IVGCVSW-1987 : registry for backend creation functions (factories)

Change-Id: I13d2d3dc763e1d05dffddb34472bd4f9e632c776
diff --git a/src/backends/BackendRegistry.cpp b/src/backends/BackendRegistry.cpp
new file mode 100644
index 0000000..68336c4
--- /dev/null
+++ b/src/backends/BackendRegistry.cpp
@@ -0,0 +1,45 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "BackendRegistry.hpp"
+#include <armnn/Exceptions.hpp>
+
+namespace armnn
+{
+
+BackendRegistry& BackendRegistry::Instance()
+{
+    static BackendRegistry instance;
+    return instance;
+}
+
+void BackendRegistry::Register(const std::string& name, FactoryFunction factory)
+{
+    if (m_BackendFactories.count(name) > 0)
+    {
+        throw InvalidArgumentException(name + " already registered as backend");
+    }
+
+    m_BackendFactories[name] = factory;
+}
+
+BackendRegistry::FactoryFunction BackendRegistry::GetFactory(const std::string& name) const
+{
+    auto it = m_BackendFactories.find(name);
+    if (it == m_BackendFactories.end())
+    {
+        throw InvalidArgumentException(name + " has no backend factory registered");
+    }
+
+    return it->second;
+}
+
+void BackendRegistry::Swap(BackendRegistry::FactoryStorage& other)
+{
+    BackendRegistry& instance = Instance();
+    std::swap(instance.m_BackendFactories, other);
+}
+
+}