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Editing: symtable.py
"""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, 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() class SymbolTable: 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__ if self._table.name == "top": 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 returned 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 view object containing the 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) module_scope = (self._table.name == "top") sym = self._symbols[name] = Symbol(name, flags, namespaces, module_scope=module_scope) 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: locs = (LOCAL, CELL) test = lambda x: ((x >> SCOPE_OFF) & SCOPE_MASK) in locs self.__locals = self.__idents_matching(test) return self.__locals 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 self.__methods = tuple(d) return self.__methods class Symbol: def __init__(self, name, flags, namespaces=None, *, module_scope=False): self.__name = name self.__flags = flags self.__scope = (flags >> SCOPE_OFF) & SCOPE_MASK # like PyST_GetScope() self.__namespaces = namespaces or () self.__module_scope = module_scope 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 symbol is global. """ return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT) or (self.__module_scope and self.__flags & DEF_BOUND)) 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) or (self.__module_scope and self.__flags & DEF_BOUND)) 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 or no namespace. """ if len(self.__namespaces) == 0: raise ValueError("name is not bound to any namespaces") elif len(self.__namespaces) > 1: raise ValueError("name is bound to multiple namespaces") else: 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())
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