Enhanced is_empty_op for our seq2seq model (#10704)

* Added kernel to is_empty_op

* Added python API

* Updated code as required

* Updated unittests

paddle/fluid/operators/is_empty_op.cc

@@ -12,45 +12,41 @@ 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. */
 
+#include "paddle/fluid/operators/is_empty_op.h"
 #include "paddle/fluid/framework/op_registry.h"
 #include "paddle/fluid/framework/operator.h"
 
 namespace paddle {
 namespace operators {
 
-constexpr char kInput[] = "X";
-constexpr char kOutput[] = "Out";
-
-class IsEmptyOp : public framework::OperatorBase {
+class IsEmptyOp : public framework::OperatorWithKernel {
  public:
-  IsEmptyOp(const std::string &type, const framework::VariableNameMap &inputs,
-            const framework::VariableNameMap &outputs,
-            const framework::AttributeMap &attrs)
-      : OperatorBase(type, inputs, outputs, attrs) {}
+  using framework::OperatorWithKernel::OperatorWithKernel;
 
- private:
-  void RunImpl(const framework::Scope &scope,
-               const platform::Place &place) const override {
-    // get input
-    auto *var = scope.FindVar(Input(kInput));
-    PADDLE_ENFORCE_NOT_NULL(var);
-    auto &tensor = var->Get<framework::LoDTensor>();
-    // get output
-    auto *out = scope.FindVar(Output(kOutput));
-    PADDLE_ENFORCE_NOT_NULL(out);
-    auto *out_tensor = out->GetMutable<framework::LoDTensor>();
+ protected:
+  void InferShape(framework::InferShapeContext *ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("X"),
+                   "Input(X) of IsEmptyOp should not be null.");
+    PADDLE_ENFORCE(ctx->HasOutput("Out"),
+                   "Output(Out) of IsEmptyOp should not be null.");
+    ctx->SetOutputDim("Out", {1});
+  }
 
-    out_tensor->Resize({1});
-    out_tensor->mutable_data<bool>(platform::CPUPlace())[0] =
-        framework::product(tensor.dims()) == 0;
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext &ctx) const override {
+    framework::OpKernelType kt = framework::OpKernelType(
+        framework::ToDataType(ctx.Input<framework::LoDTensor>("X")->type()),
+        platform::CPUPlace());
+    return kt;
   }
 };
 
-class IsEmptyOpProtoMaker : public framework::OpProtoAndCheckerMaker {
+class IsEmptyOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   void Make() override {
-    AddInput(kInput, "(Tensor) Tensor which is to be checked.");
-    AddOutput(kOutput, "(Tensor) a boolean Tensor that indicate empty or not.");
+    AddInput("X", "(LoDTensor) Tensor which is to be checked.");
+    AddOutput("Out",
+              "(LoDTensor) a boolean Tensor that indicate empty or not.");
     AddComment(R"DOC(
 IsEmpty Operator which checks whether a tensor is empty.
 
@@ -62,5 +58,12 @@ It will just return product(tensor.ddims()) > 0;
 }  // namespace operators
 }  // namespace paddle
 
-REGISTER_OP_WITHOUT_GRADIENT(is_empty, paddle::operators::IsEmptyOp,
-                             paddle::operators::IsEmptyOpProtoMaker);
+namespace ops = paddle::operators;
+
+REGISTER_OPERATOR(is_empty, ops::IsEmptyOp, ops::IsEmptyOpMaker,
+                  paddle::framework::EmptyGradOpMaker);
+REGISTER_OP_CPU_KERNEL(
+    is_empty, ops::IsEmptyOpKernel<paddle::platform::CPUDeviceContext, float>,
+    ops::IsEmptyOpKernel<paddle::platform::CPUDeviceContext, double>,
+    ops::IsEmptyOpKernel<paddle::platform::CPUDeviceContext, int>,
+    ops::IsEmptyOpKernel<paddle::platform::CPUDeviceContext, int64_t>);

