Lib/compiler/symbols.py

   1 """Module symbol-table generator"""
   2
   3 from compiler import ast
   4 from compiler.consts import SC_LOCAL, SC_GLOBAL, SC_FREE, SC_CELL, SC_UNKNOWN
   5 import types
   6
   7 import sys
   8
   9 MANGLE_LEN = 256
  10
  11 class Scope:
  12     # XXX how much information do I need about each name?
  13     def __init__(self, name, module, klass=None):
  14         self.name = name
  15         self.module = module
  16         self.defs = {}
  17         self.uses = {}
  18         self.globals = {}
  19         self.params = {}
  20         self.frees = {}
  21         self.cells = {}
  22         self.children = []
  23         # nested is true if the class could contain free variables,
  24         # i.e. if it is nested within another function.
  25         self.nested = None
  26         self.klass = None
  27         if klass is not None:
  28             for i in range(len(klass)):
  29                 if klass[i] != '_':
  30                     self.klass = klass[i:]
  31                     break
  32
  33     def __repr__(self):
  34         return "<%s: %s>" % (self.__class__.__name__, self.name)
  35
  36     def mangle(self, name):
  37         if self.klass is None:
  38             return name
  39         if not name.startswith('__'):
  40             return name
  41         if len(name) + 2 >= MANGLE_LEN:
  42             return name
  43         if name.endswith('__'):
  44             return name
  45         return "_%s%s" % (self.klass, name)
  46
  47     def add_def(self, name):
  48         self.defs[self.mangle(name)] = 1
  49
  50     def add_use(self, name):
  51         self.uses[self.mangle(name)] = 1
  52
  53     def add_global(self, name):
  54         name = self.mangle(name)
  55         if self.uses.has_key(name) or self.defs.has_key(name):
  56             pass # XXX warn about global following def/use
  57         if self.params.has_key(name):
  58             raise SyntaxError, "%s in %s is global and parameter" % \
  59                   (name, self.name)
  60         self.globals[name] = 1
  61         self.module.add_def(name)
  62
  63     def add_param(self, name):
  64         name = self.mangle(name)
  65         self.defs[name] = 1
  66         self.params[name] = 1
  67
  68     def get_names(self):
  69         d = {}
  70         d.update(self.defs)
  71         d.update(self.uses)
  72         d.update(self.globals)
  73         return d.keys()
  74
  75     def add_child(self, child):
  76         self.children.append(child)
  77
  78     def get_children(self):
  79         return self.children
  80
  81     def DEBUG(self):
  82         return
  83         print >> sys.stderr, self.name, self.nested and "nested" or ""
  84         print >> sys.stderr, "\tglobals: ", self.globals
  85         print >> sys.stderr, "\tcells: ", self.cells
  86         print >> sys.stderr, "\tdefs: ", self.defs
  87         print >> sys.stderr, "\tuses: ", self.uses
  88         print >> sys.stderr, "\tfrees:", self.frees
  89
  90     def check_name(self, name):
  91         """Return scope of name.
  92
  93         The scope of a name could be LOCAL, GLOBAL, FREE, or CELL.
  94         """
  95         if self.globals.has_key(name):
  96             return SC_GLOBAL
  97         if self.cells.has_key(name):
  98             return SC_CELL
  99         if self.defs.has_key(name):
 100             return SC_LOCAL
 101         if self.nested and (self.frees.has_key(name) or
 102                             self.uses.has_key(name)):
 103             return SC_FREE
 104         if self.nested:
 105             return SC_UNKNOWN
 106         else:
 107             return SC_GLOBAL
 108
 109     def get_free_vars(self):
 110         if not self.nested:
 111             return ()
 112         free = {}
 113         free.update(self.frees)
 114         for name in self.uses.keys():
 115             if not (self.defs.has_key(name) or
 116                     self.globals.has_key(name)):
 117                 free[name] = 1
 118         return free.keys()
 119
 120     def handle_children(self):
 121         for child in self.children:
 122             frees = child.get_free_vars()
 123             globals = self.add_frees(frees)
 124             for name in globals:
 125                 child.force_global(name)
 126
 127     def force_global(self, name):
 128         """Force name to be global in scope.
