cpython/Doc/library/ast.rst

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Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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.. _ast:
Abstract Syntax Trees
=====================
.. module:: ast
:synopsis: Abstract Syntax Tree classes and manipulation.
.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
.. sectionauthor:: Georg Brandl <georg@python.org>
The :mod:`ast` module helps Python applications to process trees of the Python
abstract syntax grammar. The abstract syntax itself might change with each
Python release; this module helps to find out programmatically what the current
grammar looks like.
An abstract syntax tree can be generated by passing :data:`ast.PyCF_ONLY_AST` as
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a flag to the :func:`compile` built-in function, or using the :func:`parse`
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helper provided in this module. The result will be a tree of objects whose
classes all inherit from :class:`ast.AST`. An abstract syntax tree can be
compiled into a Python code object using the built-in :func:`compile` function.
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Node classes
------------
.. class:: AST
This is the base of all AST node classes. The actual node classes are
derived from the :file:`Parser/Python.asdl` file, which is reproduced
:ref:`below <abstract-grammar>`. They are defined in the :mod:`_ast` C
module and re-exported in :mod:`ast`.
There is one class defined for each left-hand side symbol in the abstract
grammar (for example, :class:`ast.stmt` or :class:`ast.expr`). In addition,
there is one class defined for each constructor on the right-hand side; these
classes inherit from the classes for the left-hand side trees. For example,
:class:`ast.BinOp` inherits from :class:`ast.expr`. For production rules
with alternatives (aka "sums"), the left-hand side class is abstract: only
instances of specific constructor nodes are ever created.
.. attribute:: _fields
Each concrete class has an attribute :attr:`_fields` which gives the names
of all child nodes.
Each instance of a concrete class has one attribute for each child node,
of the type as defined in the grammar. For example, :class:`ast.BinOp`
instances have an attribute :attr:`left` of type :class:`ast.expr`.
If these attributes are marked as optional in the grammar (using a
question mark), the value might be ``None``. If the attributes can have
zero-or-more values (marked with an asterisk), the values are represented
as Python lists. All possible attributes must be present and have valid
values when compiling an AST with :func:`compile`.
.. attribute:: lineno
col_offset
Instances of :class:`ast.expr` and :class:`ast.stmt` subclasses have
:attr:`lineno` and :attr:`col_offset` attributes. The :attr:`lineno` is
the line number of source text (1-indexed so the first line is line 1) and
the :attr:`col_offset` is the UTF-8 byte offset of the first token that
generated the node. The UTF-8 offset is recorded because the parser uses
UTF-8 internally.
The constructor of a class :class:`ast.T` parses its arguments as follows:
* If there are positional arguments, there must be as many as there are items
in :attr:`T._fields`; they will be assigned as attributes of these names.
* If there are keyword arguments, they will set the attributes of the same
names to the given values.
For example, to create and populate an :class:`ast.UnaryOp` node, you could
use ::
node = ast.UnaryOp()
node.op = ast.USub()
node.operand = ast.Num()
node.operand.n = 5
node.operand.lineno = 0
node.operand.col_offset = 0
node.lineno = 0
node.col_offset = 0
or the more compact ::
node = ast.UnaryOp(ast.USub(), ast.Num(5, lineno=0, col_offset=0),
lineno=0, col_offset=0)
.. _abstract-grammar:
Abstract Grammar
----------------
The module defines a string constant ``__version__`` which is the decimal
Subversion revision number of the file shown below.
The abstract grammar is currently defined as follows:
.. literalinclude:: ../../Parser/Python.asdl
:mod:`ast` Helpers
------------------
Apart from the node classes, :mod:`ast` module defines these utility functions
and classes for traversing abstract syntax trees:
.. function:: parse(expr, filename='<unknown>', mode='exec')
Parse an expression into an AST node. Equivalent to ``compile(expr,
filename, mode, ast.PyCF_ONLY_AST)``.
Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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.. function:: literal_eval(node_or_string)
Safely evaluate an expression node or a string containing a Python
expression. The string or node provided may only consist of the following
Python literal structures: strings, numbers, tuples, lists, dicts, booleans,
and ``None``.
This can be used for safely evaluating strings containing Python expressions
from untrusted sources without the need to parse the values oneself.
