mirror of https://github.com/python/cpython
228 lines
6.2 KiB
ReStructuredText
228 lines
6.2 KiB
ReStructuredText
:mod:`!symtable` --- Access to the compiler's symbol tables
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===========================================================
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.. module:: symtable
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:synopsis: Interface to the compiler's internal symbol tables.
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**Source code:** :source:`Lib/symtable.py`
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--------------
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.. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu>
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.. sectionauthor:: Benjamin Peterson <benjamin@python.org>
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Symbol tables are generated by the compiler from AST just before bytecode is
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generated. The symbol table is responsible for calculating the scope of every
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identifier in the code. :mod:`symtable` provides an interface to examine these
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tables.
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Generating Symbol Tables
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------------------------
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.. function:: symtable(code, filename, compile_type)
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Return the toplevel :class:`SymbolTable` for the Python source *code*.
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*filename* is the name of the file containing the code. *compile_type* is
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like the *mode* argument to :func:`compile`.
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Examining Symbol Tables
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-----------------------
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.. class:: SymbolTable
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A namespace table for a block. The constructor is not public.
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.. method:: get_type()
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Return the type of the symbol table. Possible values are ``'class'``,
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``'module'``, ``'function'``, ``'annotation'``, ``'TypeVar bound'``,
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``'type alias'``, and ``'type parameter'``. The latter four refer to
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different flavors of :ref:`annotation scopes <annotation-scopes>`.
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.. versionchanged:: 3.12
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Added ``'annotation'``, ``'TypeVar bound'``, ``'type alias'``,
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and ``'type parameter'`` as possible return values.
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.. method:: get_id()
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Return the table's identifier.
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.. method:: get_name()
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Return the table's name. This is the name of the class if the table is
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for a class, the name of the function if the table is for a function, or
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``'top'`` if the table is global (:meth:`get_type` returns ``'module'``).
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For type parameter scopes (which are used for generic classes, functions,
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and type aliases), it is the name of the underlying class, function, or
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type alias. For type alias scopes, it is the name of the type alias.
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For :class:`~typing.TypeVar` bound scopes, it is the name of the ``TypeVar``.
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.. method:: get_lineno()
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Return the number of the first line in the block this table represents.
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.. method:: is_optimized()
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Return ``True`` if the locals in this table can be optimized.
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.. method:: is_nested()
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Return ``True`` if the block is a nested class or function.
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.. method:: has_children()
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Return ``True`` if the block has nested namespaces within it. These can
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be obtained with :meth:`get_children`.
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.. method:: get_identifiers()
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Return a view object containing the names of symbols in the table.
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See the :ref:`documentation of view objects <dict-views>`.
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.. method:: lookup(name)
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Lookup *name* in the table and return a :class:`Symbol` instance.
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.. method:: get_symbols()
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Return a list of :class:`Symbol` instances for names in the table.
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.. method:: get_children()
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Return a list of the nested symbol tables.
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.. class:: Function
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A namespace for a function or method. This class inherits from
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:class:`SymbolTable`.
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.. method:: get_parameters()
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Return a tuple containing names of parameters to this function.
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.. method:: get_locals()
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Return a tuple containing names of locals in this function.
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.. method:: get_globals()
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Return a tuple containing names of globals in this function.
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.. method:: get_nonlocals()
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Return a tuple containing names of nonlocals in this function.
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.. method:: get_frees()
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Return a tuple containing names of free variables in this function.
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.. class:: Class
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A namespace of a class. This class inherits from :class:`SymbolTable`.
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.. method:: get_methods()
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Return a tuple containing the names of methods declared in the class.
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.. class:: Symbol
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An entry in a :class:`SymbolTable` corresponding to an identifier in the
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source. The constructor is not public.
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.. method:: get_name()
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Return the symbol's name.
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.. method:: is_referenced()
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Return ``True`` if the symbol is used in its block.
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.. method:: is_imported()
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Return ``True`` if the symbol is created from an import statement.
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.. method:: is_parameter()
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Return ``True`` if the symbol is a parameter.
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.. method:: is_global()
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Return ``True`` if the symbol is global.
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.. method:: is_nonlocal()
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Return ``True`` if the symbol is nonlocal.
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.. method:: is_declared_global()
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Return ``True`` if the symbol is declared global with a global statement.
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.. method:: is_local()
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Return ``True`` if the symbol is local to its block.
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.. method:: is_annotated()
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Return ``True`` if the symbol is annotated.
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.. versionadded:: 3.6
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.. method:: is_free()
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Return ``True`` if the symbol is referenced in its block, but not assigned
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to.
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.. method:: is_assigned()
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Return ``True`` if the symbol is assigned to in its block.
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.. method:: is_namespace()
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Return ``True`` if name binding introduces new namespace.
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If the name is used as the target of a function or class statement, this
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will be true.
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For example::
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>>> table = symtable.symtable("def some_func(): pass", "string", "exec")
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>>> table.lookup("some_func").is_namespace()
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True
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Note that a single name can be bound to multiple objects. If the result
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is ``True``, the name may also be bound to other objects, like an int or
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list, that does not introduce a new namespace.
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.. method:: get_namespaces()
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Return a list of namespaces bound to this name.
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.. method:: get_namespace()
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Return the namespace bound to this name. If more than one or no namespace
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is bound to this name, a :exc:`ValueError` is raised.
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.. _symtable-cli:
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Command-Line Usage
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------------------
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.. versionadded:: 3.13
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The :mod:`symtable` module can be executed as a script from the command line.
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.. code-block:: sh
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python -m symtable [infile...]
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Symbol tables are generated for the specified Python source files and
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dumped to stdout.
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If no input file is specified, the content is read from stdin.
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