1 files changed, 74 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/common/Optional.h b/gfx/angle/checkout/src/common/Optional.h
new file mode 100644
index 0000000000..46c65dde4e
--- /dev/null
+++ b/gfx/angle/checkout/src/common/Optional.h
@@ -0,0 +1,74 @@
+//
+// Copyright 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Optional.h:
+//   Represents a type that may be invalid, similar to std::optional.
+//
+
+#ifndef COMMON_OPTIONAL_H_
+#define COMMON_OPTIONAL_H_
+
+#include <utility>
+
+template <class T>
+struct Optional
+{
+    Optional() : mValid(false), mValue(T()) {}
+
+    Optional(const T &valueIn) : mValid(true), mValue(valueIn) {}
+
+    Optional(const Optional &other) : mValid(other.mValid), mValue(other.mValue) {}
+
+    Optional &operator=(const Optional &other)
+    {
+        this->mValid = other.mValid;
+        this->mValue = other.mValue;
+        return *this;
+    }
+
+    Optional &operator=(const T &value)
+    {
+        mValue = value;
+        mValid = true;
+        return *this;
+    }
+
+    Optional &operator=(T &&value)
+    {
+        mValue = std::move(value);
+        mValid = true;
+        return *this;
+    }
+
+    void reset() { mValid = false; }
+    T &&release()
+    {
+        mValid = false;
+        return std::move(mValue);
+    }
+
+    static Optional Invalid() { return Optional(); }
+
+    bool valid() const { return mValid; }
+    T &value() { return mValue; }
+    const T &value() const { return mValue; }
+
+    bool operator==(const Optional &other) const
+    {
+        return ((mValid == other.mValid) && (!mValid || (mValue == other.mValue)));
+    }
+
+    bool operator!=(const Optional &other) const { return !(*this == other); }
+
+    bool operator==(const T &value) const { return mValid && (mValue == value); }
+
+    bool operator!=(const T &value) const { return !(*this == value); }
+
+  private:
+    bool mValid;
+    T mValue;
+};
+
+#endif  // COMMON_OPTIONAL_H_