +57,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
@@ -65,6 +68,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
@@ -78,6 +82,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[1], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
@@ -88,6 +93,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
@@ -100,6 +106,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(6), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
@@ -112,6 +119,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(true, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(7), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(4), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[4], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(true, buffer.Write().IsEmpty());
@@ -122,6 +130,7 @@ public:
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Read().IsEmpty());
+		CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(size_t(3), buffer.Read().size);
 		CPPUNIT_ASSERT_EQUAL(&data[0], buffer.Read().data);
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
@@ -135,6 +144,7 @@ public:
 		buffer.Consume(3);
 		CPPUNIT_ASSERT_EQUAL(true, buffer.IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.IsFull());
+		CPPUNIT_ASSERT_EQUAL(size_t(0), buffer.GetSize());
 		CPPUNIT_ASSERT_EQUAL(true, buffer.Read().IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(false, buffer.Write().IsEmpty());
 		CPPUNIT_ASSERT_EQUAL(&data[3], buffer.Write().data);
-- 
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