1 files changed, 86 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/utils/SkCallableTraits.h b/gfx/skia/skia/src/utils/SkCallableTraits.h
new file mode 100644
index 0000000000..003db21280
--- /dev/null
+++ b/gfx/skia/skia/src/utils/SkCallableTraits.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCallableTraits_DEFINED
+#define SkCallableTraits_DEFINED
+
+#include <type_traits>
+#include <tuple>
+
+template <typename R, typename... Args> struct sk_base_callable_traits {
+    using return_type = R;
+    static constexpr std::size_t arity = sizeof...(Args);
+    template <std::size_t N> struct argument {
+        static_assert(N < arity, "");
+        using type = typename std::tuple_element<N, std::tuple<Args...>>::type;
+    };
+};
+
+#define SK_CALLABLE_TRAITS__COMMA ,
+
+#define SK_CALLABLE_TRAITS__VARARGS(quals, _) \
+SK_CALLABLE_TRAITS__INSTANCE(quals,) \
+SK_CALLABLE_TRAITS__INSTANCE(quals, SK_CALLABLE_TRAITS__COMMA ...)
+
+#ifdef __cpp_noexcept_function_type
+#define SK_CALLABLE_TRAITS__NE_VARARGS(quals, _) \
+SK_CALLABLE_TRAITS__VARARGS(quals,) \
+SK_CALLABLE_TRAITS__VARARGS(quals noexcept,)
+#else
+#define SK_CALLABLE_TRAITS__NE_VARARGS(quals, _) \
+SK_CALLABLE_TRAITS__VARARGS(quals,)
+#endif
+
+#define SK_CALLABLE_TRAITS__REF_NE_VARARGS(quals, _) \
+SK_CALLABLE_TRAITS__NE_VARARGS(quals,) \
+SK_CALLABLE_TRAITS__NE_VARARGS(quals &,) \
+SK_CALLABLE_TRAITS__NE_VARARGS(quals &&,)
+
+#define SK_CALLABLE_TRAITS__CV_REF_NE_VARARGS() \
+SK_CALLABLE_TRAITS__REF_NE_VARARGS(,) \
+SK_CALLABLE_TRAITS__REF_NE_VARARGS(const,) \
+SK_CALLABLE_TRAITS__REF_NE_VARARGS(volatile,) \
+SK_CALLABLE_TRAITS__REF_NE_VARARGS(const volatile,)
+
+/** Infer the return_type and argument<N> of a callable type T. */
+template <typename T> struct SkCallableTraits : SkCallableTraits<decltype(&T::operator())> {};
+
+// function (..., (const, volatile), (&, &&), noexcept)
+#define SK_CALLABLE_TRAITS__INSTANCE(quals, varargs) \
+template <typename R, typename... Args> \
+struct SkCallableTraits<R(Args... varargs) quals> : sk_base_callable_traits<R, Args...> {};
+
+SK_CALLABLE_TRAITS__CV_REF_NE_VARARGS()
+#undef SK_CALLABLE_TRAITS__INSTANCE
+
+// pointer to function (..., noexcept)
+#define SK_CALLABLE_TRAITS__INSTANCE(quals, varargs) \
+template <typename R, typename... Args> \
+struct SkCallableTraits<R(*)(Args... varargs) quals> : sk_base_callable_traits<R, Args...> {};
+
+SK_CALLABLE_TRAITS__NE_VARARGS(,)
+#undef SK_CALLABLE_TRAITS__INSTANCE
+
+// pointer to method (..., (const, volatile), (&, &&), noexcept)
+#define SK_CALLABLE_TRAITS__INSTANCE(quals, varargs) \
+template <typename T, typename R, typename... Args> \
+struct SkCallableTraits<R(T::*)(Args... varargs) quals> : sk_base_callable_traits<R, Args...> {};
+
+SK_CALLABLE_TRAITS__CV_REF_NE_VARARGS()
+#undef SK_CALLABLE_TRAITS__INSTANCE
+
+// pointer to field
+template <typename T, typename R>
+struct SkCallableTraits<R T::*> : sk_base_callable_traits<typename std::add_lvalue_reference<R>::type> {};
+
+#undef SK_CALLABLE_TRAITS__CV_REF_NE_VARARGS
+#undef SK_CALLABLE_TRAITS__REF_NE_VARARGS
+#undef SK_CALLABLE_TRAITS__NE_VARARGS
+#undef SK_CALLABLE_TRAITS__VARARGS
+#undef SK_CALLABLE_TRAITS__COMMA
+
+#endif