mirror of
https://github.com/python/cpython.git
synced 2025-11-03 19:34:08 +00:00
366 lines
9.9 KiB
ReStructuredText
366 lines
9.9 KiB
ReStructuredText
:mod:`!symtable` --- Access to the compiler's symbol tables
|
|
===========================================================
|
|
|
|
.. module:: symtable
|
|
:synopsis: Interface to the compiler's internal symbol tables.
|
|
|
|
**Source code:** :source:`Lib/symtable.py`
|
|
|
|
--------------
|
|
|
|
.. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu>
|
|
.. sectionauthor:: Benjamin Peterson <benjamin@python.org>
|
|
|
|
|
|
Symbol tables are generated by the compiler from AST just before bytecode is
|
|
generated. The symbol table is responsible for calculating the scope of every
|
|
identifier in the code. :mod:`symtable` provides an interface to examine these
|
|
tables.
|
|
|
|
|
|
Generating Symbol Tables
|
|
------------------------
|
|
|
|
.. function:: symtable(code, filename, compile_type)
|
|
|
|
Return the toplevel :class:`SymbolTable` for the Python source *code*.
|
|
*filename* is the name of the file containing the code. *compile_type* is
|
|
like the *mode* argument to :func:`compile`.
|
|
|
|
|
|
Examining Symbol Tables
|
|
-----------------------
|
|
|
|
.. class:: SymbolTableType
|
|
|
|
An enumeration indicating the type of a :class:`SymbolTable` object.
|
|
|
|
.. attribute:: MODULE
|
|
:value: "module"
|
|
|
|
Used for the symbol table of a module.
|
|
|
|
.. attribute:: FUNCTION
|
|
:value: "function"
|
|
|
|
Used for the symbol table of a function.
|
|
|
|
.. attribute:: CLASS
|
|
:value: "class"
|
|
|
|
Used for the symbol table of a class.
|
|
|
|
The following members refer to different flavors of
|
|
:ref:`annotation scopes <annotation-scopes>`.
|
|
|
|
.. attribute:: ANNOTATION
|
|
:value: "annotation"
|
|
|
|
Used for annotations if ``from __future__ import annotations`` is active.
|
|
|
|
.. attribute:: TYPE_ALIAS
|
|
:value: "type alias"
|
|
|
|
Used for the symbol table of :keyword:`type` constructions.
|
|
|
|
.. attribute:: TYPE_PARAMETERS
|
|
:value: "type parameters"
|
|
|
|
Used for the symbol table of :ref:`generic functions <generic-functions>`
|
|
or :ref:`generic classes <generic-classes>`.
|
|
|
|
.. attribute:: TYPE_VARIABLE
|
|
:value: "type variable"
|
|
|
|
Used for the symbol table of the bound, the constraint tuple or the
|
|
default value of a single type variable in the formal sense, i.e.,
|
|
a TypeVar, a TypeVarTuple or a ParamSpec object (the latter two do
|
|
not support a bound or a constraint tuple).
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. class:: SymbolTable
|
|
|
|
A namespace table for a block. The constructor is not public.
|
|
|
|
.. method:: get_type()
|
|
|
|
Return the type of the symbol table. Possible values are members
|
|
of the :class:`SymbolTableType` enumeration.
|
|
|
|
.. versionchanged:: 3.12
|
|
Added ``'annotation'``, ``'TypeVar bound'``, ``'type alias'``,
|
|
and ``'type parameter'`` as possible return values.
|
|
|
|
.. versionchanged:: 3.13
|
|
Return values are members of the :class:`SymbolTableType` enumeration.
|
|
|
|
The exact values of the returned string may change in the future,
|
|
and thus, it is recommended to use :class:`SymbolTableType` members
|
|
instead of hard-coded strings.
|
|
|
|
.. method:: get_id()
|
|
|
|
Return the table's identifier.
