[LITE][API] Add GetOutput API for CXX and Mobile. test=develop

lite/api/cxx_api.h

@@ -88,6 +88,7 @@ class LITE_API Predictor {
 
   // Get offset-th col of fetch results.
   const lite::Tensor* GetOutput(size_t offset) const;
+  const lite::Tensor* GetOutput(const std::string& name) const;
   std::vector<const lite::Tensor*> GetOutputs() const;
 
   const cpp::ProgramDesc& program_desc() const;
@@ -131,6 +132,8 @@ class CxxPaddleApiImpl : public lite_api::PaddlePredictor {
   std::unique_ptr<lite_api::Tensor> GetInput(int i) override;
 
   std::unique_ptr<const lite_api::Tensor> GetOutput(int i) const override;
+  std::unique_ptr<const lite_api::Tensor> GetOutput(
+      const std::string& name) const override;
 
   void Run() override;
 

lite/api/cxx_api_impl.cc

@@ -46,6 +46,11 @@ std::unique_ptr<const lite_api::Tensor> CxxPaddleApiImpl::GetOutput(
   return std::unique_ptr<lite_api::Tensor>(new lite_api::Tensor(x));
 }
 
+std::unique_ptr<const lite_api::Tensor> CxxPaddleApiImpl::GetOutput(
+    const std::string &name) const {
+  return CxxPaddleApiImpl::GetTensor(name);
+}
+
 std::vector<std::string> CxxPaddleApiImpl::GetInputNames() {
   return raw_predictor_.GetInputNames();
 }

lite/api/light_api.h

@@ -57,6 +57,7 @@ class LITE_API LightPredictor {
   Tensor* GetInputByName(const std::string& name);
   // Get offset-th col of fetch outputs.
   const Tensor* GetOutput(size_t offset);
+  const Tensor* GetOutput(const std::string& name);
 
   const lite::Tensor* GetTensor(const std::string& name) const {
     auto* var = program_->exec_scope()->FindVar(name);
@@ -94,6 +95,9 @@ class LightPredictorImpl : public lite_api::PaddlePredictor {
 
   std::unique_ptr<const lite_api::Tensor> GetOutput(int i) const override;
 
+  std::unique_ptr<const lite_api::Tensor> GetOutput(
+      const std::string& name) const override;
+
   void Run() override;
 
   std::shared_ptr<lite_api::PaddlePredictor> Clone() override;

lite/api/light_api_impl.cc

@@ -45,6 +45,11 @@ std::unique_ptr<const lite_api::Tensor> LightPredictorImpl::GetOutput(
       new lite_api::Tensor(raw_predictor_->GetOutput(i)));
 }
 
+std::unique_ptr<const lite_api::Tensor> LightPredictorImpl::GetOutput(
+    const std::string& name) const {
+  return LightPredictorImpl::GetTensor(name);
+}
+
 void LightPredictorImpl::Run() {
 #ifdef LITE_WITH_ARM
   lite::DeviceInfo::Global().SetRunMode(mode_, threads_);
@@ -63,6 +68,7 @@ std::unique_ptr<const lite_api::Tensor> LightPredictorImpl::GetTensor(
   return std::unique_ptr<const lite_api::Tensor>(
       new lite_api::Tensor(raw_predictor_->GetTensor(name)));
 }
+
 std::unique_ptr<lite_api::Tensor> LightPredictorImpl::GetInputByName(
     const std::string& name) {
   return std::unique_ptr<lite_api::Tensor>(

lite/api/paddle_api.h

@@ -77,6 +77,10 @@ class LITE_API PaddlePredictor {
   /// Get i-th output.
   virtual std::unique_ptr<const Tensor> GetOutput(int i) const = 0;
 
+  /// Get output tensor with `name` existed.
+  virtual std::unique_ptr<const Tensor> GetOutput(
+      const std::string& name) const = 0;
+
   virtual void Run() = 0;
   virtual std::shared_ptr<PaddlePredictor> Clone() = 0;