State Stack-3.ipynb

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     "text": [
      "{'fill': {'mode': 'rgba', 'value': (1.0, 1.0, 1.0, 1.0)}, 'stroke': {'mode': 'rgba', 'value': (0.0, 0.0, 0.0, 1.0)}}\n",
      "\n",
      "<Color (1.0, 1.0, 1.0, 1.0) mode=rgba>\n"
     ]
    },
    {
     "ename": "AttributeError",
     "evalue": "'Context' object has no attribute 'state_manager'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAttributeError\u001b[0m                            Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-1-28bb2ccde438>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m    299\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mctx\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mfill\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    300\u001b[0m \u001b[0;31m#print(ctx)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 301\u001b[0;31m \u001b[0;32mwith\u001b[0m \u001b[0mctx\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mfill\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m0.0\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m0\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m0\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m1.0\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m    302\u001b[0m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"Inside CM\"\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    303\u001b[0m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mctx\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mstate\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mstates\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m<ipython-input-1-28bb2ccde438>\u001b[0m in \u001b[0;36m__enter__\u001b[0;34m(self)\u001b[0m\n\u001b[1;32m    154\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    155\u001b[0m     \u001b[0;32mdef\u001b[0m \u001b[0m__enter__\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 156\u001b[0;31m         return ColorState(self.ctx.state_manager, \n\u001b[0m\u001b[1;32m    157\u001b[0m                           \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_state\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mkey\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    158\u001b[0m                           \u001b[0mmode\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_state\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m\"mode\"\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mAttributeError\u001b[0m: 'Context' object has no attribute 'state_manager'"
     ]
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   "source": [
    "# TODO - naming, state, key...\n",
    "from contextlib import contextmanager\n",
    "\n",
    "\n",
    "\"\"\"\n",
    "State Management.\n",
    "\n",
    "Everything that needs to store some data delegates it to a State object, stored at _state.\n",
    "\n",
    "Centralising data seperates data storage from the API presented to users.\n",
    "This opens up potential to implement different user facing APIs e.g. drawBot on top of the\n",
    "same underlying state.\n",
    "\n",
    "State Management tracks the current fill, stroke, transformation etc.\n",
    "\n",
    "Program->Nodebox API->[State[->Cairo Renderer->Output\n",
    "\n",
    "Program->\n",
    "\"\"\"\n",
    "\n",
    "class StateException(Exception):\n",
    "    pass\n",
    "\n",
    "\n",
    "class State:\n",
    "    def __init__(self, store, key, data, *args, **kwargs):\n",
    "        self.key = key\n",
    "        self.data = data\n",
    "        self.store = store\n",
    "        self.store.update(key, data)\n",
    "        \n",
    "    def __getitem__(self, key):\n",
    "        \"\"\"\n",
    "        :return:  Values stored in current state.\n",
    "        >>> state[\"fill\"]\n",
    "        {\"value\": (0.1, 0.1, 0.1, 0.1), \"mode\": \"rgba\"}\n",
    "        \"\"\"\n",
    "        return self.state[key]\n",
    "    \n",
    "    def __repr__(self):\n",
    "        return f\"<{self.__class__.__name__} {self.state}>\"\n",
    "\n",
    "\n",
    "class ContextManagerState(State):\n",
    "    \"\"\"\n",
    "    State that may optionally be used as in a with statement.\n",
    "    \n",
    "    When used as ContextManager new state is pushed onto a stack,\n",
    "    and popped when the Context Manager exits.\n",
    "    \n",
    "    Users may want to raise an exception under some circumstances,\n",
    "    e.g. many APIs do not allow the color to change when during a Path.\n",
    "    \n",
    "    ContextManagerState can raise an arbitrary exception by setting\n",
    "    cm_raises_exception to a tuple of (exception, args, kwargs),\n",
    "    args and kwargs are optional.\n",
    "    \n",
    "    :param cm_raises_exception: None if use as a context manager is allowed.\n",
    "    :param cm_raises_exception: (exception, args, kwargs) \n",
