Order state elements to generate more readable YAML.
[python-bulletml.git] / bulletml / parser.py
index a89d1c5..51e15ad 100644 (file)
@@ -24,6 +24,7 @@ except ImportError:
 from bulletml.errors import Error
 from bulletml.expr import NumberDef, INumberDef
 
+
 __all_ = ["ParseError", "BulletML"]
 
 class ParseError(Error):
@@ -44,20 +45,11 @@ class ParamList(object):
         self.params = list(params)
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls([NumberDef(subelem.text) for subelem in element
                     if realtag(subelem) == "param"])
 
-    def __getstate__(self):
-        if self.params:
-            return dict(params=[param.expr for param in self.params])
-        else:
-            return {}
-
-    def __setstate__(self, state):
-        self.__init__(NumberDef(param) for param in state.get("params", []))
-
     def __call__(self, params, rank):
         return [param(params, rank) for param in self.params]
 
@@ -76,13 +68,14 @@ class Direction(object):
         self.value = value
 
     def __getstate__(self):
-        return dict(type=self.type, value=self.value.expr)
+        return [('type', self.type), ('value', self.value.expr)]
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(state["type"], NumberDef(state["value"]))
 
     @classmethod
-    def FromElement(cls, doc, element, default="absolute"):
+    def FromXML(cls, doc, element, default="absolute"):
         """Construct using an ElementTree-style element."""
         return cls(element.get("type", default), NumberDef(element.text))
 
@@ -101,21 +94,22 @@ class ChangeDirection(object):
         self.direction = direction
 
     def __getstate__(self):
-        return dict(frames=self.term.expr,
-                    type=self.direction.type,
-                    value=self.direction.value.expr)
+        return [('frames', self.term.expr),
+                ('type', self.direction.type),
+                ('value', self.direction.value.expr)]
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(INumberDef(state["frames"]),
                       Direction(state["type"], NumberDef(state["value"])))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         for subelem in element.getchildren():
             tag = realtag(subelem)
             if tag == "direction":
-                direction = Direction.FromElement(doc, subelem)
+                direction = Direction.FromXML(doc, subelem)
             elif tag == "term":
                 term = INumberDef(subelem.text)
         try:
@@ -142,13 +136,14 @@ class Speed(object):
         self.value = value
 
     def __getstate__(self):
-        return dict(type=self.type, value=self.value.expr)
+        return [('type', self.type), ('value', self.value.expr)]
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(state["type"], NumberDef(state["value"]))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls(element.get("type", "absolute"), NumberDef(element.text))
 
@@ -166,21 +161,22 @@ class ChangeSpeed(object):
         self.speed = speed
 
     def __getstate__(self):
-        return dict(frames=self.term.expr,
-                    type=self.speed.type,
-                    value=self.speed.value.expr)
+        return [('frames', self.term.expr),
+                ('type', self.speed.type),
+                ('value', self.speed.value.expr)]
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(INumberDef(state["frames"]),
                       Speed(state["type"], NumberDef(state["value"])))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         for subelem in element.getchildren():
             tag = realtag(subelem)
             if tag == "speed":
-                speed = Speed.FromElement(doc, subelem)
+                speed = Speed.FromXML(doc, subelem)
             elif tag == "term":
                 term = INumberDef(subelem.text)
         try:
@@ -208,7 +204,7 @@ class Wait(object):
         self.__init__(INumberDef(state["frames"]))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls(INumberDef(element.text))
 
@@ -231,7 +227,7 @@ class Tag(object):
         self.__init__(state["tag"])
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls(element.text)
 
@@ -248,7 +244,7 @@ class Untag(object):
         self.__init__(state["tag"])
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls(element.text)
 
@@ -259,7 +255,7 @@ class Vanish(object):
         pass
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         return cls()
 
@@ -274,22 +270,23 @@ class Repeat(object):
         self.action = action
 
     def __getstate__(self):
-        return dict(times=self.times.expr, action=self.action)
+        return [('times', self.times.expr), ('action', self.action)]
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(INumberDef(state["times"]), state["action"])
     