 129
 130         Some child of the current node had a free reference to name.
 131         When the child was processed, it was labelled a free
 132         variable.  Now that all its enclosing scope have been
 133         processed, the name is known to be a global or builtin.  So
 134         walk back down the child chain and set the name to be global
 135         rather than free.
 136
 137         Be careful to stop if a child does not think the name is
 138         free.
 139         """
 140         self.globals[name] = 1
 141         if self.frees.has_key(name):
 142             del self.frees[name]
 143         for child in self.children:
 144             if child.check_name(name) == SC_FREE:
 145                 child.force_global(name)
 146
 147     def add_frees(self, names):
 148         """Process list of free vars from nested scope.
 149
 150         Returns a list of names that are either 1) declared global in the
 151         parent or 2) undefined in a top-level parent.  In either case,
 152         the nested scope should treat them as globals.
 153         """
 154         child_globals = []
 155         for name in names:
 156             sc = self.check_name(name)
 157             if self.nested:
 158                 if sc == SC_UNKNOWN or sc == SC_FREE \
 159                    or isinstance(self, ClassScope):
 160                     self.frees[name] = 1
 161                 elif sc == SC_GLOBAL:
 162                     child_globals.append(name)
 163                 elif isinstance(self, FunctionScope) and sc == SC_LOCAL:
 164                     self.cells[name] = 1
 165                 else:
 166                     child_globals.append(name)
 167             else:
 168                 if sc == SC_LOCAL:
 169                     self.cells[name] = 1
 170                 else:
 171                     child_globals.append(name)
 172         return child_globals
 173
 174     def get_cell_vars(self):
 175         return self.cells.keys()
 176
 177 class ModuleScope(Scope):
 178     __super_init = Scope.__init__
 179
 180     def __init__(self):
 181         self.__super_init("global", self)
 182
 183 class FunctionScope(Scope):
 184     pass
 185
 186 class LambdaScope(FunctionScope):
 187     __super_init = Scope.__init__
 188
 189     __counter = 1
 190
 191     def __init__(self, module, klass=None):
 192         i = self.__counter
 193         self.__counter += 1
 194         self.__super_init("lambda.%d" % i, module, klass)
 195
 196 class ClassScope(Scope):
 197     __super_init = Scope.__init__
 198
 199     def __init__(self, name, module):
 200         self.__super_init(name, module, name)
 201
 202 class SymbolVisitor:
 203     def __init__(self):
 204         self.scopes = {}
 205         self.klass = None
 206
 207     # node that define new scopes
 208
 209     def visitModule(self, node):
 210         scope = self.module = self.scopes[node] = ModuleScope()
 211         self.visit(node.node, scope)
 212
 213     def visitFunction(self, node, parent):
 214         parent.add_def(node.name)
 215         for n in node.defaults:
 216             self.visit(n, parent)
 217         scope = FunctionScope(node.name, self.module, self.klass)
 218         if parent.nested or isinstance(parent, FunctionScope):
 219             scope.nested = 1
 220         self.scopes[node] = scope
 221         self._do_args(scope, node.argnames)
 222         self.visit(node.code, scope)
 223         self.handle_free_vars(scope, parent)
 224         scope.DEBUG()
 225
 226     def visitLambda(self, node, parent):
 227         for n in node.defaults:
 228             self.visit(n, parent)
 229         scope = LambdaScope(self.module, self.klass)
 230         if parent.nested or isinstance(parent, FunctionScope):
 231             scope.nested = 1
 232         self.scopes[node] = scope
 233         self._do_args(scope, node.argnames)
 234         self.visit(node.code, scope)
 235         self.handle_free_vars(scope, parent)
 236
 237     def _do_args(self, scope, args):
 238         for name in args:
 239             if type(name) == types.TupleType:
 240                 self._do_args(scope, name)
 241             else:
 242                 scope.add_param(name)
 243
 244     def handle_free_vars(self, scope, parent):
 245         parent.add_child(scope)
 246         if scope.children:
 247             scope.DEBUG()
 248         scope.handle_children()
 249
 250     def visitClass(self, node, parent):
 251         parent.add_def(node.name)
 252         for n in node.bases:
 253             self.visit(n, parent)
 254         scope = ClassScope(node.name, self.module)
 255         if parent.nested or isinstance(parent, FunctionScope):
 256             scope.nested = 1
 257         self.scopes[node] = scope
 258         prev = self.klass
 259         self.klass = node.name
 260         self.visit(node.code, scope)
 261         self.klass = prev
 262         self.handle_free_vars(scope, parent)
 263
 264     # name can be a def or a use
 265
 266     # XXX a few calls and nodes expect a third "assign" arg that is
 267     # true if the name is being used as an assignment.  only
 268     # expressions contained within statements may have the assign arg.
