--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/grease/world.py	Tue Jul 12 10:16:48 2011 +0200
@@ -0,0 +1,302 @@
+#############################################################################
+#
+# Copyright (c) 2010 by Casey Duncan and contributors
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the MIT License
+# A copy of the license should accompany this distribution.
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+#
+#############################################################################
+"""Worlds are environments described by a configuration of components, systems and 
+renderers. These parts describe the data, behavioral and presentation aspects
+of the world respectively.
+
+The world environment is the context within which entities exist. A typical
+application consists of one or more worlds containing entities that evolve
+over time and react to internal and external interaction.
+
+See :ref:`an example of world configuration in the tutorial <tut-world-example>`.
+"""
+
+__version__ = '$Id$'
+
+import itertools
+from grease import mode
+from grease.component import ComponentError
+from grease.entity import Entity, ComponentEntitySet
+
+
+class BaseWorld(object):
+	"""A coordinated collection of components, systems and entities
+	
+	A world is also a mode that may be pushed onto a 
+	:class:`grease.mode.Manager`
+	"""
+
+	components = None
+	""":class:`ComponentParts` object containing all world components.
+	:class:`grease.component.Component` objects define and contain all entity data
+	"""
+
+	systems = None
+	""":class:`Parts` object containing all world systems. 
+	:class:`grease.System` objects define world and entity behavior
+	"""
+
+	renderers = None
+	""":class:`Parts` object containing all world renderers. 
+	:class:`grease.Renderer` objects define world presentation
+	"""
+
+	entities = None
+	"""Set of all entities that exist in the world"""
+
+	def __init__(self):
+		self.components = ComponentParts(self)
+		self.systems = Parts(self)
+		self.renderers = Parts(self)
+		self.new_entity_id = itertools.count().next
+		self.new_entity_id() # skip id 0
+		self.entities = WorldEntitySet(self)
+		self._full_extent = EntityExtent(self, self.entities)
+		self._extents = {}
+		self.configure()
+
+	def configure(self):
+		"""Hook to configure the world after construction. This method
+		is called immediately after the world is initialized. Override
+		in a subclass to configure the world's components, systems,
+		and renderers.
+
+		The default implementation does nothing.
+		"""
+	
+	def __getitem__(self, entity_class):
+		"""Return an :class:`EntityExtent` for the given entity class. This extent
+		can be used to access the set of entities of that class in the world
+		or to query these entities via their components. 
+
+		Examples::
+
+			world[MyEntity]
+			world[...]
+
+		:param entity_class: The entity class for the extent.
+
+			May also be a tuple of entity classes, in which case
+			the extent returned contains union of all entities of the classes
+			in the world.
+
+			May also be the special value ellipsis (``...``), which
+			returns an extent containing all entities in the world.  This allows
+			you to conveniently query all entities using ``world[...]``.
+		"""
+		if isinstance(entity_class, tuple):
+			entities = set()
+			for cls in entity_class:
+				if cls in self._extents:
+					entities |= self._extents[cls].entities
+			return EntityExtent(self, entities)
+		elif entity_class is Ellipsis:
+			return self._full_extent
+		try:
+			return self._extents[entity_class]
+		except KeyError:
+			extent = self._extents[entity_class] = EntityExtent(self, set())
+			return extent
+	
+	def draw_renderers(self):
+		"""Draw all renderers"""
+		for renderer in self.renderers:
+			renderer.draw()
+
+class WorldEntitySet(set):
+	"""Entity set for a :class:`World`"""
+
+	def __init__(self, world):
+		self.world = world
+	
+	def add(self, entity):
+		"""Add the entity to the set and all necessary class sets
+		Return the unique entity id for the entity, creating one
+		as needed.
+		"""
+		super(WorldEntitySet, self).add(entity)
+		for cls in entity.__class__.__mro__:
+			if issubclass(cls, Entity):
+				self.world[cls].entities.add(entity)
+
+	def remove(self, entity):
+		"""Remove the entity from the set and, world components,
+		and all necessary class sets
+		"""
+		super(WorldEntitySet, self).remove(entity)
+		for component in self.world.components:
+			try:
+				del component[entity]
+			except KeyError:
+				pass
+		for cls in entity.__class__.__mro__:
+			if issubclass(cls, Entity):
+				self.world[cls].entities.discard(entity)
+	
+	def discard(self, entity):
+		"""Remove the entity from the set if it exists, if not,
+		do nothing
+		"""
+		try:
+			self.remove(entity)
+		except KeyError:
+			pass
+
+
+class EntityExtent(object):
+	"""Encapsulates a set of entities queriable by component. Extents
+	are accessed by using an entity class as a key on the :class:`World`::
+
+		extent = world[MyEntity]
+	"""
+
+	entities = None
+	"""The full set of entities in the extent""" 
+
+	def __init__(self, world, entities):
+		self.__world = world
+		self.entities = entities
+
+	def __getattr__(self, name):
+		"""Return a queriable :class:`ComponentEntitySet` for the named component 
+
+		Example::
+
+			world[MyEntity].movement.velocity > (0, 0)
+
+		Returns a set of entities where the value of the :attr:`velocity` field
+		of the :attr:`movement` component is greater than ``(0, 0)``.
