!4023 change sampler parameter to support std::move

Merge pull request !4023 from 章一智/cpp_api_sampler

mindspore/ccsrc/minddata/dataset/api/samplers.cc

@@ -71,8 +71,8 @@ std::shared_ptr<SequentialSamplerObj> SequentialSampler(int64_t start_index, int
 }
 
 /// Function to create a Subset Random Sampler.
-std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(const std::vector<int64_t> &indices, int64_t num_samples) {
-  auto sampler = std::make_shared<SubsetRandomSamplerObj>(indices, num_samples);
+std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(std::vector<int64_t> indices, int64_t num_samples) {
+  auto sampler = std::make_shared<SubsetRandomSamplerObj>(std::move(indices), num_samples);
   // Input validation
   if (!sampler->ValidateParams()) {
     return nullptr;
@@ -81,9 +81,9 @@ std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(const std::vector<in
 }
 
 /// Function to create a Weighted Random Sampler.
-std::shared_ptr<WeightedRandomSamplerObj> WeightedRandomSampler(const std::vector<double> &weights, int64_t num_samples,
+std::shared_ptr<WeightedRandomSamplerObj> WeightedRandomSampler(std::vector<double> weights, int64_t num_samples,
                                                                 bool replacement) {
-  auto sampler = std::make_shared<WeightedRandomSamplerObj>(weights, num_samples, replacement);
+  auto sampler = std::make_shared<WeightedRandomSamplerObj>(std::move(weights), num_samples, replacement);
   // Input validation
   if (!sampler->ValidateParams()) {
     return nullptr;
@@ -190,8 +190,8 @@ std::shared_ptr<Sampler> SequentialSamplerObj::Build() {
 }
 
 // SubsetRandomSampler
-SubsetRandomSamplerObj::SubsetRandomSamplerObj(const std::vector<int64_t> &indices, int64_t num_samples)
-    : indices_(indices), num_samples_(num_samples) {}
+SubsetRandomSamplerObj::SubsetRandomSamplerObj(std::vector<int64_t> indices, int64_t num_samples)
+    : indices_(std::move(indices)), num_samples_(num_samples) {}
 
 bool SubsetRandomSamplerObj::ValidateParams() {
   if (num_samples_ < 0) {
@@ -208,9 +208,8 @@ std::shared_ptr<Sampler> SubsetRandomSamplerObj::Build() {
 }
 
 // WeightedRandomSampler
-WeightedRandomSamplerObj::WeightedRandomSamplerObj(const std::vector<double> &weights, int64_t num_samples,
-                                                   bool replacement)
-    : weights_(weights), num_samples_(num_samples), replacement_(replacement) {}
+WeightedRandomSamplerObj::WeightedRandomSamplerObj(std::vector<double> weights, int64_t num_samples, bool replacement)
+    : weights_(std::move(weights)), num_samples_(num_samples), replacement_(replacement) {}
 
 bool WeightedRandomSamplerObj::ValidateParams() {
   if (num_samples_ < 0) {

mindspore/ccsrc/minddata/dataset/include/samplers.h

@@ -87,8 +87,7 @@ std::shared_ptr<SequentialSamplerObj> SequentialSampler(int64_t start_index = 0,
 /// \param[in] indices - A vector sequence of indices.
 /// \param[in] num_samples - The number of samples to draw (default to all elements).
 /// \return Shared pointer to the current Sampler.
-std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(const std::vector<int64_t> &indices,
-                                                            int64_t num_samples = 0);
+std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(std::vector<int64_t> indices, int64_t num_samples = 0);
 
 /// Function to create a Weighted Random Sampler.
 /// \notes Samples the elements from [0, len(weights) - 1] randomly with the given
@@ -97,8 +96,8 @@ std::shared_ptr<SubsetRandomSamplerObj> SubsetRandomSampler(const std::vector<in
 /// \param[in] num_samples - The number of samples to draw (default to all elements).
 /// \param[in] replacement - If True, put the sample ID back for the next draw.
 /// \return Shared pointer to the current Sampler.
-std::shared_ptr<WeightedRandomSamplerObj> WeightedRandomSampler(const std::vector<double> &weights,
-                                                                int64_t num_samples = 0, bool replacement = true);
+std::shared_ptr<WeightedRandomSamplerObj> WeightedRandomSampler(std::vector<double> weights, int64_t num_samples = 0,
+                                                                bool replacement = true);
 
 /* ####################################### Derived Sampler classes ################################# */
 class DistributedSamplerObj : public SamplerObj {
@@ -169,7 +168,7 @@ class SequentialSamplerObj : public SamplerObj {
 
 class SubsetRandomSamplerObj : public SamplerObj {
  public:
-  SubsetRandomSamplerObj(const std::vector<int64_t> &indices, int64_t num_samples);
+  SubsetRandomSamplerObj(std::vector<int64_t> indices, int64_t num_samples);
 
   ~SubsetRandomSamplerObj() = default;
 
@@ -178,14 +177,13 @@ class SubsetRandomSamplerObj : public SamplerObj {
   bool ValidateParams() override;
 
  private:
-  const std::vector<int64_t> &indices_;
+  const std::vector<int64_t> indices_;
   int64_t num_samples_;
 };
 
 class WeightedRandomSamplerObj : public SamplerObj {
  public:
-  explicit WeightedRandomSamplerObj(const std::vector<double> &weights, int64_t num_samples = 0,
-                                    bool replacement = true);
+  explicit WeightedRandomSamplerObj(std::vector<double> weights, int64_t num_samples = 0, bool replacement = true);
 
   ~WeightedRandomSamplerObj() = default;
 
@@ -194,7 +192,7 @@ class WeightedRandomSamplerObj : public SamplerObj {
   bool ValidateParams() override;
 
  private:
-  const std::vector<double> &weights_;
+  const std::vector<double> weights_;
   int64_t num_samples_;
   bool replacement_;
 };

tests/ut/cpp/dataset/c_api_test.cc

@@ -369,6 +369,16 @@ TEST_F(MindDataTestPipeline, TestImageFolderWithSamplers) {
   iter->Stop();
 }
 
+TEST_F(MindDataTestPipeline, TestSamplersMoveParameters) {
+  std::vector<int64_t> indices = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23};
+  std::shared_ptr<SamplerObj> sampl1 = SubsetRandomSampler(indices);
+  EXPECT_FALSE(indices.empty());
+  EXPECT_NE(sampl1->Build(), nullptr);
+  std::shared_ptr<SamplerObj> sampl2 = SubsetRandomSampler(std::move(indices));
+  EXPECT_TRUE(indices.empty());
+  EXPECT_NE(sampl2->Build(), nullptr);
+}
+
 TEST_F(MindDataTestPipeline, TestPad) {
   MS_LOG(INFO) << "Doing MindDataTestPipeline-TestPad.";