First plugin support

1 files changed, 367 insertions, 0 deletions

diff --git a/portato/plugin.py b/portato/plugin.py
new file mode 100644
index 0000000..70d27e1
--- /dev/null
+++ b/portato/plugin.py
@@ -0,0 +1,367 @@
+# -*- coding: utf-8 -*-
+#
+# File: portato/plugin.py
+# This file is part of the Portato-Project, a graphical portage-frontend.
+#
+# Copyright (C) 2007 René 'Necoro' Neumann
+# This is free software.  You may redistribute copies of it under the terms of
+# the GNU General Public License version 2.
+# There is NO WARRANTY, to the extent permitted by law.
+#
+# Written by René 'Necoro' Neumann <necoro@necoro.net>
+
+import os, os.path
+from xml.dom.minidom import parse
+
+from constants import PLUGIN_DIR
+from helper import debug
+
+class ParseException (Exception):
+	pass
+
+def error (reason, p):
+	reason = "("+reason+")"
+	debug("Malformed plugin:", p, reason, minus=1, error = 1)
+
+class Connect:
+	"""A single <connect>-element."""
+
+	def __init__ (self, hook, type, depend_plugin):
+		"""Constructor.
+
+		@param hook: the parent Hook
+		@type hook: Hook
+		@param type: the type of the connect ("before", "after", "override")
+		@type type: string
+		@param depend_plugin: a plugin we are dependant on
+		@type depend_plugin: string or None
+		
+		@raises ParseException: on parsing errors"""
+
+		if not type in ["before", "after", "override"]:
+			raise ParseException, "Unknown connect type %s" % type
+
+		self.type = type
+		self.hook = hook
+		self.depend_plugin = depend_plugin
+
+	def is_before_type (self):
+		return self.type == "before"
+
+	def is_after_type (self):
+		return self.type == "after"
+
+	def is_override_type (self):
+		return self.type == "override"
+
+class Hook:
+	"""A single <hook>-element."""
+
+	def __init__ (self, plugin, hook, call):
+		"""Constructor.
+
+		@param plugin: the parent Plugin
+		@type plugin: Plugin
+		@param hook: the hook to add to
+		@type hook: string
+		@param call: the call to make
+		@type call: string
+
+		@raises ParseException: on parsing errors"""
+
+		if not hook: 
+			raise ParseException, "hook attribute missing"
+
+		if not call: 
+			raise ParseException, "call attribute missing"
+		
+		self.plugin = plugin
+		self.hook = hook
+		self.call = call
+		self.connects = []
+
+	def parse_connects (self, connects):
+		"""This gets a list of <connect>-elements and parses them.
+		
+		@param connects: the list of <connect>'s
+		@type connects: NodeList
+		
+		@raises ParseException: on parsing errors"""
+		
+		if not connects:
+			raise ParseException, "No connect elements in hook"
+
+		for c in connects:
+			type = c.getAttribute("type")
+			if type == '': 
+				type = "before"
+
+			# get dep_plugin if available
+			dep_plugin = None
+			if c.hasChildNodes():
+				nodes = c.childNodes
+				if len(nodes) > 1:
+					raise ParseException, "Malformed connect"
+				
+				if nodes[0].nodeType != nodes[0].TEXT_NODE:
+					raise ParseException, "Malformed connect"
+
+				dep_plugin = nodes[0].nodeValue.strip()
+
+			connect = Connect(self, type, dep_plugin)
+			self.connects.append(connect)
+		
+class Plugin:
+	"""A complete plugin."""
+
+	def __init__ (self, file, name, author):
+		"""Constructor.
+
+		@param file: the file name of the plugin.xml
+		@type file: string
+		@param name: the name of the plugin
+		@type name: string
+		@param author: the author of the plugin
+		@type author: string"""
+
+		self.file = file
+		self.name = name
+		self.author = author
+		self._import = None
+		self.hooks = []
+
+	def parse_hooks (self, hooks):
+		"""Gets a list of <hook>-elements and parses them.
