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Apache Commons Text is a library focused on algorithms working on strings.
/*
* 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.text;
import java.util.Formattable;
import java.util.Formatter;
import static java.util.FormattableFlags.LEFT_JUSTIFY;
/**
* Provides utilities for working with the {@code Formattable} interface.
*
* The {@link Formattable} interface provides basic control over formatting
* when using a {@code Formatter}. It is primarily concerned with numeric precision
* and padding, and is not designed to allow generalised alternate formats.
*
* @since 1.0
*
*/
public class FormattableUtils {
/**
* A format that simply outputs the value as a string.
*/
private static final String SIMPLEST_FORMAT = "%s";
/**
* {@code FormattableUtils} instances should NOT be constructed in
* standard programming. Instead, the methods of the class should be invoked
* statically.
*
* This constructor is public to permit tools that require a JavaBean
* instance to operate.
*/
public FormattableUtils() {
super();
}
//-----------------------------------------------------------------------
/**
* Get the default formatted representation of the specified
* {@code Formattable}.
*
* @param formattable the instance to convert to a string, not null
* @return the resulting string, not null
*/
public static String toString(final Formattable formattable) {
return String.format(SIMPLEST_FORMAT, formattable);
}
/**
* Handles the common {@code Formattable} operations of truncate-pad-append,
* with no ellipsis on precision overflow, and padding width underflow with
* spaces.
*
* @param seq the string to handle, not null
* @param formatter the destination formatter, not null
* @param flags the flags for formatting, see {@code Formattable}
* @param width the width of the output, see {@code Formattable}
* @param precision the precision of the output, see {@code Formattable}
* @return the {@code formatter} instance, not null
*/
public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
final int precision) {
return append(seq, formatter, flags, width, precision, ' ', null);
}
/**
* Handles the common {@link Formattable} operations of truncate-pad-append,
* with no ellipsis on precision overflow.
*
* @param seq the string to handle, not null
* @param formatter the destination formatter, not null
* @param flags the flags for formatting, see {@code Formattable}
* @param width the width of the output, see {@code Formattable}
* @param precision the precision of the output, see {@code Formattable}
* @param padChar the pad character to use
* @return the {@code formatter} instance, not null
*/
public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
final int precision, final char padChar) {
return append(seq, formatter, flags, width, precision, padChar, null);
}
/**
* Handles the common {@link Formattable} operations of truncate-pad-append,
* padding width underflow with spaces.
*
* @param seq the string to handle, not null
* @param formatter the destination formatter, not null
* @param flags the flags for formatting, see {@code Formattable}
* @param width the width of the output, see {@code Formattable}
* @param precision the precision of the output, see {@code Formattable}
* @param ellipsis the ellipsis to use when precision dictates truncation, null or
* empty causes a hard truncation
* @return the {@code formatter} instance, not null
*/
public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
final int precision, final CharSequence ellipsis) {
return append(seq, formatter, flags, width, precision, ' ', ellipsis);
}
/**
* Handles the common {@link Formattable} operations of truncate-pad-append.
*
* @param seq the string to handle, not null
* @param formatter the destination formatter, not null
* @param flags the flags for formatting, see {@code Formattable}
* @param width the width of the output, see {@code Formattable}
* @param precision the precision of the output, see {@code Formattable}
* @param padChar the pad character to use
* @param ellipsis the ellipsis to use when precision dictates truncation, null or
* empty causes a hard truncation
* @return the {@code formatter} instance, not null
*/
public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
final int precision, final char padChar, final CharSequence ellipsis) {
if (!(ellipsis == null || precision < 0 || ellipsis.length() <= precision)) {
throw new IllegalArgumentException(
String.format("Specified ellipsis '%s' exceeds precision of %s",
ellipsis,
precision));
}
final StringBuilder buf = new StringBuilder(seq);
if (precision >= 0 && precision < seq.length()) {
final CharSequence _ellipsis;
if (ellipsis == null) {
_ellipsis = "";
} else {
_ellipsis = ellipsis;
}
buf.replace(precision - _ellipsis.length(), seq.length(), _ellipsis.toString());
}
final boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
for (int i = buf.length(); i < width; i++) {
buf.insert(leftJustify ? i : 0, padChar);
}
formatter.format(buf.toString());
return formatter;
}
}