    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 *      https://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>
    030 * The {@link Formattable} interface provides basic control over formatting when using a {@code Formatter}. It is primarily concerned with numeric precision and
    031 * padding, and is not designed to allow generalized alternate formats.
    032 * </p>
    033 *
    034 * @since 1.0
    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     * Handles the common {@code Formattable} operations of truncate-pad-append, 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, with no ellipsis on precision overflow.
    061     *
    062     * @param seq       the string to handle, not null.
    063     * @param formatter the destination formatter, not null.
    064     * @param flags     the flags for formatting, see {@code Formattable}.
    065     * @param width     the width of the output, see {@code Formattable}.
    066     * @param precision the precision of the output, see {@code Formattable}.
    067     * @param padChar   the pad character to use.
    068     * @return The {@code formatter} instance, not null.
    069     */
    070    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    071            final int precision, final char padChar) {
    072        return append(seq, formatter, flags, width, precision, padChar, null);
    073    }
    074
    075    /**
    076     * Handles the common {@link Formattable} operations of truncate-pad-append.
    077     *
    078     * @param seq              the string to handle, not null.
    079     * @param formatter        the destination formatter, not null.
    080     * @param flags            the flags for formatting, see {@code Formattable}.
    081     * @param width            the width of the output, see {@code Formattable}.
    082     * @param precision        the precision of the output, see {@code Formattable}.
    083     * @param padChar          the pad character to use.
    084     * @param truncateEllipsis the ellipsis to use when precision dictates truncation, null or empty causes a hard truncation.
    085     * @return The {@code formatter} instance, not null.
    086     * @throws IllegalArgumentException if {@code ellipsis.length() > precision}, given that {@code ellipsis} is not null and {@code precision >= 0}.
    087     */
    088    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    089            final int precision, final char padChar, final CharSequence truncateEllipsis) {
    090        if (!(truncateEllipsis == null || precision < 0 || truncateEllipsis.length() <= precision)) {
    091            throw new IllegalArgumentException(
    092                    String.format("Specified ellipsis '%s' exceeds precision of %s",
    093                            truncateEllipsis,
    094                            precision));
    095        }
    096        final StringBuilder buf = new StringBuilder(seq);
    097        if (precision >= 0 && precision < seq.length()) {
    098            final CharSequence ellipsis;
    099            if (truncateEllipsis == null) {
    100                ellipsis = StringUtils.EMPTY;
    101            } else {
    102                ellipsis = truncateEllipsis;
    103            }
    104            buf.replace(precision - ellipsis.length(), seq.length(), ellipsis.toString());
    105        }
    106        final boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
    107        for (int i = buf.length(); i < width; i++) {
    108            buf.insert(leftJustify ? i : 0, padChar);
    109        }
    110        formatter.format(buf.toString());
    111        return formatter;
    112    }
    113
    114    /**
    115     * Handles the common {@link Formattable} operations of truncate-pad-append, padding width underflow with spaces.
    116     *
    117     * @param seq       the string to handle, not null.
    118     * @param formatter the destination formatter, not null.
    119     * @param flags     the flags for formatting, see {@code Formattable}.
    120     * @param width     the width of the output, see {@code Formattable}.
    121     * @param precision the precision of the output, see {@code Formattable}.
    122     * @param ellipsis  the ellipsis to use when precision dictates truncation, null or empty causes a hard truncation..
    123     * @return The {@code formatter} instance, not null
    124     * @throws IllegalArgumentException if {@code ellipsis.length() > precision}, given that {@code ellipsis} is not null and {@code precision >= 0}.
    125     */
    126    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width, final int precision,
    127            final CharSequence ellipsis) {
    128        return append(seq, formatter, flags, width, precision, ' ', ellipsis);
    129    }
    130
    131    /**
    132     * Gets the default formatted representation of the specified {@code Formattable}.
    133     *
    134     * @param formattable the instance to convert to a string, not null.
    135     * @return The resulting string, not null.
    136     */
    137    public static String toString(final Formattable formattable) {
    138        return String.format(SIMPLEST_FORMAT, formattable);
    139    }
    140
    141    /**
    142     * {@code FormattableUtils} instances should NOT be constructed in standard programming. Instead, the methods of the class should be invoked statically.
    143     *
    144     * <p>
    145     * This constructor is public to permit tools that require a JavaBean instance to operate.
    146     * </p>
    147     */
    148    public FormattableUtils() {
    149    }
    150
    151}