Edit: 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 from enum import StrEnum __all__ = ["symtable", "SymbolTableType", "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 SymbolTableType(StrEnum): MODULE = "module" FUNCTION = "function" CLASS = "class" ANNOTATION = "annotation" TYPE_ALIAS = "type alias" TYPE_PARAMETERS = "type parameters" TYPE_VARIABLE = "type variable" 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 value returned is one of the values in the ``SymbolTableType`` enumeration. """ if self._table.type == _symtable.TYPE_MODULE: return SymbolTableType.MODULE if self._table.type == _symtable.TYPE_FUNCTION: return SymbolTableType.FUNCTION if self._table.type == _symtable.TYPE_CLASS: return SymbolTableType.CLASS if self._table.type == _symtable.TYPE_ANNOTATION: return SymbolTableType.ANNOTATION if self._table.type == _symtable.TYPE_TYPE_ALIAS: return SymbolTableType.TYPE_ALIAS if self._table.type == _symtable.TYPE_TYPE_PARAMETERS: return SymbolTableType.TYPE_PARAMETERS if self._table.type == _symtable.TYPE_TYPE_VARIABLE: return SymbolTableType.TYPE_VARIABLE assert False, f"unexpected type: {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 = {} def is_local_symbol(ident): flags = self._table.symbols.get(ident, 0) return ((flags >> SCOPE_OFF) & SCOPE_MASK) == LOCAL for st in self._table.children: # pick the function-like symbols that are local identifiers if is_local_symbol(st.name): match st.type: case _symtable.TYPE_FUNCTION: # generators are of type TYPE_FUNCTION with a ".0" # parameter as a first parameter (which makes them # distinguishable from a function named 'genexpr') if st.name == 'genexpr' and '.0' in st.varnames: continue d[st.name] = 1 case _symtable.TYPE_TYPE_PARAMETERS: # Get the function-def block in the annotation # scope 'st' with the same identifier, if any. scope_name = st.name for c in st.children: if c.name == scope_name and c.type == _symtable.TYPE_FUNCTION: # A generic generator of type TYPE_FUNCTION # cannot be a direct child of 'st' (but it # can be a descendant), e.g.: # # class A: # type genexpr[genexpr] = (x for x in []) assert scope_name != 'genexpr' or '.0' not in c.varnames d[scope_name] = 1 break 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): flags_str = '|'.join(self._flags_str()) return f'<symbol {self.__name!r}: {self._scope_str()}, {flags_str}>' def _scope_str(self): return _scopes_value_to_name.get(self.__scope) or str(self.__scope) def _flags_str(self): for flagname, flagvalue in _flags: if self.__flags & flagvalue == flagvalue: yield flagname 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] _flags = [('USE', USE)] _flags.extend(kv for kv in globals().items() if kv[0].startswith('DEF_')) _scopes_names = ('FREE', 'LOCAL', 'GLOBAL_IMPLICIT', 'GLOBAL_EXPLICIT', 'CELL') _scopes_value_to_name = {globals()[n]: n for n in _scopes_names} def main(args): import sys def print_symbols(table, level=0): indent = ' ' * level nested = "nested " if table.is_nested() else "" if table.get_type() == 'module': what = f'from file {table._filename!r}' else: what = f'{table.get_name()!r}' print(f'{indent}symbol table for {nested}{table.get_type()} {what}:') for ident in table.get_identifiers(): symbol = table.lookup(ident) flags = ', '.join(symbol._flags_str()).lower() print(f' {indent}{symbol._scope_str().lower()} symbol {symbol.get_name()!r}: {flags}') print() for table2 in table.get_children(): print_symbols(table2, level + 1) for filename in args or ['-']: if filename == '-': src = sys.stdin.read() filename = '<stdin>' else: with open(filename, 'rb') as f: src = f.read() mod = symtable(src, filename, 'exec') print_symbols(mod) if __name__ == "__main__": import sys main(sys.argv[1:])
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