IVGCVSW-1952 : add BackendId class to prepare for the replacement of Compute enum

!armnn:152674

Change-Id: I1bcdfdfbfb73e502d58f35717e2558e24651013c

3 files changed, 137 insertions, 47 deletions

diff --git a/include/armnn/BackendId.hpp b/include/armnn/BackendId.hpp
new file mode 100644
index 0000000000..d1f06beba7
--- /dev/null
+++ b/include/armnn/BackendId.hpp
@@ -0,0 +1,132 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include <set>
+#include <unordered_set>
+#include <string>
+#include <memory>
+
+namespace armnn
+{
+
+//
+// The Compute enum is now deprecated and it is now
+// replaced by BackendId
+//
+enum class Compute
+{
+    /// CPU Execution: Reference C++ kernels
+    CpuRef      = 0,
+    /// CPU Execution: NEON: ArmCompute
+    CpuAcc      = 1,
+    /// GPU Execution: OpenCL: ArmCompute
+    GpuAcc      = 2,
+    Undefined   = 5
+};
+
+constexpr char const* GetComputeDeviceAsCString(Compute compute)
+{
+    switch (compute)
+    {
+        case armnn::Compute::CpuRef: return "CpuRef";
+        case armnn::Compute::CpuAcc: return "CpuAcc";
+        case armnn::Compute::GpuAcc: return "GpuAcc";
+        default:                     return "Unknown";
+    }
+}
+
+inline std::ostream& operator<<(std::ostream& os, const std::vector<Compute>& compute)
+{
+    for (const Compute& comp : compute) {
+        os << GetComputeDeviceAsCString(comp) << " ";
+    }
+    return os;
+}
+
+inline std::ostream& operator<<(std::ostream& os, const std::set<Compute>& compute)
+{
+    for (const Compute& comp : compute) {
+        os << GetComputeDeviceAsCString(comp) << " ";
+    }
+    return os;
+}
+
+inline std::ostream& operator<<(std::ostream& os, const Compute& compute)
+{
+    os << GetComputeDeviceAsCString(compute);
+    return os;
+}
+
+class BackendId final
+{
+public:
+    BackendId(const std::string& id) : m_Id{id} {}
+    BackendId(const char* id) : m_Id{id} {}
+    BackendId(Compute compute) : m_Id{GetComputeDeviceAsCString(compute)} {}
+
+    operator std::string() const { return m_Id; }
+
+    BackendId& operator=(const std::string& other)
+    {
+        m_Id = other;
+        return *this;
+    }
+
+    BackendId& operator=(Compute compute)
+    {
+        BackendId temp{compute};
+        std::swap(temp.m_Id, m_Id);
+        return *this;
+    }
+
+    bool operator==(const BackendId& other) const
+    {
+        return m_Id == other.m_Id;
+    }
+
+    bool operator<(const BackendId& other) const
+    {
+        return m_Id < other.m_Id;
+    }
+
+    const std::string& Get() const { return m_Id; }
+
+private:
+    // backend Id mustn't be empty:
+    BackendId() = delete;
+    std::string m_Id;
+};
+
+template <template <class...> class TContainer>
+inline std::ostream& operator<<(std::ostream& os,
+                                const TContainer<BackendId>& ids)
+{
+    os << '[';
+    for (const auto& id : ids) { os << id.Get() << " "; }
+    os << ']';
+    return os;
+}
+
+using BackendIdSet = std::unordered_set<BackendId>;
+
+} // namespace armnn
+
+namespace std
+{
+
+// make BackendId compatible with std hashtables by reusing the hash
+// function for strings
+template <>
+struct hash<armnn::BackendId>
+{
+    std::size_t operator()(const armnn::BackendId& id) const
+    {
+        std::hash<std::string> hasher;
+        return hasher(id.Get());
+    }
+};
+
+} // namespace std
diff --git a/include/armnn/Types.hpp b/include/armnn/Types.hpp
index b7ee9472a3..4afc50b1b1 100644
--- a/include/armnn/Types.hpp
+++ b/include/armnn/Types.hpp
@@ -7,6 +7,7 @@
 #include <array>
 #include <memory>
 #include "ILayerSupport.hpp"
+#include "BackendId.hpp"
 
 namespace armnn
 {
@@ -94,17 +95,6 @@ enum class OutputShapeRounding
     Ceiling     = 1
 };
 
-enum class Compute
-{
-    /// CPU Execution: Reference C++ kernels
-    CpuRef      = 0,
-    /// CPU Execution: NEON: ArmCompute
-    CpuAcc      = 1,
-    /// GPU Execution: OpenCL: ArmCompute
-    GpuAcc      = 2,
-    Undefined   = 5
-};
-
 /// Each backend should implement an IBackend.
 class IBackend
 {
@@ -113,7 +103,7 @@ protected:
     virtual ~IBackend() {}
 
 public:
-    virtual const std::string& GetId() const = 0;
+    virtual const BackendId& GetId() const = 0;
     virtual const ILayerSupport& GetLayerSupport() const = 0;
 };
 
@@ -189,4 +179,4 @@ private:
 /// Define LayerGuid type.
 using LayerGuid = unsigned int;
 
-}
+} // namespace armnn
diff --git a/include/armnn/TypesUtils.hpp b/include/armnn/TypesUtils.hpp
index c6db905bb9..a9755bd112 100644
--- a/include/armnn/TypesUtils.hpp
+++ b/include/armnn/TypesUtils.hpp
@@ -15,9 +15,9 @@
 namespace armnn
 {
 
-constexpr char const* GetStatusAsCString(Status compute)
+constexpr char const* GetStatusAsCString(Status status)
 {
-    switch (compute)
+    switch (status)
     {
         case armnn::Status::Success: return "Status::Success";
         case armnn::Status::Failure: return "Status::Failure";
@@ -25,17 +25,6 @@ constexpr char const* GetStatusAsCString(Status compute)
     }
 }
 
-constexpr char const* GetComputeDeviceAsCString(Compute compute)
-{
-    switch (compute)
-    {
-        case armnn::Compute::CpuRef: return "CpuRef";
-        case armnn::Compute::CpuAcc: return "CpuAcc";
-        case armnn::Compute::GpuAcc: return "GpuAcc";
-        default:                     return "Unknown";
-    }
-}
-
 constexpr char const* GetActivationFunctionAsCString(ActivationFunction activation)
 {
     switch (activation)
@@ -194,27 +183,6 @@ inline std::ostream& operator<<(std::ostream& os, Status stat)
     return os;
 }
 
-inline std::ostream& operator<<(std::ostream& os, const std::vector<Compute>& compute)
-{
-    for (const Compute& comp : compute) {
-        os << GetComputeDeviceAsCString(comp) << " ";
-    }
-    return os;
-}
-
-inline std::ostream& operator<<(std::ostream& os, const std::set<Compute>& compute)
-{
-    for (const Compute& comp : compute) {
-        os << GetComputeDeviceAsCString(comp) << " ";
-    }
-    return os;
-}
-
-inline std::ostream& operator<<(std::ostream& os, const Compute& compute)
-{
-    os << GetComputeDeviceAsCString(compute);
-    return os;
-}
 
 inline std::ostream & operator<<(std::ostream & os, const armnn::TensorShape & shape)
 {