paddle/fluid/operators/is_empty_op.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+
+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
+#include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/framework/operator.h"
+
+namespace paddle {
+namespace operators {
+
+template <typename DeviceContext, typename T>
+class IsEmptyOpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& context) const override {
+    // get input
+    auto* input_tensor = context.Input<framework::LoDTensor>("X");
+    // get output
+    auto* output_tensor = context.Output<framework::LoDTensor>("Out");
+
+    output_tensor->mutable_data<bool>(platform::CPUPlace())[0] =
+        framework::product(input_tensor->dims()) == 0;
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

python/paddle/fluid/layers/control_flow.py

@@ -49,6 +49,7 @@ __all__ = [
     'reorder_lod_tensor_by_rank',
     'ParallelDo',
     'Print',
+    'is_empty',
 ]
 
 
@@ -1562,3 +1563,40 @@ def reorder_lod_tensor_by_rank(x, rank_table):
                 'RankTable': [rank_table]},
         outputs={'Out': [out]})
     return out
+
+
+def is_empty(x, cond=None, **ignored):
+    """
+    **Is Empty**
+
+    This layer returns the truth value of whether the variable is empty.
+
+    Args:
+        x(Variable): Operand of *is_empty*
+        cond(Variable|None): Optional output variable to store the result
+                             of *is_empty*
+
+    Returns:
+        Variable: The tensor variable storing the output of *is_empty*.
+
+    Raises:
+        TypeError: If input cond is not a variable, or cond's dtype is
+                   not bool
+
+    Examples:
+        .. code-block:: python
+
+          less = fluid.layers.is_empty(x=input)
+    """
+    helper = LayerHelper("is_empty", **locals())
+    if cond is None:
+        cond = helper.create_tmp_variable(dtype='bool')
+        cond.stop_gradient = True
+    elif not isinstance(cond, Variable):
+        raise TypeError("cond takes a variable")
+    elif cond.dtype != 'bool':
+        raise TypeError("The data type of cond must be bool")
+
+    helper.append_op(
+        type='is_empty', inputs={'X': [x]}, outputs={'Out': [cond]})
+    return cond

python/paddle/fluid/tests/unittests/test_is_empty_op.py

@@ -14,42 +14,24 @@
 
 import unittest
 import numpy as np
-from paddle.fluid.op import Operator
-import paddle.fluid.core as core
+from op_test import OpTest
 
 
-def create_tensor(scope, name, np_data):
-    tensor = scope.var(name).get_tensor()
-    tensor.set_dims(np_data.shape)
-    tensor.set(np_data, core.CPUPlace())
-    return tensor
-
-
-class TestIsEmptyOp(unittest.TestCase):
+class TestEmpty(OpTest):
     def setUp(self):
-        self.scope = core.Scope()
-        # create input variables
-        np_data0 = np.array([0, 1, 2])
-        create_tensor(self.scope, "X0", np_data0)
-
-        np_data1 = np.array([1])
-        t = create_tensor(self.scope, "X1", np_data1)
-        t.set_dims([0])
+        self.op_type = "is_empty"
+        self.inputs = {'X': np.array([1, 2, 3])}
+        self.outputs = {'Out': np.array([False])}
 
-        # create output variables
-        self.scope.var("out")
+    def test_check_output(self):
+        self.check_output()
 
-    def test_no_empty(self):
-        self.one_case("X0", False)
 
-    def test_empty(self):
-        self.one_case("X1", True)
-
-    def one_case(self, input, target):
-        op = Operator(type="is_empty", X=input, Out="out")
-        op.run(self.scope, core.CPUPlace())
-        out = self.scope.var("out").get_tensor()
-        self.assertEqual(np.array(out)[0], target)
+class TestNotEmpty(TestEmpty):
+    def setUp(self):
+        self.op_type = "is_empty"
+        self.inputs = {'X': np.array([])}
+        self.outputs = {'Out': np.array([True])}
 
 
 if __name__ == "__main__":