From f1bbf06cd83cb55b5285bbed6a5788766f55dc8d Mon Sep 17 00:00:00 2001
From: Billy Laws <blaws05@gmail.com>
Date: Sat, 17 Jul 2021 14:01:39 +0100
Subject: [PATCH] Allow supplying a custom ResultValue result type and optimise
 span

This allows PosixResultValue to be created easily.
---
 app/src/main/cpp/skyline/common.h | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/app/src/main/cpp/skyline/common.h b/app/src/main/cpp/skyline/common.h
index 5e991af7..45a4ed41 100644
--- a/app/src/main/cpp/skyline/common.h
+++ b/app/src/main/cpp/skyline/common.h
@@ -83,26 +83,27 @@ namespace skyline {
 
     /**
      * @brief A wrapper around std::optional that also stores a HOS result code
-     * @tparam T The object type to hold
+     * @tparam ValueType The object type to hold
+     * @tparam ResultType The result type to hold
      */
-    template<typename T>
+    template<typename ValueType, typename ResultType = Result>
     class ResultValue {
-        static_assert(!std::is_same<T, Result>::value);
+        static_assert(!std::is_same<ValueType, ResultType>::value);
 
       private:
-        std::optional<T> value;
+        std::optional<ValueType> value;
 
       public:
-        Result result;
+        ResultType result{};
 
-        constexpr ResultValue(T value) : value(value) {};
+        constexpr ResultValue(ValueType value) : value(value) {};
 
-        constexpr ResultValue(Result result) : result(result) {};
+        constexpr ResultValue(ResultType result) : result(result) {};
 
         template<typename U>
         constexpr ResultValue(ResultValue<U> result) : result(result) {};
 
-        constexpr operator Result() const {
+        constexpr operator ResultType() const {
             return result;
         }
 
@@ -110,11 +111,11 @@ namespace skyline {
             return value.has_value();
         }
 
-        constexpr T& operator*()  {
+        constexpr ValueType& operator*()  {
             return *value;
         }
 
-        constexpr T* operator->()  {
+        constexpr ValueType* operator->()  {
             return &*value;
         }
     };
@@ -362,6 +363,9 @@ namespace skyline {
 
         template<typename Out>
         constexpr Out &as() {
+            if constexpr (Extent != std::dynamic_extent && sizeof(T) * Extent >= sizeof(Out))
+                return *reinterpret_cast<Out *>(span::data());
+
             if (span::size_bytes() >= sizeof(Out))
                 return *reinterpret_cast<Out *>(span::data());
             throw exception("Span size is less than Out type size (0x{:X}/0x{:X})", span::size_bytes(), sizeof(Out));