+
+		@param hooks: the list of elements
+		@type hooks: NodeList
+		
+		@raises ParseException: on parsing errors"""
+
+		for h in hooks:
+			hook = Hook(self, h.getAttribute("hook"), h.getAttribute("call"))
+			hook.parse_connects(h.getElementsByTagName("connect"))
+			self.hooks.append(hook)
+
+	def set_import (self, imports):
+		"""This gets a list of imports and parses them - setting the import needed to call the plugin.
+
+		@param imports: list of imports
+		@type imports: NodeList
+		
+		@raises ParseException: on parsing errors"""
+
+		if len(imports) > 1:
+			raise ParseException, "More than one import statement."
+
+		if imports[0].hasChildNodes():
+			nodes = imports[0].childNodes
+			
+			if len(nodes) > 1:
+				raise ParseException, "Malformed import"
+			
+			if nodes[0].nodeType != nodes[0].TEXT_NODE:
+				raise ParseException, "Malformed import"
+
+			self._import = nodes[0].nodeValue.strip()
+
+			try: # try loading
+				mod = __import__(self._import)
+				del mod
+			except ImportError:
+				raise ParseException, self._import+" cannot be imported"
+		else:
+			raise ParseException, "Malformed import"
+
+	def needs_import (self):
+		"""Returns True if an import is required prior to calling the plugin.
+		@rtype: bool"""
+		return self._import is not None
+
+	def get_import (self):
+		"""Returns the module to import.
+		@rtype: string"""
+		return self._import
+
+class PluginQueue:
+	"""Class managing and loading the plugins."""
+
+	def __init__ (self, load = True):
+		"""Constructor.
+
+		@param load: if False nothing is loaded
+		@type load: bool"""
+
+		self.list = []
+		self.hooks = {}
+		if load:
+			self._load()
+
+	def hook (self, hook, *hargs, **hkwargs):
+		"""This is a method taking care of calling the plugins.
+		
+		B{Example}::
+			
+			@pluginQueue.hook("some_hook", data)
+			def function (a, b, c):
+				orig_call(b,c,data)
+			
+			def function (a, b, c):
+				hook = pluginQueue.hook("some_hook", data)
+				hook(orig_call)(b,c,data)
+
+		@param hook: the name of the hook
+		@type hook: string"""
+			
+		def call (cmd):
+			"""Convienience function for calling a connect.
+			@param cmd: the actual Connect
+			@type cmd: Connect"""
+
+			imp = ""
+			if cmd.hook.plugin.needs_import(): # get import
+				imp = cmd.hook.plugin.get_import()
+				try:
+					mod = __import__(imp, globals(), locals(), [cmd.hook.call])
+				except ImportError:
+					debug(imp,"cannot be imported", error = 1)
+					return
+
+				f = eval("mod."+cmd.hook.call) # build function
+			else:
+				f = eval(cmd.hook.call)
+
+			f(*hargs, **hkwargs) # call function
+
+		def hook_decorator (func):
+			"""This is the real decorator."""
+			if hook in self.hooks:
+				list = self.hooks[hook]
+			else:
+				list = ([],[],[])
+
+			def wrapper (self, *args, **kwargs):
+				
+				# before
+				for cmd in list[0]:
+					debug("Accessing hook '%s' of plugin '%s' (before)" % (hook, cmd.hook.plugin.name))
+					call(cmd)
+				
+				if list[1]: # override
+					debug("Overriding hook '%s' with plugin '%s'" % (hook, list[1][0].hook.plugin.name))
+					call(list[1][0])
+				else: # normal
+					func(self, *args, **kwargs)
+
+				# after
+				for cmd in list[2]:
+					debug("Accessing hook '%s' of plugin '%s' (after)" % (hook, cmd.hook.plugin.name))
+					call(cmd)
+
+			return wrapper
+
+		return hook_decorator
+
+	def _load (self):
+		"""Load the plugins."""
