1 files changed, 74 insertions, 0 deletions
diff --git a/gfx/angle/src/common/Optional.h b/gfx/angle/src/common/Optional.h
new file mode 100755
index 000000000..5a79048d6
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+++ b/gfx/angle/src/common/Optional.h
@@ -0,0 +1,74 @@
+//
+// Copyright (c) 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_
+
+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;
+    }
+
+    static Optional Invalid() { return Optional(); }
+
+    bool valid() const { return mValid; }
+    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);
+    }
+
+  private:
+    bool mValid;
+    T mValue;
+};
+
+#endif // COMMON_OPTIONAL_H_