001    /*
002     * SonarQube, open source software quality management tool.
003     * Copyright (C) 2008-2014 SonarSource
004     * mailto:contact AT sonarsource DOT com
005     *
006     * SonarQube is free software; you can redistribute it and/or
007     * modify it under the terms of the GNU Lesser General Public
008     * License as published by the Free Software Foundation; either
009     * version 3 of the License, or (at your option) any later version.
010     *
011     * SonarQube is distributed in the hope that it will be useful,
012     * but WITHOUT ANY WARRANTY; without even the implied warranty of
013     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014     * Lesser General Public License for more details.
015     *
016     * You should have received a copy of the GNU Lesser General Public License
017     * along with this program; if not, write to the Free Software Foundation,
018     * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
019     */
020    package org.sonar.api.measures;
021    
022    import java.util.Collection;
023    import java.util.Collections;
024    import java.util.List;
025    
026    /**
027     * @since 2.0
028     */
029    public class MeanAggregationFormula implements Formula {
030    
031      private boolean forceZeroIfMissingData=false;
032    
033      public MeanAggregationFormula(boolean forceZeroIfMissingData) {
034        this.forceZeroIfMissingData = forceZeroIfMissingData;
035      }
036    
037      public MeanAggregationFormula() {
038        this(false);
039      }
040    
041      public List<Metric> dependsUponMetrics() {
042        return Collections.emptyList();
043      }
044    
045      public Measure calculate(FormulaData data, FormulaContext context) {
046        double sum=0.0;
047        int count=0;
048        boolean hasValue=false;
049        Collection<Measure> measures = data.getChildrenMeasures(context.getTargetMetric());
050        for (Measure measure : measures) {
051          if (MeasureUtils.hasValue(measure)) {
052            sum+=measure.getValue();
053            count++;
054            hasValue=true;
055          }
056        }
057    
058        if (!hasValue && !forceZeroIfMissingData) {
059          return null;
060        }
061        return new Measure(context.getTargetMetric(), count==0 ? 0.0 : sum/count);
062      }
063    }