add some documentation for symtable

Doc/library/language.rst

@@ -16,6 +16,7 @@ These modules include:
 
    parser.rst
    ast.rst
+   symtable.rst
    symbol.rst
    token.rst
    keyword.rst

Doc/library/symtable.rst

@@ -0,0 +1,188 @@
+
+:mod:`symtable` -- Access to the compiler's symbol tables
+=========================================================
+
+.. module:: symtable
+   :synopsis: Interface to the compiler's internal symbol tables.
+
+.. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu>
+.. sectionauthor:: Benjamin Peterson
+
+
+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:: 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 ``'class'``,
+      ``'module'``, and ``'function'``.
+
+   .. 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.
+
+   .. 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 nested in another.
+
+   .. method:: has_children()
+
+      Return ``True`` if the block has nested namespaces within it.  These can
+      be obtained with :meth:`get_children`.
+
+   .. method:: has_exec()
+
+      Return ``True`` if the block uses ``exec``.
+
+   .. method:: has_import_start()
+
+      Return ``True`` if the block uses a starred import.
+
+   .. method:: get_identifiers()
+
+      Return a list of names of symbols in this table.
+
+   .. 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
+   :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_frees()
+
+      Return a tuple containing names of free variables in this function.
+
+
+.. class:: Class
+
+   A namespace of a class.  This class inherits :class:`SymbolTable`.
+
+   .. method:: get_methods()
+
+      Return a tuple containing the names of methods declared in the class.
+
+
+.. class:: Symbol
+
+   An entry in a :class:`SymbolTable` corresponding to a 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_global()
+
+      Return ``True`` if the symbol is global.
+
+   .. method:: is_vararg()
+
+      Return ``True`` if the symbol is a star arg (receives varargs).
+
+   .. method:: is_kewordarg()
+
+      Return ``True`` if symbol is a starred arg (receives keywrod arguments).
+
+   .. method:: is_local()
+
+      Return ``True`` if the symbol is local to its block.
+
+   .. method:: is_free()
+
+      Return ``True`` if the symbol is used in its block, but not declared.
+
+   .. method:: is_assigned()
+
+      Return ``True`` if the symbol is assigned to in its block.
+
+   .. 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.
+
+      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 namespace is
+      bound, a :exc:`ValueError` is raised.