--- a/python/tree.py	Tue Dec 31 12:38:15 2013 +0100
+++ b/python/tree.py	Sat Jan 18 18:58:43 2014 +0100
@@ -1,8 +1,49 @@
 
 class Tree:
+    """ Tree node with a name and possibly some child nodes """
     def __init__(self, name, *args):
         self.name = name
         self.children = args
 
     def __repr__(self):
-        return 'Tree({}, {})'.format(self.name, self.children)
+        if self.children:
+            ch = ', '.join(str(c) for c in self.children)
+            return '{}({})'.format(self.name, ch)
+        else:
+            return '{}'.format(self.name)
+
+
+class State:
+    def __init__(self):
+        self.labels = {}
+    def has_goal(self, goal):
+        return goal in self.labels
+    def get_cost(self, goal):
+        if not self.has_goal(goal): return 999999
+        return self.labels[goal][0]
+    def get_rule(self, goal):
+        return self.labels[goal][1]
+    def set_cost(self, goal, cost, rule):
+        if self.has_goal(goal):
+            if self.get_cost(goal) > cost:
+                self.labels[goal] = (cost, rule)
+        else:
+            self.labels[goal] = (cost, rule)
+
+class BaseMatcher:
+    def kids(self, tree, rule):
+        return self.kid_functions[rule](tree)
+
+    def nts(self, rule):
+        return self.nts_map[rule]
+
+    def burm_label(self, tree):
+        for c in tree.children:
+            self.burm_label(c)
+        self.burm_state(tree)
+
+    def apply_rules(self, tree, goal):
+        print(tree.state.get_rule(goal))
+        rule = tree.state.get_rule(goal)
+        for kid_tree, kid_goal in zip(self.kids(tree, rule), self.nts(rule)):
+            self.apply_rules(kid_tree, kid_goal)