/telescope/sparql/queryforms.py

 1from telescope.exceptions import *
 2from telescope.sparql.query import *
 3
 4__all__ = ['Ask', 'Construct', 'Select', 'Describe']
 5
 6class Ask(SPARQLQuery):
 7    """Programmatically build a SPARQL ASK query."""
 8
 9    query_form = 'ASK'
10
11
12class Construct(SolutionModifierSupportingQuery):
13    """Programmatically build a SPARQL CONSTRUCT query."""
14
15    query_form = 'CONSTRUCT'
16    
17    def __init__(self, template, pattern=None, order_by=None, limit=None,
18                 offset=None):
19        super(Construct, self).__init__(pattern, order_by=order_by,
20                                        limit=limit, offset=offset)
21        self._template = template
22
23    def _get_compiler_class(self):
24        from telescope.sparql.compiler import ConstructCompiler
25        return ConstructCompiler
26    
27    def template(self, template):
28        return self._clone(_template=template)
29
30
31class Select(ProjectionSupportingQuery):
32    """Programmatically build a SPARQL SELECT query."""
33    
34    query_form = 'SELECT'
35
36    def __init__(self, projection, pattern=None, distinct=False,
37                 reduced=False, order_by=None, limit=None, offset=None):
38        super(Select, self).__init__(projection, pattern, order_by=order_by,
39                                     limit=limit, offset=offset)
40        if distinct and reduced:
41            raise InvalidRequestError("DISTINCT and REDUCED are mutually exclusive.")
42        self._distinct = distinct
43        self._reduced = reduced
44
45    def _get_compiler_class(self):
46        from telescope.sparql.compiler import SelectCompiler
47        return SelectCompiler
48    
49    def distinct(self, flag=True):
50        """
51        Return a new `Select` with the DISTINCT modifier (or without it if
52        `flag` is false).
53        
54        If `flag` is true (the default), then `reduced` is forced to False.
55        
56        """
57        return self._clone(_distinct=flag, _reduced=not flag and self._reduced)
58    
59    def reduced(self, flag=True):
60        """Return a new `Select` with the REDUCED modifier (or without it if
61        `flag` is false).
62        
63        If `flag` is true (the default), then `distinct` is forced to False.
64        
65        """
66        return self._clone(_reduced=flag, _distinct=not flag and self._distinct)
67
68
69class Describe(ProjectionSupportingQuery):
70    """Programmatically build a SPARQL DESCRIBE query."""
71
72    query_form = 'DESCRIBE'
73