+		"""
+		component = getattr(self.__world.components, name)
+		return ComponentEntitySet(component, self.entities & component.entities)
+
+
+class Parts(object):
+	"""Maps world parts to attributes. The parts are kept in the
+	order they are set. Parts may also be inserted out of order.
+	
+	Used for:
+	
+	- :attr:`World.systems`
+	- :attr:`World.renderers`
+	"""
+
+	_world = None
+	_parts = None
+	_reserved_names = ('entities', 'entity_id', 'world')
+
+	def __init__(self, world):
+		self._world = world
+		self._parts = []
+	
+	def _validate_name(self, name):
+		if (name in self._reserved_names or name.startswith('_') 
+			or hasattr(self.__class__, name)):
+			raise ComponentError('illegal part name: %s' % name)
+		return name
+
+	def __setattr__(self, name, part):
+		if not hasattr(self.__class__, name):
+			self._validate_name(name)
+			if not hasattr(self, name):
+				self._parts.append(part)
+			else:
+				old_part = getattr(self, name)
+				self._parts[self._parts.index(old_part)] = part
+			super(Parts, self).__setattr__(name, part)
+			if hasattr(part, 'set_world'):
+				part.set_world(self._world)
+		elif name.startswith("_"):
+			super(Parts, self).__setattr__(name, part)
+		else:
+			raise AttributeError("%s attribute is read only" % name)
+	
+	def __delattr__(self, name):
+		self._validate_name(name)
+		part = getattr(self, name)
+		self._parts.remove(part)
+		super(Parts, self).__delattr__(name)
+
+	def insert(self, name, part, before=None, index=None):
+		"""Add a part with a particular name at a particular index.
+		If a part by that name already exists, it is replaced.
+			
+		:arg name: The name of the part.
+		:type name: str
+
+		:arg part: The component, system, or renderer part to insert
+	
+		:arg before: A part object or name. If specified, the part is
+			inserted before the specified part in order.
+
+		:arg index: If specified, the part is inserted in the position
+			specified. You cannot specify both before and index.
+		:type index: int
+		"""
+		assert before is not None or index is not None, (
+			"Must specify a value for 'before' or 'index'")
+		assert before is None or index is None, (
+			"Cannot specify both 'before' and 'index' arguments when inserting")
+		self._validate_name(name)
+		if before is not None:
+			if isinstance(before, str):
+				before = getattr(self, before)
+			index = self._parts.index(before)
+		if hasattr(self, name):
+			old_part = getattr(self, name)
+			self._parts.remove(old_part)
+		self._parts.insert(index, part)
+		super(Parts, self).__setattr__(name, part)
+		if hasattr(part, 'set_world'):
+			part.set_world(self._world)
+
+	def __iter__(self):
+		"""Iterate the parts in order"""
+		return iter(tuple(self._parts))
+	
+	def __len__(self):
+		return len(self._parts)
+
+
+class ComponentParts(Parts):
+	"""Maps world components to attributes. The components are kept in the
+	order they are set. Components may also be inserted out of order.
+
+	Used for: :attr:`World.components`
+	"""
+
+	def join(self, *component_names):
+		"""Join and iterate entity data from multiple components together.
+
+		For each entity in all of the components named, yield a tuple containing
+		the entity data from each component specified.
+
+		This is useful in systems that pull data from multiple components.
+		
+		Typical Usage::
+
+			for position, movement in world.components.join("position", "movement"):
+				# Do something with each entity's position and movement data
+		"""
+		if component_names:
+			components = [getattr(self, self._validate_name(name)) 
+				for name in component_names]
+			if len(components) > 1:
+				entities = components[0].entities & components[1].entities
+				for comp in components[2:]:
+					entities &= comp.entities
+			else:
+				entities = components[0].entities
+			for entity in entities:
+				yield tuple(comp[entity] for comp in components)
+