    "    exception to raise on use as context manager.\n",
    "    \"\"\"\n",
    "    def __init__(self, store, key, data, \n",
    "                 cm_raises_exception=None, \n",
    "                 *args, **kwargs):\n",
    "        self.cm_raises_exception = cm_raises_exception\n",
    "        self.entered = False\n",
    "\n",
    "        if cm_raises_exception:\n",
    "            self.restore_state = None\n",
    "        else:\n",
    "            # restore state for when used as context manager.\n",
    "            self.restore_state = {**store.get(key)}\n",
    "        \n",
    "        State.__init__(self, store, key, data, **kwargs)\n",
    "    \n",
    "    def __enter__(self):\n",
    "        \"\"\"\n",
    "        Enter context manager.\n",
    "        Since state was already set in the constructor it is nessacary\n",
    "        to reset the state to that saved in self.restore_state, then\n",
    "        push the desired state stored in self.state to the stack.\n",
    "        \n",
    "        Throw exception if self.cm_raises_exception is set.\n",
    "        \"\"\"\n",
    "        if self.cm_raises_exception:\n",
    "            ex = self.cm_raises_exception[0]            \n",
    "            if len(self.cm_raises_exception) == 1:\n",
    "                raise ex()\n",
    "                \n",
    "            args = self.cm_raises_exception[1]\n",
    "            if len(self.cm_raises_exception) == 2:\n",
    "                raise ex(*args)\n",
    "                \n",
    "            kwargs = self.cm_raises_exception[2]\n",
    "            raise ex(*args, **kwargs)\n",
    "            \n",
    "        # Avoid expensive list insert: restore state, then pushing desired state. \n",
    "        self.store.update(self.key, self.restore_state)\n",
    "        self.store.push(self.key, self.state)\n",
    "        \n",
    "    def __exit__(self, *args):\n",
    "        self.store.pop()\n",
    "        self.state = self.restore_state\n",
    "\n",
    "\n",
    "class ColorState(ContextManagerState):\n",
    "    def __init__(self, store, key, **kwargs):\n",
    "        \"\"\"\n",
    "        :param store: Backend to store color data.\n",
    "        :param mode: rgba| indexed\n",
    "        :param value: channel data\n",
    "        \"\"\"\n",
    "        ContextManagerState.__init__(self, store, key,\n",
    "                                     {\"mode\": kwargs.pop(\"mode\"),\n",
    "                                      \"value\": kwargs.pop(\"value\")},\n",
    "                                     **kwargs)\n",
    "        \n",
    "class Color:\n",
    "    def __init__(self, ctx, *args, **kwargs):\n",
    "        self._state = {\"mode\": kwargs.pop(\"mode\", \"rgba\"), \"value\": args}\n",
    "#         self._state = ColorState(ctx.state, \n",
    "#                                  ctx.state.current_key,\n",
    "#                                  value=args,\n",
    "#                                  mode=kwargs.pop(\"mode\", \"rgba\"),\n",
    "#                                  cm_raises_exception=kwargs.pop(\"cm_raises_exception\", False))\n",
    "        self.ctx = ctx\n",
    "        \n",
    "    @staticmethod\n",
    "    def from_state(ctx, state, **kwargs):\n",
    "        _kwargs = {**state}\n",
    "        _kwargs.update(kwargs)\n",
    "        value = _kwargs.pop(\"value\")\n",
    "        return Color(ctx, *value, **_kwargs)\n",
    "        \n",
    "    @property\n",
    "    def r(self):\n",
    "        return self._state[\"r\"]\n",
    "    \n",
    "    @property\n",
    "    def g(self):\n",
    "        return self._state[\"g\"]\n",
    "\n",
    "    @property\n",
    "    def b(self):\n",
    "        return self._state[\"b\"]\n",
    "\n",
    "    @property\n",
    "    def a(self):\n",
    "        return self._state[\"a\"]\n",
    "    \n",
    "    @property\n",
    "    def mode(self):\n",
    "        return self._state[\"mode\"]\n",
    "    \n",
    "    def __enter__(self):\n",
    "        return ColorState(self.ctx.state_manager, \n",
    "                          self._state.key,\n",
    "                          mode=self._state[\"mode\"],\n",
    "                          value=self._state[\"value\"],\n",
    "                          cm_raises_exception=self._state.cm_raises_exception)\n",
    "    \n",
    "    def __exit__(self, *args):\n",
    "        return False\n",
    "    \n",
    "    def __repr__(self):\n",
    "        return f\"<Color {self._state['value']} mode={self.mode}>\"\n",
    "\n",
    "\n",
    "        \n",
    "        \n",
    "class BlendModeState(ContextManagerState):\n",
    "    def __init__(self, store, key, state, blendmode, **kwargs):\n",
    "        \"\"\"\n",
    "        :param store: Backend to store color data.\n",
    "        :param blendmode: rgba, indexed\n",
    "        \"\"\"\n",
