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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 org.apache.commons.math3.exception.MathIllegalArgumentException;
+import org.apache.commons.math3.exception.MathParseException;
+import org.apache.commons.math3.exception.util.LocalizedFormats;
+
+import java.text.FieldPosition;
+import java.text.NumberFormat;
+import java.text.ParsePosition;
+import java.util.Locale;
+
+/**
+ * Formats a Fraction number in proper format or improper format. The number format for each of the
+ * whole number, numerator and, denominator can be configured.
+ *
+ * @since 1.1
+ */
+public class FractionFormat extends AbstractFormat {
+
+ /** Serializable version identifier */
+ private static final long serialVersionUID = 3008655719530972611L;
+
+ /**
+ * Create an improper formatting instance with the default number format for the numerator and
+ * denominator.
+ */
+ public FractionFormat() {}
+
+ /**
+ * Create an improper formatting instance with a custom number format for both the numerator and
+ * denominator.
+ *
+ * @param format the custom format for both the numerator and denominator.
+ */
+ public FractionFormat(final NumberFormat format) {
+ super(format);
+ }
+
+ /**
+ * Create an improper formatting instance with a custom number format for the numerator and a
+ * custom number format for the denominator.
+ *
+ * @param numeratorFormat the custom format for the numerator.
+ * @param denominatorFormat the custom format for the denominator.
+ */
+ public FractionFormat(
+ final NumberFormat numeratorFormat, final NumberFormat denominatorFormat) {
+ super(numeratorFormat, denominatorFormat);
+ }
+
+ /**
+ * Get the set of locales for which complex formats are available. This is the same set as the
+ * {@link NumberFormat} set.
+ *
+ * @return available complex format locales.
+ */
+ public static Locale[] getAvailableLocales() {
+ return NumberFormat.getAvailableLocales();
+ }
+
+ /**
+ * This static method calls formatFraction() on a default instance of FractionFormat.
+ *
+ * @param f Fraction object to format
+ * @return a formatted fraction in proper form.
+ */
+ public static String formatFraction(Fraction f) {
+ return getImproperInstance().format(f);
+ }
+
+ /**
+ * Returns the default complex format for the current locale.
+ *
+ * @return the default complex format.
+ */
+ public static FractionFormat getImproperInstance() {
+ return getImproperInstance(Locale.getDefault());
+ }
+
+ /**
+ * Returns the default complex format for the given locale.
+ *
+ * @param locale the specific locale used by the format.
+ * @return the complex format specific to the given locale.
+ */
+ public static FractionFormat getImproperInstance(final Locale locale) {
+ return new FractionFormat(getDefaultNumberFormat(locale));
+ }
+
+ /**
+ * Returns the default complex format for the current locale.
+ *
+ * @return the default complex format.
+ */
+ public static FractionFormat getProperInstance() {
+ return getProperInstance(Locale.getDefault());
+ }
+
+ /**
+ * Returns the default complex format for the given locale.
+ *
+ * @param locale the specific locale used by the format.
+ * @return the complex format specific to the given locale.
+ */
+ public static FractionFormat getProperInstance(final Locale locale) {
+ return new ProperFractionFormat(getDefaultNumberFormat(locale));
+ }
+
+ /**
+ * Create a default number format. The default number format is based on {@link
+ * NumberFormat#getNumberInstance(java.util.Locale)} with the only customizing is the maximum
+ * number of fraction digits, which is set to 0.
+ *
+ * @return the default number format.
+ */
+ protected static NumberFormat getDefaultNumberFormat() {
+ return getDefaultNumberFormat(Locale.getDefault());
+ }
+
+ /**
+ * Formats a {@link Fraction} object to produce a string. The fraction is output in improper
+ * 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.
+ */
+ public StringBuffer format(
+ final Fraction fraction, final StringBuffer toAppendTo, final FieldPosition pos) {
+
+ pos.setBeginIndex(0);
+ pos.setEndIndex(0);
+
+ getNumeratorFormat().format(fraction.getNumerator(), toAppendTo, pos);
+ toAppendTo.append(" / ");
+ getDenominatorFormat().format(fraction.getDenominator(), toAppendTo, pos);
+
+ return toAppendTo;
+ }
+
+ /**
+ * Formats an object and appends the result to a StringBuffer. <code>obj</code> must be either a
+ * {@link Fraction} object or a {@link Number} object. Any other type of object will result in
+ * an {@link IllegalArgumentException} being thrown.
+ *
+ * @param obj 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.
+ * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer,
+ * java.text.FieldPosition)
+ * @throws FractionConversionException if the number cannot be converted to a fraction
+ * @throws MathIllegalArgumentException if <code>obj</code> is not a valid type.
+ */
+ @Override
+ public StringBuffer format(
+ final Object obj, final StringBuffer toAppendTo, final FieldPosition pos)
+ throws FractionConversionException, MathIllegalArgumentException {
+ StringBuffer ret = null;
+
+ if (obj instanceof Fraction) {
+ ret = format((Fraction) obj, toAppendTo, pos);
+ } else if (obj instanceof Number) {
+ ret = format(new Fraction(((Number) obj).doubleValue()), toAppendTo, pos);
+ } else {
+ throw new MathIllegalArgumentException(
+ LocalizedFormats.CANNOT_FORMAT_OBJECT_TO_FRACTION);
+ }
+
+ return ret;
+ }
+
+ /**
+ * Parses a string to produce a {@link Fraction} object.
+ *
+ * @param source the string to parse
+ * @return the parsed {@link Fraction} object.
+ * @exception MathParseException if the beginning of the specified string cannot be parsed.
+ */
+ @Override
+ public Fraction parse(final String source) throws MathParseException {
+ final ParsePosition parsePosition = new ParsePosition(0);
+ final Fraction result = parse(source, parsePosition);
+ if (parsePosition.getIndex() == 0) {
+ throw new MathParseException(source, parsePosition.getErrorIndex(), Fraction.class);
+ }
+ return result;
+ }
+
+ /**
+ * Parses a string to produce a {@link Fraction} object. This method expects the string to be
+ * formatted as an improper fraction.
+ *
+ * @param source the string to parse
+ * @param pos input/output parsing parameter.
+ * @return the parsed {@link Fraction} object.
+ */
+ @Override
+ public Fraction parse(final String source, final ParsePosition pos) {
+ final int initialIndex = pos.getIndex();
+
+ // parse whitespace
+ parseAndIgnoreWhitespace(source, pos);
+
+ // parse numerator
+ final 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;
+ }
+
+ // parse '/'
+ final int startIndex = pos.getIndex();
+ final 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
+ final 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;
+ }
+
+ return new Fraction(num.intValue(), den.intValue());
+ }
+}