#ifndef CAFFE_COMMON_LAYERS_HPP_
#define CAFFE_COMMON_LAYERS_HPP_

#include <string>
#include <utility>
#include <vector>

#include "caffe/blob.hpp"
#include "caffe/common.hpp"
#include "caffe/data_layers.hpp"
#include "caffe/layer.hpp"
#include "caffe/loss_layers.hpp"
#include "caffe/neuron_layers.hpp"
#include "caffe/proto/caffe.pb.h"

namespace caffe {

/**
 * @brief Compute the index of the @f$ K @f$ max values for each datum across
 *        all dimensions @f$ (C \times H \times W) @f$.
 *
 * Intended for use after a classification layer to produce a prediction.
 * If parameter out_max_val is set to true, output is a vector of pairs
 * (max_ind, max_val) for each image.
 *
 * NOTE: does not implement Backwards operation.
 */
template <typename Dtype>
class ArgMaxLayer : public Layer<Dtype> {
 public:
  /**
   * @param param provides ArgMaxParameter argmax_param,
   *     with ArgMaxLayer options:
   *   - top_k (\b optional uint, default 1).
   *     the number @f$ K @f$ of maximal items to output.
   *   - out_max_val (\b optional bool, default false).
   *     if set, output a vector of pairs (max_ind, max_val) for each image.
   */
  explicit ArgMaxLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "ArgMax"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  /**
   * @param bottom input Blob vector (length 1)
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs @f$ x @f$
   * @param top output Blob vector (length 1)
   *   -# @f$ (N \times 1 \times K \times 1) @f$ or, if out_max_val
   *      @f$ (N \times 2 \times K \times 1) @f$
   *      the computed outputs @f$
   *       y_n = \arg\max\limits_i x_{ni}
   *      @f$ (for @f$ K = 1 @f$).
   */
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  /// @brief Not implemented (non-differentiable function)
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom) {
    NOT_IMPLEMENTED;
  }
  bool out_max_val_;
  size_t top_k_;
};

/**
 * @brief Takes at least two Blob%s and concatenates them along either the num
 *        or channel dimension, outputting the result.
 */
template <typename Dtype>
class ConcatLayer : public Layer<Dtype> {
 public:
  explicit ConcatLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Concat"; }
  virtual inline int MinBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  /**
   * @param bottom input Blob vector (length 2+)
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs @f$ x_1 @f$
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs @f$ x_2 @f$
   *   -# ...
   *   - K @f$ (N \times C \times H \times W) @f$
   *      the inputs @f$ x_K @f$
   * @param top output Blob vector (length 1)
   *   -# @f$ (KN \times C \times H \times W) @f$ if axis == 0, or
   *      @f$ (N \times KC \times H \times W) @f$ if axis == 1:
   *      the concatenated output @f$
   *        y = [\begin{array}{cccc} x_1 & x_2 & ... & x_K \end{array}]
   *      @f$
   */
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  /**
   * @brief Computes the error gradient w.r.t. the concatenate inputs.
   *
   * @param top output Blob vector (length 1), providing the error gradient with
   *        respect to the outputs
   *   -# @f$ (KN \times C \times H \times W) @f$ if axis == 0, or
   *      @f$ (N \times KC \times H \times W) @f$ if axis == 1:
   *      containing error gradients @f$ \frac{\partial E}{\partial y} @f$
   *      with respect to concatenated outputs @f$ y @f$
   * @param propagate_down see Layer::Backward.
   * @param bottom input Blob vector (length K), into which the top gradient
   *        @f$ \frac{\partial E}{\partial y} @f$ is deconcatenated back to the
   *        inputs @f$
   *        \left[ \begin{array}{cccc}
   *          \frac{\partial E}{\partial x_1} &
   *          \frac{\partial E}{\partial x_2} &
   *          ... &
   *          \frac{\partial E}{\partial x_K}
   *        \end{array} \right] =
   *        \frac{\partial E}{\partial y}
   *        @f$
   */
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int count_;
  int num_concats_;
  int concat_input_size_;
  int concat_axis_;
};

/**
 * @brief Compute elementwise operations, such as product and sum,
 *        along multiple input Blobs.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class EltwiseLayer : public Layer<Dtype> {
 public:
  explicit EltwiseLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Eltwise"; }
  virtual inline int MinBottomBlobs() const { return 2; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  EltwiseParameter_EltwiseOp op_;
  vector<Dtype> coeffs_;
  Blob<int> max_idx_;

  bool stable_prod_grad_;
};