Merged revisions 64089,64098,64100-64102,64113,64115-64116,64118,64120,64132,64342 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r64089 | armin.ronacher | 2008-06-10 22:37:02 +0200 (mar., 10 juin 2008) | 3 lines Fix a formatting error in the ast documentation. ........ r64098 | raymond.hettinger | 2008-06-11 02:25:29 +0200 (mer., 11 juin 2008) | 6 lines Mini-PEP: Simplifying numbers.py * Convert binary methods in Integral to mixin methods * Remove three-arg __pow__ as a required method * Make __int__ the root method instead of __long__. ........ r64100 | raymond.hettinger | 2008-06-11 02:28:51 +0200 (mer., 11 juin 2008) | 1 line Update numbers doc for the Integral simplification. ........ r64101 | raymond.hettinger | 2008-06-11 02:44:47 +0200 (mer., 11 juin 2008) | 3 lines Handle the case with zero arguments. ........ r64102 | benjamin.peterson | 2008-06-11 03:31:28 +0200 (mer., 11 juin 2008) | 4 lines convert test_struct to a unittest thanks to Giampaolo Rodola I had to disable one test because it was functioning incorrectly, see #1530559 I also removed the debugging prints ........ r64113 | thomas.heller | 2008-06-11 09:10:43 +0200 (mer., 11 juin 2008) | 2 lines Fix markup. Document the new 'offset' parameter for the 'ctypes.byref' function. ........ r64115 | raymond.hettinger | 2008-06-11 12:30:54 +0200 (mer., 11 juin 2008) | 1 line Multi-arg form for set.difference() and set.difference_update(). ........ r64116 | raymond.hettinger | 2008-06-11 14:06:49 +0200 (mer., 11 juin 2008) | 1 line Issue 3051: Let heapq work with either __lt__ or __le__. ........ r64118 | raymond.hettinger | 2008-06-11 14:39:09 +0200 (mer., 11 juin 2008) | 1 line Optimize previous checkin for heapq. ........ r64120 | raymond.hettinger | 2008-06-11 15:14:50 +0200 (mer., 11 juin 2008) | 1 line Add test for heapq using both __lt__ and __le__. ........ r64132 | gregory.p.smith | 2008-06-11 20:00:52 +0200 (mer., 11 juin 2008) | 3 lines Correct an incorrect comment about our #include of stddef.h. (see Doug Evans' comment on python-dev 2008-06-10) ........ r64342 | guido.van.rossum | 2008-06-17 19:38:02 +0200 (mar., 17 juin 2008) | 3 lines Roll back Raymond's -r64098 while we think of something better. (See issue 3056 -- we're close to a resolution but need unittests.) ........
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.. function:: get_docstring(node, clean=True)
Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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Return the docstring of the given *node* (which must be a
:class:`FunctionDef`, :class:`ClassDef` or :class:`Module` node), or ``None``
if it has no docstring. If *clean* is true, clean up the docstring's
indentation with :func:`inspect.cleandoc`.
.. function:: fix_missing_locations(node)
When you compile a node tree with :func:`compile`, the compiler expects
:attr:`lineno` and :attr:`col_offset` attributes for every node that supports
them. This is rather tedious to fill in for generated nodes, so this helper
adds these attributes recursively where not already set, by setting them to
the values of the parent node. It works recursively starting at *node*.
.. function:: increment_lineno(node, n=1)
Increment the line number of each node in the tree starting at *node* by *n*.
This is useful to "move code" to a different location in a file.
.. function:: copy_location(new_node, old_node)
Copy source location (:attr:`lineno` and :attr:`col_offset`) from *old_node*
to *new_node* if possible, and return *new_node*.
.. function:: iter_fields(node)
Yield a tuple of ``(fieldname, value)`` for each field in ``node._fields``
that is present on *node*.
.. function:: iter_child_nodes(node)
Yield all direct child nodes of *node*, that is, all fields that are nodes
and all items of fields that are lists of nodes.
.. function:: walk(node)
Recursively yield all child nodes of *node*, in no specified order. This is
useful if you only want to modify nodes in place and don't care about the
context.
.. class:: NodeVisitor()
A node visitor base class that walks the abstract syntax tree and calls a
visitor function for every node found. This function may return a value
which is forwarded by the :meth:`visit` method.
Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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This class is meant to be subclassed, with the subclass adding visitor
methods.
.. method:: visit(node)
Visit a node. The default implementation calls the method called
:samp:`self.visit_{classname}` where *classname* is the name of the node
class, or :meth:`generic_visit` if that method doesn't exist.
.. method:: generic_visit(node)
This visitor calls :meth:`visit` on all children of the node.
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Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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Note that child nodes of nodes that have a custom visitor method won't be
visited unless the visitor calls :meth:`generic_visit` or visits them
itself.
