Java tutorial
/** * 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.collect.ImmutableList; 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.primitives.Ints.saturatedCast; public class Abbreviate extends AbstractFunction<String> { public static final String NAME = "abbreviate"; private static final String VALUE = "value"; private static final String WIDTH = "width"; private final ParameterDescriptor<String, String> valueParam; private final ParameterDescriptor<Long, Long> widthParam; public Abbreviate() { valueParam = ParameterDescriptor.string(VALUE).description("The string to abbreviate").build(); widthParam = ParameterDescriptor.integer(WIDTH) .description("The maximum number of characters including the '...' (at least 4)").build(); } @Override public String evaluate(FunctionArgs args, EvaluationContext context) { final String value = valueParam.required(args, context); final Long required = widthParam.required(args, context); if (required == null) { return null; } final Long maxWidth = Math.max(required, 4L); return StringUtils.abbreviate(value, saturatedCast(maxWidth)); } @Override public FunctionDescriptor<String> descriptor() { ImmutableList.Builder<ParameterDescriptor> params = ImmutableList.builder(); params.add(); return FunctionDescriptor.<String>builder().name(NAME).returnType(String.class) .params(ImmutableList.of(valueParam, widthParam)) .description("Abbreviates a string by appending '...' to fit into a maximum amount of characters") .build(); } }