UnIndex.py

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"""Simple column indices"""
__version__='$Revision: 1.9 $'[11:-2]

from Globals import Persistent
import BTree
import IOBTree
from intSet import intSet
import operator
from Missing import MV
import string, pdb

ListType=type([])
StringType=type('s')


def nonEmpty(s):
    "returns true if a non-empty string or any other (nonstring) type"
    if type(s) is StringType:
        if s: return 1
        else: return 0
    else:
        return 1


class UnIndex(Persistent):
    """UnIndex object interface"""

    def __init__(self, id=None, ignore_ex=None, call_methods=None):
        """Create an unindex

        UnIndexes are indexes that contain two index components, the
        forward index (like plain index objects) and an inverted
        index.  The inverted index is so that objects can be unindexed 
        even when the old value of the object is not known.

        The arguments are:

          'id' -- the name of the item attribute to index.  This is
          either an attribute name or a record key.

          'ignore_ex' -- should be set to true if you want the index
          to ignore exceptions raised while indexing instead of
          propagating them.

          'call_methods' -- should be set to true if you want the index 
          to call the attribute 'id' (note: 'id' should be callable!)
          You will also need to pass in an object in the index and
          uninded methods for this to work.

        """
	######################################################################
	# For b/w compatability, have to allow __init__ calls with zero args

        if not id==ignore_ex==call_methods==None:
            self.id = id
            self.ignore_ex=ignore_ex        # currently unimplimented
            self.call_methods=call_methods
            self._index = BTree.BTree()
            self._unindex = IOBTree.BTree()

        else:
            pass


    def __len__(self):
        return len(self._unindex)

    def index_object(self, i, obj, threshold=None):
        """ index and object 'obj' with integer id 'i'"""

        index = self._index
        unindex = self._unindex

        id = self.id

        try:
            k=getattr(obj, id)
            if callable(k):
                k = k()
        except:
            k = MV
 
##        if k is None or k == MV:
##            return 0

        set = index.get(k)
        if set is None:
            index[k] = set = intSet()
            
        set.insert(i)
        unindex[i] = k


        self._index = index
        self._unindex = unindex

        return 1
    

    def unindex_object(self, i):
        """ Unindex the object with integer id 'i' """
        index = self._index
        unindex = self._unindex

        k = unindex[i]
        if k is None:
            return None
        set = index.get(k)
        if set is not None: set.remove(i)
        del unindex[i]
        
        self._index = index
        self._unindex = unindex


    def _apply_index(self, request, cid=''): 
        """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.

        If the request contains a parameter with the name of the
        column + '_usage', it is sniffed for information on how to
        handle applying the index.

        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              #name of the column

        cidid = "%s/%s" % (cid,id)
        has_key = request.has_key
        if has_key(cidid): keys = request[cidid]
        elif has_key(id): keys = request[id]
        else: return None

        if type(keys) is not ListType: keys=[keys]
        index = self._index
        r = None
        anyTrue = 0
        opr = None

        if request.has_key(id+'_usage'):
            # see if any usage params are sent to field
            opr=string.split(string.lower(request[id+"_usage"]),':')
            opr, opr_args=opr[0], opr[1:]

        if opr=="range":
            if 'min' in opr_args: lo = min(keys)
            else: lo = None
            if 'max' in opr_args: hi = max(keys)
            else: hi = None

            anyTrue=1
            try:
                if hi:
                    setlist = index.items(lo,hi)
                else:
                    setlist = index.items(lo)

                for k, set in setlist:
                    if r is None:
                        r = set
                    else:
                        r = r.union(set)

            except KeyError:
                pass

        else:           #not a range
            get = index.get
            for key in keys:
                if key:
                    anyTrue = 1
                set=get(key)
                if set is not None:
                    if r is None:
                        r = set
                    else:
                        r = r.union(set)

        if r is None:
            if anyTrue:
                r=intSet()
            else:
                return None

        return r, (id,)


    def hasUniqueValuesFor(self, name):
        ' has unique values for column NAME '
        if name == self.id:
            return 1
        else:
            return 0


    def uniqueValues(self, name=None, withLengths=0):
        """\
        returns the unique values for name

        if withLengths is true, returns a sequence of
        tuples of (value, length)
        """
        if name is None:
            name = self.id
        elif name != self.id:
            return []
        if not withLengths: return tuple(
            filter(nonEmpty,self._index.keys())
            )
        else: 
            rl=[]
            for i in self._index.keys():
                if not nonEmpty(i): continue
                else: rl.append((i, len(self._index[i])))
            return tuple(rl)


    def clear(self):
        self._index = BTree.BTree()
        self._unindex = IOBTree.BTree()