Don't use the :class:`NodeVisitor` if you want to apply changes to nodes
during traversal. For this a special visitor exists
(:class:`NodeTransformer`) that allows modifications.
.. class:: NodeTransformer()
A :class:`NodeVisitor` subclass that walks the abstract syntax tree and
allows modification of nodes.
The :class:`NodeTransformer` will walk the AST and use the return value of
the visitor methods to replace or remove the old node. If the return value
of the visitor method is ``None``, the node will be removed from its
location, otherwise it is replaced with the return value. The return value
may be the original node in which case no replacement takes place.
Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
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Here is an example transformer that rewrites all occurrences of name lookups
(``foo``) to ``data['foo']``::
class RewriteName(NodeTransformer):
def visit_Name(self, node):
return copy_location(Subscript(
value=Name(id='data', ctx=Load()),
slice=Index(value=Str(s=node.id)),
ctx=node.ctx
), node)
Keep in mind that if the node you're operating on has child nodes you must
either transform the child nodes yourself or call the :meth:`generic_visit`
method for the node first.
For nodes that were part of a collection of statements (that applies to all
statement nodes), the visitor may also return a list of nodes rather than
just a single node.
Usually you use the transformer like this::
node = YourTransformer().visit(node)
.. function:: dump(node, annotate_fields=True, include_attributes=False)
Return a formatted dump of the tree in *node*. This is mainly useful for
debugging purposes. The returned string will show the names and the values
for fields. This makes the code impossible to evaluate, so if evaluation is
wanted *annotate_fields* must be set to False. Attributes such as line
Merged revisions 64434-64435,64440-64443,64445,64447-64448,64450,64452,64455,64461,64464,64466,64468 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r64434 | andrew.kuchling | 2008-06-20 18:13:58 -0500 (Fri, 20 Jun 2008) | 1 line Remove request for e-mail; it's unlikely these classes will be saved ........ r64435 | andrew.kuchling | 2008-06-20 18:14:32 -0500 (Fri, 20 Jun 2008) | 1 line Grammar fixes ........ r64440 | andrew.kuchling | 2008-06-21 08:29:12 -0500 (Sat, 21 Jun 2008) | 1 line Docstring typo ........ r64441 | andrew.kuchling | 2008-06-21 08:47:20 -0500 (Sat, 21 Jun 2008) | 1 line Use repr() for bad input strings; this makes the empty string or binary characters more visible ........ r64442 | andrew.kuchling | 2008-06-21 08:48:38 -0500 (Sat, 21 Jun 2008) | 1 line Docstring correction ........ r64443 | georg.brandl | 2008-06-21 09:26:19 -0500 (Sat, 21 Jun 2008) | 2 lines Documentation fix. ........ r64445 | facundo.batista | 2008-06-21 12:30:06 -0500 (Sat, 21 Jun 2008) | 3 lines Reviewed and updated the documentation. Fixes #3017. ........ r64447 | facundo.batista | 2008-06-21 13:58:04 -0500 (Sat, 21 Jun 2008) | 6 lines Now a from submitted via POST that also has a query string will contain both FieldStorage and MiniFieldStorage items. Fixes #1817. ........ r64448 | facundo.batista | 2008-06-21 14:48:19 -0500 (Sat, 21 Jun 2008) | 5 lines In the deprecated functions I added an alert to review specially a section of the subprocess documentation that helps with the replacing of those functionss. ........ r64450 | georg.brandl | 2008-06-22 04:05:29 -0500 (Sun, 22 Jun 2008) | 2 lines Turn section references into proper cross-references. ........ r64452 | facundo.batista | 2008-06-22 08:36:20 -0500 (Sun, 22 Jun 2008) | 5 lines Issue #2722. Now the char buffer to support the path string has not fixed length, it mallocs memory if needed. As a result, we don't have a maximum for the getcwd() method. ........ r64455 | facundo.batista | 2008-06-22 10:27:10 -0500 (Sun, 22 Jun 2008) | 4 lines Issue 3164. Small fix to don't repeat a comparation without necessity. ........ r64461 | georg.brandl | 2008-06-22 13:11:52 -0500 (Sun, 22 Jun 2008) | 2 lines #3085: Fix syntax error. ........ r64464 | georg.brandl | 2008-06-22 13:31:54 -0500 (Sun, 22 Jun 2008) | 2 lines Expand docstrings of sqlite3 functions. ........ r64466 | georg.brandl | 2008-06-22 14:07:59 -0500 (Sun, 22 Jun 2008) | 2 lines Write out "phi" consistently. ........ r64468 | facundo.batista | 2008-06-22 14:35:24 -0500 (Sun, 22 Jun 2008) | 4 lines Just returning nothing instead of rising TestSkipped, because it makes the test fail in the trunk.loewis-sun buildbot. ........