/**
 * @brief A layer for learning "embeddings" of one-hot vector input.
 *        Equivalent to an InnerProductLayer with one-hot vectors as input, but
 *        for efficiency the input is the "hot" index of each column itself.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class EmbedLayer : public Layer<Dtype> {
 public:
  explicit EmbedLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Embed"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int M_;
  int K_;
  int N_;
  bool bias_term_;
  Blob<Dtype> bias_multiplier_;
};

/**
 * @brief Takes two+ Blobs, interprets last Blob as a selector and
 *  filter remaining Blobs accordingly with selector data (0 means that
 * the corresponding item has to be filtered, non-zero means that corresponding
 * item needs to stay).
 */
template <typename Dtype>
class FilterLayer : public Layer<Dtype> {
 public:
  explicit FilterLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Filter"; }
  virtual inline int MinBottomBlobs() const { return 2; }
  virtual inline int MinTopBlobs() const { return 1; }

 protected:
  /**
   * @param bottom input Blob vector (length 2+)
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs to be filtered @f$ x_1 @f$
   *   -# ...
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs to be filtered @f$ x_K @f$
   *   -# @f$ (N \times 1 \times 1 \times 1) @f$
   *      the selector blob
   * @param top output Blob vector (length 1+)
   *   -# @f$ (S \times C \times H \times W) @f$ ()
   *        the filtered output @f$ x_1 @f$
   *        where S is the number of items
   *        that haven't been filtered
   *      @f$ (S \times C \times H \times W) @f$
   *        the filtered output @f$ x_K @f$
   *        where S is the number of items
   *        that haven't been filtered
   */
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
    const vector<Blob<Dtype>*>& top);

  /**
   * @brief Computes the error gradient w.r.t. the forwarded inputs.
   *
   * @param top output Blob vector (length 1+), providing the error gradient with
   *        respect to the outputs
   * @param propagate_down see Layer::Backward.
   * @param bottom input Blob vector (length 2+), into which the top error
   *        gradient is copied
   */
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
    const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  bool first_reshape_;
  vector<int> indices_to_forward_;
};

/**
 * @brief Reshapes the input Blob into flat vectors.
 *
 * Note: because this layer does not change the input values -- merely the
 * dimensions -- it can simply copy the input. The copy happens "virtually"
 * (thus taking effectively 0 real time) by setting, in Forward, the data
 * pointer of the top Blob to that of the bottom Blob (see Blob::ShareData),
 * and in Backward, the diff pointer of the bottom Blob to that of the top Blob
 * (see Blob::ShareDiff).
 */
template <typename Dtype>
class FlattenLayer : public Layer<Dtype> {
 public:
  explicit FlattenLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Flatten"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  /**
   * @param bottom input Blob vector (length 2+)
   *   -# @f$ (N \times C \times H \times W) @f$
   *      the inputs
   * @param top output Blob vector (length 1)
   *   -# @f$ (N \times CHW \times 1 \times 1) @f$
   *      the outputs -- i.e., the (virtually) copied, flattened inputs
   */
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  /**
   * @brief Computes the error gradient w.r.t. the concatenate inputs.
   *
   * @param top output Blob vector (length 1), providing the error gradient with
   *        respect to the outputs
   * @param propagate_down see Layer::Backward.
   * @param bottom input Blob vector (length K), into which the top error
   *        gradient is (virtually) copied
   */
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
};

/**
 * @brief Also known as a "fully-connected" layer, computes an inner product
 *        with a set of learned weights, and (optionally) adds biases.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class InnerProductLayer : public Layer<Dtype> {
 public:
  explicit InnerProductLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "InnerProduct"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int M_;
  int K_;
  int N_;
  bool bias_term_;
  Blob<Dtype> bias_multiplier_;
};

/**
 * @brief Normalizes the input to have 0-mean and/or unit (1) variance.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class MVNLayer : public Layer<Dtype> {
 public:
  explicit MVNLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "MVN"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
     const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  Blob<Dtype> mean_, variance_, temp_;

  /// sum_multiplier is used to carry out sum using BLAS
  Blob<Dtype> sum_multiplier_;
  Dtype eps_;
};

/*
 * @brief Reshapes the input Blob into an arbitrary-sized output Blob.
 *
 * Note: similarly to FlattenLayer, this layer does not change the input values
 * (see FlattenLayer, Blob::ShareData and Blob::ShareDiff).
 */
template <typename Dtype>
class ReshapeLayer : public Layer<Dtype> {
 public:
  explicit ReshapeLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Reshape"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top) {}
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom) {}
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top) {}
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom) {}

