    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 * <p>Provides utilities for working with the {@code Formattable} interface.</p>
    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 *
    035 */
    036public class FormattableUtils {
    037
    038    /**
    039     * A format that simply outputs the value as a string.
    040     */
    041    private static final String SIMPLEST_FORMAT = "%s";
    042
    043    /**
    044     * <p>{@code FormattableUtils} instances should NOT be constructed in
    045     * standard programming. Instead, the methods of the class should be invoked
    046     * statically.</p>
    047     *
    048     * <p>This constructor is public to permit tools that require a JavaBean
    049     * instance to operate.</p>
    050     */
    051    public FormattableUtils() {
    052        super();
    053    }
    054
    055    //-----------------------------------------------------------------------
    056    /**
    057     * Get the default formatted representation of the specified
    058     * {@code Formattable}.
    059     *
    060     * @param formattable  the instance to convert to a string, not null
    061     * @return The resulting string, not null
    062     */
    063    public static String toString(final Formattable formattable) {
    064        return String.format(SIMPLEST_FORMAT, formattable);
    065    }
    066
    067    /**
    068     * Handles the common {@code Formattable} operations of truncate-pad-append,
    069     * with no ellipsis on precision overflow, and padding width underflow with
    070     * spaces.
    071     *
    072     * @param seq  the string to handle, not null
    073     * @param formatter  the destination formatter, not null
    074     * @param flags  the flags for formatting, see {@code Formattable}
    075     * @param width  the width of the output, see {@code Formattable}
    076     * @param precision  the precision of the output, see {@code Formattable}
    077     * @return The {@code formatter} instance, not null
    078     */
    079    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    080            final int precision) {
    081        return append(seq, formatter, flags, width, precision, ' ', null);
    082    }
    083
    084    /**
    085     * Handles the common {@link Formattable} operations of truncate-pad-append,
    086     * with no ellipsis on precision overflow.
    087     *
    088     * @param seq  the string to handle, not null
    089     * @param formatter  the destination formatter, not null
    090     * @param flags  the flags for formatting, see {@code Formattable}
    091     * @param width  the width of the output, see {@code Formattable}
    092     * @param precision  the precision of the output, see {@code Formattable}
    093     * @param padChar  the pad character to use
    094     * @return The {@code formatter} instance, not null
    095     */
    096    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    097            final int precision, final char padChar) {
    098        return append(seq, formatter, flags, width, precision, padChar, null);
    099    }
    100
    101    /**
    102     * Handles the common {@link Formattable} operations of truncate-pad-append,
    103     * padding width underflow with spaces.
    104     *
    105     * @param seq  the string to handle, not null
    106     * @param formatter  the destination formatter, not null
    107     * @param flags  the flags for formatting, see {@code Formattable}
    108     * @param width  the width of the output, see {@code Formattable}
    109     * @param precision  the precision of the output, see {@code Formattable}
    110     * @param ellipsis  the ellipsis to use when precision dictates truncation, null or
    111     *  empty causes a hard truncation
    112     * @return The {@code formatter} instance, not null
    113     */
    114    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    115            final int precision, final CharSequence ellipsis) {
    116        return append(seq, formatter, flags, width, precision, ' ', ellipsis);
    117    }
    118
    119    /**
    120     * Handles the common {@link Formattable} operations of truncate-pad-append.
    121     *
    122     * @param seq  the string to handle, not null
    123     * @param formatter  the destination formatter, not null
    124     * @param flags  the flags for formatting, see {@code Formattable}
    125     * @param width  the width of the output, see {@code Formattable}
    126     * @param precision  the precision of the output, see {@code Formattable}
    127     * @param padChar  the pad character to use
    128     * @param ellipsis  the ellipsis to use when precision dictates truncation, null or
    129     *  empty causes a hard truncation
    130     * @return The {@code formatter} instance, not null
    131     */
    132    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    133            final int precision, final char padChar, final CharSequence ellipsis) {
    134        if (!(ellipsis == null || precision < 0 || ellipsis.length() <= precision)) {
    135            throw new IllegalArgumentException(
    136                    String.format("Specified ellipsis '%s' exceeds precision of %s",
    137                            ellipsis,
    138                            precision));
    139        }
    140        final StringBuilder buf = new StringBuilder(seq);
    141        if (precision >= 0 && precision < seq.length()) {
    142            final CharSequence _ellipsis;
    143            if (ellipsis == null) {
    144                _ellipsis = StringUtils.EMPTY;
    145            } else {
    146                _ellipsis = ellipsis;
    147            }
    148            buf.replace(precision - _ellipsis.length(), seq.length(), _ellipsis.toString());
    149        }
    150        final boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
    151        for (int i = buf.length(); i < width; i++) {
    152            buf.insert(leftJustify ? i : 0, padChar);
    153        }
    154        formatter.format(buf.toString());
    155        return formatter;
    156    }
    157
    158}