From 7fb9bebd463afc67909ae9220e38a6d3ca938c12 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Thu, 24 Apr 2014 09:46:52 +0200
Subject: util/{Const,Writable}Buffer: add front(), back(), pop_{front,back}(),
 shift()

---
 src/util/ConstBuffer.hxx    | 59 +++++++++++++++++++++++++++++++++++++++++++++
 src/util/WritableBuffer.hxx | 59 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)

diff --git a/src/util/ConstBuffer.hxx b/src/util/ConstBuffer.hxx
index bb114d44d..319102126 100644
--- a/src/util/ConstBuffer.hxx
+++ b/src/util/ConstBuffer.hxx
@@ -164,6 +164,65 @@ struct ConstBuffer {
 
 		return data[i];
 	}
+
+	/**
+	 * Returns a reference to the first element.  Buffer must not
+	 * be empty.
+	 */
+#ifdef NDEBUG
+	constexpr
+#endif
+	reference_type front() const {
+#ifndef NDEBUG
+		assert(!IsEmpty());
+#endif
+		return data[0];
+	}
+
+	/**
+	 * Returns a reference to the last element.  Buffer must not
+	 * be empty.
+	 */
+#ifdef NDEBUG
+	constexpr
+#endif
+	reference_type back() const {
+#ifndef NDEBUG
+		assert(!IsEmpty());
+#endif
+		return data[size - 1];
+	}
+
+	/**
+	 * Remove the first element (by moving the head pointer, does
+	 * not actually modify the buffer).  Buffer must not be empty.
+	 */
+	void pop_front() {
+		assert(!IsEmpty());
+
+		++data;
+		--size;
+	}
+
+	/**
+	 * Remove the last element (by moving the tail pointer, does
+	 * not actually modify the buffer).  Buffer must not be empty.
+	 */
+	void pop_back() {
+		assert(!IsEmpty());
+
+		--size;
+	}
+
+	/**
+	 * Remove the first element and return a reference to it.
+	 * Buffer must not be empty.
+	 */
+	reference_type shift() {
+		reference_type result = front();
+		pop_front();
+		return result;
+	}
 };
 
 #endif
diff --git a/src/util/WritableBuffer.hxx b/src/util/WritableBuffer.hxx
index 1fe1b254f..f9e6d4a96 100644
--- a/src/util/WritableBuffer.hxx
+++ b/src/util/WritableBuffer.hxx
@@ -158,6 +158,65 @@ struct WritableBuffer {
 
 		return data[i];
 	}
+
+	/**
+	 * Returns a reference to the first element.  Buffer must not
+	 * be empty.
+	 */
+#ifdef NDEBUG
+	constexpr
+#endif
+	reference_type front() const {
+#ifndef NDEBUG
+		assert(!IsEmpty());
+#endif
+		return data[0];
+	}
+
+	/**
+	 * Returns a reference to the last element.  Buffer must not
+	 * be empty.
+	 */
+#ifdef NDEBUG
+	constexpr
+#endif
+	reference_type back() const {
+#ifndef NDEBUG
+		assert(!IsEmpty());
+#endif
+		return data[size - 1];
+	}
+
+	/**
+	 * Remove the first element (by moving the head pointer, does
+	 * not actually modify the buffer).  Buffer must not be empty.
+	 */
+	void pop_front() {
+		assert(!IsEmpty());
+
+		++data;
+		--size;
+	}
+
+	/**
+	 * Remove the last element (by moving the tail pointer, does
+	 * not actually modify the buffer).  Buffer must not be empty.
+	 */
+	void pop_back() {
+		assert(!IsEmpty());
+
+		--size;
+	}
+
+	/**
+	 * Remove the first element and return a reference to it.
+	 * Buffer must not be empty.
+	 */
+	reference_type shift() {
+		reference_type result = front();
+		pop_front();
+		return result;
+	}
 };
 
 #endif
-- 
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