First cut at a high-level symbol table interface
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Jeremy Hylton
parent
987f1332fe
commit
816e149c85
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"""Interface to the compiler's internal symbol tables"""
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from __future__ import nested_scopes
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import _symtable
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from _symtable import USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM, \
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DEF_STAR, DEF_DOUBLESTAR, DEF_INTUPLE, DEF_FREE, \
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DEF_FREE_GLOBAL, DEF_FREE_CLASS, DEF_IMPORT, DEF_BOUND
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import weakref
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__all__ = ["symtable", "SymbolTable", "newSymbolTable"]
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def symtable(code, filename, compile_type):
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raw = _symtable.symtable(code, filename, compile_type)
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return newSymbolTable(raw[0], 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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def bool(x):
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"""Helper to force boolean result to 1 or 0"""
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if x:
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return 1
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return 0
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def is_free(flags):
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if (flags & (USE | DEF_FREE)) \
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and (flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
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return 1
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if flags & DEF_FREE_CLASS:
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return 1
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return 0
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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 == "global":
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return "<%sSymbolTable for module %s>" % (kind, self._filename)
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else:
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return "<%sSymbolTable for %s in %s>" % (kind, 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: %s" % 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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and not self._table.optimized)
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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 has_exec(self):
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return bool()
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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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sym = self._symbols[name] = Symbol(name, flags, namespaces)
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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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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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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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self.__locals = self.__idents_matching(lambda x:x & DEF_BOUND)
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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 = DEF_GLOBAL | DEF_FREE_GLOBAL
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self.__globals = self.__idents_matching(lambda x:x & glob)
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return self.__globals
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def get_frees(self):
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if self.__frees is None:
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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.keys())
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return self.__methods
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class Symbol:
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def __init__(self, name, flags, namespaces=None):
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self.__name = name
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self.__flags = flags
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self.__namespaces = namespaces or ()
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def __repr__(self):
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return "<symbol '%s'>" % 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 bool((self.__flags & DEF_GLOBAL)
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or (self.__flags & DEF_FREE_GLOBAL))
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def is_vararg(self):
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return bool(self.flag & DEF_STAR)
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def is_keywordarg(self):
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return bool(self.__flags & DEF_STARSTAR)
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def is_local(self):
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return bool(self.__flags & DEF_BOUND)
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def is_free(self):
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if (self.__flags & (USE | DEF_FREE)) \
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and (self.__flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
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return 1
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if self.__flags & DEF_FREE_CLASS:
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return 1
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return 0
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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_in_tuple(self):
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return bool(self.__flags & DEF_INTUPLE)
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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 __debug__:
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class Foo:
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version = 1
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class Foo:
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version = 2
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class Foo:
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version = 3
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def execfunc(x):
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exec x in y
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if __name__ == "__main__":
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import os, sys
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src = open(sys.argv[0]).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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