def translate()

in assets/lambda_helper_neptune/python/rdflib/plugins/sparql/algebra.py [0:0]


def translate(q):
    """
    http://www.w3.org/TR/sparql11-query/#convertSolMod

    """

    _traverse(q, _simplifyFilters)

    q.where = traverse(q.where, visitPost=translatePath)

    # TODO: Var scope test
    VS = set()
    traverse(q.where, functools.partial(_findVars, res=VS))

    # all query types have a where part
    M = translateGroupGraphPattern(q.where)

    aggregate = False
    if q.groupby:
        conditions = []
        # convert "GROUP BY (?expr as ?var)" to an Extend
        for c in q.groupby.condition:
            if isinstance(c, CompValue) and c.name == 'GroupAs':
                M = Extend(M, c.expr, c.var)
                c = c.var
            conditions.append(c)

        M = Group(p=M, expr=conditions)
        aggregate = True
    elif traverse(q.having, _hasAggregate, complete=False) or \
            traverse(q.orderby, _hasAggregate, complete=False) or \
            any(traverse(x.expr, _hasAggregate, complete=False)
                for x in q.projection or [] if x.evar):
        # if any aggregate is used, implicit group by
        M = Group(p=M)
        aggregate = True

    if aggregate:
        M, E = translateAggregates(q, M)
    else:
        E = []

    # HAVING
    if q.having:
        M = Filter(expr=and_(*q.having.condition), p=M)

    # VALUES
    if q.valuesClause:
        M = Join(p1=M, p2=ToMultiSet(translateValues(q.valuesClause)))

    if not q.projection:
        # select *
        PV = list(VS)
    else:
        PV = list()
        for v in q.projection:
            if v.var:
                if v not in PV:
                    PV.append(v.var)
            elif v.evar:
                if v not in PV:
                    PV.append(v.evar)

                E.append((v.expr, v.evar))
            else:
                raise Exception("I expected a var or evar here!")

    for e, v in E:
        M = Extend(M, e, v)

    # ORDER BY
    if q.orderby:
        M = OrderBy(M, [CompValue('OrderCondition', expr=c.expr,
                    order=c.order) for c in q.orderby.condition])

    # PROJECT
    M = Project(M, PV)

    if q.modifier:
        if q.modifier == 'DISTINCT':
            M = CompValue('Distinct', p=M)
        elif q.modifier == 'REDUCED':
            M = CompValue('Reduced', p=M)

    if q.limitoffset:
        offset = 0
        if q.limitoffset.offset != None:
            offset = q.limitoffset.offset.toPython()

        if q.limitoffset.limit != None:
            M = CompValue('Slice', p=M, start=offset,
                          length=q.limitoffset.limit.toPython())
        else:
            M = CompValue('Slice', p=M, start=offset)

    return M, PV