 269
 270     def visitName(self, node, scope, assign=0):
 271         if assign:
 272             scope.add_def(node.name)
 273         else:
 274             scope.add_use(node.name)
 275
 276     # operations that bind new names
 277
 278     def visitFor(self, node, scope):
 279         self.visit(node.assign, scope, 1)
 280         self.visit(node.list, scope)
 281         self.visit(node.body, scope)
 282         if node.else_:
 283             self.visit(node.else_, scope)
 284
 285     def visitFrom(self, node, scope):
 286         for name, asname in node.names:
 287             if name == "*":
 288                 continue
 289             scope.add_def(asname or name)
 290
 291     def visitImport(self, node, scope):
 292         for name, asname in node.names:
 293             i = name.find(".")
 294             if i > -1:
 295                 name = name[:i]
 296             scope.add_def(asname or name)
 297
 298     def visitAssName(self, node, scope, assign=1):
 299         scope.add_def(node.name)
 300
 301     def visitAugAssign(self, node, scope):
 302         # If the LHS is a name, then this counts as assignment.
 303         # Otherwise, it's just use.
 304         self.visit(node.node, scope)
 305         if isinstance(node.node, ast.Name):
 306             self.visit(node.node, scope, 1) # XXX worry about this
 307         self.visit(node.expr, scope)
 308
 309     def visitAssign(self, node, scope):
 310         for n in node.nodes:
 311             self.visit(n, scope, 1)
 312         self.visit(node.expr, scope)
 313
 314     def visitGlobal(self, node, scope):
 315         for name in node.names:
 316             scope.add_global(name)
 317
 318     # prune if statements if tests are false
 319
 320     _const_types = types.StringType, types.IntType, types.FloatType
 321
 322     def visitIf(self, node, scope):
 323         for test, body in node.tests:
 324             if isinstance(test, ast.Const):
 325                 if type(test.value) in self._const_types:
 326                     if not test.value:
 327                         continue
 328             self.visit(test, scope)
 329             self.visit(body, scope)
 330         if node.else_:
 331             self.visit(node.else_, scope)
 332
 333 def sort(l):
 334     l = l[:]
 335     l.sort()
 336     return l
 337
 338 def list_eq(l1, l2):
 339     return sort(l1) == sort(l2)
 340
 341 if __name__ == "__main__":
 342     import sys
 343     from compiler import parseFile, walk
 344     import symtable
 345
 346     def get_names(syms):
 347         return [s for s in [s.get_name() for s in syms.get_symbols()]
 348                 if not (s.startswith('_[') or s.startswith('.'))]
 349
 350     for file in sys.argv[1:]:
 351         print file
 352         f = open(file)
 353         buf = f.read()
 354         f.close()
 355         syms = symtable.symtable(buf, file, "exec")
 356         mod_names = get_names(syms)
 357         tree = parseFile(file)
 358         s = SymbolVisitor()
 359         walk(tree, s)
 360
 361         # compare module-level symbols
 362         names2 = s.scopes[tree].get_names()
 363
 364         if not list_eq(mod_names, names2):
 365             print
 366             print "oops", file
 367             print sort(mod_names)
 368             print sort(names2)
 369             sys.exit(-1)
 370
 371         d = {}
 372         d.update(s.scopes)
 373         del d[tree]
 374         scopes = d.values()
 375         del d
 376
 377         for s in syms.get_symbols():
 378             if s.is_namespace():
 379                 l = [sc for sc in scopes
 380                      if sc.name == s.get_name()]
 381                 if len(l) > 1:
 382                     print "skipping", s.get_name()
 383                 else:
 384                     if not list_eq(get_names(s.get_namespace()),
 385                                    l[0].get_names()):
 386                         print s.get_name()
 387                         print sort(get_names(s.get_namespace()))
 388                         print sort(l[0].get_names())
 389                         sys.exit(-1)