From 6f47c1ca207965366ef1bc8143f118dbcd68da6b Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Mon, 11 Nov 2013 22:34:57 +0100
Subject: util/ConstBuffer: new utility class
---
src/util/ConstBuffer.hxx | 118 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 118 insertions(+)
create mode 100644 src/util/ConstBuffer.hxx
(limited to 'src/util')
diff --git a/src/util/ConstBuffer.hxx b/src/util/ConstBuffer.hxx
new file mode 100644
index 000000000..bd3c405e5
--- /dev/null
+++ b/src/util/ConstBuffer.hxx
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2013 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CONST_BUFFER_HPP
+#define CONST_BUFFER_HPP
+
+#include "Compiler.h"
+
+#include <cstddef>
+
+#ifndef NDEBUG
+#include <assert.h>
+#endif
+
+/**
+ * A reference to a memory area that is read-only.
+ */
+template<typename T>
+struct ConstBuffer {
+ typedef size_t size_type;
+ typedef const T *pointer_type;
+ typedef pointer_type const_pointer_type;
+ typedef pointer_type iterator;
+ typedef pointer_type const_iterator;
+
+ pointer_type data;
+ size_type size;
+
+ ConstBuffer() = default;
+
+ constexpr ConstBuffer(std::nullptr_t):data(nullptr), size(0) {}
+
+ constexpr ConstBuffer(pointer_type _data, size_type _size)
+ :data(_data), size(_size) {}
+
+ constexpr static ConstBuffer Null() {
+ return ConstBuffer(nullptr, 0);
+ }
+
+ /**
+ * Cast a ConstBuffer<void> to a ConstBuffer<T>. A "void"
+ * buffer records its size in bytes, and when casting to "T",
+ * the assertion below ensures that the size is a multiple of
+ * sizeof(T).
+ */
+#ifdef NDEBUG
+ constexpr
+#endif
+ static ConstBuffer<T> FromVoid(ConstBuffer<void> other) {
+ static_assert(sizeof(T) > 0, "Empty base type");
+#ifndef NDEBUG
+ assert(other.size % sizeof(T) == 0);
+#endif
+ return ConstBuffer<T>(pointer_type(other.data),
+ other.size / sizeof(T));
+ }
+
+ constexpr ConstBuffer<void> ToVoid() const {
+ static_assert(sizeof(T) > 0, "Empty base type");
+ return ConstBuffer<void>(data, size * sizeof(T));
+ }
+
+ constexpr bool IsNull() const {
+ return data == nullptr;
+ }
+
+ constexpr bool IsEmpty() const {
+ return size == 0;
+ }
+
+ constexpr iterator begin() const {
+ return data;
+ }
+
+ constexpr iterator end() const {
+ return data + size;
+ }
+
+ constexpr const_iterator cbegin() const {
+ return data;
+ }
+
+ constexpr const_iterator cend() const {
+ return data + size;
+ }
+
+ constexpr operator ConstBuffer<void>() const {
+ return { data, size };
+ }
+};
+
+#endif
--
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