Add type-specific get_children

get_children is elegant and flexible and slow.

    def get_children(self):
        for field in self._astroid_fields:
            attr = getattr(self, field)
            if attr is None:
                continue
            if isinstance(attr, (list, tuple)):
                for elt in attr:
                    yield elt
            else:
                yield attr

It iterates over a list, dynamically accesses attributes, does null
checks, and does type checking. This function gets called a lot, and
all that extra work is a real drag on performance.

In most cases there isn't any need to do any of these checks. Take an
Assign node for instance:

    def get_children(self):
        for elt in self.targets:
            yield elt

        yield self.value

It's known in advance that Assign nodes have a list of targets and a
value, so just yield those without checking anything.

astroid/node_classes.py

@@ -965,6 +965,9 @@ class _BaseContainer(mixins.ParentAssignTypeMixin,
         :rtype: str
         """
+    def get_children(self):
+        yield from self.elts
+
 class LookupMixIn(object):
     """Mixin to look up a name in the right scope."""
@@ -1170,6 +1173,9 @@ class AssignName(LookupMixIn, mixins.ParentAssignTypeMixin, NodeNG):
         super(AssignName, self).__init__(lineno, col_offset, parent)
+    def get_children(self):
+        yield from ()
+
 class DelName(LookupMixIn, mixins.ParentAssignTypeMixin, NodeNG):
     """Variation of :class:`ast.Delete` represention deletion of a name.
@@ -1207,6 +1213,9 @@ class DelName(LookupMixIn, mixins.ParentAssignTypeMixin, NodeNG):
         super(DelName, self).__init__(lineno, col_offset, parent)
+    def get_children(self):
+        yield from ()
+
 class Name(LookupMixIn, NodeNG):
     """Class representing an :class:`ast.Name` node.
@@ -1247,6 +1256,9 @@ class Name(LookupMixIn, NodeNG):
         super(Name, self).__init__(lineno, col_offset, parent)
+    def get_children(self):
+        yield from ()
+
 class Arguments(mixins.AssignTypeMixin, NodeNG):
     """Class representing an :class:`ast.arguments` node.
@@ -1489,16 +1501,28 @@ class Arguments(mixins.AssignTypeMixin, NodeNG):
         return None, None
     def get_children(self):
-        """Get the child nodes below this node.
-        This skips over `None` elements in :attr:`kw_defaults`.
-        :returns: The children.
-        :rtype: iterable(NodeNG)
-        """
-        for child in super(Arguments, self).get_children():
-            if child is not None:
-                yield child
+        yield from self.args or ()
+        yield from self.defaults
+        yield from self.kwonlyargs
+        if self.varargannotation is not None:
+            yield self.varargannotation
+
+        if self.kwargannotation is not None:
+            yield self.kwargannotation
+
+        for elt in self.kw_defaults:
+            if elt is not None:
+                yield elt
+
+        for elt in self.annotations:
+            if elt is not None:
+                yield elt
+
+        for elt in self.kwonlyargs_annotations:
+            if elt is not None:
+                yield elt
 def _find_arg(argname, args, rec=False):
@@ -1587,6 +1611,9 @@ class AssignAttr(mixins.ParentAssignTypeMixin, NodeNG):
         """
         self.expr = expr
+    def get_children(self):
+        yield self.expr
+
 class Assert(Statement):
     """Class representing an :class:`ast.Assert` node.
@@ -1621,6 +1648,12 @@ class Assert(Statement):
         self.fail = fail
         self.test = test
+    def get_children(self):
+        yield self.test
+
+        if self.fail is not None:
+            yield self.fail
+
 class Assign(mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.Assign` node.
@@ -1656,6 +1689,11 @@ class Assign(mixins.AssignTypeMixin, Statement):
         self.targets = targets
         self.value = value
+    def get_children(self):
+        yield from self.targets
+
+        yield self.value
+
 class AnnAssign(mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.AnnAssign` node.
