Lib/symtable.py

   1 """Interface to the compiler's internal symbol tables"""
   2
   3 import _symtable
   4 from _symtable import USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM, \
   5      DEF_STAR, DEF_DOUBLESTAR, DEF_INTUPLE, DEF_FREE, \
   6      DEF_FREE_GLOBAL, DEF_FREE_CLASS, DEF_IMPORT, DEF_BOUND, \
   7      OPT_IMPORT_STAR, OPT_EXEC, OPT_BARE_EXEC
   8
   9 import weakref
  10
  11 __all__ = ["symtable", "SymbolTable", "newSymbolTable", "Class",
  12            "Function", "Symbol"]
  13
  14 def symtable(code, filename, compile_type):
  15     raw = _symtable.symtable(code, filename, compile_type)
  16     for top in raw.itervalues():
  17         if top.name == 'top':
  18             break
  19     return newSymbolTable(top, filename)
  20
  21 class SymbolTableFactory:
  22     def __init__(self):
  23         self.__memo = weakref.WeakValueDictionary()
  24
  25     def new(self, table, filename):
  26         if table.type == _symtable.TYPE_FUNCTION:
  27             return Function(table, filename)
  28         if table.type == _symtable.TYPE_CLASS:
  29             return Class(table, filename)
  30         return SymbolTable(table, filename)
  31
  32     def __call__(self, table, filename):
  33         key = table, filename
  34         obj = self.__memo.get(key, None)
  35         if obj is None:
  36             obj = self.__memo[key] = self.new(table, filename)
  37         return obj
  38
  39 newSymbolTable = SymbolTableFactory()
  40
  41 def is_free(flags):
  42     if (flags & (USE | DEF_FREE)) \
  43        and (flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
  44         return True
  45     if flags & DEF_FREE_CLASS:
  46         return True
  47     return False
  48
  49 class SymbolTable:
  50     def __init__(self, raw_table, filename):
  51         self._table = raw_table
  52         self._filename = filename
  53         self._symbols = {}
  54
  55     def __repr__(self):
  56         if self.__class__ == SymbolTable:
  57             kind = ""
  58         else:
  59             kind = "%s " % self.__class__.__name__
  60
  61         if self._table.name == "global":
  62             return "<%sSymbolTable for module %s>" % (kind, self._filename)
  63         else:
  64             return "<%sSymbolTable for %s in %s>" % (kind, self._table.name,
  65                                                      self._filename)
  66
  67     def get_type(self):
  68         if self._table.type == _symtable.TYPE_MODULE:
  69             return "module"
  70         if self._table.type == _symtable.TYPE_FUNCTION:
  71             return "function"
  72         if self._table.type == _symtable.TYPE_CLASS:
  73             return "class"
  74         assert self._table.type in (1, 2, 3), \
  75                "unexpected type: %s" % self._table.type
  76
  77     def get_id(self):
  78         return self._table.id
  79
  80     def get_name(self):
  81         return self._table.name
  82
  83     def get_lineno(self):
  84         return self._table.lineno
  85
  86     def is_optimized(self):
  87         return bool(self._table.type == _symtable.TYPE_FUNCTION
  88                     and not self._table.optimized)
  89
  90     def is_nested(self):
  91         return bool(self._table.nested)
  92
  93     def has_children(self):
  94         return bool(self._table.children)
  95
  96     def has_exec(self):
  97         """Return true if the scope uses exec"""
  98         return bool(self._table.optimized & (OPT_EXEC | OPT_BARE_EXEC))
  99
 100     def has_import_star(self):
 101         """Return true if the scope uses import *"""
 102         return bool(self._table.optimized & OPT_IMPORT_STAR)
 103
 104     def get_identifiers(self):
 105         return self._table.symbols.keys()
 106
 107     def lookup(self, name):
 108         sym = self._symbols.get(name)
 109         if sym is None:
 110             flags = self._table.symbols[name]
 111             namespaces = self.__check_children(name)
 112             sym = self._symbols[name] = Symbol(name, flags, namespaces)
 113         return sym
 114
 115     def get_symbols(self):
 116         return [self.lookup(ident) for ident in self.get_identifiers()]
 117
 118     def __check_children(self, name):
 119         return [newSymbolTable(st, self._filename)
 120                 for st in self._table.children
 121                 if st.name == name]
 122
 123     def get_children(self):
