BucketMetricsParser.java example

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 * 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,
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package org.elasticsearch.search.aggregations.pipeline.bucketmetrics;

import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.xcontent.XContentParser.Token;
import org.elasticsearch.search.SearchParseException;
import org.elasticsearch.search.aggregations.pipeline.BucketHelpers.GapPolicy;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregatorFactory;
import org.elasticsearch.search.aggregations.support.format.ValueFormat;
import org.elasticsearch.search.aggregations.support.format.ValueFormatter;
import org.elasticsearch.search.internal.SearchContext;

import java.io.IOException;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A parser for parsing requests for a {@link BucketMetricsPipelineAggregator}
 */
public abstract class BucketMetricsParser implements PipelineAggregator.Parser {

    public static final ParseField FORMAT = new ParseField("format");

    public BucketMetricsParser() {
        super();
    }

    @Override
    public final PipelineAggregatorFactory parse(String pipelineAggregatorName, XContentParser parser, SearchContext context) throws IOException {
        XContentParser.Token token;
        String currentFieldName = null;
        String[] bucketsPaths = null;
        String format = null;
        GapPolicy gapPolicy = GapPolicy.SKIP;
        Map<String, Object> leftover = new HashMap<>(5);

        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
            if (token == XContentParser.Token.FIELD_NAME) {
                currentFieldName = parser.currentName();
            } else if (token == XContentParser.Token.VALUE_STRING) {
                if (context.parseFieldMatcher().match(currentFieldName, FORMAT)) {
                    format = parser.text();
                } else if (context.parseFieldMatcher().match(currentFieldName, BUCKETS_PATH)) {
                    bucketsPaths = new String[] { parser.text() };
                } else if (context.parseFieldMatcher().match(currentFieldName, GAP_POLICY)) {
                    gapPolicy = GapPolicy.parse(context, parser.text(), parser.getTokenLocation());
                } else {
                    leftover.put(currentFieldName, parser.text());
                }
            } else if (token == XContentParser.Token.START_ARRAY) {
                if (context.parseFieldMatcher().match(currentFieldName, BUCKETS_PATH)) {
                    List<String> paths = new ArrayList<>();
                    while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
                        String path = parser.text();
                        paths.add(path);
                    }
                    bucketsPaths = paths.toArray(new String[paths.size()]);
                } else {
                    leftover.put(currentFieldName, parser.list());
                }
            } else {
                leftover.put(currentFieldName, parser.objectText());
            }
        }

        if (bucketsPaths == null) {
            throw new SearchParseException(context, "Missing required field [" + BUCKETS_PATH.getPreferredName()
                    + "] for aggregation [" + pipelineAggregatorName + "]", parser.getTokenLocation());
        }

        ValueFormatter formatter = null;
        if (format != null) {
            formatter = ValueFormat.Patternable.Number.format(format).formatter();
        } else {
            formatter = ValueFormatter.RAW;
        }

        PipelineAggregatorFactory factory = null;
        try {
            factory = buildFactory(pipelineAggregatorName, bucketsPaths, gapPolicy, formatter, leftover);
        } catch (ParseException exception) {
            throw new SearchParseException(context, "Could not parse settings for aggregation ["
                    + pipelineAggregatorName + "].", null, exception);
        }

        if (leftover.size() > 0) {
            throw new SearchParseException(context, "Unexpected tokens " + leftover.keySet() + " in [" + pipelineAggregatorName + "].", null);
        }
        assert(factory != null);

        return factory;
    }

    protected abstract PipelineAggregatorFactory buildFactory(String pipelineAggregatorName, String[] bucketsPaths, GapPolicy gapPolicy,
            ValueFormatter formatter, Map<String, Object> unparsedParams) throws ParseException;

}