From d8cc21da53e1113aaee3b43ea77d136bbbd204bb Mon Sep 17 00:00:00 2001
From: fengjiayi <fengjiayi@baidu.com>
Date: Thu, 1 Feb 2018 12:58:14 +0800
Subject: [PATCH] refine inheritance relationship

---
 paddle/framework/reader.cc |  2 +-
 paddle/framework/reader.h  | 66 +++++++++++++++++++++-----------------
 2 files changed, 37 insertions(+), 31 deletions(-)

diff --git a/paddle/framework/reader.cc b/paddle/framework/reader.cc
index e11662166c..a05bef42ff 100644
--- a/paddle/framework/reader.cc
+++ b/paddle/framework/reader.cc
@@ -17,7 +17,7 @@
 namespace paddle {
 namespace framework {
 
-DDim Reader::shape(size_t idx) const {
+DDim FileReader::shape(size_t idx) const {
   PADDLE_ENFORCE_LT(
       idx, shapes_.size(),
       "Cannot get the %d'th shape, 'shapes_' only has %d elements.", idx,
diff --git a/paddle/framework/reader.h b/paddle/framework/reader.h
index 58675863e5..3954a1bea8 100644
--- a/paddle/framework/reader.h
+++ b/paddle/framework/reader.h
@@ -20,32 +20,48 @@
 namespace paddle {
 namespace framework {
 
-class Reader {
+class ReaderBase {
  public:
-  Reader() {}
-  explicit Reader(const std::vector<DDim>& shapes) : shapes_(shapes) {}
-
   virtual std::vector<LoDTensor> ReadNext() = 0;
   virtual bool HasNext() const = 0;
 
-  virtual DDim shape(size_t idx) const;
-  virtual std::vector<DDim> shapes() const { return shapes_; }
+  virtual DDim shape(size_t idx) const = 0;
+  virtual std::vector<DDim> shapes() const = 0;
 
-  virtual ~Reader() {}
+  virtual ~ReaderBase() {}
+};
 
- private:
-  // set private to prevent directly access in decorators
-  // a decorator should access its underlying reader_'s shape, not its own.
+class FileReader : public ReaderBase {
+ public:
+  explicit FileReader(const std::vector<DDim>& shapes) : shapes_(shapes) {}
+
+  DDim shape(size_t idx) const override;
+  std::vector<DDim> shapes() const override { return shapes_; }
+
+ protected:
   std::vector<DDim> shapes_;
 };
 
+class ReaderDecorator : public ReaderBase {
+ public:
+  explicit ReaderDecorator(ReaderBase* reader) : reader_(reader) {}
+
+  bool HasNext() const override { return reader_->HasNext(); }
+
+  DDim shape(size_t idx) const override { return reader_->shape(idx); }
+  std::vector<DDim> shapes() const override { return reader_->shapes(); }
+
+ protected:
+  ReaderBase* reader_;
+};
+
 // file readers
 
 template <typename T>
-class RandomReader : public Reader {
+class RandomReader : public FileReader {
  public:
   RandomReader(const std::vector<DDim>& shapes, float min, float max)
-      : Reader(shapes), min_(min), max_(max) {
+      : FileReader(shapes), min_(min), max_(max) {
     PADDLE_ENFORCE_LE(min, max,
                       "'min' should be less than or equal to 'max'.(%f vs %f)",
                       min, max);
@@ -58,8 +74,8 @@ class RandomReader : public Reader {
     std::uniform_real_distribution<float> dist(min_, max_);
 
     std::vector<LoDTensor> res;
-    res.reserve(shapes().size());
-    for (const DDim& shape : shapes()) {
+    res.reserve(shapes_.size());
+    for (const DDim& shape : shapes_) {
       PADDLE_ENFORCE_GE(
           shape.size(), 2,
           "The rank of input data should be 2 at least.(Now it's %d)",
@@ -85,37 +101,27 @@ class RandomReader : public Reader {
 
 // decorators
 
-class ShuffleReader : public Reader {
+class ShuffleReader : public ReaderDecorator {
  public:
-  ShuffleReader(Reader* reader, int buffer_size)
-      : reader_(reader), buffer_size_(buffer_size), iteration_pos_(0) {
+  ShuffleReader(ReaderBase* reader, int buffer_size)
+      : ReaderDecorator(reader), buffer_size_(buffer_size), iteration_pos_(0) {
     buffer_.reserve(buffer_size);
   }
   std::vector<LoDTensor> ReadNext() override;
-  bool HasNext() const override { return reader_->HasNext(); }
-
-  DDim shape(size_t idx) const override { return reader_->shape(idx); }
-  std::vector<DDim> shapes() const override { return reader_->shapes(); }
 
  private:
-  Reader* reader_;
   int buffer_size_;
   std::vector<std::vector<LoDTensor>> buffer_;
   size_t iteration_pos_;
 };
 
-class BatchReader : public Reader {
+class BatchReader : public ReaderDecorator {
  public:
-  BatchReader(Reader* reader, int batch_size)
-      : reader_(reader), batch_size_(batch_size) {}
+  BatchReader(ReaderBase* reader, int batch_size)
+      : ReaderDecorator(reader), batch_size_(batch_size) {}
   std::vector<LoDTensor> ReadNext() override;
-  bool HasNext() const override { return reader_->HasNext(); };
-
-  DDim shape(size_t idx) const override { return reader_->shape(idx); }
-  std::vector<DDim> shapes() const override { return reader_->shapes(); }
 
  private:
-  Reader* reader_;
   int batch_size_;
   std::vector<std::vector<LoDTensor>> buffer_;
 };
-- 
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