org.graylog.plugins.pipelineprocessor.functions.strings.Substring.java Source code

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Here is the source code for org.graylog.plugins.pipelineprocessor.functions.strings.Substring.java

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/**
 * This file is part of Graylog Pipeline Processor.
 *
 * Graylog Pipeline Processor is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog Pipeline Processor is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Graylog Pipeline Processor.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.graylog.plugins.pipelineprocessor.functions.strings;

import com.google.common.primitives.Ints;
import org.apache.commons.lang3.StringUtils;
import org.graylog.plugins.pipelineprocessor.EvaluationContext;
import org.graylog.plugins.pipelineprocessor.ast.functions.AbstractFunction;
import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionArgs;
import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionDescriptor;
import org.graylog.plugins.pipelineprocessor.ast.functions.ParameterDescriptor;

import static com.google.common.collect.ImmutableList.of;

public class Substring extends AbstractFunction<String> {

    public static final String NAME = "substring";
    private final ParameterDescriptor<String, String> valueParam;
    private final ParameterDescriptor<Long, Long> startParam;
    private final ParameterDescriptor<Long, Long> endParam;

    public Substring() {
        valueParam = ParameterDescriptor.string("value").description("The string to extract from").build();
        startParam = ParameterDescriptor.integer("start").description(
                "The position to start from, negative means count back from the end of the String by this many characters")
                .build();
        endParam = ParameterDescriptor.integer("end").optional().description(
                "The position to end at (exclusive), negative means count back from the end of the String by this many characters, defaults to length of the input string")
                .build();
    }

    @Override
    public String evaluate(FunctionArgs args, EvaluationContext context) {
        final String value = valueParam.required(args, context);
        final Long startValue = startParam.required(args, context);
        if (value == null || startValue == null) {
            return null;
        }
        final int start = Ints.saturatedCast(startValue);
        final int end = Ints.saturatedCast(endParam.optional(args, context).orElse((long) value.length()));

        return StringUtils.substring(value, start, end);
    }

    @Override
    public FunctionDescriptor<String> descriptor() {
        return FunctionDescriptor.<String>builder().name(NAME).returnType(String.class)
                .params(of(valueParam, startParam, endParam)).description("Extract a substring from a string")
                .build();
    }
}