@@ -1711,6 +1749,13 @@ class AnnAssign(mixins.AssignTypeMixin, Statement):
         self.value = value
         self.simple = simple
+    def get_children(self):
+        yield self.target
+        yield self.annotation
+
+        if self.value is not None:
+            yield self.value
+
 class AugAssign(mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.AugAssign` node.
@@ -1792,6 +1837,10 @@ class AugAssign(mixins.AssignTypeMixin, Statement):
         except exceptions.InferenceError:
             return []
+    def get_children(self):
+        yield self.target
+        yield self.value
+
 class Repr(NodeNG):
     """Class representing an :class:`ast.Repr` node.
@@ -1896,6 +1945,10 @@ class BinOp(NodeNG):
         except exceptions.InferenceError:
             return []
+    def get_children(self):
+        yield self.left
+        yield self.right
+
 class BoolOp(NodeNG):
     """Class representing an :class:`ast.BoolOp` node.
@@ -1945,6 +1998,9 @@ class BoolOp(NodeNG):
         """
         self.values = values
+    def get_children(self):
+        yield from self.values
+
 class Break(Statement):
     """Class representing an :class:`ast.Break` node.
@@ -1954,6 +2010,9 @@ class Break(Statement):
     <Break l.1 at 0x7f23b2e9e5c0>
     """
+    def get_children(self):
+        yield from ()
+
 class Call(NodeNG):
     """Class representing an :class:`ast.Call` node.
@@ -2015,6 +2074,13 @@ class Call(NodeNG):
         keywords = self.keywords or []
         return [keyword for keyword in keywords if keyword.arg is None]
+    def get_children(self):
+        yield self.func
+
+        yield from self.args
+
+        yield from self.keywords or ()
+
 class Compare(NodeNG):
     """Class representing an :class:`ast.Compare` node.
@@ -2183,6 +2249,12 @@ class Comprehension(NodeNG):
         return stmts, False
+    def get_children(self):
+        yield self.target
+        yield self.iter
+
+        yield from self.ifs
+
 class Const(NodeNG, bases.Instance):
     """Class representing any constant including num, str, bool, None, bytes.
@@ -2295,6 +2367,9 @@ class Const(NodeNG, bases.Instance):
         """
         return bool(self.value)
+    def get_children(self):
+        yield from ()
+
 class Continue(Statement):
     """Class representing an :class:`ast.Continue` node.
@@ -2304,6 +2379,9 @@ class Continue(Statement):
     <Continue l.1 at 0x7f23b2e35588>
     """
+    def get_children(self):
+        yield from ()
+
 class Decorators(NodeNG):
     """A node representing a list of decorators.
@@ -2345,6 +2423,9 @@ class Decorators(NodeNG):
         # skip the function node to go directly to the upper level scope
         return self.parent.parent.scope()
+    def get_children(self):
+        yield from self.nodes
+
 class DelAttr(mixins.ParentAssignTypeMixin, NodeNG):
     """Variation of :class:`ast.Delete` representing deletion of an attribute.
@@ -2394,6 +2475,9 @@ class DelAttr(mixins.ParentAssignTypeMixin, NodeNG):
         """
         self.expr = expr
+    def get_children(self):
+        yield self.expr
+
 class Delete(mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.Delete` node.
@@ -2419,6 +2503,9 @@ class Delete(mixins.AssignTypeMixin, Statement):
         """
         self.targets = targets
+    def get_children(self):
+        yield from self.targets
+
 class Dict(NodeNG, bases.Instance):
     """Class representing an :class:`ast.Dict` node.
@@ -2579,6 +2666,9 @@ class Expr(Statement):
         """
         self.value = value
+    def get_children(self):
+        yield self.value
+
 class Ellipsis(NodeNG): # pylint: disable=redefined-builtin
     """Class representing an :class:`ast.Ellipsis` node.
@@ -2599,12 +2689,18 @@ class Ellipsis(NodeNG): # pylint: disable=redefined-builtin
         """
         return True
+    def get_children(self):
+        yield from ()
+
 class EmptyNode(NodeNG):
     """Holds an arbitrary object in the :attr:`LocalsDictNodeNG.locals`."""
     object = None
+    def get_children(self):
+        yield from ()
+