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         for subelem in element.getchildren():
             tag = realtag(subelem)
             if tag == "times":
                 times = INumberDef(subelem.text)
             elif tag == "action":
-                action = ActionDef.FromElement(doc, subelem)
+                action = ActionDef.FromXML(doc, subelem)
             elif tag == "actionRef":
-                action = ActionRef.FromElement(doc, subelem)
+                action = ActionRef.FromXML(doc, subelem)
         try:
             return cls(times, action)
         except UnboundLocalError as exc:
@@ -313,19 +310,20 @@ class Accel(object):
         self.vertical = vertical
 
     def __getstate__(self):
-        state = dict(frames=self.term.expr)
+        state = [('frames', self.term.expr)]
         if self.horizontal:
-            state["horizontal"] = self.horizontal
+            state.append(('horizontal', self.horizontal))
         if self.vertical:
-            state["vertical"] = self.vertical
+            state.append(('vertical', self.vertical))
         return state
 
     def __setstate__(self, state):
-        self.__init__(INumberDef(state["term"]), state.get("horizontal"),
+        state = dict(state)
+        self.__init__(INumberDef(state["frames"]), state.get("horizontal"),
                       state.get("vertical"))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         horizontal = None
         vertical = None
@@ -335,9 +333,9 @@ class Accel(object):
             if tag == "term":
                 term = INumberDef(subelem.text)
             elif tag == "horizontal":
-                horizontal = Speed.FromElement(doc, subelem)
+                horizontal = Speed.FromXML(doc, subelem)
             elif tag == "vertical":
-                vertical = Speed.FromElement(doc, subelem)
+                vertical = Speed.FromXML(doc, subelem)
 
         try:
             return cls(term, horizontal, vertical)
@@ -366,20 +364,21 @@ class BulletDef(object):
         self.actions = list(actions)
 
     def __getstate__(self):
-        state = dict()
+        state = []
         if self.direction:
-            state["direction"] = self.direction
+            state.append(("direction", self.direction))
         if self.speed:
-            state["speed"] = self.speed
+            state.append(("speed", self.speed))
         if self.actions:
-            state["actions"] = self.actions
+            state.append(("actions", self.actions))
         return state
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(**state)
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         actions = []
         speed = None
@@ -387,13 +386,13 @@ class BulletDef(object):
         for subelem in element.getchildren():
             tag = realtag(subelem)
             if tag == "direction":
-                direction = Direction.FromElement(doc, subelem)
+                direction = Direction.FromXML(doc, subelem)
             elif tag == "speed":
-                speed = Speed.FromElement(doc, subelem)
+                speed = Speed.FromXML(doc, subelem)
             elif tag == "action":
-                actions.append(ActionDef.FromElement(doc, subelem))
+                actions.append(ActionDef.FromXML(doc, subelem))
             elif tag == "actionRef":
-                actions.append(ActionRef.FromElement(doc, subelem))
+                actions.append(ActionRef.FromXML(doc, subelem))
         dfn = cls(actions, direction, speed)
         doc.bullets[element.get("label")] = dfn
         return dfn
@@ -417,20 +416,23 @@ class BulletRef(object):
         self.params = ParamList() if params is None else params
 
     def __getstate__(self):
-        state = dict(bullet=self.bullet)
+        state = []
         if self.params.params:
-            state["params"] = self.params.__getstate__()
+            params = [param.expr for param in self.params.params]
+            state.append(("params", params))
+        state.append(('bullet', self.bullet))
         return state
 
     def __setstate__(self, state):
+        state = dict(state)
         bullet = state["bullet"]
         params = [NumberDef(param) for param in state.get("params", [])]
-        self.__init__(bullet, params)
+        self.__init__(bullet, ParamList(params))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
-        bullet = cls(element.get("label"), ParamList.FromElement(doc, element))
+        bullet = cls(element.get("label"), ParamList.FromXML(doc, element))
         doc._bullet_refs.append(bullet)
         return bullet
 
