modified by luotao's suggestion

paddle/fluid/operators/math/sequence_pooling.cc

@@ -104,11 +104,10 @@ class MaxSeqPoolGradFunctor {
 };
 
 template <typename T>
-class LastFirstSeqPoolFunctor {
+class LastSeqPoolFunctor {
  public:
   void operator()(const platform::CPUDeviceContext& context,
-                  const framework::LoDTensor& input, framework::Tensor* output,
-                  const std::string pooltype) {
+                  const framework::LoDTensor& input, framework::Tensor* output) {
     // Create pointers to input and output data
     auto* in_data = input.data<T>();
     auto* out_data = output->data<T>();
@@ -117,29 +116,40 @@ class LastFirstSeqPoolFunctor {
     int64_t item_size = input.numel() / input.dims()[0];
     auto lod = input.lod()[0];
     int seq_num = static_cast<int>(lod.size()) - 1;
-    if (pooltype == "LAST") {
-      for (int i = 0; i < seq_num; ++i) {
-        // Calculate the length of each sequence
-        int64_t seq_len = static_cast<int64_t>(lod[i + 1] - lod[i]);
-        // Point to the begin of next sequence
-        in_data += seq_len * item_size;
-        // Copy the last item of sequence to output
-        std::memcpy(out_data, (in_data - item_size), item_size * sizeof(T));
-        out_data += item_size;
-      }
-    } else if (pooltype == "FIRST") {
-      for (int i = 0; i < seq_num; ++i) {
-        // Calculate the length of each sequence
-        int64_t seq_len = static_cast<int64_t>(lod[i + 1] - lod[i]);
-        // Copy the first item of sequence to output
-        std::memcpy(out_data, in_data, item_size * sizeof(T));
-        // Point to the next sequence
-        in_data += seq_len * item_size;
-        out_data += item_size;
+    for (int i = 0; i < seq_num; ++i) {
+      // Calculate the length of each sequence
+      int64_t seq_len = static_cast<int64_t>(lod[i + 1] - lod[i]);
+      // Point to the begin of next sequence
+      in_data += seq_len * item_size;
+      // Copy the last item of sequence to output
+      std::memcpy(out_data, (in_data - item_size), item_size * sizeof(T));
+      out_data += item_size;
+     }
+  }
+};
+
+template <typename T>
+class FirstSeqPoolFunctor {
+ public:
+  void operator()(const platform::CPUDeviceContext& context,
+                  const framework::LoDTensor& input, framework::Tensor* output) {
+    // Create pointers to input and output data
+    auto* in_data = input.data<T>();
+    auto* out_data = output->data<T>();
+
+    // Calculate the size of each item in sequence
+    int64_t item_size = input.numel() / input.dims()[0];
+    auto lod = input.lod()[0];
+    int seq_num = static_cast<int>(lod.size()) - 1;
+    for (int i = 0; i < seq_num; ++i) {
+      // Calculate the length of each sequence
+      int64_t seq_len = static_cast<int64_t>(lod[i + 1] - lod[i]);
+      // Copy the first item of sequence to output
+      std::memcpy(out_data, in_data, item_size * sizeof(T));
+      // Point to the next sequence
+      in_data += seq_len * item_size;
+      out_data += item_size;
       }
-    } else {
-      PADDLE_THROW("it's not LAST or FIRST pool type");
-    }
   }
 };
 
@@ -156,11 +166,17 @@ class SequencePoolFunctor<platform::CPUDeviceContext, T> {
       max_pool(context, input, output, index);
       return;
     }
-    if (pooltype == "LAST" || pooltype == "FIRST") {
-      math::LastFirstSeqPoolFunctor<T> lastfirst_pool;
-      lastfirst_pool(context, input, output, pooltype);
+    if (pooltype == "LAST") {
+      math::LastSeqPoolFunctor<T> last_pool;
+      last_pool(context, input, output);
       return;
     }
+    if (pooltype == "FIRST") {
+      math::FirstSeqPoolFunctor<T> first_pool;
+      first_pool(context, input, output);
+      return;
+    }
+
 
     auto lod = input.lod()[0];
     auto& place = *context.eigen_device();