 class ExceptHandler(mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.ExceptHandler`. node.
@@ -2639,6 +2735,15 @@ class ExceptHandler(mixins.AssignTypeMixin, Statement):
     :type: list(NodeNG) or None
     """
+    def get_children(self):
+        if self.type is not None:
+            yield self.type
+
+        if self.name is not None:
+            yield self.name
+
+        yield from self.body
+
     # pylint: disable=redefined-builtin; had to use the same name as builtin ast module.
     def postinit(self, type=None, name=None, body=None):
         """Do some setup after initialisation.
@@ -2820,6 +2925,13 @@ class For(mixins.BlockRangeMixIn, mixins.AssignTypeMixin, Statement):
         """
         return self.iter.tolineno
+    def get_children(self):
+        yield self.target
+        yield self.iter
+
+        yield from self.body
+        yield from self.orelse
+
 class AsyncFor(For):
     """Class representing an :class:`ast.AsyncFor` node.
@@ -2871,6 +2983,9 @@ class Await(NodeNG):
         """
         self.value = value
+    def get_children(self):
+        yield self.value
+
 class ImportFrom(mixins.ImportFromMixin, Statement):
     """Class representing an :class:`ast.ImportFrom` node.
@@ -2931,6 +3046,9 @@ class ImportFrom(mixins.ImportFromMixin, Statement):
         super(ImportFrom, self).__init__(lineno, col_offset, parent)
+    def get_children(self):
+        yield from ()
+
 class Attribute(NodeNG):
     """Class representing an :class:`ast.Attribute` node."""
@@ -2973,6 +3091,9 @@ class Attribute(NodeNG):
         """
         self.expr = expr
+    def get_children(self):
+        yield self.expr
+
 class Global(Statement):
     """Class representing an :class:`ast.Global` node.
@@ -3009,6 +3130,9 @@ class Global(Statement):
     def _infer_name(self, frame, name):
         return name
+    def get_children(self):
+        yield from ()
+
 class If(mixins.BlockRangeMixIn, Statement):
     """Class representing an :class:`ast.If` node.
@@ -3075,6 +3199,12 @@ class If(mixins.BlockRangeMixIn, Statement):
         return self._elsed_block_range(lineno, self.orelse,
                                        self.body[0].fromlineno - 1)
+    def get_children(self):
+        yield self.test
+
+        yield from self.body
+        yield from self.orelse
+
 class IfExp(NodeNG):
     """Class representing an :class:`ast.IfExp` node.
@@ -3116,6 +3246,12 @@ class IfExp(NodeNG):
         self.body = body
         self.orelse = orelse
+    def get_children(self):
+        yield self.test
+        yield self.body
+        yield self.orelse
+
+
 class Import(mixins.ImportFromMixin, Statement):
     """Class representing an :class:`ast.Import` node.
@@ -3151,6 +3287,9 @@ class Import(mixins.ImportFromMixin, Statement):
         super(Import, self).__init__(lineno, col_offset, parent)
+    def get_children(self):
+        yield from ()
+
 class Index(NodeNG):
     """Class representing an :class:`ast.Index` node.
@@ -3178,6 +3317,9 @@ class Index(NodeNG):
         """
         self.value = value
+    def get_children(self):
+        yield self.value
+
 class Keyword(NodeNG):
     """Class representing an :class:`ast.keyword` node.
@@ -3227,6 +3369,9 @@ class Keyword(NodeNG):
         """
         self.value = value
+    def get_children(self):
+        yield self.value
+
 class List(_BaseContainer):
     """Class representing an :class:`ast.List` node.
@@ -3318,6 +3463,9 @@ class Nonlocal(Statement):
     def _infer_name(self, frame, name):
         return name
+    def get_children(self):
+        yield from ()
+
 class Pass(Statement):
     """Class representing an :class:`ast.Pass` node.
@@ -3327,6 +3475,9 @@ class Pass(Statement):
     <Pass l.1 at 0x7f23b2e9e748>
     """
+    def get_children(self):
+        yield from ()
+
 class Print(Statement):
     """Class representing an :class:`ast.Print` node.
@@ -3428,6 +3579,13 @@ class Raise(Statement):
                 return True
         return False
+    def get_children(self):
+        if self.exc is not None:
+            yield self.exc
+
+        if self.cause is not None:
+            yield self.cause
+
 class Return(Statement):
     """Class representing an :class:`ast.Return` node.
@@ -3451,6 +3609,10 @@ class Return(Statement):
         """
         self.value = value
+    def get_children(self):
+        if self.value is not None:
+            yield self.value
+
 class Set(_BaseContainer):
     """Class representing an :class:`ast.Set` node.
@@ -3554,6 +3716,16 @@ class Slice(NodeNG):
     def getattr(self, attrname, context=None):
         return self._proxied.getattr(attrname, context)
+    def get_children(self):
+        if self.lower is not None:
+            yield self.lower
+
+        if self.step is not None:
+            yield self.step
+
+        if self.upper is not None:
+            yield self.upper
+
 class Starred(mixins.ParentAssignTypeMixin, NodeNG):
     """Class representing an :class:`ast.Starred` node.
@@ -3602,6 +3774,9 @@ class Starred(mixins.ParentAssignTypeMixin, NodeNG):
         """
         self.value = value
+    def get_children(self):
+        yield self.value
+
 class Subscript(NodeNG):
     """Class representing an :class:`ast.Subscript` node.
@@ -3660,6 +3835,10 @@ class Subscript(NodeNG):
         self.value = value
         self.slice = slice
+    def get_children(self):
+        yield self.value
+        yield self.slice
+
 class TryExcept(mixins.BlockRangeMixIn, Statement):
     """Class representing an :class:`ast.TryExcept` node.
@@ -3729,6 +3908,12 @@ class TryExcept(mixins.BlockRangeMixIn, Statement):
                 last = exhandler.body[0].fromlineno - 1
         return self._elsed_block_range(lineno, self.orelse, last)
+    def get_children(self):
+        yield from self.body
+
+        yield from self.handlers or ()
+        yield from self.orelse or ()
+
 class TryFinally(mixins.BlockRangeMixIn, Statement):
     """Class representing an :class:`ast.TryFinally` node.
@@ -3785,6 +3970,10 @@ class TryFinally(mixins.BlockRangeMixIn, Statement):
             return child.block_range(lineno)
         return self._elsed_block_range(lineno, self.finalbody)
+    def get_children(self):
+        yield from self.body
+        yield from self.finalbody
+
 class Tuple(_BaseContainer):
     """Class representing an :class:`ast.Tuple` node.
@@ -3903,6 +4092,9 @@ class UnaryOp(NodeNG):
         except exceptions.InferenceError:
             return []
+    def get_children(self):
+        yield self.operand
+
 class While(mixins.BlockRangeMixIn, Statement):
     """Class representing an :class:`ast.While` node.
@@ -3967,6 +4159,12 @@ class While(mixins.BlockRangeMixIn, Statement):
         """
         return self. _elsed_block_range(lineno, self.orelse)
+    def get_children(self):
+        yield self.test
+
+        yield from self.body
+        yield from self.orelse
+
 class With(mixins.BlockRangeMixIn, mixins.AssignTypeMixin, Statement):
     """Class representing an :class:`ast.With` node.
@@ -4051,6 +4249,10 @@ class Yield(NodeNG):
         """
         self.value = value
+    def get_children(self):
+        if self.value is not None:
+            yield self.value
+
 class YieldFrom(Yield):
     """Class representing an :class:`ast.YieldFrom` node."""
@@ -4059,6 +4261,9 @@ class YieldFrom(Yield):
 class DictUnpack(NodeNG):
     """Represents the unpacking of dicts into dicts using :pep:`448`."""
+    def get_children(self):
+        yield from ()
+
 class FormattedValue(NodeNG):
     """Class representing an :class:`ast.FormattedValue` node.
@@ -4110,6 +4315,12 @@ class FormattedValue(NodeNG):
         self.conversion = conversion
         self.format_spec = format_spec
+    def get_children(self):
+        yield self.value
+
+        if self.format_spec is not None:
+            yield self.format_spec
+
 class JoinedStr(NodeNG):
     """Represents a list of string expressions to be joined.
@@ -4134,6 +4345,9 @@ class JoinedStr(NodeNG):
         """
         self.values = values
+    def get_children(self):
+        yield from self.values
+
 class Unknown(mixins.AssignTypeMixin, NodeNG):
     """This node represents a node in a constructed AST where

