cpython/Lib/compiler/symbols.py

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"""Module symbol-table generator"""
from compiler import ast
from compiler.consts import SC_LOCAL, SC_GLOBAL, SC_FREE, SC_CELL, SC_UNKNOWN
import types
import sys
MANGLE_LEN = 256
class Scope:
# XXX how much information do I need about each name?
def __init__(self, name, module, klass=None):
self.name = name
self.module = module
self.defs = {}
self.uses = {}
self.globals = {}
self.params = {}
self.frees = {}
self.cells = {}
self.children = []
# nested is true if the class could contain free variables,
# i.e. if it is nested within another function.
self.nested = None
self.klass = None
if klass is not None:
for i in range(len(klass)):
if klass[i] != '_':
self.klass = klass[i:]
break
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.name)
def mangle(self, name):
if self.klass is None:
return name
if not name.startswith('__'):
return name
if len(name) + 2 >= MANGLE_LEN:
return name
if name.endswith('__'):
return name
return "_%s%s" % (self.klass, name)
def add_def(self, name):
self.defs[self.mangle(name)] = 1
def add_use(self, name):
self.uses[self.mangle(name)] = 1
def add_global(self, name):
name = self.mangle(name)
if self.uses.has_key(name) or self.defs.has_key(name):
pass # XXX warn about global following def/use
if self.params.has_key(name):
raise SyntaxError, "%s in %s is global and parameter" % \
(name, self.name)
self.globals[name] = 1
self.module.add_def(name)
def add_param(self, name):
name = self.mangle(name)
self.defs[name] = 1
self.params[name] = 1
def get_names(self):
d = {}
d.update(self.defs)
d.update(self.uses)
d.update(self.globals)
return d.keys()
def add_child(self, child):
self.children.append(child)
def get_children(self):
return self.children
def DEBUG(self):
return
print >> sys.stderr, self.name, self.nested and "nested" or ""
print >> sys.stderr, "\tglobals: ", self.globals
print >> sys.stderr, "\tcells: ", self.cells
print >> sys.stderr, "\tdefs: ", self.defs
print >> sys.stderr, "\tuses: ", self.uses
print >> sys.stderr, "\tfrees:", self.frees
def check_name(self, name):
"""Return scope of name.
The scope of a name could be LOCAL, GLOBAL, FREE, or CELL.
"""
if self.globals.has_key(name):
return SC_GLOBAL
if self.cells.has_key(name):
return SC_CELL
if self.defs.has_key(name):
return SC_LOCAL
if self.nested and (self.frees.has_key(name) or
self.uses.has_key(name)):
return SC_FREE
if self.nested:
return SC_UNKNOWN
else:
return SC_GLOBAL
def get_free_vars(self):
if not self.nested:
return ()
free = {}
free.update(self.frees)
for name in self.uses.keys():
if not (self.defs.has_key(name) or
self.globals.has_key(name)):
free[name] = 1
return free.keys()
def handle_children(self):
for child in self.children:
frees = child.get_free_vars()
globals = self.add_frees(frees)
for name in globals:
child.force_global(name)
def force_global(self, name):
"""Force name to be global in scope.
Some child of the current node had a free reference to name.
When the child was processed, it was labelled a free
variable. Now that all its enclosing scope have been
processed, the name is known to be a global or builtin. So
walk back down the child chain and set the name to be global
rather than free.
Be careful to stop if a child does not think the name is
free.
"""
self.globals[name] = 1
if self.frees.has_key(name):
del self.frees[name]
for child in self.children:
if child.check_name(name) == SC_FREE:
child.force_global(name)
def add_frees(self, names):
"""Process list of free vars from nested scope.
Returns a list of names that are either 1) declared global in the
parent or 2) undefined in a top-level parent. In either case,
the nested scope should treat them as globals.