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numbers and column offsets are not dumped by default. If this is wanted,
Merged revisions 63829-63831,63858,63865,63879,63882,63948,63970-63972,63976,63989,64014-64015,64021-64022,64063-64065,64067 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r63829 | mark.summerfield | 2008-05-31 15:05:34 +0200 (Sat, 31 May 2008) | 4 lines Added a note to [] that special forms & special chars lose their meaning and backrefs can't be used inside [] ........ r63830 | georg.brandl | 2008-05-31 16:40:09 +0200 (Sat, 31 May 2008) | 2 lines #3010: clarification about stdin/use_rawinput. ........ r63831 | georg.brandl | 2008-05-31 16:45:55 +0200 (Sat, 31 May 2008) | 2 lines #3005: add explaining sentence to easydialogs docs. ........ r63858 | georg.brandl | 2008-06-01 18:41:31 +0200 (Sun, 01 Jun 2008) | 2 lines Add plain text make target. ........ r63865 | georg.brandl | 2008-06-01 21:24:36 +0200 (Sun, 01 Jun 2008) | 2 lines Spaces vs. tabs. ........ r63879 | gregory.p.smith | 2008-06-02 00:57:47 +0200 (Mon, 02 Jun 2008) | 3 lines Make the _H #define's match the header file names. Fix comments to mention the correct type names. ........ r63882 | gregory.p.smith | 2008-06-02 01:48:47 +0200 (Mon, 02 Jun 2008) | 3 lines Adds a Thread.getIdent() method to provide the _get_ident() value for any given threading.Thread object. feature request issue 2871. ........ r63948 | alexandre.vassalotti | 2008-06-04 22:41:44 +0200 (Wed, 04 Jun 2008) | 2 lines Fixed complex.__getnewargs__() to not emit another complex object. ........ r63970 | andrew.kuchling | 2008-06-06 01:33:54 +0200 (Fri, 06 Jun 2008) | 1 line Document 'utc' parameter ........ r63971 | andrew.kuchling | 2008-06-06 01:35:31 +0200 (Fri, 06 Jun 2008) | 1 line Add various items ........ r63972 | andrew.kuchling | 2008-06-06 01:35:48 +0200 (Fri, 06 Jun 2008) | 1 line Grammar fix ........ r63976 | georg.brandl | 2008-06-06 09:34:50 +0200 (Fri, 06 Jun 2008) | 2 lines Markup fix. ........ r63989 | thomas.heller | 2008-06-06 20:42:11 +0200 (Fri, 06 Jun 2008) | 2 lines Add a reminder for the maintainer of whatsnew. ........ r64014 | georg.brandl | 2008-06-07 17:59:10 +0200 (Sat, 07 Jun 2008) | 3 lines Factor out docstring dedenting from inspect.getdoc() into inspect.cleandoc() to ease standalone use of the algorithm. ........ r64015 | georg.brandl | 2008-06-07 18:04:01 +0200 (Sat, 07 Jun 2008) | 2 lines Revert unwanted changes. ........ r64021 | georg.brandl | 2008-06-07 20:16:12 +0200 (Sat, 07 Jun 2008) | 2 lines X-ref to numbers module. ........ r64022 | georg.brandl | 2008-06-07 20:17:37 +0200 (Sat, 07 Jun 2008) | 3 lines Document the "st" API, to avoid confusion with the "new" AST. Add a note about using the new AST module. ........ r64063 | martin.v.loewis | 2008-06-10 07:03:35 +0200 (Tue, 10 Jun 2008) | 2 lines Add Gregor Lingl. ........ r64064 | georg.brandl | 2008-06-10 09:45:28 +0200 (Tue, 10 Jun 2008) | 2 lines Add the "ast" module, containing helpers to ease use of the "_ast" classes. ........ r64065 | raymond.hettinger | 2008-06-10 09:57:15 +0200 (Tue, 10 Jun 2008) | 1 line Add Arnaud for his efforts on multi-arg set operations. ........ r64067 | georg.brandl | 2008-06-10 14:46:39 +0200 (Tue, 10 Jun 2008) | 2 lines #2536: fix itertools.permutations and itertools.combinations docstrings. ........
2008-06-10 13:37:50 -03:00
*include_attributes* can be set to ``True``.