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1 | #---------------------------------------------------------------------------- |
2 | # Name: dependencymgr.py | |
3 | # Purpose: Dependency Manager | |
4 | # | |
5 | # Author: Jeff Norton | |
6 | # | |
7 | # Created: 01/28/05 | |
8 | # CVS-ID: $Id$ | |
9 | # Copyright: (c) 2004-2005 ActiveGrid, Inc. | |
10 | #---------------------------------------------------------------------------- | |
11 | ||
12 | DM_NO_ID = 0 | |
13 | DM_ID_ATTR = "_DependencyMgr__ID" | |
14 | ||
15 | ##class ManageableObject(object): | |
16 | ## | |
17 | ## def __init__(self): | |
18 | ## self.__id = DM_NO_ID | |
19 | ## | |
20 | ## def __repr__(self): | |
21 | ## return "<ManageableObject id = %s>" % self.__id | |
22 | ## | |
23 | ## def __getID(self): | |
24 | ## return self.__id | |
25 | ## | |
26 | ## def __setID(self, value): | |
27 | ## if (self.__id != DM_NO_ID): | |
28 | ## raise DependencyMgrException("Cannot set the dependency ID on object %s to \"%s\" because it already has one (\"%s\")." % (repr(self), value, self.__id)) | |
29 | ## self.__id = value | |
30 | ## | |
31 | ## _DependencyMgr__ID = property(__getID, __setID) | |
32 | ||
33 | class DependencyMgr(object): | |
34 | ||
35 | def __init__(self): | |
36 | self.clear() | |
37 | ||
38 | def clear(self): | |
39 | self.__dependencies = {} | |
40 | self.__lastID = DM_NO_ID | |
41 | ||
42 | def addDependency(self, parent, child): | |
43 | pid = self._initObjectID(parent) | |
44 | try: | |
45 | parentCollection = self.__dependencies[pid] | |
46 | except KeyError: | |
47 | parentCollection = self._newDependencyCollection() | |
48 | self.__dependencies[pid] = parentCollection | |
49 | if (child not in parentCollection): | |
50 | parentCollection.append(child) | |
51 | ||
52 | def removeDependency(self, parent, child): | |
53 | pid = self._getObjectID(parent) | |
54 | if (pid != DM_NO_ID): | |
55 | try: | |
56 | parentCollection = self.__dependencies[pid] | |
57 | parentCollection.remove(child) | |
58 | if (len(parentCollection) == 0): | |
59 | del self.__dependencies[pid] | |
60 | except KeyError, ValueError: | |
61 | pass | |
62 | ||
63 | def clearDependencies(self, parent): | |
64 | "Returns a list of objects or an empty list if no dependencies exist as for getDependencies, and then removes the dependency list." | |
65 | pid = self._getObjectID(parent) | |
66 | try: | |
67 | deps = self.__dependencies[pid] | |
68 | del self.__dependencies[pid] | |
69 | return deps | |
70 | except KeyError: | |
71 | return [] | |
72 | ||
73 | def hasDependency(self, parent): | |
74 | "Returns a boolean" | |
75 | return (self._getObjectID(parent) in self.__dependencies) | |
76 | ||
77 | def getDependencies(self, parent): | |
78 | "Returns a list of objects or an empty list if no dependencies exist." | |
79 | try: | |
80 | return self.__dependencies[self._getObjectID(parent)] | |
81 | except KeyError: | |
82 | return [] | |
83 | ||
84 | def dumpState(self, out): | |
85 | "Writes the state of the dependency manager (as reported by getState) to out" | |
86 | for line in self.getState(): | |
87 | print >> out, line | |
88 | ||
89 | def getState(self): | |
90 | "Returns the state of the dependency manager including all managed objects as a list of strings" | |
91 | out = [] | |
92 | out.append("DependencyMgr %s has %i parent objects, last id assigned is %i" % (repr(self), len(self.__dependencies), self.__lastID)) | |
93 | for key, val in self.__dependencies.iteritems(): | |
94 | out.append("Object %s has dependents: %s " % (repr(key), ", ".join([repr(d) for d in val]))) | |
95 | return out | |
96 | ||
97 | def _initObjectID(self, obj): | |
98 | try: | |
99 | id = getattr(obj, DM_ID_ATTR) | |
100 | except AttributeError: | |
101 | id = DM_NO_ID | |
102 | if (id == DM_NO_ID): | |
103 | id = self._newID() | |
104 | setattr(obj, DM_ID_ATTR, id) | |
105 | return id | |
106 | ||
107 | def _getObjectID(self, obj): | |
108 | try: | |
109 | id = getattr(obj, DM_ID_ATTR) | |
110 | except AttributeError: | |
111 | id = DM_NO_ID | |
112 | return id | |
113 | ||
114 | def _newID(self): | |
115 | self.__lastID += 1 | |
116 | return self.__lastID | |
117 | ||
118 | def _newDependencyCollection(self): | |
119 | return [] | |
120 | ||
121 | globalDM = DependencyMgr() | |
122 | ||
123 | def addDependency(parent, child): | |
124 | getGlobalDM().addDependency(parent, child) | |
125 | ||
126 | def removeDependency(parent, child): | |
127 | getGlobalDM().removeDependency(parent, child) | |
128 | ||
129 | def clearDependencies(parent): | |
130 | return getGlobalDM().clearDependencies(parent) | |
131 | ||
132 | def hasDependency(parent): | |
133 | return getGlobalDM().hasDependency(parent) | |
134 | ||
135 | def getDependencies(parent): | |
136 | return getGlobalDM().getDependencies(parent) | |
137 | ||
138 | def getState(): | |
139 | return getGlobalDM().getState() | |
140 | ||
141 | def dumpState(out): | |
142 | getGlobalDM().dumpState(out) | |
143 | ||
144 | def getGlobalDM(): | |
145 | return globalDM |