First Commit

3rdparty/rapidyaml/include/c4/szconv.hpp

@@ -0,0 +1,68 @@
+#ifndef _C4_SZCONV_HPP_
+#define _C4_SZCONV_HPP_
+
+/** @file szconv.hpp utilities to deal safely with narrowing conversions */
+
+#include "c4/config.hpp"
+#include "c4/error.hpp"
+
+#include <limits>
+
+namespace c4 {
+
+C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH("-Wold-style-cast")
+
+/** @todo this would be so much easier with calls to numeric_limits::max()... */
+template<class SizeOut, class SizeIn>
+struct is_narrower_size : std::conditional
+<
+   (std::is_signed<SizeOut>::value == std::is_signed<SizeIn>::value)
+   ?
+   (sizeof(SizeOut) < sizeof(SizeIn))
+   :
+   (
+       (sizeof(SizeOut) < sizeof(SizeIn))
+       ||
+       (
+           (sizeof(SizeOut) == sizeof(SizeIn))
+           &&
+           (std::is_signed<SizeOut>::value && std::is_unsigned<SizeIn>::value)
+       )
+   ),
+   std::true_type,
+   std::false_type
+>::type
+{
+    static_assert(std::is_integral<SizeIn >::value, "must be integral type");
+    static_assert(std::is_integral<SizeOut>::value, "must be integral type");
+};
+
+
+/** when SizeOut is wider than SizeIn, assignment can occur without reservations */
+template<class SizeOut, class SizeIn>
+C4_ALWAYS_INLINE
+typename std::enable_if< ! is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
+szconv(SizeIn sz) noexcept
+{
+    return static_cast<SizeOut>(sz);
+}
+
+/** when SizeOut is narrower than SizeIn, narrowing will occur, so we check
+ * for overflow. Note that this check is done only if C4_XASSERT is enabled.
+ * @see C4_XASSERT */
+template<class SizeOut, class SizeIn>
+C4_ALWAYS_INLINE
+typename std::enable_if<is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
+szconv(SizeIn sz) C4_NOEXCEPT_X
+{
+    C4_XASSERT(sz >= 0);
+    C4_XASSERT_MSG((SizeIn)sz <= (SizeIn)std::numeric_limits<SizeOut>::max(), "size conversion overflow: in=%zu", (size_t)sz);
+    SizeOut szo = static_cast<SizeOut>(sz);
+    return szo;
+}
+
+C4_SUPPRESS_WARNING_GCC_CLANG_POP
+
+} // namespace c4
+
+#endif /* _C4_SZCONV_HPP_ */