Merge pull request #2611 from wangkuiyi/tensor

Add tensor.h

paddle/framework/tensor.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+
+namespace paddle {
+namespace framework {
+
+class Tensor {
+  using paddle::platform::Place;
+  using paddle::platform::get_place;
+
+ public:
+  template <typename T>
+  const T* data() const {
+    PADDLE_ASSERT(holder_ != nullptr,
+                  "Tensor::data must be called after Tensor::mutable_data");
+    return static_cast<const T*>(holder->Ptr());
+  }
+
+  template <typename T,  // must be POD types
+            typename = std::enable_if<std::is_pod<T>::value>::type>
+  T* mutable_data(DDim dims, Place place) {
+    if (holder_ == nullptr || holder_->Place() != place ||
+        holder_->Size() < dims.product() * sizeof(T)) {
+      holder_.reset(new PlaceholderImpl(place, dims.product() * sizeof(T)));
+    }
+    return static_cast<T*>(holder_->Ptr());
+  }
+
+  template <typename T,  // must be POD types
+            typename = std::enable_if<std::is_pod<T>::value>::type>
+  T* mutable_data(DDim dims) {
+    return mutable_data<T>(dims, paddle::platform::get_place());
+  }
+
+ private:
+  // Placeholder hides type T, so it doesn't appear as a template
+  // parameter of Variable.
+  struct Placeholder {
+    virtual ~Placeholder() {}
+    virtual void* Ptr() const = 0;
+    virtual Place Place() const = 0;
+    virtual size_t Size() const = 0;
+  };
+
+  template <typename T>
+  struct PlaceholderImpl : public Placeholder {
+    PlaceholderImpl(Place pl, size_t size)
+        : ptr_(paddle::memory::Alloc(pl, size), paddle::memory::Deleter(pl)),
+          place_(pl),
+          size_(size) {}
+
+    virtual void* Ptr() const { return static_cast<void*>(ptr_.get()); }
+    virtual size_t Size() const { return size_; }
+    virtual Place Place() const { return place_; }
+
+    std::unique_ptr<T, memory::Deleter> ptr_;
+    Place place_;  // record the place of ptr_.
+    size_t size_;  // size of the memory block.
+  };
+
+  std::unique_ptr<Placeholder> holder_;  // holds the memory block if allocated.
+};
+
+}  // namespace framework
+}  // namespace paddle