 124         return [newSymbolTable(st, self._filename)
 125                 for st in self._table.children]
 126
 127 class Function(SymbolTable):
 128
 129     # Default values for instance variables
 130     __params = None
 131     __locals = None
 132     __frees = None
 133     __globals = None
 134
 135     def __idents_matching(self, test_func):
 136         return tuple([ident for ident in self.get_identifiers()
 137                       if test_func(self._table.symbols[ident])])
 138
 139     def get_parameters(self):
 140         if self.__params is None:
 141             self.__params = self.__idents_matching(lambda x:x & DEF_PARAM)
 142         return self.__params
 143
 144     def get_locals(self):
 145         if self.__locals is None:
 146             self.__locals = self.__idents_matching(lambda x:x & DEF_BOUND)
 147         return self.__locals
 148
 149     def get_globals(self):
 150         if self.__globals is None:
 151             glob = DEF_GLOBAL | DEF_FREE_GLOBAL
 152             self.__globals = self.__idents_matching(lambda x:x & glob)
 153         return self.__globals
 154
 155     def get_frees(self):
 156         if self.__frees is None:
 157             self.__frees = self.__idents_matching(is_free)
 158         return self.__frees
 159
 160 class Class(SymbolTable):
 161
 162     __methods = None
 163
 164     def get_methods(self):
 165         if self.__methods is None:
 166             d = {}
 167             for st in self._table.children:
 168                 d[st.name] = 1
 169             self.__methods = tuple(d)
 170         return self.__methods
 171
 172 class Symbol:
 173     def __init__(self, name, flags, namespaces=None):
 174         self.__name = name
 175         self.__flags = flags
 176         self.__namespaces = namespaces or ()
 177
 178     def __repr__(self):
 179         return "<symbol '%s'>" % self.__name
 180
 181     def get_name(self):
 182         return self.__name
 183
 184     def is_referenced(self):
 185         return bool(self.__flags & _symtable.USE)
 186
 187     def is_parameter(self):
 188         return bool(self.__flags & DEF_PARAM)
 189
 190     def is_global(self):
 191         return bool((self.__flags & DEF_GLOBAL)
 192                     or (self.__flags & DEF_FREE_GLOBAL))
 193
 194     def is_vararg(self):
 195         return bool(self.__flags & DEF_STAR)
 196
 197     def is_keywordarg(self):
 198         return bool(self.__flags & DEF_DOUBLESTAR)
 199
 200     def is_local(self):
 201         return bool(self.__flags & DEF_BOUND)
 202
 203     def is_free(self):
 204         if (self.__flags & (USE | DEF_FREE)) \
 205             and (self.__flags & (DEF_LOCAL | DEF_PARAM | DEF_GLOBAL)):
 206             return True
 207         if self.__flags & DEF_FREE_CLASS:
 208             return True
 209         return False
 210
 211     def is_imported(self):
 212         return bool(self.__flags & DEF_IMPORT)
 213
 214     def is_assigned(self):
 215         return bool(self.__flags & DEF_LOCAL)
 216
 217     def is_in_tuple(self):
 218         return bool(self.__flags & DEF_INTUPLE)
 219
 220     def is_namespace(self):
 221         """Returns true if name binding introduces new namespace.
 222
 223         If the name is used as the target of a function or class
 224         statement, this will be true.
 225
 226         Note that a single name can be bound to multiple objects.  If
 227         is_namespace() is true, the name may also be bound to other
 228         objects, like an int or list, that does not introduce a new
 229         namespace.
 230         """
 231         return bool(self.__namespaces)
 232
 233     def get_namespaces(self):
 234         """Return a list of namespaces bound to this name"""
 235         return self.__namespaces
 236
 237     def get_namespace(self):
 238         """Returns the single namespace bound to this name.
 239
 240         Raises ValueError if the name is bound to multiple namespaces.
 241         """
 242         if len(self.__namespaces) != 1:
 243             raise ValueError, "name is bound to multiple namespaces"
 244         return self.__namespaces[0]
 245
 246 if __name__ == "__main__":
 247     import os, sys
 248     src = open(sys.argv[0]).read()
 249     mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
 250     for ident in mod.get_identifiers():
 251         info = mod.lookup(ident)
 252         print info, info.is_local(), info.is_namespace()