# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1342287406 -7200
# Node ID a7d2b3dc0f65659e12717d25fcada79eae7f3a9b
# Parent  948ff107ee00f4e06ccfa739135e5a3e8d28bb2d
Introduced an AttributeUser superclass so that attribute usage annotations can
be made on nodes without having to add attributes to nodes after their
initialisation.

diff -r 948ff107ee00 -r a7d2b3dc0f65 compiler/ast.py
--- a/compiler/ast.py	Sat Jul 14 19:32:22 2012 +0200
+++ b/compiler/ast.py	Sat Jul 14 19:36:46 2012 +0200
@@ -40,17 +40,46 @@
 
 nodes = {}
 
-class Node:
-    """Abstract base class for ast nodes."""
+class AttributeUser:
+
+    "Annotation-related node."
+
+    def __init__(self):
+
+        # Name and usage observations.
+
+        self._attrnames = None
+        self._attrcombined = None
+        self._attrmerged = None
+
+        # Related nodes.
+
+        self._attrbranches = None
+        self._attrcontributors = None
+        self._attrdefs = None
+
+        # Deductions.
+
+        self._attrtypes = None
+        self._attrspecifictypes = None
+
+class Node(AttributeUser):
+
+    "Abstract base class for ast nodes."
+
     def getChildren(self):
         pass # implemented by subclasses
+
     def __iter__(self):
         for n in self.getChildren():
             yield n
+
     def asList(self): # for backwards compatibility
         return self.getChildren()
+
     def getChildNodes(self):
         pass # implemented by subclasses
+
     def visit(self, visitor, *args):
         visitor.default(self, *args)
 
@@ -61,6 +90,7 @@
     # Expression is an artificial node class to support "eval"
     nodes["expression"] = "Expression"
     def __init__(self, node):
+        Node.__init__(self)
         self.node = node
 
     def getChildren(self):
@@ -80,6 +110,7 @@
 
 class Add(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -101,6 +132,7 @@
 
 class And(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -123,11 +155,17 @@
 
 class AssAttr(Node):
     def __init__(self, expr, attrname, flags, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.attrname = attrname
         self.flags = flags
         self.lineno = lineno
 
+        # Additional annotations.
+
+        self._attr = None
+        self._attrusers = None
+
     def getChildren(self):
         return self.expr, self.attrname, self.flags
 
@@ -148,6 +186,7 @@
 
 class AssList(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -170,6 +209,7 @@
 
 class AssName(Node):
     def __init__(self, name, flags, lineno=None):
+        Node.__init__(self)
         self.name = name
         self.flags = flags
         self.lineno = lineno
@@ -194,6 +234,7 @@
 
 class AssTuple(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -216,6 +257,7 @@
 
 class Assert(Node):
     def __init__(self, test, fail, lineno=None):
+        Node.__init__(self)
         self.test = test
         self.fail = fail
         self.lineno = lineno
@@ -244,6 +286,7 @@
 
 class Assign(Node):
     def __init__(self, nodes, expr, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.expr = expr
         self.lineno = lineno
@@ -271,6 +314,7 @@
 
 class AugAssign(Node):
     def __init__(self, node, op, expr, lineno=None):
+        Node.__init__(self)
         self.node = node
         self.op = op
         self.expr = expr
@@ -293,6 +337,7 @@
 
 class Backquote(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -313,6 +358,7 @@
 
 class Bitand(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -335,6 +381,7 @@
 
 class Bitor(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -357,6 +404,7 @@
 
 class Bitxor(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -379,6 +427,7 @@
 
 class Break(Node):
     def __init__(self, lineno=None):
+        Node.__init__(self)
         self.lineno = lineno
 
     def getChildren(self):
@@ -398,6 +447,7 @@
 
 class CallFunc(Node):
     def __init__(self, node, args, star_args = None, dstar_args = None, lineno=None):
+        Node.__init__(self)
         self.node = node
         self.args = args
         self.star_args = star_args
@@ -435,6 +485,7 @@
 
 class Class(Node):
     def __init__(self, name, bases, doc, code, decorators = None, lineno=None):
+        Node.__init__(self)
         self.name = name
         self.bases = bases
         self.doc = doc
@@ -476,6 +527,7 @@
 
 class Compare(Node):
     def __init__(self, expr, ops, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.ops = ops
         self.lineno = lineno
@@ -503,6 +555,7 @@
 
 class Const(Node):
     def __init__(self, value, lineno=None):
+        Node.__init__(self)
         self.value = value
         self.lineno = lineno
 
