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authorMax Kellermann <max@duempel.org>2013-12-15 23:01:01 +0100
committerMax Kellermann <max@duempel.org>2013-12-15 23:01:06 +0100
commitf2a20a0a800e879b0e52681b7f9b8829047c55a7 (patch)
tree411bb5f054a236aaf1680cd452707ccb67436ef6 /src/util
parente5a2efaa659436f3ca335804cef9a6ce34be2fbd (diff)
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util/WritableBuffer: add cast methods
Diffstat (limited to 'src/util')
-rw-r--r--src/util/WritableBuffer.hxx31
1 files changed, 30 insertions, 1 deletions
diff --git a/src/util/WritableBuffer.hxx b/src/util/WritableBuffer.hxx
index 1b37b56cb..7267813f5 100644
--- a/src/util/WritableBuffer.hxx
+++ b/src/util/WritableBuffer.hxx
@@ -32,7 +32,11 @@
#include "Compiler.h"
-#include <stddef.h>
+#include <cstddef>
+
+#ifndef NDEBUG
+#include <assert.h>
+#endif
/**
* A reference to a memory area that is writable.
@@ -52,6 +56,8 @@ struct WritableBuffer {
WritableBuffer() = default;
+ constexpr WritableBuffer(std::nullptr_t):data(nullptr), size(0) {}
+
constexpr WritableBuffer(pointer_type _data, size_type _size)
:data(_data), size(_size) {}
@@ -59,6 +65,29 @@ struct WritableBuffer {
return { nullptr, 0 };
}
+ /**
+ * Cast a WritableBuffer<void> to a WritableBuffer<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 WritableBuffer<T> FromVoid(WritableBuffer<void> other) {
+ static_assert(sizeof(T) > 0, "Empty base type");
+#ifndef NDEBUG
+ assert(other.size % sizeof(T) == 0);
+#endif
+ return WritableBuffer<T>(pointer_type(other.data),
+ other.size / sizeof(T));
+ }
+
+ constexpr WritableBuffer<void> ToVoid() const {
+ static_assert(sizeof(T) > 0, "Empty base type");
+ return WritableBuffer<void>(data, size * sizeof(T));
+ }
+
constexpr bool IsNull() const {
return data == nullptr;
}