diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst index 92bf8912eb53dd..cb8e7ec829bed7 100644 --- a/Doc/library/ast.rst +++ b/Doc/library/ast.rst @@ -319,7 +319,7 @@ and classes for traversing abstract syntax trees: node = YourTransformer().visit(node) -.. function:: dump(node, annotate_fields=True, include_attributes=False) +.. function:: dump(node, annotate_fields=True, include_attributes=False, *, indent=None) Return a formatted dump of the tree in *node*. This is mainly useful for debugging purposes. If *annotate_fields* is true (by default), @@ -329,6 +329,17 @@ and classes for traversing abstract syntax trees: numbers and column offsets are not dumped by default. If this is wanted, *include_attributes* can be set to true. + If *indent* is a non-negative integer or string, then the tree will be + pretty-printed with that indent level. An indent level + of 0, negative, or ``""`` will only insert newlines. ``None`` (the default) + selects the single line representation. Using a positive integer indent + indents that many spaces per level. If *indent* is a string (such as ``"\t"``), + that string is used to indent each level. + + .. versionchanged:: 3.9 + Added the *indent* option. + + .. seealso:: `Green Tree Snakes `_, an external documentation resource, has good diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst index e20ae47462eb42..fb1d27c5346d4a 100644 --- a/Doc/whatsnew/3.9.rst +++ b/Doc/whatsnew/3.9.rst @@ -109,6 +109,14 @@ New Modules Improved Modules ================ +ast +--- + +Added the *indent* option to :func:`~ast.dump` which allows it to produce a +multiline indented output. +(Contributed by Serhiy Storchaka in :issue:`37995`.) + + threading --------- diff --git a/Lib/ast.py b/Lib/ast.py index 5ab023f6c3c069..498484f1985599 100644 --- a/Lib/ast.py +++ b/Lib/ast.py @@ -96,7 +96,7 @@ def _convert(node): return _convert(node_or_string) -def dump(node, annotate_fields=True, include_attributes=False): +def dump(node, annotate_fields=True, include_attributes=False, *, indent=None): """ Return a formatted dump of the tree in node. This is mainly useful for debugging purposes. If annotate_fields is true (by default), @@ -104,11 +104,21 @@ def dump(node, annotate_fields=True, include_attributes=False): If annotate_fields is false, the result string will be more compact by omitting unambiguous field names. Attributes such as line numbers and column offsets are not dumped by default. If this is wanted, - include_attributes can be set to true. + include_attributes can be set to true. If indent is a non-negative + integer or string, then the tree will be pretty-printed with that indent + level. None (the default) selects the single line representation. """ - def _format(node): + def _format(node, level=0): + if indent is not None: + level += 1 + prefix = '\n' + indent * level + sep = ',\n' + indent * level + else: + prefix = '' + sep = ', ' if isinstance(node, AST): args = [] + allsimple = True keywords = annotate_fields for field in node._fields: try: @@ -116,23 +126,36 @@ def _format(node): except AttributeError: keywords = True else: + value, simple = _format(value, level) + allsimple = allsimple and simple if keywords: - args.append('%s=%s' % (field, _format(value))) + args.append('%s=%s' % (field, value)) else: - args.append(_format(value)) + args.append(value) if include_attributes and node._attributes: - for a in node._attributes: + for attr in node._attributes: try: - args.append('%s=%s' % (a, _format(getattr(node, a)))) + value = getattr(node, attr) except AttributeError: pass - return '%s(%s)' % (node.__class__.__name__, ', '.join(args)) + else: + value, simple = _format(value, level) + allsimple = allsimple and simple + args.append('%s=%s' % (attr, 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): - return '[%s]' % ', '.join(_format(x) for x in node) - return repr(node) + 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 not isinstance(node, AST): raise TypeError('expected AST, got %r' % node.__class__.__name__) - return _format(node) + if indent is not None and not isinstance(indent, str): + indent = ' ' * indent + return _format(node)[0] def copy_location(new_node, old_node): diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py index 07bbb4cc772305..47e259eb2656c7 100644 --- a/Lib/test/test_ast.py +++ b/Lib/test/test_ast.py @@ -645,6 +645,68 @@ def test_dump(self): "lineno=1, col_offset=0, end_lineno=1, end_col_offset=24)], type_ignores=[])" ) + def test_dump_indent(self): + node = ast.parse('spam(eggs, "and cheese")') + self.assertEqual(ast.dump(node, indent=3), """\ +Module( + body=[ + Expr( + value=Call( + func=Name(id='spam', ctx=Load()), + args=[ + Name(id='eggs', ctx=Load()), + Constant(value='and cheese', kind=None)], + keywords=[]))], + type_ignores=[])""") + self.assertEqual(ast.dump(node, annotate_fields=False, indent='\t'), """\ +Module( +\t[ +\t\tExpr( +\t\t\tCall( +\t\t\t\tName('spam', Load()), +\t\t\t\t[ +\t\t\t\t\tName('eggs', Load()), +\t\t\t\t\tConstant('and cheese', None)], +\t\t\t\t[]))], +\t[])""") + self.assertEqual(ast.dump(node, include_attributes=True, indent=3), """\ +Module( + body=[ + Expr( + value=Call( + func=Name( + id='spam', + ctx=Load(), + lineno=1, + col_offset=0, + end_lineno=1, + end_col_offset=4), + args=[ + Name( + id='eggs', + ctx=Load(), + lineno=1, + col_offset=5, + end_lineno=1, + end_col_offset=9), + Constant( + value='and cheese', + kind=None, + lineno=1, + col_offset=11, + end_lineno=1, + end_col_offset=23)], + keywords=[], + lineno=1, + col_offset=0, + end_lineno=1, + end_col_offset=24), + lineno=1, + col_offset=0, + end_lineno=1, + end_col_offset=24)], + type_ignores=[])""") + def test_dump_incomplete(self): node = ast.Raise(lineno=3, col_offset=4) self.assertEqual(ast.dump(node), diff --git a/Misc/NEWS.d/next/Library/2019-08-31-13-36-09.bpo-37995.rS8HzT.rst b/Misc/NEWS.d/next/Library/2019-08-31-13-36-09.bpo-37995.rS8HzT.rst new file mode 100644 index 00000000000000..19482b644e14df --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-08-31-13-36-09.bpo-37995.rS8HzT.rst @@ -0,0 +1,2 @@ +Added the *indent* option to :func:`ast.dump` which allows it to produce a +multiline indented output.