*** empty log message ***

lib/python/SearchIndex/Index.py

+############################################################################## 
+#
+#     Copyright 
+#
+#       Copyright 1996 Digital Creations, L.C., 910 Princess Anne
+#       Street, Suite 300, Fredericksburg, Virginia 22401 U.S.A. All
+#       rights reserved. 
+#
+############################################################################## 
+__doc__='''Simple column indexes
+
+
+$Id: Index.py,v 1.1 1997/09/08 18:52:04 jim Exp $'''
+__version__='$Revision: 1.1 $'[11:-2]
+
+from oiTree import BTree
+from intSet import intSet
+import operator
+
+ListType=type([])
+
+class Index:
+    """Index object interface"""
+
+    def _init(self,data,schema,id):
+	"""Create an index
+
+	The arguments are:
+
+	  'data' -- a mapping from integer object ids to objects or records,
+
+	  'schema' -- a mapping from item name to index into data records.
+              If 'data' is a mapping to objects, then schema should ne 'None'.
+
+	  'id' -- the name of the item attribute to index.  This is either
+	      an attribute name or a record key.
+	"""
+	self._data=data
+	self._schema=schema
+	self.id=id
+	self._index=BTree()
+	
+	self._reindex()
+
+    def clear(self):
+	self._init()
+
+    def _reindex(self,start=0):
+	"""Recompute index data for data with ids >= start."""
+
+	index=self._index
+	
+	if not start: index.clear()
+
+	id=self.id
+	if self._schema is None:
+	    f=getattr
+	else:
+	    f=operator.__getitem__
+	    id=self._schema[id]
+
+	for i,row in self._data.items(start):
+	    k=f(row,id)
+	    try: set=index[k]
+	    except KeyError:
+		set=intSet()
+		index[k]=set
+	    set.insert(i)
+
+    def index_item(self,i):
+	"""Recompute index data for data with ids >= start."""
+
+	index=self._index
+
+	id=self.id
+	if self._schema is None:
+	    f=getattr
+	else:
+	    f=operator.__getitem__
+	    id=self._schema[id]
+
+	row=self._data[i]
+	k=f(row,id)
+	try: set=index[k]
+	except KeyError:
+	    set=intSet()
+	    index[k]=set
+	set.insert(i)
+
+    def unindex_item(self,i):
+	"""Recompute index data for data with ids >= start."""
+
+	index=self._index
+
+	id=self.id
+	if self._schema is None:
+	    f=getattr
+	else:
+	    f=operator.__getitem__
+	    id=self._schema[id]
+
+	row=self._data[i]
+	k=f(row,id)
+	try:
+	    set=index[k]
+	    set.remove(k)
+	except KeyError: pass
+
+    def _apply_index(self, request):
+	"""Apply the index to query parameters given in the argument, request
+
+	The argument should be a mapping object.
+
+	If the request does not contain the needed parameters, then None is
+	returned.
+
+	Otherwise two objects are returned.  The first object is a
+	ResultSet containing the record numbers of the matching
+	records.  The second object is a tuple containing the names of
+	all data fields used.
+
+	"""
+	id=self.id
+	try: keys=request[id]
+	except: return None
+
+	if type(keys) is not ListType: keys=[keys]
+	index=self._index
+	r=None
+	for key in keys:
+	    try:
+		set=index[key]
+		if r is None: r=set
+		else: r = r.union(set)
+	    except KeyError: pass
+
+	if r is not None: return r, (id,)
+	
+
+############################################################################## 
+#
+# $Log: Index.py,v $
+# Revision 1.1  1997/09/08 18:52:04  jim
+# *** empty log message ***
+#
+#