[Dy2stat] Refine code of DygraphToStaticAst (#28103)

* refine code of DygraphToStaticAst

* add __init__ function

python/paddle/fluid/dygraph/dygraph_to_static/ast_transformer.py

@@ -47,6 +47,9 @@ class DygraphToStaticAst(gast.NodeTransformer):
     Main class to transform Dygraph to Static Graph
     """
 
+    def __init__(self):
+        self.translator_logger = logging_utils.TranslatorLogger()
+
     def get_static_ast(self, root):
         # save root for some analysis may need global AST
         self.root = root
@@ -57,71 +60,37 @@ class DygraphToStaticAst(gast.NodeTransformer):
         self.transfer_from_node_type(self.static_analysis_root)
         return self.static_analysis_root
 
+    def _apply(self, transformer, node_wrapper, log_level):
+        transformer(node_wrapper).transform()
+        self.translator_logger.log_transformed_code(log_level, self.root,
+                                                    transformer.__name__)
+
     def transfer_from_node_type(self, node_wrapper):
-        translator_logger = logging_utils.TranslatorLogger()
-        translator_logger.log(
+        self.translator_logger.log(
             1, "Source code: \n{}".format(ast_to_source_code(self.root)))
         # Generic transformation
         self.visit(node_wrapper.node)
 
-        # Transform basic api of dygraph to static graph and get feed_name_to_arg_name
-        BasicApiTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(1, self.root,
-                                               "BasicApiTransformer")
-
-        # Transform Tensor.shape into fluid.layers.shape(Tensor)
-        TensorShapeTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(2, self.root,
-                                               "TensorShapeTransformer")
-
-        # Transform list used in control flow
-        ListTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(3, self.root, "ListTransformer")
-
-        # Transform break/continue in loops
-        BreakContinueTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(4, self.root,
-                                               "BreakContinueTransformer")
-
-        # Transform return in functions
-        ReturnTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(5, self.root,
-                                               "ReturnTransformer")
-
-        # Transform logical and/or/not
-        LogicalTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(6, self.root,
-                                               "LogicalTransformer")
-
-        # Transform for loop and while loop
-        LoopTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(7, self.root, "LoopTransformer")
-
-        # Transform all if/else statement of Dygraph into Static Graph.
-        IfElseTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(8, self.root,
-                                               "IfElseTransformer")
-
-        # Transform python assert statement
-        AssertTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(9, self.root,
-                                               "AssertTransformer")
-
-        # Transform all python print statement
-        PrintTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(10, self.root,
-                                               "PrintTransformer")
-
-        # Transform call recursively
-        CallTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(11, self.root, "CallTransformer")
-
-        # Transform python type casting statement
-        CastTransformer(node_wrapper).transform()
-        translator_logger.log_transformed_code(12, self.root, "CastTransformer")
-
-        translator_logger.log_transformed_code(logging_utils.LOG_AllTransformer,
-                                               self.root, "All Transformers")
+        transformers = [
+            BasicApiTransformer,  # Basic Api
+            TensorShapeTransformer,  # Tensor.shape -> layers.shape(Tensor)
+            ListTransformer,  # List used in control flow
+            BreakContinueTransformer,  # break/continue in loops
+            ReturnTransformer,  # return in functions
+            LogicalTransformer,  # logical and/or/not
+            LoopTransformer,  # for/while -> while_op
+            IfElseTransformer,  # if/else -> cond_op
+            AssertTransformer,  # assert statement
+            PrintTransformer,  # print statement
+            CallTransformer,  # transform call recursively
+            CastTransformer,  # type casting statement
+        ]
+
+        for index, transformer in enumerate(transformers):
+            self._apply(transformer, node_wrapper, log_level=index + 1)
+
+        self.translator_logger.log_transformed_code(
+            logging_utils.LOG_AllTransformer, self.root, "All Transformers")
 
     def visit_FunctionDef(self, node):
         if self.decorate_func_name is None: