OrderByClause.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Authors: Stefan Irimescu, Can Berker Cikis
 *
 */

package org.rumbledb.expressions.flowr;


import org.rumbledb.exceptions.ExceptionMetadata;
import org.rumbledb.exceptions.SemanticException;
import org.rumbledb.expressions.AbstractNodeVisitor;
import org.rumbledb.expressions.Node;

import java.util.ArrayList;
import java.util.List;

public class OrderByClause extends Clause {

    private static final long serialVersionUID = 1L;

    private final List<OrderByClauseSortingKey> sortingKeys;
    private final boolean isStable;

    public OrderByClause(List<OrderByClauseSortingKey> exprs, boolean stable, ExceptionMetadata metadata) {
        super(FLWOR_CLAUSES.ORDER_BY, metadata);
        if (exprs == null || exprs.isEmpty()) {
            throw new SemanticException("Group clause must have at least one variable", metadata);
        }
        this.sortingKeys = exprs;
        this.isStable = stable;
    }

    @Override
    public List<Node> getChildren() {
        List<Node> result = new ArrayList<>();
        this.sortingKeys.forEach(e -> {
            if (e != null) {
                result.add(e.getExpression());
            }
        });
        return result;
    }

    @Override
    public void serializeToJSONiq(StringBuffer sb, int indent) {
        indentIt(sb, indent);
        if (this.isStable)
            sb.append("stable ");
        sb.append("order by ");
        int i = 0;
        for (OrderByClauseSortingKey orderby : this.sortingKeys) {
            orderby.getExpression().serializeToJSONiq(sb, 0);
            if (orderby.isAscending())
                sb.append(" ascending");
            else
                sb.append(" descending");
            if (orderby.getEmptyOrder() != OrderByClauseSortingKey.EMPTY_ORDER.NONE) {
                if (orderby.getEmptyOrder() == OrderByClauseSortingKey.EMPTY_ORDER.LEAST)
                    sb.append(" empty least");
                else
                    sb.append(" empty greatest");
            }
            if (orderby.getUri() != null && !orderby.getUri().equals("")) {
                sb.append(" collation \"" + orderby.getUri() + "\"");
            }
            if (i == this.sortingKeys.size() - 1) {
                sb.append("\n");
            } else {
                sb.append(", ");
            }
            i++;
        }
    }

    @Override
    public <T> T accept(AbstractNodeVisitor<T> visitor, T argument) {
        return visitor.visitOrderByClause(this, argument);
    }

    public boolean isStable() {
        return this.isStable;
    }

    public List<OrderByClauseSortingKey> getSortingKeys() {
        return this.sortingKeys;
    }

}