@@ -446,7 +448,7 @@ class ActionDef(object):
 
     To support parsing new actions, add tags to
     ActionDef.CONSTRUCTORS. It maps tag names to classes with a
-    FromElement classmethod, which take the BulletML instance and
+    FromXML classmethod, which take the BulletML instance and
     ElementTree element as arguments.
     """
 
@@ -460,10 +462,11 @@ class ActionDef(object):
         return dict(actions=self.actions)
 
     def __setstate__(self, state):
-        self.__init__(state)
+        state = dict(state)
+        self.__init__(state["actions"])
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         actions = []
         for subelem in element.getchildren():
@@ -473,7 +476,7 @@ class ActionDef(object):
             except KeyError:
                 continue
             else:
-                actions.append(ctr.FromElement(doc, subelem))
+                actions.append(ctr.FromXML(doc, subelem))
         dfn = cls(actions)
         doc.actions[element.get("label")] = dfn
         return dfn
@@ -492,20 +495,23 @@ class ActionRef(object):
         self.params = params or ParamList()
 
     def __getstate__(self):
-        state = dict(action=self.action)
+        state = []
         if self.params.params:
-            state["params"] = self.params.__getstate__()
+            params = [param.expr for param in self.params.params]
+            state.append(("params", params))
+        state.append(('action', self.action))
         return state
 
     def __setstate__(self, state):
+        state = dict(state)
         action = state["action"]
         params = [NumberDef(param) for param in state.get("params", [])]
-        self.__init__(action, params)
+        self.__init__(action, ParamList(params))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
-        action = cls(element.get("label"), ParamList.FromElement(doc, element))
+        action = cls(element.get("label"), ParamList.FromXML(doc, element))
         doc._action_refs.append(action)
         return action
 
@@ -529,18 +535,19 @@ class Offset(object):
         self.y = y
 
     def __getstate__(self):
-        state = dict(type=self.type)
+        state = [('type', self.type)]
         if self.x:
-            state["x"] = self.x.expr
+            state.append(('x', self.x.expr))
         if self.y:
-            state["y"] = self.y.expr
+            state.append(('y', self.y.expr))
         return state
 
     def __setstate__(self, state):
+        state = dict(state)
         self.__init__(state["type"], state.get("x"), state.get("y"))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         type = element.get("type", "relative")
         x = None
@@ -567,25 +574,31 @@ class FireDef(object):
         self.offset = offset
 
     def __getstate__(self):
+        state = []
+        if self.direction:
+            state.append(("direction", self.direction))
+        if self.speed:
+            state.append(("speed", self.speed))
+        if self.offset:
+            state.append(("offset", self.offset))
         try:
             params = self.bullet.params
         except AttributeError:
             state = dict(bullet=self.bullet)
         else:
             if params.params:
-                state = dict(bullet=self.bullet)
+                state.append(('bullet', self.bullet))
             else:
-                state = dict(bullet=self.bullet.bullet)
-        if self.direction:
-            state["direction"] = self.direction
-        if self.speed:
-            state["speed"] = self.speed
-        if self.offset:
-            state["offset"] = self.offset
+                # Strip out empty BulletRefs.
+                state.append(('bullet', self.bullet.bullet))
         return state
 
+    def __setstate__(self, state):
+        state = dict(state)
+        self.__init__(**state)
+
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
         direction = None
         speed = None
@@ -594,15 +607,15 @@ class FireDef(object):
         for subelem in element.getchildren():
             tag = realtag(subelem)
             if tag == "direction":
-                direction = Direction.FromElement(doc, subelem, "aim")
+                direction = Direction.FromXML(doc, subelem, "aim")
             elif tag == "speed":
-                speed = Speed.FromElement(doc, subelem)
+                speed = Speed.FromXML(doc, subelem)
             elif tag == "bullet":
-                bullet = BulletDef.FromElement(doc, subelem)
+                bullet = BulletDef.FromXML(doc, subelem)
             elif tag == "bulletRef":
-                bullet = BulletRef.FromElement(doc, subelem)
+                bullet = BulletRef.FromXML(doc, subelem)
             elif tag == "offset":
-                offset = Offset.FromElement(doc, subelem)
+                offset = Offset.FromXML(doc, subelem)
         try:
             fire = cls(bullet, direction, speed, offset)
         except UnboundLocalError as exc:
@@ -631,20 +644,23 @@ class FireRef(object):
         self.params = params or ParamList()
 
