Пример #1
0
 protected ForwardPositionQuery(ForwardPositionQuery other) : base((CacheOutputQuery)other)
 {
 }
        private Query ProcessFilter(Filter root, Flags flags, out Props props)
        {
            bool first = ((flags & Flags.Filter) == 0);

            Props propsCond;
            Query cond = ProcessNode(root.Condition, Flags.None, out propsCond);

            if (
                CanBeNumber(cond) ||
                (propsCond & (Props.HasPosition | Props.HasLast)) != 0
                )
            {
                propsCond |= Props.HasPosition;
                flags     |= Flags.PosFilter;
            }

            // We don't want DescendantOverDescendant pattern to be recognized here (in case descendent::foo[expr]/descendant::bar)
            // So we clean this flag here:
            flags &= ~Flags.SmartDesc;
            // ToDo: Instead it would be nice to wrap descendent::foo[expr] into special query that will flatten it -- i.e.
            //       remove all nodes that are descendant of other nodes. This is very easy becuase for sorted nodesets all children
            //       follow its parent. One step caching. This can be easyly done by rightmost DescendantQuery itsef.
            //       Interesting note! Can we garatee that DescendantOverDescendant returns flat nodeset? This defenetely true if it's input is flat.

            Query qyInput = ProcessNode(root.Input, flags | Flags.Filter, out props);

            if (root.Input.Type != AstNode.AstType.Filter)
            {
                // Props.PosFilter is for nested filters only.
                // We clean it here to avoid cleaning it in all other ast nodes.
                props &= ~Props.PosFilter;
            }
            if ((propsCond & Props.HasPosition) != 0)
            {
                // this condition is positional rightmost filter should be avare of this.
                props |= Props.PosFilter;
            }

            /*merging predicates*/ {
                FilterQuery qyFilter = qyInput as FilterQuery;
                if (qyFilter != null && (propsCond & Props.HasPosition) == 0 && qyFilter.Condition.StaticType != XPathResultType.Any)
                {
                    Query prevCond = qyFilter.Condition;
                    if (prevCond.StaticType == XPathResultType.Number)
                    {
                        prevCond = new LogicalExpr(Operator.Op.EQ, new NodeFunctions(FT.FuncPosition, null), prevCond);
                    }
                    cond    = new BooleanExpr(Operator.Op.AND, prevCond, cond);
                    qyInput = qyFilter.qyInput;
                }
            }

            if ((props & Props.PosFilter) != 0 && qyInput is DocumentOrderQuery)
            {
                qyInput = ((DocumentOrderQuery)qyInput).input;
            }
            if (firstInput == null)
            {
                firstInput = qyInput as BaseAxisQuery;
            }

            bool merge   = (qyInput.Properties & QueryProps.Merge) != 0;
            bool reverse = (qyInput.Properties & QueryProps.Reverse) != 0;

            if ((propsCond & Props.HasPosition) != 0)
            {
                if (reverse)
                {
                    qyInput = new ReversePositionQuery(qyInput);
                }
                else if ((propsCond & Props.HasLast) != 0)
                {
                    qyInput = new ForwardPositionQuery(qyInput);
                }
            }

            if (first && firstInput != null)
            {
                if (merge && (props & Props.PosFilter) != 0)
                {
                    qyInput = new FilterQuery(qyInput, cond, /*noPosition:*/ false);
                    Query parent = firstInput.qyInput;
                    if (!(parent is ContextQuery))    // we don't need to wrap filter with MergeFilterQuery when cardinality is parent <: ?
                    {
                        firstInput.qyInput = new ContextQuery();
                        firstInput         = null;
                        return(new MergeFilterQuery(parent, qyInput));
                    }
                    firstInput = null;
                    return(qyInput);
                }
                firstInput = null;
            }
            return(new FilterQuery(qyInput, cond, /*noPosition:*/ (propsCond & Props.HasPosition) == 0));
        }
Пример #3
0
 protected ForwardPositionQuery(ForwardPositionQuery other) : base(other)
 {
 }