@@ -523,6 +576,7 @@
 
 class Continue(Node):
     def __init__(self, lineno=None):
+        Node.__init__(self)
         self.lineno = lineno
 
     def getChildren(self):
@@ -542,6 +596,7 @@
 
 class Decorators(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -564,6 +619,7 @@
 
 class Dict(Node):
     def __init__(self, items, lineno=None):
+        Node.__init__(self)
         self.items = items
         self.lineno = lineno
 
@@ -586,6 +642,7 @@
 
 class Discard(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -606,6 +663,7 @@
 
 class Div(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -627,6 +685,7 @@
 
 class Ellipsis(Node):
     def __init__(self, lineno=None):
+        Node.__init__(self)
         self.lineno = lineno
 
     def getChildren(self):
@@ -646,6 +705,7 @@
 
 class Exec(Node):
     def __init__(self, expr, locals, globals, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.locals = locals
         self.globals = globals
@@ -679,6 +739,7 @@
 
 class FloorDiv(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -700,6 +761,7 @@
 
 class For(Node):
     def __init__(self, assign, list, body, else_, lineno=None):
+        Node.__init__(self)
         self.assign = assign
         self.list = list
         self.body = body
@@ -738,6 +800,7 @@
 
 class From(Node):
     def __init__(self, modname, names, level, lineno=None):
+        Node.__init__(self)
         self.modname = modname
         self.names = names
         self.level = level
@@ -761,6 +824,7 @@
 
 class Function(Node):
     def __init__(self, decorators, name, argnames, defaults, flags, doc, code, lineno=None):
+        Node.__init__(self)
         self.decorators = decorators
         self.name = name
         self.argnames = argnames
@@ -813,6 +877,7 @@
 
 class GenExpr(Node):
     def __init__(self, code, lineno=None):
+        Node.__init__(self)
         self.code = code
         self.lineno = lineno
         self.argnames = ['.0']
@@ -835,6 +900,7 @@
 
 class GenExprFor(Node):
     def __init__(self, assign, iter, ifs, lineno=None):
+        Node.__init__(self)
         self.assign = assign
         self.iter = iter
         self.ifs = ifs
@@ -869,6 +935,7 @@
 
 class GenExprIf(Node):
     def __init__(self, test, lineno=None):
+        Node.__init__(self)
         self.test = test
         self.lineno = lineno
 
@@ -889,6 +956,7 @@
 
 class GenExprInner(Node):
     def __init__(self, expr, quals, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.quals = quals
         self.lineno = lineno
@@ -916,10 +984,16 @@
 
 class Getattr(Node):
     def __init__(self, expr, attrname, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.attrname = attrname
         self.lineno = lineno
 
+        # Additional annotations.
+
+        self._attr = None
+        self._attrusers = None
+
     def getChildren(self):
         return self.expr, self.attrname
 
@@ -937,6 +1011,7 @@
 
 class Global(Node):
     def __init__(self, names, lineno=None):
+        Node.__init__(self)
         self.names = names
         self.lineno = lineno
 
@@ -957,6 +1032,7 @@
 
 class If(Node):
     def __init__(self, tests, else_, lineno=None):
+        Node.__init__(self)
         self.tests = tests
         self.else_ = else_
         self.lineno = lineno
@@ -989,6 +1065,7 @@
 
 class IfExp(Node):
     def __init__(self, test, then, else_, lineno=None):
+        Node.__init__(self)
         self.test = test
         self.then = then
         self.else_ = else_
@@ -1011,6 +1088,7 @@
 
 class Import(Node):
     def __init__(self, names, lineno=None):
+        Node.__init__(self)
         self.names = names
         self.lineno = lineno
 
@@ -1032,6 +1110,7 @@
 
 class Invert(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -1052,6 +1131,7 @@
 
 class Keyword(Node):
     def __init__(self, name, expr, lineno=None):
+        Node.__init__(self)
         self.name = name
         self.expr = expr
         self.lineno = lineno
@@ -1073,6 +1153,7 @@
 
 class Lambda(Node):
     def __init__(self, argnames, defaults, flags, code, lineno=None):
+        Node.__init__(self)
         self.argnames = argnames
         self.defaults = defaults
         self.flags = flags
@@ -1110,6 +1191,7 @@
 
 class LeftShift(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1131,6 +1213,7 @@
 
 class List(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -1153,6 +1236,7 @@
 
 class ListComp(Node):
     def __init__(self, expr, quals, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.quals = quals
         self.lineno = lineno
@@ -1180,6 +1264,7 @@
 
 class ListCompFor(Node):
     def __init__(self, assign, list, ifs, lineno=None):
+        Node.__init__(self)
         self.assign = assign
         self.list = list
         self.ifs = ifs
@@ -1213,6 +1298,7 @@
 
 class ListCompIf(Node):
     def __init__(self, test, lineno=None):
+        Node.__init__(self)
         self.test = test
         self.lineno = lineno
 