     def __getstate__(self):
-        state = dict(fire=self.fire)
+        state = []
         if self.params.params:
-            state["params"] = self.params.__getstate__()
+            params = [param.expr for param in self.params.params]
+            state.append(("params", params))
+        state.append(('fire', self.fire))
         return state
 
     def __setstate__(self, state):
+        state = dict(state)
         fire = state["fire"]
         params = [NumberDef(param) for param in state.get("params", [])]
-        self.__init__(fire, params)
+        self.__init__(fire, ParamList(params))
 
     @classmethod
-    def FromElement(cls, doc, element):
+    def FromXML(cls, doc, element):
         """Construct using an ElementTree-style element."""
-        fired = cls(element.get("label"), ParamList.FromElement(doc, element))
+        fired = cls(element.get("label"), ParamList.FromXML(doc, element))
         doc._fire_refs.append(fired)
         return fired
 
@@ -662,7 +678,7 @@ class BulletML(object):
     firings, as well as a base game type.
 
     You can add tags to the BulletML.CONSTRUCTORS dictionary to extend
-    its parsing. It maps tag names to classes with a FromElement
+    its parsing. It maps tag names to classes with a FromXML
     classmethod, which take the BulletML instance and ElementTree
     element as arguments.
     
@@ -681,14 +697,15 @@ class BulletML(object):
         self.fires = {} if fires is None else fires
 
     def __getstate__(self):
-        return dict(type=self.type, actions=self.actions)
+        return [('type', self.type), ('actions', self.actions)]
 
     def __setstate__(self, state):
-        self.__init__(state["type"], state.get("actions"))
+        state = dict(state)
+        self.__init__(state["type"], actions=state.get("actions"))
 
     @classmethod
-    def FromDocument(cls, source):
-        """Return a BulletML instance based on a string or file-like."""
+    def FromXML(cls, source):
+        """Return a BulletML instance based on XML."""
         if not hasattr(source, 'read'):
             source = StringIO(source)
 
@@ -704,7 +721,7 @@ class BulletML(object):
         for element in root.getchildren():
             tag = realtag(element)
             if tag in self.CONSTRUCTORS:
-                self.CONSTRUCTORS[tag].FromElement(self, element)
+                self.CONSTRUCTORS[tag].FromXML(self, element)
 
         try:
             for ref in self._bullet_refs:
@@ -726,6 +743,39 @@ class BulletML(object):
 
         return self
 
+    @classmethod
+    def FromYAML(cls, source):
+        """Create a BulletML instance based on YAML."""
+
+        # Late import to avoid a circular dependency.
+        try:
+            import bulletml.bulletyaml
+            import yaml
+        except ImportError:
+            raise ParseError("PyYAML is not available")
+        else:
+            try:
+                return yaml.load(source)
+            except Exception, exc:
+                raise ParseError(str(exc))
+
+    @classmethod
+    def FromDocument(cls, source):
+        """Create a BulletML instance based on a seekable file or string.
+
+        This attempts to autodetect if the stream is XML or YAML.
+        """
+        if not hasattr(source, 'read'):
+            source = StringIO(source)
+        start = source.read(1)
+        source.seek(0)
+        if start == "<":
+            return cls.FromXML(source)
+        elif start == "!" or start == "#":
+            return cls.FromYAML(source)
+        else:
+            raise ParseError("unknown initial character %r" % start)
+
     @property
     def top(self):
         """Get a list of all top-level actions."""