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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.poi.ss.usermodel;
import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.poi.ss.format.SimpleFraction;
import org.apache.poi.ss.formula.eval.NotImplementedException;
import org.apache.poi.util.POILogFactory;
import org.apache.poi.util.POILogger;

/**
 * 

Format class that handles Excel style fractions, such as "# #/#" and "#/###"

* *

As of this writing, this is still not 100% accurate, but it does a reasonable job * of trying to mimic Excel's fraction calculations. It does not currently * maintain Excel's spacing.

* *

This class relies on a method lifted nearly verbatim from org.apache.math.fraction. * If further uses for Commons Math are found, we will consider adding it as a dependency. * For now, we have in-lined the one method to keep things simple.

*/ @SuppressWarnings("serial") public class FractionFormat extends Format { private static final POILogger LOGGER = POILogFactory.getLogger(FractionFormat.class); private static final Pattern DENOM_FORMAT_PATTERN = Pattern.compile("(?:(#+)|(\\d+))"); //this was chosen to match the earlier limitation of max denom power //it can be expanded to get closer to Excel's calculations //with custom formats # #/######### //but as of this writing, the numerators and denominators //with formats of that nature on very small values were quite //far from Excel's calculations private static final int MAX_DENOM_POW = 4; //there are two options: //a) an exact denominator is specified in the formatString //b) the maximum denominator can be calculated from the formatString private final int exactDenom; private final int maxDenom; private final String wholePartFormatString; /** * Single parameter ctor * @param denomFormatString The format string for the denominator */ public FractionFormat(String wholePartFormatString, String denomFormatString) { this.wholePartFormatString = wholePartFormatString; //init exactDenom and maxDenom Matcher m = DENOM_FORMAT_PATTERN.matcher(denomFormatString); int tmpExact = -1; int tmpMax = -1; if (m.find()){ if (m.group(2) != null){ try{ tmpExact = Integer.parseInt(m.group(2)); //if the denom is 0, fall back to the default: tmpExact=100 if (tmpExact == 0){ tmpExact = -1; } } catch (NumberFormatException e){ //should never happen } } else if (m.group(1) != null) { int len = m.group(1).length(); len = len > MAX_DENOM_POW ? MAX_DENOM_POW : len; tmpMax = (int)Math.pow(10, len); } else { tmpExact = 100; } } if (tmpExact <= 0 && tmpMax <= 0){ //use 100 as the default denom if something went horribly wrong tmpExact = 100; } exactDenom = tmpExact; maxDenom = tmpMax; } public String format(Number num) { final double doubleValue = num.doubleValue(); final boolean isNeg = (doubleValue < 0.0f) ? true : false; final double absDoubleValue = Math.abs(doubleValue); final double wholePart = Math.floor(absDoubleValue); final double decPart = absDoubleValue - wholePart; if (wholePart + decPart == 0) { return "0"; } // if the absolute value is smaller than 1 over the exact or maxDenom // you can stop here and return "0" // reciprocal is result of an int devision ... and so it's nearly always 0 // double reciprocal = 1/Math.max(exactDenom, maxDenom); // if (absDoubleValue < reciprocal) { // return "0"; // } //this is necessary to prevent overflow in the maxDenom calculation if (Double.compare(decPart, 0) == 0){ StringBuilder sb = new StringBuilder(); if (isNeg){ sb.append("-"); } sb.append((int)wholePart); return sb.toString(); } SimpleFraction fract = null; try{ //this should be the case because of the constructor if (exactDenom > 0){ fract = SimpleFraction.buildFractionExactDenominator(decPart, exactDenom); } else { fract = SimpleFraction.buildFractionMaxDenominator(decPart, maxDenom); } } catch (RuntimeException e){ LOGGER.log(POILogger.WARN, "Can't format fraction", e); return Double.toString(doubleValue); } StringBuilder sb = new StringBuilder(); //now format the results if (isNeg){ sb.append("-"); } //if whole part has to go into the numerator if ("".equals(wholePartFormatString)){ int trueNum = (fract.getDenominator()*(int)wholePart)+fract.getNumerator(); sb.append(trueNum).append("/").append(fract.getDenominator()); return sb.toString(); } //short circuit if fraction is 0 or 1 if (fract.getNumerator() == 0){ sb.append(Integer.toString((int)wholePart)); return sb.toString(); } else if (fract.getNumerator() == fract.getDenominator()){ sb.append(Integer.toString((int)wholePart+1)); return sb.toString(); } //as mentioned above, this ignores the exact space formatting in Excel if (wholePart > 0){ sb.append(Integer.toString((int)wholePart)).append(" "); } sb.append(fract.getNumerator()).append("/").append(fract.getDenominator()); return sb.toString(); } public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos) { return toAppendTo.append(format((Number)obj)); } public Object parseObject(String source, ParsePosition pos) { throw new NotImplementedException("Reverse parsing not supported"); } }




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