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With inspiration from other libraries
/*
* 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.io.Serializable;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
/**
* Common part shared by both {@link FractionFormat} and {@link BigFractionFormat}.
* @since 2.0
*/
public abstract class AbstractFormat extends NumberFormat implements Serializable {
/** Serializable version identifier. */
private static final long serialVersionUID = -6981118387974191891L;
/** The format used for the denominator. */
private NumberFormat denominatorFormat;
/** The format used for the numerator. */
private NumberFormat numeratorFormat;
/**
* Create an improper formatting instance with the default number format
* for the numerator and denominator.
*/
protected AbstractFormat() {
this(getDefaultNumberFormat());
}
/**
* 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.
*/
protected AbstractFormat(final NumberFormat format) {
this(format, (NumberFormat) format.clone());
}
/**
* 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.
*/
protected AbstractFormat(final NumberFormat numeratorFormat,
final NumberFormat denominatorFormat) {
this.numeratorFormat = numeratorFormat;
this.denominatorFormat = denominatorFormat;
}
/**
* Create a default number format. The default number format is based on
* {@link NumberFormat#getNumberInstance(java.util.Locale)}. The only
* customization is the maximum number of BigFraction digits, which is set to 0.
* @return the default number format.
*/
protected static NumberFormat getDefaultNumberFormat() {
return getDefaultNumberFormat(Locale.getDefault());
}
/**
* Create a default number format. The default number format is based on
* {@link NumberFormat#getNumberInstance(java.util.Locale)}. The only
* customization is the maximum number of BigFraction digits, which is set to 0.
* @param locale the specific locale used by the format.
* @return the default number format specific to the given locale.
*/
protected static NumberFormat getDefaultNumberFormat(final Locale locale) {
final NumberFormat nf = NumberFormat.getNumberInstance(locale);
nf.setMaximumFractionDigits(0);
nf.setParseIntegerOnly(true);
return nf;
}
/**
* Access the denominator format.
* @return the denominator format.
*/
public NumberFormat getDenominatorFormat() {
return denominatorFormat;
}
/**
* Access the numerator format.
* @return the numerator format.
*/
public NumberFormat getNumeratorFormat() {
return numeratorFormat;
}
/**
* Modify the denominator format.
* @param format the new denominator format value.
* @throws NullArgumentException if {@code format} is {@code null}.
*/
public void setDenominatorFormat(final NumberFormat format) {
if (format == null) {
throw new NullArgumentException(LocalizedFormats.DENOMINATOR_FORMAT);
}
this.denominatorFormat = format;
}
/**
* Modify the numerator format.
* @param format the new numerator format value.
* @throws NullArgumentException if {@code format} is {@code null}.
*/
public void setNumeratorFormat(final NumberFormat format) {
if (format == null) {
throw new NullArgumentException(LocalizedFormats.NUMERATOR_FORMAT);
}
this.numeratorFormat = format;
}
/**
* Parses source until a non-whitespace character is found.
* @param source the string to parse
* @param pos input/output parsing parameter. On output, pos
* holds the index of the next non-whitespace character.
*/
protected static void parseAndIgnoreWhitespace(final String source,
final ParsePosition pos) {
parseNextCharacter(source, pos);
pos.setIndex(pos.getIndex() - 1);
}
/**
* Parses source until a non-whitespace character is found.
* @param source the string to parse
* @param pos input/output parsing parameter.
* @return the first non-whitespace character.
*/
protected static char parseNextCharacter(final String source,
final ParsePosition pos) {
int index = pos.getIndex();
final int n = source.length();
char ret = 0;
if (index < n) {
char c;
do {
c = source.charAt(index++);
} while (Character.isWhitespace(c) && index < n);
pos.setIndex(index);
if (index < n) {
ret = c;
}
}
return ret;
}
/**
* Formats a double value as a fraction and appends the result to a StringBuffer.
*
* @param value the double value to format
* @param buffer StringBuffer to append to
* @param position On input: an alignment field, if desired. On output: the
* offsets of the alignment field
* @return a reference to the appended buffer
* @see #format(Object, StringBuffer, FieldPosition)
*/
@Override
public StringBuffer format(final double value,
final StringBuffer buffer, final FieldPosition position) {
return format(Double.valueOf(value), buffer, position);
}
/**
* Formats a long value as a fraction and appends the result to a StringBuffer.
*
* @param value the long value to format
* @param buffer StringBuffer to append to
* @param position On input: an alignment field, if desired. On output: the
* offsets of the alignment field
* @return a reference to the appended buffer
* @see #format(Object, StringBuffer, FieldPosition)
*/
@Override
public StringBuffer format(final long value,
final StringBuffer buffer, final FieldPosition position) {
return format(Long.valueOf(value), buffer, position);
}
}