    "        ContextManagerState.__init__(self, store, key,\n",
    "                                     {\"blendmode\": blendmode})\n",
    "\n",
    "\n",
    "class PathState(State):\n",
    "    def __init__(self, store, fill, stroke):\n",
    "        State.__init__(self, store, \"path\",\n",
    "                       {\n",
    "                           \"fill\": fill, \n",
    "                           \"stroke\": stroke,\n",
    "                           \"elements\": []\n",
    "                       },\n",
    "                       cm_raises_exception)\n",
    "\n",
    "\n",
    "class StateManager:\n",
    "    \"\"\"\n",
    "    Data store for state related to handling drawing.\n",
    "    State is handled seperately to the API users see,\n",
    "    this allows\n",
    "    \n",
    "    Current State is a dict of dicts, with entries like\n",
    "    \n",
    "    {\"fill\": {\"mode\": \"rgba\", \"value\", (1, 1, 1, 1)}}\n",
    "    \n",
    "    These are held in a list to implement a stack,\n",
    "    \n",
    "    If new state needs to be pushed, then current state is shallow\n",
    "    copied to a new dict, containing another new dict for the\n",
    "    key to be updated.\n",
    "    \"\"\"\n",
    "    def __init__(self, states):\n",
    "        self.stack = []\n",
    "        self.stack.append(states)\n",
    "        self.cm_key = []\n",
    "        \n",
    "    def update(self, key, state):\n",
    "        \"\"\"\n",
    "        Update state for given key.\n",
    "        \n",
    "        :param key: location to save data.\n",
    "        :param state:  dict of data to save under this key.\n",
    "        \"\"\"\n",
    "        self.get(key).update(state)\n",
    "    \n",
    "    def get(self, key):\n",
    "        return self.stack[-1][key]\n",
    "    \n",
    "    @property\n",
    "    def states(self):\n",
    "        return self.stack[-1]\n",
    "    \n",
    "    def pop(self):\n",
    "        del self.stack[-1]\n",
    "\n",
    "    def push(self, key, state):\n",
    "        states = {**self.states, **{key: {**state}}}\n",
    "        self.stack.append(states)\n",
    "        return len(self.stack) -1\n",
    "    \n",
    "    @contextmanager\n",
    "    def key(self, key):\n",
    "        \"\"\"\n",
    "        Context manager that allows the setting of a current key to\n",
    "        save data under.\n",
    "        \n",
    "        The key can then be fetched with the current_key property.\n",
    "        \n",
    "        >>> sm = StateManager()\n",
    "        >>> with sm.key(\"fill\"):\n",
    "        ...     print(sm.current_key)\n",
    "        \"fill\"\n",
    "        \"\"\"\n",
    "        self.cm_key.append(key)\n",
    "        try:\n",
    "            yield self.get(key)\n",
    "        finally:\n",
    "            del self.cm_key[-1]\n",
    "\n",
    "    @property\n",
    "    def current_key(self):\n",
    "        \"\"\"\n",
    "        Get key that was set using the key(...) context manager.\n",
    "        \"\"\"\n",
    "        try:\n",
    "            return self.cm_key[-1]\n",
    "        except IndexError:\n",
    "            raise StateException(\"No current key set, .current_key can only be called when using the key(...) context manager.\")\n",
    "    \n",
    "    def __repr__(self):\n",
    "        return f\"<StateStack {self.stack}>\"\n",
    "        \n",
    "\n",
    "class Context:\n",
    "    def __init__(self):\n",
    "        initial_state = {\n",
    "            \"fill\": {\"mode\": \"rgba\", \"value\": (1., 1., 1., 1.)},\n",
    "            \"stroke\": {\"mode\": \"rgba\", \"value\": (0., 0., 0., 1.)},\n",
    "        }\n",
    "        self.state = StateManager(initial_state)\n",
    "\n",
    "    def fill(self, *rgba):\n",
    "        if not rgba:\n",
    "            return Color.from_state(self, self.state.get(\"fill\"))\n",
    "        color = Color(self, *rgba)\n",
    "        self.state.update(\"fill\", color._state)\n",
    "        return color\n",
    "\n",
    "        #     def fill(self, *rgba):\n",
    "#         with self.store.key(\"fill\") as state:\n",
    "#             if not rgba:\n",
    "#                 return Color.from_state(self, state)\n",
    "#             return Color(self, *rgba)\n",
    "    \n",
    "    def __repr__(self):\n",
    "        return f\"<Context {self.state_manager}>\"\n",
    "    \n",
    "ctx = Context()\n",
    "#print(ctx.store.stack[-1])\n",
    "#color = ctx.fill(1., 0., 1., 1.)\n",
    "print(ctx.state.states)\n",
    "print()\n",
    "print(ctx.fill())\n",
    "#print(ctx)\n",
    "with ctx.fill(0.0, 0, 0, 1.0):\n",
    "    print(\"Inside CM\")\n",
    "    print(ctx.state.states)\n",
    "    \n",
    "print(\"Outside CM\")\n",
    "print(ctx.fill())\n",
    "print(ctx.store.states)"
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