"""
child_globals = []
for name in names:
sc = self.check_name(name)
if self.nested:
if sc == SC_UNKNOWN or sc == SC_FREE \
or isinstance(self, ClassScope):
self.frees[name] = 1
elif sc == SC_GLOBAL:
child_globals.append(name)
elif isinstance(self, FunctionScope) and sc == SC_LOCAL:
self.cells[name] = 1
else:
child_globals.append(name)
else:
if sc == SC_LOCAL:
self.cells[name] = 1
else:
child_globals.append(name)
return child_globals
def get_cell_vars(self):
return self.cells.keys()
class ModuleScope(Scope):
__super_init = Scope.__init__
def __init__(self):
self.__super_init("global", self)
class FunctionScope(Scope):
pass
class LambdaScope(FunctionScope):
__super_init = Scope.__init__
__counter = 1
def __init__(self, module, klass=None):
i = self.__counter
self.__counter += 1
self.__super_init("lambda.%d" % i, module, klass)
class ClassScope(Scope):
__super_init = Scope.__init__
def __init__(self, name, module):
self.__super_init(name, module, name)
class SymbolVisitor:
def __init__(self):
self.scopes = {}
self.klass = None
# node that define new scopes
def visitModule(self, node):
scope = self.module = self.scopes[node] = ModuleScope()
self.visit(node.node, scope)
def visitFunction(self, node, parent):
parent.add_def(node.name)
for n in node.defaults:
self.visit(n, parent)
scope = FunctionScope(node.name, self.module, self.klass)
if parent.nested or isinstance(parent, FunctionScope):
scope.nested = 1
self.scopes[node] = scope
self._do_args(scope, node.argnames)
self.visit(node.code, scope)
self.handle_free_vars(scope, parent)
scope.DEBUG()
def visitLambda(self, node, parent):
for n in node.defaults:
self.visit(n, parent)
scope = LambdaScope(self.module, self.klass)
if parent.nested or isinstance(parent, FunctionScope):
scope.nested = 1
self.scopes[node] = scope
self._do_args(scope, node.argnames)
self.visit(node.code, scope)
self.handle_free_vars(scope, parent)
def _do_args(self, scope, args):
for name in args:
if type(name) == types.TupleType:
self._do_args(scope, name)
else:
scope.add_param(name)
def handle_free_vars(self, scope, parent):
parent.add_child(scope)
if scope.children:
scope.DEBUG()
scope.handle_children()
def visitClass(self, node, parent):
parent.add_def(node.name)
for n in node.bases:
self.visit(n, parent)
scope = ClassScope(node.name, self.module)
if parent.nested or isinstance(parent, FunctionScope):
scope.nested = 1
self.scopes[node] = scope
prev = self.klass
self.klass = node.name
self.visit(node.code, scope)
self.klass = prev
self.handle_free_vars(scope, parent)
# name can be a def or a use
# XXX a few calls and nodes expect a third "assign" arg that is
# true if the name is being used as an assignment. only
# expressions contained within statements may have the assign arg.
def visitName(self, node, scope, assign=0):
if assign:
scope.add_def(node.name)
else:
scope.add_use(node.name)
# operations that bind new names
def visitFor(self, node, scope):
self.visit(node.assign, scope, 1)
self.visit(node.list, scope)
self.visit(node.body, scope)
if node.else_:
self.visit(node.else_, scope)
def visitFrom(self, node, scope):
for name, asname in node.names:
if name == "*":
continue
scope.add_def(asname or name)
def visitImport(self, node, scope):
for name, asname in node.names:
i = name.find(".")
if i > -1:
name = name[:i]
scope.add_def(asname or name)
def visitAssName(self, node, scope, assign=1):
scope.add_def(node.name)
def visitAugAssign(self, node, scope):
# If the LHS is a name, then this counts as assignment.
# Otherwise, it's just use.
self.visit(node.node, scope)
if isinstance(node.node, ast.Name):
self.visit(node.node, scope, 1) # XXX worry about this
self.visit(node.expr, scope)
def visitAssign(self, node, scope):
for n in node.nodes:
self.visit(n, scope, 1)
self.visit(node.expr, scope)
def visitGlobal(self, node, scope):
for name in node.names:
scope.add_global(name)
# prune if statements if tests are false
_const_types = types.StringType, types.IntType, types.FloatType
def visitIf(self, node, scope):
for test, body in node.tests:
if isinstance(test, ast.Const):
if type(test.value) in self._const_types:
if not test.value:
continue
self.visit(test, scope)
self.visit(body, scope)
if node.else_:
self.visit(node.else_, scope)
def sort(l):
l = l[:]
l.sort()
return l
def list_eq(l1, l2):
return sort(l1) == sort(l2)
if __name__ == "__main__":
import sys
from compiler import parseFile, walk
import symtable
def get_names(syms):
return [s for s in [s.get_name() for s in syms.get_symbols()]
if not (s.startswith('_[') or s.startswith('.'))]
for file in sys.argv[1:]:
print file
f = open(file)
buf = f.read()
f.close()
syms = symtable.symtable(buf, file, "exec")
mod_names = get_names(syms)
tree = parseFile(file)
s = SymbolVisitor()
walk(tree, s)
# compare module-level symbols
names2 = s.scopes[tree].get_names()
if not list_eq(mod_names, names2):
print
print "oops", file
print sort(mod_names)
print sort(names2)
sys.exit(-1)
d = {}
d.update(s.scopes)
del d[tree]
scopes = d.values()
del d
for s in syms.get_symbols():
if s.is_namespace():
l = [sc for sc in scopes
if sc.name == s.get_name()]
if len(l) > 1:
print "skipping", s.get_name()
else:
if not list_eq(get_names(s.get_namespace()),
l[0].get_names()):
print s.get_name()
print sort(get_names(s.get_namespace()))
print sort(l[0].get_names())
sys.exit(-1)