"""Interface to the compiler's internal symbol tables"""

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import _symtable

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from _symtable import (USE, DEF_GLOBAL, DEF_NONLOCAL, DEF_LOCAL, DEF_PARAM,

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DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE,

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LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL)

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import weakref

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__all__ = ["symtable", "SymbolTable", "Class", "Function", "Symbol"]

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def symtable(code, filename, compile_type):

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top = _symtable.symtable(code, filename, compile_type)

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return _newSymbolTable(top, filename)

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class SymbolTableFactory:

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def __init__(self):

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self.__memo = weakref.WeakValueDictionary()

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def new(self, table, filename):

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if table.type == _symtable.TYPE_FUNCTION:

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return Function(table, filename)

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if table.type == _symtable.TYPE_CLASS:

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return Class(table, filename)

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return SymbolTable(table, filename)

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def __call__(self, table, filename):

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key = table, filename

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obj = self.__memo.get(key, None)

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if obj is None:

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obj = self.__memo[key] = self.new(table, filename)

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return obj

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_newSymbolTable = SymbolTableFactory()

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class SymbolTable:

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def __init__(self, raw_table, filename):

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self._table = raw_table

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self._filename = filename

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self._symbols = {}

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def __repr__(self):

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if self.__class__ == SymbolTable:

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kind = ""

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else:

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kind = "%s " % self.__class__.__name__

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if self._table.name == "top":

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return "<{0}SymbolTable for module {1}>".format(kind, self._filename)

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else:

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return "<{0}SymbolTable for {1} in {2}>".format(kind,

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self._table.name,

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self._filename)

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def get_type(self):

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if self._table.type == _symtable.TYPE_MODULE:

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return "module"

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if self._table.type == _symtable.TYPE_FUNCTION:

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return "function"

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if self._table.type == _symtable.TYPE_CLASS:

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return "class"

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assert self._table.type in (1, 2, 3), \

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"unexpected type: {0}".format(self._table.type)

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def get_id(self):

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return self._table.id

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def get_name(self):

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return self._table.name

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def get_lineno(self):

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return self._table.lineno

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def is_optimized(self):

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return bool(self._table.type == _symtable.TYPE_FUNCTION)

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def is_nested(self):

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return bool(self._table.nested)

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def has_children(self):

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return bool(self._table.children)

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def get_identifiers(self):

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return self._table.symbols.keys()

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def lookup(self, name):

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sym = self._symbols.get(name)

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if sym is None:

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flags = self._table.symbols[name]

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namespaces = self.__check_children(name)

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module_scope = (self._table.name == "top")

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sym = self._symbols[name] = Symbol(name, flags, namespaces,

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module_scope=module_scope)

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return sym

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def get_symbols(self):

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return [self.lookup(ident) for ident in self.get_identifiers()]

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def __check_children(self, name):

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return [_newSymbolTable(st, self._filename)

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for st in self._table.children

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if st.name == name]

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def get_children(self):

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return [_newSymbolTable(st, self._filename)

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for st in self._table.children]

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class Function(SymbolTable):

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# Default values for instance variables

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__params = None

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__locals = None

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__frees = None

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__globals = None

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__nonlocals = None

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def __idents_matching(self, test_func):

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return tuple(ident for ident in self.get_identifiers()

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if test_func(self._table.symbols[ident]))

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def get_parameters(self):

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if self.__params is None:

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self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)

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return self.__params

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def get_locals(self):

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if self.__locals is None:

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locs = (LOCAL, CELL)

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test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs

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self.__locals = self.__idents_matching(test)

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return self.__locals

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def get_globals(self):

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if self.__globals is None:

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glob = (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)

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test = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) in glob

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self.__globals = self.__idents_matching(test)

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return self.__globals

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def get_nonlocals(self):

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if self.__nonlocals is None:

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self.__nonlocals = self.__idents_matching(lambda x:x & DEF_NONLOCAL)

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return self.__nonlocals

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def get_frees(self):

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if self.__frees is None:

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is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE

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self.__frees = self.__idents_matching(is_free)

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return self.__frees

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class Class(SymbolTable):

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__methods = None

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def get_methods(self):

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if self.__methods is None:

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d = {}

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for st in self._table.children:

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d[st.name] = 1

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self.__methods = tuple(d)

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return self.__methods

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class Symbol:

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def __init__(self, name, flags, namespaces=None, *, module_scope=False):

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self.__name = name

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self.__flags = flags

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self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope()

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self.__namespaces = namespaces or ()

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self.__module_scope = module_scope

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def __repr__(self):

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return "<symbol {0!r}>".format(self.__name)

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def get_name(self):

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return self.__name

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def is_referenced(self):

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return bool(self.__flags & _symtable.USE)

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def is_parameter(self):

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return bool(self.__flags & DEF_PARAM)

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def is_global(self):

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"""Return *True* if the sysmbol is global.

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"""

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return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT)

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or (self.__module_scope and self.__flags & DEF_BOUND))

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def is_nonlocal(self):

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return bool(self.__flags & DEF_NONLOCAL)

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def is_declared_global(self):

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return bool(self.__scope == GLOBAL_EXPLICIT)

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def is_local(self):

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"""Return *True* if the symbol is local.

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"""

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return bool(self.__scope in (LOCAL, CELL)

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or (self.__module_scope and self.__flags & DEF_BOUND))

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def is_annotated(self):

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return bool(self.__flags & DEF_ANNOT)

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def is_free(self):

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return bool(self.__scope == FREE)

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def is_imported(self):

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return bool(self.__flags & DEF_IMPORT)

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def is_assigned(self):

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return bool(self.__flags & DEF_LOCAL)

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def is_namespace(self):

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"""Returns true if name binding introduces new namespace.

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If the name is used as the target of a function or class

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statement, this will be true.

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Note that a single name can be bound to multiple objects. If

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is_namespace() is true, the name may also be bound to other

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objects, like an int or list, that does not introduce a new

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namespace.

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"""

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return bool(self.__namespaces)

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def get_namespaces(self):

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"""Return a list of namespaces bound to this name"""

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return self.__namespaces

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def get_namespace(self):

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"""Returns the single namespace bound to this name.

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Raises ValueError if the name is bound to multiple namespaces.

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"""

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if len(self.__namespaces) != 1:

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raise ValueError("name is bound to multiple namespaces")

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return self.__namespaces[0]

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if __name__ == "__main__":

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import os, sys

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with open(sys.argv[0]) as f:

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src = f.read()

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mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")

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for ident in mod.get_identifiers():

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info = mod.lookup(ident)

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print(info, info.is_local(), info.is_namespace())

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