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Convenient utility to build XML models by evaluating XPath expressions

There is a newer version: 2.3.9

package com.github.simy4.xpath.expr;

import com.github.simy4.xpath.XmlBuilderException;
import com.github.simy4.xpath.navigator.Node;
import com.github.simy4.xpath.view.AbstractViewVisitor;
import com.github.simy4.xpath.view.BooleanView;
import com.github.simy4.xpath.view.NumberView;
import com.github.simy4.xpath.view.View;
import com.github.simy4.xpath.view.ViewContext;

public class PredicateExpr implements Expr {

    private final Expr predicate;

    public PredicateExpr(Expr predicate) {
        this.predicate = predicate;
    }

    @Override
    public  View resolve(ViewContext context) throws XmlBuilderException {
        return predicate.resolve(context).visit(new PredicateVisitor(context));
    }

    @Override
    public String toString() {
        return "[" + predicate + "]";
    }

    private static final class PredicateVisitor extends AbstractViewVisitor> {

        private final ViewContext context;

        private PredicateVisitor(ViewContext context) {
            this.context = context;
        }

        @Override
        public View visit(NumberView numberView) throws XmlBuilderException {
            final double number = numberView.toNumber();
            if (0 == Double.compare(number, context.getPosition())) {
                context.getCurrent().mark();
                return BooleanView.of(true);
            } else if (context.isGreedy() && !context.hasNext() && number > context.getPosition()
                    && context.getCurrent().isNew()) {
                final T node = context.getCurrent().getNode();
                long numberOfNodesToCreate = (long) number - context.getPosition();
                do {
                    context.getNavigator().prependCopy(node);
                } while (--numberOfNodesToCreate > 0);
                return BooleanView.of(true);
            } else {
                return BooleanView.of(false);
            }
        }

        @Override
        protected View returnDefault(View view) throws XmlBuilderException {
            return view;
        }

    }

}