1 files changed, 81 insertions, 0 deletions
diff --git a/toolsrc/include/expected.h b/toolsrc/include/expected.h
new file mode 100644
index 000000000..affabcc02
--- /dev/null
+++ b/toolsrc/include/expected.h
@@ -0,0 +1,81 @@
+#pragma once
+
+#include "vcpkg_Checks.h"
+
+namespace vcpkg
+{
+    template <class T>
+    class expected
+    {
+    public:
+        // Constructors are intentionally implicit 
+        expected(const std::error_code& ec) : m_error_code(ec), m_t()
+        {
+        }
+
+        expected(std::errc ec) : expected(std::make_error_code(ec))
+        {
+        }
+
+        expected(const T& t) : m_error_code(), m_t(t)
+        {
+        }
+
+        expected(T&& t) : m_error_code(), m_t(std::move(t))
+        {
+        }
+
+        expected() : expected(std::error_code(), T())
+        {
+        }
+
+        expected(const expected&) = default;
+        expected(expected&&) = default;
+        expected& operator=(const expected&) = default;
+        expected& operator=(expected&&) = default;
+
+        std::error_code error_code() const
+        {
+            return this->m_error_code;
+        }
+
+        T&& get_or_throw() &&
+        {
+            throw_if_error();
+            return std::move(this->m_t);
+        }
+
+        const T& get_or_throw() const &
+        {
+            throw_if_error();
+            return this->m_t;
+        }
+
+        const T* get() const
+        {
+            if (m_error_code)
+            {
+                return nullptr;
+            }
+            return &this->m_t;
+        }
+
+        T* get()
+        {
+            if (m_error_code)
+            {
+                return nullptr;
+            }
+            return &this->m_t;
+        }
+
+    private:
+        void throw_if_error() const
+        {
+            Checks::check_throw(!this->m_error_code, this->m_error_code.message().c_str());
+        }
+
+        std::error_code m_error_code;
+        T m_t;
+    };
+}