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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.commons.math3.fraction;

import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;

import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.util.FastMath;
import org.apache.commons.math3.util.MathUtils;

/**
 * Formats a Fraction number in proper format.  The number format for each of
 * the whole number, numerator and, denominator can be configured.
 * 

* Minus signs are only allowed in the whole number part - i.e., * "-3 1/2" is legitimate and denotes -7/2, but "-3 -1/2" is invalid and * will result in a ParseException.

* * @since 1.1 */ public class ProperFractionFormat extends FractionFormat { /** Serializable version identifier */ private static final long serialVersionUID = 760934726031766749L; /** The format used for the whole number. */ private NumberFormat wholeFormat; /** * Create a proper formatting instance with the default number format for * the whole, numerator, and denominator. */ public ProperFractionFormat() { this(getDefaultNumberFormat()); } /** * Create a proper formatting instance with a custom number format for the * whole, numerator, and denominator. * @param format the custom format for the whole, numerator, and * denominator. */ public ProperFractionFormat(NumberFormat format) { this(format, (NumberFormat)format.clone(), (NumberFormat)format.clone()); } /** * Create a proper formatting instance with a custom number format for each * of the whole, numerator, and denominator. * @param wholeFormat the custom format for the whole. * @param numeratorFormat the custom format for the numerator. * @param denominatorFormat the custom format for the denominator. */ public ProperFractionFormat(NumberFormat wholeFormat, NumberFormat numeratorFormat, NumberFormat denominatorFormat) { super(numeratorFormat, denominatorFormat); setWholeFormat(wholeFormat); } /** * Formats a {@link Fraction} object to produce a string. The fraction * is output in proper format. * * @param fraction the object to format. * @param toAppendTo where the text is to be appended * @param pos On input: an alignment field, if desired. On output: the * offsets of the alignment field * @return the value passed in as toAppendTo. */ @Override public StringBuffer format(Fraction fraction, StringBuffer toAppendTo, FieldPosition pos) { pos.setBeginIndex(0); pos.setEndIndex(0); int num = fraction.getNumerator(); int den = fraction.getDenominator(); int whole = num / den; num %= den; if (whole != 0) { getWholeFormat().format(whole, toAppendTo, pos); toAppendTo.append(' '); num = FastMath.abs(num); } getNumeratorFormat().format(num, toAppendTo, pos); toAppendTo.append(" / "); getDenominatorFormat().format(den, toAppendTo, pos); return toAppendTo; } /** * Access the whole format. * @return the whole format. */ public NumberFormat getWholeFormat() { return wholeFormat; } /** * Parses a string to produce a {@link Fraction} object. This method * expects the string to be formatted as a proper fraction. *

* Minus signs are only allowed in the whole number part - i.e., * "-3 1/2" is legitimate and denotes -7/2, but "-3 -1/2" is invalid and * will result in a ParseException.

* * @param source the string to parse * @param pos input/ouput parsing parameter. * @return the parsed {@link Fraction} object. */ @Override public Fraction parse(String source, ParsePosition pos) { // try to parse improper fraction Fraction ret = super.parse(source, pos); if (ret != null) { return ret; } int initialIndex = pos.getIndex(); // parse whitespace parseAndIgnoreWhitespace(source, pos); // parse whole Number whole = getWholeFormat().parse(source, pos); if (whole == null) { // invalid integer number // set index back to initial, error index should already be set // character examined. pos.setIndex(initialIndex); return null; } // parse whitespace parseAndIgnoreWhitespace(source, pos); // parse numerator Number num = getNumeratorFormat().parse(source, pos); if (num == null) { // invalid integer number // set index back to initial, error index should already be set // character examined. pos.setIndex(initialIndex); return null; } if (num.intValue() < 0) { // minus signs should be leading, invalid expression pos.setIndex(initialIndex); return null; } // parse '/' int startIndex = pos.getIndex(); char c = parseNextCharacter(source, pos); switch (c) { case 0 : // no '/' // return num as a fraction return new Fraction(num.intValue(), 1); case '/' : // found '/', continue parsing denominator break; default : // invalid '/' // set index back to initial, error index should be the last // character examined. pos.setIndex(initialIndex); pos.setErrorIndex(startIndex); return null; } // parse whitespace parseAndIgnoreWhitespace(source, pos); // parse denominator Number den = getDenominatorFormat().parse(source, pos); if (den == null) { // invalid integer number // set index back to initial, error index should already be set // character examined. pos.setIndex(initialIndex); return null; } if (den.intValue() < 0) { // minus signs must be leading, invalid pos.setIndex(initialIndex); return null; } int w = whole.intValue(); int n = num.intValue(); int d = den.intValue(); return new Fraction(((FastMath.abs(w) * d) + n) * MathUtils.copySign(1, w), d); } /** * Modify the whole format. * @param format The new whole format value. * @throws NullArgumentException if {@code format} is {@code null}. */ public void setWholeFormat(NumberFormat format) { if (format == null) { throw new NullArgumentException(LocalizedFormats.WHOLE_FORMAT); } this.wholeFormat = format; } }




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