loops/query.py

#
#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

"""
Query management stuff.

$Id$
"""

from zope import schema, component
from zope.interface import Interface, Attribute, implements
from zope.app import traversing
from zope.cachedescriptors.property import Lazy
from zope.app.catalog.interfaces import ICatalog

from loops.interfaces import IConcept
from loops.common import AdapterBase
from loops.type import TypeInterfaceSourceList
from loops.util import _


class IQuery(Interface):
    """ The basic query interface.
    """

    def query(self, **kw):
        """ Execute the query and return a sequence of objects.
        """


class BaseQuery(object):

    implements(IQuery)

    def __init__(self, context):
        self.context = context

    @Lazy
    def catalog(self):
        return component.getUtility(ICatalog)

    @Lazy
    def loopsRoot(self):
        return self.context.context.getLoopsRoot()

    def queryConcepts(self, title=None, type=None):
        if type.endswith('*'):
            start = type[:-1]
            end = start + '\x7f'
        else:
            start = end = type
        cat = self.catalog
        if title:
            result = cat.searchResults(loops_type=(start, end), loops_title=title)
        else:
            result = cat.searchResults(loops_type=(start, end))
        result = set(r for r in result if r.getLoopsRoot() == self.loopsRoot)
        return result

    def queryConceptsWithChildren(self, title=None, type=None):
        if title:  # there are a few characters that the index doesn't like
            title = title.replace('(', ' ').replace(')', ' ')
        if not title and (type is None or '*' in type):
            return None
        result = set()
        queue = list(self.queryConcepts(title=title, type=type))
        concepts = []
        while queue:
            c = queue.pop(0)
            concepts.append(c)
            for child in c.getChildren():
                # TODO: check for tree level, use relevance factors, ...
                if child not in queue and child not in concepts:
                    queue.append(child)
        for c in concepts:
            result.add(c)
            result.update(c.getResources())
        return result


class FullQuery(BaseQuery):

    def query(self, text=None, type=None, useTitle=True, useFull=False,
                    conceptTitle=None, conceptType=None):
        result = set()
        rc = self.queryConceptsWithChildren(title=conceptTitle, type=conceptType)
        if not rc and not text and '*' in type: # there should be some sort of selection...
            return result
        if text or type != 'loops:*':  # TODO: this may be highly inefficient!
            cat = self.catalog
            if useFull and text:
                criteria = {'loops_text': text}
                r1 = set(cat.searchResults(**criteria))
            else:
                r1 = set()
            if type.endswith('*'):
                start = type[:-1]
                end = start + '\x7f'
            else:
                start = end = type
            criteria = {'loops_type': (start, end),}
            if useTitle and text:
                criteria['loops_title'] = text
            r2 = set(cat.searchResults(**criteria))
            result = r1.union(r2)
        if rc is not None:
            if result:
                result = result.intersection(rc)
            else:
                result = rc
        result = set(r for r in result if r.getLoopsRoot() == self.loopsRoot)
        return result


class ConceptQuery(BaseQuery):
    """ Find concepts of type `type` whose title starts with `title`.
    """

    def query(self, title=None, type=None):
        if title and not title.endswith('*'):
            title += '*'
        return self.queryConcepts(title=title, type=type)


# QueryConcept: concept objects that allow querying the database.

class IQueryConcept(Interface):
    """ The schema for the query type.
    """

    viewName = schema.TextLine(
        title=_(u'Adapter/View name'),
        description=_(u'The name of the (multi-) adapter (typically a view) '
                       'to be used for the query and for presenting '
                       'the results'),
        default=u'',
        required=True)


class QueryConcept(AdapterBase):

    implements(IQueryConcept)

    _schemas = list(IQueryConcept) + list(IConcept)


TypeInterfaceSourceList.typeInterfaces += (IQueryConcept,)