cpython/Lib/symtable.py

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"""Interface to the compiler's internal symbol tables"""
import _symtable
from _symtable import (USE, DEF_GLOBAL, DEF_NONLOCAL, DEF_LOCAL, DEF_PARAM,
DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE,
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LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL)
import weakref
__all__ = ["symtable", "SymbolTable", "Class", "Function", "Symbol"]
def symtable(code, filename, compile_type):
""" Return the toplevel *SymbolTable* for the source code.
*filename* is the name of the file with the code
and *compile_type* is the *compile()* mode argument.
"""
top = _symtable.symtable(code, filename, compile_type)
return _newSymbolTable(top, filename)
class SymbolTableFactory:
def __init__(self):
self.__memo = weakref.WeakValueDictionary()
def new(self, table, filename):
if table.type == _symtable.TYPE_FUNCTION:
return Function(table, filename)
if table.type == _symtable.TYPE_CLASS:
return Class(table, filename)
return SymbolTable(table, filename)
def __call__(self, table, filename):
key = table, filename
obj = self.__memo.get(key, None)
if obj is None:
obj = self.__memo[key] = self.new(table, filename)
return obj
_newSymbolTable = SymbolTableFactory()
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class SymbolTable(object):
def __init__(self, raw_table, filename):
self._table = raw_table
self._filename = filename
self._symbols = {}
def __repr__(self):
if self.__class__ == SymbolTable:
kind = ""
else:
kind = "%s " % self.__class__.__name__
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if self._table.name == "global":
return "<{0}SymbolTable for module {1}>".format(kind, self._filename)
else:
return "<{0}SymbolTable for {1} in {2}>".format(kind,
self._table.name,
self._filename)
def get_type(self):
"""Return the type of the symbol table.
The values retuned are 'class', 'module' and
'function'.
"""
if self._table.type == _symtable.TYPE_MODULE:
return "module"
if self._table.type == _symtable.TYPE_FUNCTION:
return "function"
if self._table.type == _symtable.TYPE_CLASS:
return "class"
assert self._table.type in (1, 2, 3), \
"unexpected type: {0}".format(self._table.type)
def get_id(self):
"""Return an identifier for the table.
"""
return self._table.id
def get_name(self):
"""Return the table's name.
This corresponds to the name of the class, function
or 'top' if the table is for a class, function or
global respectively.
"""
return self._table.name
def get_lineno(self):
"""Return the number of the first line in the
block for the table.
"""
return self._table.lineno
def is_optimized(self):
"""Return *True* if the locals in the table
are optimizable.
"""
return bool(self._table.type == _symtable.TYPE_FUNCTION)
def is_nested(self):
"""Return *True* if the block is a nested class
or function."""
return bool(self._table.nested)
def has_children(self):
"""Return *True* if the block has nested namespaces.
"""
return bool(self._table.children)
def get_identifiers(self):
"""Return a list of names of symbols in the table.
"""
return self._table.symbols.keys()
def lookup(self, name):
"""Lookup a *name* in the table.
Returns a *Symbol* instance.
"""
sym = self._symbols.get(name)
if sym is None:
flags = self._table.symbols[name]
namespaces = self.__check_children(name)
sym = self._symbols[name] = Symbol(name, flags, namespaces)
return sym
def get_symbols(self):
"""Return a list of *Symbol* instances for
names in the table.
"""
return [self.lookup(ident) for ident in self.get_identifiers()]
def __check_children(self, name):
return [_newSymbolTable(st, self._filename)
for st in self._table.children
if st.name == name]
def get_children(self):
"""Return a list of the nested symbol tables.
"""
return [_newSymbolTable(st, self._filename)
for st in self._table.children]
class Function(SymbolTable):
# Default values for instance variables
__params = None
__locals = None
__frees = None
__globals = None
__nonlocals = None
def __idents_matching(self, test_func):
return tuple(ident for ident in self.get_identifiers()
if test_func(self._table.symbols[ident]))
def get_parameters(self):
"""Return a tuple of parameters to the function.
"""
if self.__params is None:
self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)
return self.__params
def get_locals(self):
"""Return a tuple of locals in the function.