  /// @brief vector of axes indices whose dimensions we'll copy from the bottom
  vector<int> copy_axes_;
  /// @brief the index of the axis whose dimension we infer, or -1 if none
  int inferred_axis_;
  /// @brief the product of the "constant" output dimensions
  int constant_count_;
};

/**
 * @brief Compute "reductions" -- operations that return a scalar output Blob
 *        for an input Blob of arbitrary size, such as the sum, absolute sum,
 *        and sum of squares.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class ReductionLayer : public Layer<Dtype> {
 public:
  explicit ReductionLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Reduction"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  /// @brief the reduction operation performed by the layer
  ReductionParameter_ReductionOp op_;
  /// @brief a scalar coefficient applied to all outputs
  Dtype coeff_;
  /// @brief the index of the first input axis to reduce
  int axis_;
  /// @brief the number of reductions performed
  int num_;
  /// @brief the input size of each reduction
  int dim_;
  /// @brief a helper Blob used for summation (op_ == SUM)
  Blob<Dtype> sum_multiplier_;
};

/**
 * @brief Ignores bottom blobs while producing no top blobs. (This is useful
 *        to suppress outputs during testing.)
 */
template <typename Dtype>
class SilenceLayer : public Layer<Dtype> {
 public:
  explicit SilenceLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top) {}

  virtual inline const char* type() const { return "Silence"; }
  virtual inline int MinBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 0; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top) {}
  // We can't define Forward_gpu here, since STUB_GPU will provide
  // its own definition for CPU_ONLY mode.
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
};

/**
 * @brief Computes the softmax function.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class SoftmaxLayer : public Layer<Dtype> {
 public:
  explicit SoftmaxLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Softmax"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
     const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int outer_num_;
  int inner_num_;
  int softmax_axis_;
  /// sum_multiplier is used to carry out sum using BLAS
  Blob<Dtype> sum_multiplier_;
  /// scale is an intermediate Blob to hold temporary results.
  Blob<Dtype> scale_;
};

#ifdef USE_CUDNN
/**
 * @brief cuDNN implementation of SoftmaxLayer.
 *        Fallback to SoftmaxLayer for CPU mode.
 */
template <typename Dtype>
class CuDNNSoftmaxLayer : public SoftmaxLayer<Dtype> {
 public:
  explicit CuDNNSoftmaxLayer(const LayerParameter& param)
      : SoftmaxLayer<Dtype>(param), handles_setup_(false) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual ~CuDNNSoftmaxLayer();

 protected:
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
     const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  bool handles_setup_;
  cudnnHandle_t             handle_;
  cudnnTensorDescriptor_t bottom_desc_;
  cudnnTensorDescriptor_t top_desc_;
};
#endif

/**
 * @brief Creates a "split" path in the network by copying the bottom Blob
 *        into multiple top Blob%s to be used by multiple consuming layers.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class SplitLayer : public Layer<Dtype> {
 public:
  explicit SplitLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Split"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int MinTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int count_;
};

/**
 * @brief Takes a Blob and slices it along either the num or channel dimension,
 *        outputting multiple sliced Blob results.
 *
 * TODO(dox): thorough documentation for Forward, Backward, and proto params.
 */
template <typename Dtype>
class SliceLayer : public Layer<Dtype> {
 public:
  explicit SliceLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Slice"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int MinTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  int count_;
  int num_slices_;
  int slice_size_;
  int slice_axis_;
  vector<int> slice_point_;
};

/**
 * @brief Copy a Blob along specified dimensions.
 */
template <typename Dtype>
class TileLayer : public Layer<Dtype> {
 public:
  explicit TileLayer(const LayerParameter& param)
      : Layer<Dtype>(param) {}
  virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual inline const char* type() const { return "Tile"; }
  virtual inline int ExactNumBottomBlobs() const { return 1; }
  virtual inline int ExactNumTopBlobs() const { return 1; }

 protected:
  virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);
  virtual void Forward_gpu(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top);

  virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);
  virtual void Backward_gpu(const vector<Blob<Dtype>*>& top,
      const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom);

  unsigned int axis_, tiles_, outer_dim_, inner_dim_;
};

}  // namespace caffe

#endif  // CAFFE_COMMON_LAYERS_HPP_