mirror of
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aa64775892
git-svn-id: https://linkchecker.svn.sourceforge.net/svnroot/linkchecker/trunk/linkchecker@1196 e7d03fd6-7b0d-0410-9947-9c21f3af8025
132 lines
2.8 KiB
Python
132 lines
2.8 KiB
Python
# -*- coding: iso-8859-1 -*-
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"""implementation of an LRU queue"""
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class LRU (object):
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"""
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Implementation of a length-limited O(1) LRU queue.
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Built for and used by PyPE:
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http://pype.sourceforge.net
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Copyright 2003 Josiah Carlson. (Licensed under the GPL)
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"""
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class Node (object):
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def __init__ (self, prev, me):
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self.prev = prev
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self.me = me
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self.next = None
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def __init__ (self, count, pairs=[]):
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self.count = max(count, 1)
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self.d = {}
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self.first = None
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self.last = None
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for key, value in pairs:
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self[key] = value
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def __contains__ (self, obj):
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return obj in self.d
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def has_key (self, obj):
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return self.d.has_key(obj)
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def __getitem__ (self, obj):
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a = self.d[obj].me
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self[a[0]] = a[1]
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return a[1]
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def __setitem__ (self, obj, val):
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if obj in self.d:
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del self[obj]
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nobj = self.Node(self.last, (obj, val))
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if self.first is None:
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self.first = nobj
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if self.last:
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self.last.next = nobj
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self.last = nobj
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self.d[obj] = nobj
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if len(self.d) > self.count:
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if self.first == self.last:
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self.first = None
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self.last = None
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return
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a = self.first
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a.next.prev = None
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self.first = a.next
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a.next = None
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del self.d[a.me[0]]
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del a
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def __delitem__ (self, obj):
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nobj = self.d[obj]
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if nobj.prev:
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nobj.prev.next = nobj.next
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else:
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self.first = nobj.next
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if nobj.next:
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nobj.next.prev = nobj.prev
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else:
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self.last = nobj.prev
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del self.d[obj]
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def __iter__ (self):
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cur = self.first
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while cur != None:
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cur2 = cur.next
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yield cur.me[1]
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cur = cur2
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def iteritems (self):
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cur = self.first
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while cur != None:
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cur2 = cur.next
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yield cur.me
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cur = cur2
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def iterkeys (self):
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return iter(self.d)
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def itervalues (self):
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for i,j in self.iteritems():
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yield j
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def keys (self):
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return self.d.keys()
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def setdefault (self, key, failobj=None):
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if not self.has_key(key):
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self[key] = failobj
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return self[key]
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def _main ():
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a = LRU(4)
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a['1'] = '1'
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a['2'] = '2'
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a['3'] = '3'
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a['4'] = '4'
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a['5'] = '5'
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for i in a.iteritems():
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print i,
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print
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b = a['2']
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a['6'] = '6'
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for i in a.iteritems():
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print i,
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print
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print a.has_key('1')
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print a.has_key('2')
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if __name__=='__main__':
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_main()
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