"""
if self.__locals is None:
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locs = (LOCAL, CELL)
test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs
Merged revisions 73376,73393,73398,73400,73404-73405,73409,73419-73421,73432,73457,73460,73485-73486,73488-73489,73501-73502,73513-73514 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73376 | benjamin.peterson | 2009-06-11 17:29:23 -0500 (Thu, 11 Jun 2009) | 1 line remove check for case handled in sub-function ........ r73393 | alexandre.vassalotti | 2009-06-12 13:56:57 -0500 (Fri, 12 Jun 2009) | 2 lines Clear reference to the static PyExc_RecursionErrorInst in _PyExc_Fini. ........ r73398 | alexandre.vassalotti | 2009-06-12 15:57:12 -0500 (Fri, 12 Jun 2009) | 3 lines Add const qualifier to PyErr_SetFromErrnoWithFilename and to PyErr_SetFromErrnoWithUnicodeFilename. ........ r73400 | alexandre.vassalotti | 2009-06-12 16:43:47 -0500 (Fri, 12 Jun 2009) | 2 lines Delete outdated make file for building the parser with MSVC 6. ........ r73404 | benjamin.peterson | 2009-06-12 20:40:00 -0500 (Fri, 12 Jun 2009) | 1 line keep the slice.step field as NULL if no step expression is given ........ r73405 | benjamin.peterson | 2009-06-12 22:46:30 -0500 (Fri, 12 Jun 2009) | 1 line prevent import statements from assigning to None ........ r73409 | benjamin.peterson | 2009-06-13 08:06:21 -0500 (Sat, 13 Jun 2009) | 1 line allow importing from a module named None if it has an 'as' clause ........ r73419 | benjamin.peterson | 2009-06-13 11:19:19 -0500 (Sat, 13 Jun 2009) | 1 line set Print.values to NULL if there are no values ........ r73420 | benjamin.peterson | 2009-06-13 12:08:53 -0500 (Sat, 13 Jun 2009) | 1 line give a better error message when deleting () ........ r73421 | benjamin.peterson | 2009-06-13 15:23:33 -0500 (Sat, 13 Jun 2009) | 1 line when no module is given in a 'from' relative import, make ImportFrom.module NULL ........ r73432 | amaury.forgeotdarc | 2009-06-14 16:20:40 -0500 (Sun, 14 Jun 2009) | 3 lines #6227: Because of a wrong indentation, the test was not testing what it should. Ensure that the snippet in doctest_aliases actually contains aliases. ........ r73457 | benjamin.peterson | 2009-06-16 18:13:09 -0500 (Tue, 16 Jun 2009) | 1 line add underscores ........ r73460 | benjamin.peterson | 2009-06-16 22:23:04 -0500 (Tue, 16 Jun 2009) | 1 line remove unused 'encoding' member from the compiler struct ........ r73485 | benjamin.peterson | 2009-06-19 17:07:47 -0500 (Fri, 19 Jun 2009) | 1 line remove duplicate test ........ r73486 | benjamin.peterson | 2009-06-19 17:09:17 -0500 (Fri, 19 Jun 2009) | 1 line add missing assertion #6313 ........ r73488 | benjamin.peterson | 2009-06-19 17:16:28 -0500 (Fri, 19 Jun 2009) | 1 line show that this one isn't used ........ r73489 | benjamin.peterson | 2009-06-19 17:21:12 -0500 (Fri, 19 Jun 2009) | 1 line use closures ........ r73501 | benjamin.peterson | 2009-06-21 18:01:07 -0500 (Sun, 21 Jun 2009) | 1 line don't need to add the name 'lambda' as assigned ........ r73502 | benjamin.peterson | 2009-06-21 18:03:36 -0500 (Sun, 21 Jun 2009) | 1 line remove tmpname support since it's no longer used ........ r73513 | benjamin.peterson | 2009-06-22 20:18:57 -0500 (Mon, 22 Jun 2009) | 1 line fix grammar ........ r73514 | benjamin.peterson | 2009-06-22 22:01:56 -0500 (Mon, 22 Jun 2009) | 1 line remove some unused symtable constants ........
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self.__locals = self.__idents_matching(test)
return self.__locals
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def get_globals(self):
"""Return a tuple of globals in the function.
"""
if self.__globals is None:
glob = (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)
test = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) in glob
self.__globals = self.__idents_matching(test)
return self.__globals
def get_nonlocals(self):
"""Return a tuple of nonlocals in the function.
"""
if self.__nonlocals is None:
self.__nonlocals = self.__idents_matching(lambda x:x & DEF_NONLOCAL)
return self.__nonlocals
def get_frees(self):
"""Return a tuple of free variables in the function.
"""
if self.__frees is None:
is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE
self.__frees = self.__idents_matching(is_free)
return self.__frees
class Class(SymbolTable):
__methods = None
def get_methods(self):
"""Return a tuple of methods declared in the class.
"""
if self.__methods is None:
d = {}
for st in self._table.children:
d[st.name] = 1
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self.__methods = tuple(d)
return self.__methods
class Symbol(object):
def __init__(self, name, flags, namespaces=None):
self.__name = name
self.__flags = flags
self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope()
self.__namespaces = namespaces or ()
def __repr__(self):
return "<symbol {0!r}>".format(self.__name)
def get_name(self):
"""Return a name of a symbol.
"""
return self.__name
def is_referenced(self):
"""Return *True* if the symbol is used in
its block.
"""
return bool(self.__flags & _symtable.USE)
def is_parameter(self):
"""Return *True* if the symbol is a parameter.
"""
return bool(self.__flags & DEF_PARAM)
def is_global(self):
"""Return *True* if the sysmbol is global.
"""
return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT))
def is_nonlocal(self):
"""Return *True* if the symbol is nonlocal."""
return bool(self.__flags & DEF_NONLOCAL)
def is_declared_global(self):
"""Return *True* if the symbol is declared global
with a global statement."""
return bool(self.__scope == GLOBAL_EXPLICIT)
def is_local(self):
"""Return *True* if the symbol is local.
"""
return bool(self.__scope in (LOCAL, CELL))
def is_annotated(self):
"""Return *True* if the symbol is annotated.
"""
return bool(self.__flags & DEF_ANNOT)
def is_free(self):
"""Return *True* if a referenced symbol is
not assigned to.
"""
return bool(self.__scope == FREE)
def is_imported(self):
"""Return *True* if the symbol is created from
an import statement.
"""
return bool(self.__flags & DEF_IMPORT)
def is_assigned(self):
"""Return *True* if a symbol is assigned to."""
return bool(self.__flags & DEF_LOCAL)
def is_namespace(self):
"""Returns *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
is_namespace() is true, the name may also be bound to other
objects, like an int or list, that does not introduce a new
namespace.
"""
return bool(self.__namespaces)
def get_namespaces(self):
"""Return a list of namespaces bound to this name"""
return self.__namespaces
def get_namespace(self):
"""Return the single namespace bound to this name.
Raises ValueError if the name is bound to multiple namespaces.
"""
if len(self.__namespaces) != 1:
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raise ValueError("name is bound to multiple namespaces")
return self.__namespaces[0]
if __name__ == "__main__":
import os, sys
with open(sys.argv[0]) as f:
src = f.read()
mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
for ident in mod.get_identifiers():
info = mod.lookup(ident)
print(info, info.is_local(), info.is_namespace())