|
|
|
|
.. method:: get_name()
|
|
|
|
Return the table's name. This is the name of the class if the table is
|
|
for a class, the name of the function if the table is for a function, or
|
|
``'top'`` if the table is global (:meth:`get_type` returns ``'module'``).
|
|
For type parameter scopes (which are used for generic classes, functions,
|
|
and type aliases), it is the name of the underlying class, function, or
|
|
type alias. For type alias scopes, it is the name of the type alias.
|
|
For :class:`~typing.TypeVar` bound scopes, it is the name of the ``TypeVar``.
|
|
|
|
.. method:: get_lineno()
|
|
|
|
Return the number of the first line in the block this table represents.
|
|
|
|
.. method:: is_optimized()
|
|
|
|
Return ``True`` if the locals in this table can be optimized.
|
|
|
|
.. method:: is_nested()
|
|
|
|
Return ``True`` if the block is a nested class or function.
|
|
|
|
.. method:: has_children()
|
|
|
|
Return ``True`` if the block has nested namespaces within it. These can
|
|
be obtained with :meth:`get_children`.
|
|
|
|
.. method:: get_identifiers()
|
|
|
|
Return a view object containing the names of symbols in the table.
|
|
See the :ref:`documentation of view objects <dict-views>`.
|
|
|
|
.. method:: lookup(name)
|
|
|
|
Lookup *name* in the table and return a :class:`Symbol` instance.
|
|
|
|
.. method:: get_symbols()
|
|
|
|
Return a list of :class:`Symbol` instances for names in the table.
|
|
|
|
.. method:: get_children()
|
|
|
|
Return a list of the nested symbol tables.
|
|
|
|
|
|
.. class:: Function
|
|
|
|
A namespace for a function or method. This class inherits from
|
|
:class:`SymbolTable`.
|
|
|
|
.. method:: get_parameters()
|
|
|
|
Return a tuple containing names of parameters to this function.
|
|
|
|
.. method:: get_locals()
|
|
|
|
Return a tuple containing names of locals in this function.
|
|
|
|
.. method:: get_globals()
|
|
|
|
Return a tuple containing names of globals in this function.
|
|
|
|
.. method:: get_nonlocals()
|
|
|
|
Return a tuple containing names of explicitly declared nonlocals in this function.
|
|
|
|
.. method:: get_frees()
|
|
|
|
Return a tuple containing names of :term:`free (closure) variables <closure variable>`
|
|
in this function.
|
|
|
|
|
|
.. class:: Class
|
|
|
|
A namespace of a class. This class inherits from :class:`SymbolTable`.
|
|
|
|
.. method:: get_methods()
|
|
|
|
Return a tuple containing the names of method-like functions declared
|
|
in the class.
|
|
|
|
Here, the term 'method' designates *any* function defined in the class
|
|
body via :keyword:`def` or :keyword:`async def`.
|
|
|
|
Functions defined in a deeper scope (e.g., in an inner class) are not
|
|
picked up by :meth:`get_methods`.
|
|
|
|
For example:
|
|
|
|
.. testsetup:: symtable.Class.get_methods
|
|
|
|
import warnings
|
|
context = warnings.catch_warnings()
|
|
context.__enter__()
|
|
warnings.simplefilter("ignore", category=DeprecationWarning)
|
|
|
|
.. testcleanup:: symtable.Class.get_methods
|
|
|
|
context.__exit__()
|
|
|
|
.. doctest:: symtable.Class.get_methods
|
|
|
|
>>> import symtable
|
|
>>> st = symtable.symtable('''
|
|
... def outer(): pass
|
|
...
|
|
... class A:
|
|
... def f():
|
|
... def w(): pass
|
|
...
|
|
... def g(self): pass
|
|
...
|
|
... @classmethod
|
|
... async def h(cls): pass
|
|
...
|
|
... global outer
|
|
... def outer(self): pass
|
|
... ''', 'test', 'exec')
|
|
>>> class_A = st.get_children()[2]
|
|
>>> class_A.get_methods()
|
|
('f', 'g', 'h')
|
|
|
|
Although ``A().f()`` raises :exc:`TypeError` at runtime, ``A.f`` is still
|
|
considered as a method-like function.