+		plugins = filter(lambda x: x.endswith(".xml"), os.listdir(PLUGIN_DIR))
+		plugins = map(lambda x: os.path.join(PLUGIN_DIR, x), plugins)
+
+		for p in plugins:
+			doc = parse(p)
+			
+			try:
+				try:
+					list = doc.getElementsByTagName("plugin")
+					if len(list) != 1:
+						raise ParseException, "Number of plugin elements unequal to 1"
+					
+					elem = list[0]
+
+					plugin = Plugin(p, elem.getAttribute("name"), elem.getAttribute("author"))
+					plugin.parse_hooks(elem.getElementsByTagName("hook"))
+					plugin.set_import(elem.getElementsByTagName("import"))
+					
+					self.list.append(plugin)
+
+				except ParseException, e:
+					error(e[0],p)
+			finally:
+				doc.unlink()
+
+		self._organize()
+
+	def _organize (self):
+		"""Creates the lists of connects in a way, that all dependencies are fullfilled."""
+		unresolved_before = {} 
+		unresolved_after = {}
+
+		for plugin in self.list: # plugins
+			for hook in plugin.hooks: # hooks in plugin
+				if not hook.hook in self.hooks:
+					self.hooks[hook.hook] = ([], [], [])
+
+				for connect in hook.connects: # connects in hook
+					
+					# type="before"
+					if connect.is_before_type():
+						if connect.depend_plugin is None: # no dependency -> straight add
+							self.hooks[hook.hook][0].append(connect)
+						else:
+							named = [x.plugin.name for x in self.hooks[hook.hook][0]]
+							if connect.depend_plugin in named:
+								self.hooks[hook.hook][0].insert(named.index(connect.depend_plugin), connect)
+							else:
+								if not hook.hook in unresolved_before:
+									unresolved_before[hook.hook] = []
+								
+								unresolved_before[hook.hook].append(connect)
+
+					# type = "after"
+					elif connect.is_after_type():
+						if connect.depend_plugin is None: # no dependency -> straight add
+							self.hooks[hook.hook][2].append(connect)
+						else:
+							named = [x.plugin.name for x in self.hooks[hook.hook][2]]
+							if connect.depend_plugin in named:
+								self.hooks[hook.hook][2].insert(named.index(connect.depend_plugin)+1, connect)
+							else:
+								if not hook.hook in unresolved_after:
+									unresolved_after[hook.hook] = []
+								
+								unresolved_after[hook.hook].append(connect)
+					
+					# type = "override"
+					elif connect.is_override_type():
+						if self.hooks[hook.hook][1]:
+							debug("For hook '%s' an override is already defined by plugin '%s'!" % (hook.hook, self.hooks[hook.hook][1][0]), warn = 1)
+						
+						self.hooks[hook.hook][1][:1] = [connect]
+						continue
+		
+		self._resolve_unresolved(unresolved_before, unresolved_after)
+
+	def _resolve_unresolved (self, before, after):
+		def resolve(hook, list, idx, add):
+			if not list: 
+				return
+			
+			changed = False
+			for connect in list:
+				named = [x.plugin.name for x in self.hooks[hook][idx]]
+				if connect.depend_plugin in named:
+					changed = True
+					self.hooks[hook][idx].insert(named.index(connect.depend_plugin)+add, connect)
+					list.remove(connect)
+
+			if changed:
+				resolve(hook, list, idx, add)
+
+			for l in list:
+				debug("Command for hook '%s' in plugin '%s' could not be added due to missing dependant: '%s'!"% (hook, l.hook.plugin.name, l.depend_plugin), warn = 1)
+
+		for hook in before:
+			resolve(hook, before[hook], 0, 0)
+		
+		for hook in after:
+			resolve(hook, after[hook], 2, 1)