@@ -1233,6 +1319,7 @@
 
 class Mod(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1254,6 +1341,7 @@
 
 class Module(Node):
     def __init__(self, doc, node, lineno=None):
+        Node.__init__(self)
         self.doc = doc
         self.node = node
         self.lineno = lineno
@@ -1275,6 +1363,7 @@
 
 class Mul(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1296,9 +1385,15 @@
 
 class Name(Node):
     def __init__(self, name, lineno=None):
+        Node.__init__(self)
         self.name = name
         self.lineno = lineno
 
+        # Additional annotations.
+
+        self._scope = None
+        self._attr = None
+
     def getChildren(self):
         return self.name,
 
@@ -1316,6 +1411,7 @@
 
 class Not(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -1336,6 +1432,7 @@
 
 class Or(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -1358,6 +1455,7 @@
 
 class Pass(Node):
     def __init__(self, lineno=None):
+        Node.__init__(self)
         self.lineno = lineno
 
     def getChildren(self):
@@ -1377,6 +1475,7 @@
 
 class Power(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1398,6 +1497,7 @@
 
 class Print(Node):
     def __init__(self, nodes, dest, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.dest = dest
         self.lineno = lineno
@@ -1427,6 +1527,7 @@
 
 class Printnl(Node):
     def __init__(self, nodes, dest, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.dest = dest
         self.lineno = lineno
@@ -1456,6 +1557,7 @@
 
 class Raise(Node):
     def __init__(self, expr1, expr2, expr3, lineno=None):
+        Node.__init__(self)
         self.expr1 = expr1
         self.expr2 = expr2
         self.expr3 = expr3
@@ -1492,6 +1594,7 @@
 
 class Return(Node):
     def __init__(self, value, lineno=None):
+        Node.__init__(self)
         self.value = value
         self.lineno = lineno
 
@@ -1512,6 +1615,7 @@
 
 class RightShift(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1533,6 +1637,7 @@
 
 class Slice(Node):
     def __init__(self, expr, flags, lower, upper, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.flags = flags
         self.lower = lower
@@ -1570,6 +1675,7 @@
 
 class Sliceobj(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -1592,6 +1698,7 @@
 
 class Stmt(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -1614,6 +1721,7 @@
 
 class Sub(Node):
     def __init__(self, leftright, lineno=None):
+        Node.__init__(self)
         self.left = leftright[0]
         self.right = leftright[1]
         self.lineno = lineno
@@ -1635,6 +1743,7 @@
 
 class Subscript(Node):
     def __init__(self, expr, flags, subs, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.flags = flags
         self.subs = subs
@@ -1664,6 +1773,7 @@
 
 class TryExcept(Node):
     def __init__(self, body, handlers, else_, lineno=None):
+        Node.__init__(self)
         self.body = body
         self.handlers = handlers
         self.else_ = else_
@@ -1704,6 +1814,7 @@
 
 class TryFinally(Node):
     def __init__(self, body, final, lineno=None):
+        Node.__init__(self)
         self.body = body
         self.final = final
         self.lineno = lineno
@@ -1728,6 +1839,7 @@
 
 class Tuple(Node):
     def __init__(self, nodes, lineno=None):
+        Node.__init__(self)
         self.nodes = nodes
         self.lineno = lineno
 
@@ -1750,6 +1862,7 @@
 
 class UnaryAdd(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -1770,6 +1883,7 @@
 
 class UnarySub(Node):
     def __init__(self, expr, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.lineno = lineno
 
@@ -1790,6 +1904,7 @@
 
 class While(Node):
     def __init__(self, test, body, else_, lineno=None):
+        Node.__init__(self)
         self.test = test
         self.body = body
         self.else_ = else_
@@ -1825,6 +1940,7 @@
 
 class With(Node):
     def __init__(self, expr, vars, body, lineno=None):
+        Node.__init__(self)
         self.expr = expr
         self.vars = vars
         self.body = body
@@ -1860,6 +1976,7 @@
 
 class Yield(Node):
     def __init__(self, value, lineno=None):
+        Node.__init__(self)
         self.value = value
         self.lineno = lineno