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323 lines
10 KiB
Python
323 lines
10 KiB
Python
"""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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""" Return the toplevel *SymbolTable* for the source code.
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*filename* is the name of the file with the code
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and *compile_type* is the *compile()* mode argument.
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"""
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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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"""Return the type of the symbol table.
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The values retuned are 'class', 'module' and
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'function'.
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"""
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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 an identifier for the table.
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"""
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return self._table.id
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def get_name(self):
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"""Return the table's name.
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This corresponds to the name of the class, function
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or 'top' if the table is for a class, function or
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global respectively.
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"""
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return self._table.name
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def get_lineno(self):
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"""Return the number of the first line in the
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block for the table.
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"""
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return self._table.lineno
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def is_optimized(self):
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"""Return *True* if the locals in the table
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are optimizable.
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"""
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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 *True* if the block is a nested class
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or function."""
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return bool(self._table.nested)
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def has_children(self):
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"""Return *True* if the block has nested namespaces.
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"""
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return bool(self._table.children)
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def get_identifiers(self):
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"""Return a view object containing the names of symbols in the table.
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"""
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return self._table.symbols.keys()
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def lookup(self, name):
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"""Lookup a *name* in the table.
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Returns a *Symbol* instance.
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"""
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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 a list of *Symbol* instances for
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names in the table.
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"""
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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 a list of the nested symbol tables.
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"""
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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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"""Return a tuple of parameters to the function.
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"""
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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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"""Return a tuple of locals in the function.
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"""
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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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"""Return a tuple of globals in the function.
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"""
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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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"""Return a tuple of nonlocals in the function.
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"""
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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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"""Return a tuple of free variables in the function.
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"""
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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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"""Return a tuple of methods declared in the class.
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"""
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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 a name of a symbol.
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"""
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return self.__name
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def is_referenced(self):
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"""Return *True* if the symbol is used in
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its block.
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"""
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return bool(self.__flags & _symtable.USE)
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def is_parameter(self):
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"""Return *True* if the symbol is a parameter.
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"""
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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 *True* if the symbol is nonlocal."""
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return bool(self.__flags & DEF_NONLOCAL)
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def is_declared_global(self):
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"""Return *True* if the symbol is declared global
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with a global statement."""
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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 *True* if the symbol is annotated.
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"""
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return bool(self.__flags & DEF_ANNOT)
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def is_free(self):
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"""Return *True* if a referenced symbol is
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not assigned to.
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"""
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return bool(self.__scope == FREE)
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def is_imported(self):
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"""Return *True* if the symbol is created from
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an import statement.
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"""
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return bool(self.__flags & DEF_IMPORT)
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def is_assigned(self):
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"""Return *True* if a symbol is assigned to."""
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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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"""Return 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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