mirror of https://github.com/python/cpython
452 lines
15 KiB
Python
452 lines
15 KiB
Python
"""Interface to the compiler's internal symbol tables"""
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import _symtable
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from _symtable import (
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USE,
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DEF_GLOBAL, # noqa: F401
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DEF_NONLOCAL, DEF_LOCAL,
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DEF_PARAM, DEF_TYPE_PARAM, DEF_FREE_CLASS,
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DEF_IMPORT, DEF_BOUND, DEF_ANNOT,
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DEF_COMP_ITER, DEF_COMP_CELL,
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SCOPE_OFF, SCOPE_MASK,
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FREE, LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL
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)
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import weakref
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from enum import StrEnum
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__all__ = ["symtable", "SymbolTableType", "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 SymbolTableType(StrEnum):
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MODULE = "module"
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FUNCTION = "function"
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CLASS = "class"
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ANNOTATION = "annotation"
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TYPE_ALIAS = "type alias"
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TYPE_PARAMETERS = "type parameters"
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TYPE_VARIABLE = "type variable"
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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 value returned is one of the values in
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the ``SymbolTableType`` enumeration.
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"""
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if self._table.type == _symtable.TYPE_MODULE:
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return SymbolTableType.MODULE
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if self._table.type == _symtable.TYPE_FUNCTION:
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return SymbolTableType.FUNCTION
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if self._table.type == _symtable.TYPE_CLASS:
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return SymbolTableType.CLASS
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if self._table.type == _symtable.TYPE_ANNOTATION:
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return SymbolTableType.ANNOTATION
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if self._table.type == _symtable.TYPE_TYPE_ALIAS:
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return SymbolTableType.TYPE_ALIAS
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if self._table.type == _symtable.TYPE_TYPE_PARAMETERS:
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return SymbolTableType.TYPE_PARAMETERS
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if self._table.type == _symtable.TYPE_TYPE_VARIABLE:
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return SymbolTableType.TYPE_VARIABLE
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assert False, f"unexpected type: {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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def _get_scope(flags): # like _PyST_GetScope()
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return (flags >> SCOPE_OFF) & SCOPE_MASK
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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: _get_scope(x) 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: _get_scope(x) 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: _get_scope(x) == 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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import warnings
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typename = f'{self.__class__.__module__}.{self.__class__.__name__}'
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warnings.warn(f'{typename}.get_methods() is deprecated '
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f'and will be removed in Python 3.16.',
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DeprecationWarning, stacklevel=2)
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if self.__methods is None:
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d = {}
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def is_local_symbol(ident):
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flags = self._table.symbols.get(ident, 0)
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return ((flags >> SCOPE_OFF) & SCOPE_MASK) == LOCAL
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for st in self._table.children:
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# pick the function-like symbols that are local identifiers
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if is_local_symbol(st.name):
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match st.type:
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case _symtable.TYPE_FUNCTION:
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# generators are of type TYPE_FUNCTION with a ".0"
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# parameter as a first parameter (which makes them
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# distinguishable from a function named 'genexpr')
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if st.name == 'genexpr' and '.0' in st.varnames:
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continue
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d[st.name] = 1
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case _symtable.TYPE_TYPE_PARAMETERS:
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# Get the function-def block in the annotation
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# scope 'st' with the same identifier, if any.
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scope_name = st.name
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for c in st.children:
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if c.name == scope_name and c.type == _symtable.TYPE_FUNCTION:
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# A generic generator of type TYPE_FUNCTION
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# cannot be a direct child of 'st' (but it
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# can be a descendant), e.g.:
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#
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# class A:
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# type genexpr[genexpr] = (x for x in [])
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assert scope_name != 'genexpr' or '.0' not in c.varnames
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d[scope_name] = 1
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break
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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 = _get_scope(flags)
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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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flags_str = '|'.join(self._flags_str())
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return f'<symbol {self.__name!r}: {self._scope_str()}, {flags_str}>'
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def _scope_str(self):
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return _scopes_value_to_name.get(self.__scope) or str(self.__scope)
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def _flags_str(self):
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for flagname, flagvalue in _flags:
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if self.__flags & flagvalue == flagvalue:
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yield flagname
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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 & 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_type_parameter(self):
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"""Return *True* if the symbol is a type parameter.
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"""
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return bool(self.__flags & DEF_TYPE_PARAM)
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def is_global(self):
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"""Return *True* if the symbol 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_free_class(self):
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"""Return *True* if a class-scoped symbol is free from
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the perspective of a method."""
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return bool(self.__flags & DEF_FREE_CLASS)
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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_comp_iter(self):
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"""Return *True* if the symbol is a comprehension iteration variable.
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"""
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return bool(self.__flags & DEF_COMP_ITER)
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def is_comp_cell(self):
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"""Return *True* if the symbol is a cell in an inlined comprehension.
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"""
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return bool(self.__flags & DEF_COMP_CELL)
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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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or no namespace.
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"""
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if len(self.__namespaces) == 0:
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raise ValueError("name is not bound to any namespaces")
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elif len(self.__namespaces) > 1:
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raise ValueError("name is bound to multiple namespaces")
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else:
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return self.__namespaces[0]
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_flags = [('USE', USE)]
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_flags.extend(kv for kv in globals().items() if kv[0].startswith('DEF_'))
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_scopes_names = ('FREE', 'LOCAL', 'GLOBAL_IMPLICIT', 'GLOBAL_EXPLICIT', 'CELL')
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_scopes_value_to_name = {globals()[n]: n for n in _scopes_names}
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def main(args):
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import sys
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def print_symbols(table, level=0):
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indent = ' ' * level
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nested = "nested " if table.is_nested() else ""
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if table.get_type() == 'module':
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what = f'from file {table._filename!r}'
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else:
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what = f'{table.get_name()!r}'
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print(f'{indent}symbol table for {nested}{table.get_type()} {what}:')
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for ident in table.get_identifiers():
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symbol = table.lookup(ident)
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flags = ', '.join(symbol._flags_str()).lower()
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print(f' {indent}{symbol._scope_str().lower()} symbol {symbol.get_name()!r}: {flags}')
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print()
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for table2 in table.get_children():
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print_symbols(table2, level + 1)
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for filename in args or ['-']:
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if filename == '-':
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src = sys.stdin.read()
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filename = '<stdin>'
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else:
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with open(filename, 'rb') as f:
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src = f.read()
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mod = symtable(src, filename, 'exec')
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print_symbols(mod)
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if __name__ == "__main__":
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import sys
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main(sys.argv[1:])
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