add insert_op for block

python/paddle/fluid/framework.py

@@ -659,7 +659,7 @@ class Block(object):
     def __init__(self, program, idx):
         self.desc = program.desc.block(idx)
         self.vars = dict()  # var_name --> var
-        self.ops = collections.deque()  # operator list
+        self.ops = list()  # operator list
         self.program = program
         self.removed_vars = dict()
 
@@ -831,6 +831,13 @@ class Block(object):
         self.ops.append(op)
         return op
 
+    def insert_op(self, index, *args, **kwargs):
+        self.sync_with_cpp()
+        op_desc = self.desc.insert_op(index)
+        op = Operator(block=self, desc=op_desc, *args, **kwargs)
+        self.ops.insert(index, op)
+        return op
+
     def delete_ops(self, ops):
         # remove from cpp
         # FIXME(typhoonzero): remove only the first occurrence.
@@ -842,12 +849,12 @@ class Block(object):
         self.desc.remove_op(start, end + 1)
 
     def slice_ops(self, start, end):
-        return list(self.ops)[start:end]
+        return self.ops[start:end]
 
     def prepend_op(self, *args, **kwargs):
         op_desc = self.desc.prepend_op()
         op = Operator(self, op_desc, *args, **kwargs)
-        self.ops.appendleft(op)
+        self.ops.insert(0, op)
         return op
 
     def sync_with_cpp(self):
@@ -892,7 +899,7 @@ class Block(object):
         for index in range((start_index - 1 - 1), -1, -1):
             op_desc = ops_in_cpp[index]
             op = Operator(self, op_desc)
-            self.ops.appendleft(op)
+            self.ops.insert(0, op)
 
         # sync ops append to the end of cpp_ops
         for index in range((end_index + 1), len(ops_in_cpp)):