1 files changed, 161 insertions, 0 deletions
diff --git a/gsl/gsl_byte b/gsl/gsl_byte
new file mode 100644
index 0000000..3f77923
--- /dev/null
+++ b/gsl/gsl_byte
@@ -0,0 +1,161 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#pragma once
+
+#ifndef GSL_BYTE_H
+#define GSL_BYTE_H
+
+#ifdef _MSC_VER
+
+#pragma warning(push)
+
+// don't warn about function style casts in byte related operators
+#pragma warning(disable : 26493)
+
+// MSVC 2013 workarounds
+#if _MSC_VER <= 1800
+
+// constexpr is not understood
+#pragma push_macro("constexpr")
+#define constexpr /*constexpr*/
+
+// noexcept is not understood
+#pragma push_macro("noexcept")
+#define noexcept /*noexcept*/
+
+#endif // _MSC_VER <= 1800
+
+#endif // _MSC_VER
+
+namespace gsl
+{
+// This is a simple definition for now that allows
+// use of byte within span<> to be standards-compliant
+enum class byte : unsigned char
+{
+};
+
+template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>>
+inline constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept
+{
+    return b = byte(static_cast<unsigned char>(b) << shift);
+}
+
+template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>>
+inline constexpr byte operator<<(byte b, IntegerType shift) noexcept
+{
+    return byte(static_cast<unsigned char>(b) << shift);
+}
+
+template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>>
+inline constexpr byte& operator>>=(byte& b, IntegerType shift) noexcept
+{
+    return b = byte(static_cast<unsigned char>(b) >> shift);
+}
+
+template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>>
+inline constexpr byte operator>>(byte b, IntegerType shift) noexcept
+{
+    return byte(static_cast<unsigned char>(b) >> shift);
+}
+
+inline constexpr byte& operator|=(byte& l, byte r) noexcept
+{
+    return l = byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r));
+}
+
+inline constexpr byte operator|(byte l, byte r) noexcept
+{
+    return byte(static_cast<unsigned char>(l) | static_cast<unsigned char>(r));
+}
+
+inline constexpr byte& operator&=(byte& l, byte r) noexcept
+{
+    return l = byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r));
+}
+
+inline constexpr byte operator&(byte l, byte r) noexcept
+{
+    return byte(static_cast<unsigned char>(l) & static_cast<unsigned char>(r));
+}
+
+inline constexpr byte& operator^=(byte& l, byte r) noexcept
+{
+    return l = byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r));
+}
+
+inline constexpr byte operator^(byte l, byte r) noexcept
+{
+    return byte(static_cast<unsigned char>(l) ^ static_cast<unsigned char>(r));
+}
+
+inline constexpr byte operator~(byte b) noexcept { return byte(~static_cast<unsigned char>(b)); }
+
+template <class IntegerType, class = std::enable_if_t<std::is_integral<IntegerType>::value>>
+inline constexpr IntegerType to_integer(byte b) noexcept
+{
+    return static_cast<IntegerType>(b);
+}
+
+template<bool E, typename T>
+inline constexpr byte to_byte_impl(T t) noexcept
+{
+    static_assert(
+        E,
+        "gsl::to_byte(t) must be provided an unsigned char, otherwise data loss may occur. "
+        "If you are calling to_byte with an integer contant use: gsl::to_byte<t>() version."
+    );
+    return static_cast<byte>(t);
+}
+template<>
+inline constexpr byte to_byte_impl<true, unsigned char>(unsigned char t) noexcept
+{
+     return byte(t);
+}
+
+template<typename T>
+inline constexpr byte to_byte(T t) noexcept
+{
+     return to_byte_impl<std::is_same<T, unsigned char>::value, T>(t);
+}
+
+template <int I>
+inline constexpr byte to_byte() noexcept
+{
+    static_assert(I >= 0 && I <= 255, "gsl::byte only has 8 bits of storage, values must be in range 0-255");
+    return static_cast<byte>(I);
+}
+
+} // namespace gsl
+
+#ifdef _MSC_VER
+
+#if _MSC_VER <= 1800
+
+#undef constexpr
+#pragma pop_macro("constexpr")
+
+#undef noexcept
+#pragma pop_macro("noexcept")
+
+#endif // _MSC_VER <= 1800
+
+#pragma warning(pop)
+
+#endif // _MSC_VER
+
+#endif // GSL_BYTE_H