IVGCVSW-1964 : replace optional biases with home-grown Optional

!android-nn-driver:151788

Change-Id: Ibdc41d09b8df05e7a0360dcb8a060860dfb1bd99

4 files changed, 135 insertions, 8 deletions

diff --git a/include/armnn/Exceptions.hpp b/include/armnn/Exceptions.hpp
index 4f3bea0e30..89b6f2cfbb 100644
--- a/include/armnn/Exceptions.hpp
+++ b/include/armnn/Exceptions.hpp
@@ -95,6 +95,11 @@ class GraphValidationException : public Exception
     using Exception::Exception;
 };
 
+class BadOptionalAccessException : public Exception
+{
+    using Exception::Exception;
+};
+
 template <typename ExceptionType>
 void ConditionalThrow(bool condition, const std::string& message)
 {
diff --git a/include/armnn/ILayerSupport.hpp b/include/armnn/ILayerSupport.hpp
index 7962393f34..b9b41b7fcf 100644
--- a/include/armnn/ILayerSupport.hpp
+++ b/include/armnn/ILayerSupport.hpp
@@ -5,9 +5,9 @@
 #pragma once
 
 #include <armnn/DescriptorsFwd.hpp>
-
-#include <boost/optional.hpp>
+#include <armnn/Optional.hpp>
 #include <vector>
+#include <cctype>
 
 namespace armnn
 {
@@ -61,7 +61,7 @@ public:
                                           const TensorInfo& output,
                                           const Convolution2dDescriptor& descriptor,
                                           const TensorInfo& weights,
-                                          const boost::optional<TensorInfo>& biases,
+                                          const Optional<TensorInfo>& biases,
                                           char* reasonIfUnsupported = nullptr,
                                           size_t reasonIfUnsupportedMaxLength = 1024) const;
 
@@ -69,7 +69,7 @@ public:
                                                  const TensorInfo& output,
                                                  const DepthwiseConvolution2dDescriptor& descriptor,
                                                  const TensorInfo& weights,
-                                                 const boost::optional<TensorInfo>& biases,
+                                                 const Optional<TensorInfo>& biases,
                                                  char* reasonIfUnsupported = nullptr,
                                                  size_t reasonIfUnsupportedMaxLength = 1024) const;
 
diff --git a/include/armnn/LayerSupport.hpp b/include/armnn/LayerSupport.hpp
index 25e888e71e..31874fe944 100644
--- a/include/armnn/LayerSupport.hpp
+++ b/include/armnn/LayerSupport.hpp
@@ -7,8 +7,7 @@
 #include <armnn/DescriptorsFwd.hpp>
 #include <armnn/Types.hpp>
 #include <armnn/Tensor.hpp>
-
-#include <boost/optional.hpp>
+#include <armnn/Optional.hpp>
 
 namespace armnn
 {
@@ -60,7 +59,7 @@ bool IsConvolution2dSupported(Compute compute,
                               const TensorInfo& output,
                               const Convolution2dDescriptor& descriptor,
                               const TensorInfo& weights,
-                              const boost::optional<TensorInfo>& biases,
+                              const Optional<TensorInfo>& biases,
                               char* reasonIfUnsupported = nullptr,
                               size_t reasonIfUnsupportedMaxLength = 1024);
 
@@ -69,7 +68,7 @@ bool IsDepthwiseConvolutionSupported(Compute compute,
                                      const TensorInfo& output,
                                      const DepthwiseConvolution2dDescriptor& descriptor,
                                      const TensorInfo& weights,
-                                     const boost::optional<TensorInfo>& biases,
+                                     const Optional<TensorInfo>& biases,
                                      char* reasonIfUnsupported = nullptr,
                                      size_t reasonIfUnsupportedMaxLength = 1024);
 
diff --git a/include/armnn/Optional.hpp b/include/armnn/Optional.hpp
new file mode 100644
index 0000000000..6fc207f425
--- /dev/null
+++ b/include/armnn/Optional.hpp
@@ -0,0 +1,123 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include "Exceptions.hpp"
+
+namespace armnn
+{
+
+// NOTE: the members of the Optional class don't follow the ArmNN
+//       coding convention because the interface to be close to
+//       the C++-17 interface so we can easily migrate to std::optional
+//       later.
+
+template <typename T>
+class Optional final
+{
+public:
+    Optional(T&& value)
+        : m_HasValue{true}
+    {
+        new (m_Storage) T(value);
+    }
+
+    Optional(const T& value)
+        : m_HasValue{true}
+    {
+        new (m_Storage) T(value);
+    }
+
+    Optional(const Optional& other)
+        : m_HasValue{false}
+    {
+        *this = other;
+    }
+
+    Optional() noexcept
+        : m_HasValue{false}
+    {
+    }
+
+    ~Optional()
+    {
+        reset();
+    }
+
+    operator bool() const noexcept
+    {
+        return has_value();
+    }
+
+    Optional& operator=(T&& value)
+    {
+        reset();
+        new (m_Storage) T(value);
+        m_HasValue = true;
+        return *this;
+    }
+
+    Optional& operator=(const T& value)
+    {
+        reset();
+        new(m_Storage) T(value);
+        m_HasValue = true;
+        return *this;
+    }
+
+    Optional& operator=(const Optional& other)
+    {
+        reset();
+        if (other.has_value())
+        {
+            new (m_Storage) T(other.value());
+            m_HasValue = true;
+        }
+
+        return *this;
+    }
+
+    const T& value() const
+    {
+        if (!has_value())
+        {
+            throw BadOptionalAccessException("Optional has no value");
+        }
+
+        auto valuePtr = reinterpret_cast<const T*>(m_Storage);
+        return *valuePtr;
+    }
+
+    T& value()
+    {
+        if (!has_value())
+        {
+            throw BadOptionalAccessException("Optional has no value");
+        }
+
+        auto valuePtr = reinterpret_cast<T*>(m_Storage);
+        return *valuePtr;
+    }
+
+    bool has_value() const noexcept
+    {
+        return m_HasValue;
+    }
+
+    void reset()
+    {
+        if (has_value())
+        {
+            value().T::~T();
+            m_HasValue = false;
+        }
+    }
+
+private:
+    alignas(alignof(T)) unsigned char m_Storage[sizeof(T)];
+    bool m_HasValue;
+};
+
+}