Index: roundup/backends/back_anydbm.py
===================================================================
--- roundup/backends/back_anydbm.py	(Revision 4543)
+++ roundup/backends/back_anydbm.py	(Arbeitskopie)
@@ -49,6 +49,60 @@
 def db_nuke(config):
     shutil.rmtree(config.DATABASE)
 
+class Equals:
+    def __init__(self, x):
+        self.x = x
+
+    def evaluate(self, v):
+        return self.x in v
+
+class Not:
+    def __init__(self, x):
+        self.x = x
+
+    def evaluate(self, v):
+        return not self.x.evaluate(v)
+
+class Or:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def evaluate(self, v):
+        return self.x.evaluate(v) or self.y.evaluate(v)
+
+class And:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def evaluate(self, v):
+        return self.x.evaluate(v) and self.y.evaluate(v)
+        
+
+class Expression:
+
+    def __init__(self, v):
+        try:
+            opcodes = [int(x) for x in v]
+            if min(opcodes) >= -1: raise ValueError()
+
+            stack = []
+            for opcode in opcodes:
+                if opcode == -2: # not
+                    stack.append(Not(stack.pop()))
+                elif opcode == -3: # and
+                    stack.append(And(stack.pop(), stack.pop()))
+                elif opcode == -4: # or
+                    stack.append(Or(stack.pop(), stack.pop()))
+                else: # =
+                    stack.append(Equals(opcode))
+
+            compiled = stack.pop()
+            self.evaluate = lambda x: compiled.evaluate([int(y) for y in x])
+        except:
+            self.evaluate = lambda x: bool(set(x) & set(v))
+
 #
 # Now the database
 #
@@ -1700,12 +1754,10 @@
                         if not v:
                             match = not nv
                         else:
-                            # othewise, make sure this node has each of the
+                            # otherwise, make sure this node has each of the
                             # required values
-                            for want in v:
-                                if want in nv:
-                                    match = 1
-                                    break
+                            expr = Expression(v)
+                            if expr.evaluate(nv): match = 1
                     elif t == STRING:
                         if nv is None:
                             nv = ''