co.cask.cdap.data2.metadata.dataset.SortInfo.java Source code

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Here is the source code for co.cask.cdap.data2.metadata.dataset.SortInfo.java

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/*
 * Copyright  2015-2016 Cask Data, Inc.
 *
 * Licensed 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.
 */

package co.cask.cdap.data2.metadata.dataset;

import co.cask.cdap.common.BadRequestException;
import co.cask.cdap.data2.metadata.system.AbstractSystemMetadataWriter;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.Iterables;

import java.util.Iterator;
import java.util.Objects;
import java.util.regex.Pattern;
import javax.annotation.Nullable;

/**
 * Represents sorting info for search results.
 */
public class SortInfo {

    private static final Pattern SPACE_SPLIT_PATTERN = Pattern.compile("\\s+");

    /**
     * Default sort order, when no custom sorting is desired. Sorts search results as a function of relative weights for
     * the specified search query.
     */
    public static final SortInfo DEFAULT = new SortInfo(null, SortOrder.WEIGHTED);

    /**
     * Represents sorting order.
     */
    public enum SortOrder {
        ASC, DESC, WEIGHTED
    }

    private final String sortBy;
    private final SortOrder sortOrder;

    public SortInfo(@Nullable String sortBy, SortOrder sortOrder) {
        this.sortBy = sortBy;
        this.sortOrder = sortOrder;
    }

    /**
     * Returns the sort by column, unless the column does not matter, when the sort order is {@link SortOrder#WEIGHTED}.
     */
    @Nullable
    public String getSortBy() {
        return sortBy;
    }

    public SortOrder getSortOrder() {
        return sortOrder;
    }

    /**
     * Parses a {@link SortInfo} object from the specified string. The supported format is
     * <pre>[sortBy][whitespace][sortOrder]</pre>.
     *
     * @param sort the string to parse into a {@link SortInfo}. If {@code null}, {@link #DEFAULT} is returned
     * @return the parsed {@link SortInfo}
     * @throws BadRequestException if the string does not conform to the expected format
     */
    public static SortInfo of(@Nullable String sort) throws BadRequestException {
        if (Strings.isNullOrEmpty(sort)) {
            return SortInfo.DEFAULT;
        }
        Iterable<String> sortSplit = Splitter.on(SPACE_SPLIT_PATTERN).trimResults().omitEmptyStrings().split(sort);
        if (Iterables.size(sortSplit) != 2) {
            throw new BadRequestException(String.format(
                    "'sort' parameter should be a space separated string containing the field ('%s' or '%s') and "
                            + "the sort order ('%s' or '%s'). Found %s.",
                    AbstractSystemMetadataWriter.ENTITY_NAME_KEY, AbstractSystemMetadataWriter.CREATION_TIME_KEY,
                    SortOrder.ASC, SortOrder.DESC, sort));
        }
        Iterator<String> iterator = sortSplit.iterator();
        String sortBy = iterator.next();
        String sortOrder = iterator.next();
        if (!AbstractSystemMetadataWriter.ENTITY_NAME_KEY.equalsIgnoreCase(sortBy)
                && !AbstractSystemMetadataWriter.CREATION_TIME_KEY.equalsIgnoreCase(sortBy)) {
            throw new BadRequestException(String.format("Sort field must be '%s' or '%s'. Found %s.",
                    AbstractSystemMetadataWriter.ENTITY_NAME_KEY, AbstractSystemMetadataWriter.CREATION_TIME_KEY,
                    sortBy));
        }
        if (!"asc".equalsIgnoreCase(sortOrder) && !"desc".equalsIgnoreCase(sortOrder)) {
            throw new BadRequestException(String.format("Sort order must be one of '%s' or '%s'. Found %s.",
                    SortOrder.ASC, SortOrder.DESC, sortOrder));
        }

        return new SortInfo(sortBy, SortInfo.SortOrder.valueOf(sortOrder.toUpperCase()));
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        SortInfo that = (SortInfo) o;

        return Objects.equals(sortBy, that.sortBy) && Objects.equals(sortOrder, that.sortOrder);
    }

    @Override
    public int hashCode() {
        return Objects.hash(sortBy, sortOrder);
    }
}