Fix some scripts in the peg generator folder (GH-19853)

Tools/peg_generator/pegen/ast_dump.py

@@ -0,0 +1,63 @@
+"""
+Copy-parse of ast.dump, removing the `isinstance` checks. This is needed,
+because testing pegen requires generating a C extension module, which contains
+a copy of the symbols defined in Python-ast.c. Thus, the isinstance check would
+always fail. We rely on string comparison of the base classes instead.
+TODO: Remove the above-described hack.
+"""
+
+
+def ast_dump(node, annotate_fields=True, include_attributes=False, *, indent=None):
+    def _format(node, level=0):
+        if indent is not None:
+            level += 1
+            prefix = "\n" + indent * level
+            sep = ",\n" + indent * level
+        else:
+            prefix = ""
+            sep = ", "
+        if any(cls.__name__ == "AST" for cls in node.__class__.__mro__):
+            cls = type(node)
+            args = []
+            allsimple = True
+            keywords = annotate_fields
+            for name in node._fields:
+                try:
+                    value = getattr(node, name)
+                except AttributeError:
+                    keywords = True
+                    continue
+                if value is None and getattr(cls, name, ...) is None:
+                    keywords = True
+                    continue
+                value, simple = _format(value, level)
+                allsimple = allsimple and simple
+                if keywords:
+                    args.append("%s=%s" % (name, value))
+                else:
+                    args.append(value)
+            if include_attributes and node._attributes:
+                for name in node._attributes:
+                    try:
+                        value = getattr(node, name)
+                    except AttributeError:
+                        continue
+                    if value is None and getattr(cls, name, ...) is None:
+                        continue
+                    value, simple = _format(value, level)
+                    allsimple = allsimple and simple
+                    args.append("%s=%s" % (name, value))
+            if allsimple and len(args) <= 3:
+                return "%s(%s)" % (node.__class__.__name__, ", ".join(args)), not args
+            return "%s(%s%s)" % (node.__class__.__name__, prefix, sep.join(args)), False
+        elif isinstance(node, list):
+            if not node:
+                return "[]", True
+            return "[%s%s]" % (prefix, sep.join(_format(x, level)[0] for x in node)), False
+        return repr(node), True
+
+    if all(cls.__name__ != "AST" for cls in node.__class__.__mro__):
+        raise TypeError("expected AST, got %r" % node.__class__.__name__)
+    if indent is not None and not isinstance(indent, str):
+        indent = " " * indent
+    return _format(node)[0]