|
|
|
|
.. deprecated-removed:: 3.14 3.16
|
|
|
|
|
|
.. class:: Symbol
|
|
|
|
An entry in a :class:`SymbolTable` corresponding to an identifier in the
|
|
source. The constructor is not public.
|
|
|
|
.. method:: get_name()
|
|
|
|
Return the symbol's name.
|
|
|
|
.. method:: is_referenced()
|
|
|
|
Return ``True`` if the symbol is used in its block.
|
|
|
|
.. method:: is_imported()
|
|
|
|
Return ``True`` if the symbol is created from an import statement.
|
|
|
|
.. method:: is_parameter()
|
|
|
|
Return ``True`` if the symbol is a parameter.
|
|
|
|
.. method:: is_type_parameter()
|
|
|
|
Return ``True`` if the symbol is a type parameter.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. method:: is_global()
|
|
|
|
Return ``True`` if the symbol is global.
|
|
|
|
.. method:: is_nonlocal()
|
|
|
|
Return ``True`` if the symbol is nonlocal.
|
|
|
|
.. method:: is_declared_global()
|
|
|
|
Return ``True`` if the symbol is declared global with a global statement.
|
|
|
|
.. method:: is_local()
|
|
|
|
Return ``True`` if the symbol is local to its block.
|
|
|
|
.. method:: is_annotated()
|
|
|
|
Return ``True`` if the symbol is annotated.
|
|
|
|
.. versionadded:: 3.6
|
|
|
|
.. method:: is_free()
|
|
|
|
Return ``True`` if the symbol is referenced in its block, but not assigned
|
|
to.
|
|
|
|
.. method:: is_free_class()
|
|
|
|
Return *True* if a class-scoped symbol is free from
|
|
the perspective of a method.
|
|
|
|
Consider the following example::
|
|
|
|
def f():
|
|
x = 1 # function-scoped
|
|
class C:
|
|
x = 2 # class-scoped
|
|
def method(self):
|
|
return x
|
|
|
|
In this example, the class-scoped symbol ``x`` is considered to
|
|
be free from the perspective of ``C.method``, thereby allowing
|
|
the latter to return *1* at runtime and not *2*.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. method:: is_assigned()
|
|
|
|
Return ``True`` if the symbol is assigned to in its block.
|
|
|
|
.. method:: is_comp_iter()
|
|
|
|
Return ``True`` if the symbol is a comprehension iteration variable.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. method:: is_comp_cell()
|
|
|
|
Return ``True`` if the symbol is a cell in an inlined comprehension.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. method:: is_namespace()
|
|
|
|
Return ``True`` if name binding introduces new namespace.
|
|
|
|
If the name is used as the target of a function or class statement, this
|
|
will be true.
|
|
|
|
For example::
|
|
|
|
>>> table = symtable.symtable("def some_func(): pass", "string", "exec")
|
|
>>> table.lookup("some_func").is_namespace()
|
|
True
|
|
|
|
Note that a single name can be bound to multiple objects. If the result
|
|
is ``True``, the name may also be bound to other objects, like an int or
|
|
list, that does not introduce a new namespace.
|
|
|
|
.. method:: get_namespaces()
|
|
|
|
Return a list of namespaces bound to this name.
|
|
|
|
.. method:: get_namespace()
|
|
|
|
Return the namespace bound to this name. If more than one or no namespace
|
|
is bound to this name, a :exc:`ValueError` is raised.
|
|
|
|
|
|
.. _symtable-cli:
|
|
|
|
Command-Line Usage
|
|
------------------
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
The :mod:`symtable` module can be executed as a script from the command line.
|
|
|
|
.. code-block:: sh
|
|
|
|
python -m symtable [infile...]
|
|
|
|
Symbol tables are generated for the specified Python source files and
|
|
dumped to stdout.
|
|
If no input file is specified, the content is read from stdin.
|