    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.text;
    018
    019import static java.util.FormattableFlags.LEFT_JUSTIFY;
    020
    021import java.util.Formattable;
    022import java.util.Formatter;
    023
    024import org.apache.commons.lang3.StringUtils;
    025
    026/**
    027 * Provides utilities for working with the {@code Formattable} interface.
    028 *
    029 * <p>The {@link Formattable} interface provides basic control over formatting
    030 * when using a {@code Formatter}. It is primarily concerned with numeric precision
    031 * and padding, and is not designed to allow generalised alternate formats.</p>
    032 *
    033 * @since 1.0
    034 */
    035public class FormattableUtils {
    036
    037    /**
    038     * A format that simply outputs the value as a string.
    039     */
    040    private static final String SIMPLEST_FORMAT = "%s";
    041
    042    /**
    043     * Handles the common {@code Formattable} operations of truncate-pad-append,
    044     * with no ellipsis on precision overflow, and padding width underflow with
    045     * spaces.
    046     *
    047     * @param seq  the string to handle, not null
    048     * @param formatter  the destination formatter, not null
    049     * @param flags  the flags for formatting, see {@code Formattable}
    050     * @param width  the width of the output, see {@code Formattable}
    051     * @param precision  the precision of the output, see {@code Formattable}
    052     * @return The {@code formatter} instance, not null
    053     */
    054    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    055            final int precision) {
    056        return append(seq, formatter, flags, width, precision, ' ', null);
    057    }
    058
    059    /**
    060     * Handles the common {@link Formattable} operations of truncate-pad-append,
    061     * with no ellipsis on precision overflow.
    062     *
    063     * @param seq  the string to handle, not null
    064     * @param formatter  the destination formatter, not null
    065     * @param flags  the flags for formatting, see {@code Formattable}
    066     * @param width  the width of the output, see {@code Formattable}
    067     * @param precision  the precision of the output, see {@code Formattable}
    068     * @param padChar  the pad character to use
    069     * @return The {@code formatter} instance, not null
    070     */
    071    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    072            final int precision, final char padChar) {
    073        return append(seq, formatter, flags, width, precision, padChar, null);
    074    }
    075
    076    /**
    077     * Handles the common {@link Formattable} operations of truncate-pad-append.
    078     *
    079     * @param seq  the string to handle, not null
    080     * @param formatter  the destination formatter, not null
    081     * @param flags  the flags for formatting, see {@code Formattable}
    082     * @param width  the width of the output, see {@code Formattable}
    083     * @param precision  the precision of the output, see {@code Formattable}
    084     * @param padChar  the pad character to use
    085     * @param truncateEllipsis  the ellipsis to use when precision dictates truncation, null or
    086     *  empty causes a hard truncation
    087     * @return The {@code formatter} instance, not null
    088     * @throws IllegalArgumentException if {@code ellipsis.length() > precision},
    089     *  given that {@code ellipsis} is not null and {@code precision >= 0}
    090     */
    091    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    092            final int precision, final char padChar, final CharSequence truncateEllipsis) {
    093        if (!(truncateEllipsis == null || precision < 0 || truncateEllipsis.length() <= precision)) {
    094            throw new IllegalArgumentException(
    095                    String.format("Specified ellipsis '%s' exceeds precision of %s",
    096                            truncateEllipsis,
    097                            precision));
    098        }
    099        final StringBuilder buf = new StringBuilder(seq);
    100        if (precision >= 0 && precision < seq.length()) {
    101            final CharSequence ellipsis;
    102            if (truncateEllipsis == null) {
    103                ellipsis = StringUtils.EMPTY;
    104            } else {
    105                ellipsis = truncateEllipsis;
    106            }
    107            buf.replace(precision - ellipsis.length(), seq.length(), ellipsis.toString());
    108        }
    109        final boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
    110        for (int i = buf.length(); i < width; i++) {
    111            buf.insert(leftJustify ? i : 0, padChar);
    112        }
    113        formatter.format(buf.toString());
    114        return formatter;
    115    }
    116
    117    /**
    118     * Handles the common {@link Formattable} operations of truncate-pad-append,
    119     * padding width underflow with spaces.
    120     *
    121     * @param seq  the string to handle, not null
    122     * @param formatter  the destination formatter, not null
    123     * @param flags  the flags for formatting, see {@code Formattable}
    124     * @param width  the width of the output, see {@code Formattable}
    125     * @param precision  the precision of the output, see {@code Formattable}
    126     * @param ellipsis  the ellipsis to use when precision dictates truncation, null or
    127     *  empty causes a hard truncation
    128     * @return The {@code formatter} instance, not null
    129     * @throws IllegalArgumentException if {@code ellipsis.length() > precision},
    130     *  given that {@code ellipsis} is not null and {@code precision >= 0}
    131     */
    132    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    133            final int precision, final CharSequence ellipsis) {
    134        return append(seq, formatter, flags, width, precision, ' ', ellipsis);
    135    }
    136
    137    /**
    138     * Gets the default formatted representation of the specified
    139     * {@code Formattable}.
    140     *
    141     * @param formattable  the instance to convert to a string, not null
    142     * @return The resulting string, not null
    143     */
    144    public static String toString(final Formattable formattable) {
    145        return String.format(SIMPLEST_FORMAT, formattable);
    146    }
    147
    148    /**
    149     * {@code FormattableUtils} instances should NOT be constructed in
    150     * standard programming. Instead, the methods of the class should be invoked
    151     * statically.
    152     *
    153     * <p>This constructor is public to permit tools that require a JavaBean
    154     * instance to operate.</p>
    155     */
    156    public FormattableUtils() {
    157    }
    158
    159}