astroid/scoped_nodes.py

@@ -696,6 +696,10 @@ class Module(LocalsDictNodeNG):
         """
         return True
+    def get_children(self):
+        for elt in self.body:
+            yield elt
+
 class ComprehensionScope(LocalsDictNodeNG):
     """Scoping for different types of comprehensions."""
@@ -777,6 +781,11 @@ class GeneratorExp(ComprehensionScope):
         """
         return True
+    def get_children(self):
+        yield self.elt
+
+        yield from self.generators
+
 class DictComp(ComprehensionScope):
     """Class representing an :class:`ast.DictComp` node.
@@ -851,6 +860,12 @@ class DictComp(ComprehensionScope):
         """
         return util.Uninferable
+    def get_children(self):
+        yield self.key
+        yield self.value
+
+        yield from self.generators
+
 class SetComp(ComprehensionScope):
     """Class representing an :class:`ast.SetComp` node.
@@ -916,6 +931,11 @@ class SetComp(ComprehensionScope):
         """
         return util.Uninferable
+    def get_children(self):
+        yield self.elt
+
+        yield from self.generators
+
 class _ListComp(node_classes.NodeNG):
     """Class representing an :class:`ast.ListComp` node.
@@ -957,6 +977,11 @@ class _ListComp(node_classes.NodeNG):
         """
         return util.Uninferable
+    def get_children(self):
+        yield self.elt
+
+        yield from self.generators
+
 class ListComp(_ListComp, ComprehensionScope):
     """Class representing an :class:`ast.ListComp` node.
@@ -1174,6 +1199,10 @@ class Lambda(mixins.FilterStmtsMixin, LocalsDictNodeNG):
         """
         return True
+    def get_children(self):
+        yield self.args
+        yield self.body
+
 class FunctionDef(node_classes.Statement, Lambda):
     """Class representing an :class:`ast.FunctionDef`.
@@ -1554,6 +1583,18 @@ class FunctionDef(node_classes.Statement, Lambda):
         """
         return True
+    def get_children(self):
+        if self.decorators is not None:
+            yield self.decorators
+
+        yield self.args
+
+        if self.returns is not None:
+            yield self.returns
+
+        for elt in self.body:
+            yield elt
+
 class AsyncFunctionDef(FunctionDef):
     """Class representing an :class:`ast.FunctionDef` node.
@@ -2651,6 +2692,16 @@ class ClassDef(mixins.FilterStmtsMixin, LocalsDictNodeNG,
         """
         return True
+    def get_children(self):
+        for elt in self.body:
+            yield elt
+
+        for elt in self.bases:
+            yield elt
+
+        if self.decorators is not None:
+            yield self.decorators
+
 # Backwards-compatibility aliases
 Class = util.proxy_alias('Class', ClassDef)