--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/skaapsteker/dialogue.py	Tue Apr 05 22:18:26 2011 +0200
@@ -0,0 +1,126 @@
+import json
+
+from . import data
+
+
+class DSM(object):
+    """Dialogue State Machine!
+
+       Parameters
+       ----------
+       json_filename : str
+           Path to file under data/ that contains JSON description
+           of state machine.
+       world : object
+           Something to allow states to introspect the game state with.
+       """
+
+    def __init__(self, json_filename, world):
+        self.world = world
+        self.state = "start"
+        self.states = AttrDict()
+        src = json.loads(data.load(json_filename).read())
+        for state, state_src in src.iteritems():
+            pseudo_path = [json_filename, state]
+            self.states[state] = DsmState(state, state_src, pseudo_path)
+        assert self.state in self.states, "DSM must have start state"
+
+    def get_state(self):
+        return self.states[self.state]
+
+    def event(self, ev):
+        my_locals = {
+            "state": self.states,
+            "world" : self.world,
+        }
+        my_locals.update(ev.items)
+        state = self.states[self.state]
+        next_state = state.event(my_locals)
+        if next_state.name in self.states:
+            self.state = next_state.name
+
+    def choice(self, i):
+        self.event(DsmEvent(choice=i))
+
+
+class AttrDict(dict):
+
+    def __getattr__(self, name):
+        if name not in self:
+            raise AttributeError("No attribute %r" % (name,))
+        return self[name]
+
+
+class DsmEvent(object):
+
+    def __init__(self, choice=None):
+        self.items = {
+            "choice": choice,
+        }
+
+
+class DsmState(object):
+    """State within a DSM.
+       """
+
+    def __init__(self, name, state_src, base_path):
+        self.name = name
+        self.text = state_src.get("text", None)
+        self.choices = []
+        self.triggers = []
+
+        choices = state_src.get("choices", [])
+        for i, choice in enumerate(choices):
+            pseudo_path = base_path + ["choice-%d" % i]
+            self.choices.append((i, choice["text"]))
+            next_state_code = choice.get("next", None)
+            if next_state_code is not None:
+                self.triggers.append(
+                    Trigger("choice == %d" % i, next_state_code, pseudo_path))
+
+        events = state_src.get("events", [])
+        for i, event in enumerate(events):
+            pseudo_path = base_path + ["event-%d" % i]
+            self.triggers.append(Trigger(event["matches"], event["next"],
+                                         pseudo_path))
+
+        auto_next = state_src.get("auto_next", None)
+        if auto_next is not None:
+            pseudo_path = base_path + ["auto_next"]
+            self.triggers.append(Trigger("""True""", auto_next, pseudo_path))
+
+    def __repr__(self):
+        return "<%r name=%r>" % (self.__class__.__name__, self.name)
+
+    def event(self, my_locals):
+        for trigger in self.triggers:
+            next_state = trigger.fire(my_locals)
+            if next_state is not None:
+                return next_state
+
+
+class Trigger(object):
+    """Matches DSM events and triggers state transitions.
+       """
+
+    def __init__(self, matches_code, next_state_code, pseudo_path):
+        self._matches = compile(matches_code,
+                                "<%s>" % ":".join(pseudo_path + ["match"]),
+                                "eval")
+        self._next_state = compile(next_state_code,
+                                   "<%s>" % ":".join(pseudo_path + ["next"]),
+                                   "eval")
+
+    def fire(self, my_locals):
+        if eval(self._matches, {}, my_locals.copy()):
+            return eval(self._next_state, {}, my_locals.copy())
+        return None
+
+
+class DummyWorld(object):
+
+    def __init__(self):
+        self._fox_has_tea = False
+
+    def fox_has_tea(self):
+        return self._fox_has_tea