Expose read-only versions of tensors in tflite.

PiperOrigin-RevId: 195491701

1 files changed, 31 insertions, 6 deletions

diff --git a/tensorflow/contrib/lite/interpreter.h b/tensorflow/contrib/lite/interpreter.h
index 1074f64263..0450e86ae7 100644
--- a/tensorflow/contrib/lite/interpreter.h
+++ b/tensorflow/contrib/lite/interpreter.h
@@ -201,7 +201,7 @@ class Interpreter {
   // Overrides execution plan. This bounds checks indices sent in.
   TfLiteStatus SetExecutionPlan(const std::vector<int>& new_plan);
 
-  // Get a tensor data structure.
+  // Get a mutable tensor data structure.
   // TODO(aselle): Create a safe ArrayHandle interface to avoid exposing this
   // read/write access to structure
   TfLiteTensor* tensor(int tensor_index) {
@@ -210,9 +210,14 @@ class Interpreter {
     return &context_.tensors[tensor_index];
   }
 
+  // Get an immutable tensor data structure.
+  const TfLiteTensor* tensor(int tensor_index) const {
+    if (tensor_index >= context_.tensors_size || tensor_index < 0)
+      return nullptr;
+    return &context_.tensors[tensor_index];
+  }
+
   // Get a pointer to an operation and registration data structure if in bounds.
-  // TODO(aselle): Create a safe ArrayHandle interface to avoid exposing this
-  // read/write access to structure
   const std::pair<TfLiteNode, TfLiteRegistration>* node_and_registration(
       int node_index) const {
     if (node_index >= nodes_and_registration_.size() || node_index < 0)
@@ -220,7 +225,8 @@ class Interpreter {
     return &nodes_and_registration_[node_index];
   }
 
-  // Perform a checked cast to the appropriate tensor type.
+  // Perform a checked cast to the appropriate tensor type (mutable pointer
+  // version).
   template <class T>
   T* typed_tensor(int tensor_index) {
     if (TfLiteTensor* tensor_ptr = tensor(tensor_index)) {
@@ -231,6 +237,18 @@ class Interpreter {
     return nullptr;
   }
 
+  // Perform a checked cast to the appropriate tensor type (immutable pointer
+  // version).
+  template <class T>
+  const T* typed_tensor(int tensor_index) const {
+    if (const TfLiteTensor* tensor_ptr = tensor(tensor_index)) {
+      if (tensor_ptr->type == typeToTfLiteType<T>()) {
+        return reinterpret_cast<const T*>(tensor_ptr->data.raw);
+      }
+    }
+    return nullptr;
+  }
+
   // Return a pointer into the data of a given input tensor. The given index
   // must be between 0 and inputs().size().
   template <class T>
@@ -238,13 +256,20 @@ class Interpreter {
     return typed_tensor<T>(inputs_[index]);
   }
 
-  // Return a pointer into the data of a given output tensor. The given index
-  // must be between 0 and outputs().size().
+  // Return a mutable pointer into the data of a given output tensor. The given
+  // index must be between 0 and outputs().size().
   template <class T>
   T* typed_output_tensor(int index) {
     return typed_tensor<T>(outputs_[index]);
   }
 
+  // Return an immutable pointer into the data of a given output tensor. The
+  // given index must be between 0 and outputs().size().
+  template <class T>
+  const T* typed_output_tensor(int index) const {
+    return typed_tensor<T>(outputs_[index]);
+  }
+
   // Change the dimensionality of a given tensor. Note, this is only acceptable
   // for tensor indices that are inputs.
   // Returns status of failure or success.