    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 java.util.Formattable;
    020import java.util.Formatter;
    021
    022import static java.util.FormattableFlags.LEFT_JUSTIFY;
    023
    024/**
    025 * <p>Provides utilities for working with the {@code Formattable} interface.</p>
    026 *
    027 * <p>The {@link Formattable} interface provides basic control over formatting
    028 * when using a {@code Formatter}. It is primarily concerned with numeric precision
    029 * and padding, and is not designed to allow generalised alternate formats.</p>
    030 *
    031 * @since 1.0
    032 *
    033 */
    034public class FormattableUtils {
    035
    036    /**
    037     * A format that simply outputs the value as a string.
    038     */
    039    private static final String SIMPLEST_FORMAT = "%s";
    040
    041    /**
    042     * <p>{@code FormattableUtils} instances should NOT be constructed in
    043     * standard programming. Instead, the methods of the class should be invoked
    044     * statically.</p>
    045     *
    046     * <p>This constructor is public to permit tools that require a JavaBean
    047     * instance to operate.</p>
    048     */
    049    public FormattableUtils() {
    050        super();
    051    }
    052
    053    //-----------------------------------------------------------------------
    054    /**
    055     * Get the default formatted representation of the specified
    056     * {@code Formattable}.
    057     *
    058     * @param formattable  the instance to convert to a string, not null
    059     * @return the resulting string, not null
    060     */
    061    public static String toString(final Formattable formattable) {
    062        return String.format(SIMPLEST_FORMAT, formattable);
    063    }
    064
    065    /**
    066     * Handles the common {@code Formattable} operations of truncate-pad-append,
    067     * with no ellipsis on precision overflow, and padding width underflow with
    068     * spaces.
    069     *
    070     * @param seq  the string to handle, not null
    071     * @param formatter  the destination formatter, not null
    072     * @param flags  the flags for formatting, see {@code Formattable}
    073     * @param width  the width of the output, see {@code Formattable}
    074     * @param precision  the precision of the output, see {@code Formattable}
    075     * @return the {@code formatter} instance, not null
    076     */
    077    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    078            final int precision) {
    079        return append(seq, formatter, flags, width, precision, ' ', null);
    080    }
    081
    082    /**
    083     * Handles the common {@link Formattable} operations of truncate-pad-append,
    084     * with no ellipsis on precision overflow.
    085     *
    086     * @param seq  the string to handle, not null
    087     * @param formatter  the destination formatter, not null
    088     * @param flags  the flags for formatting, see {@code Formattable}
    089     * @param width  the width of the output, see {@code Formattable}
    090     * @param precision  the precision of the output, see {@code Formattable}
    091     * @param padChar  the pad character to use
    092     * @return the {@code formatter} instance, not null
    093     */
    094    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    095            final int precision, final char padChar) {
    096        return append(seq, formatter, flags, width, precision, padChar, null);
    097    }
    098
    099    /**
    100     * Handles the common {@link Formattable} operations of truncate-pad-append,
    101     * padding width underflow with spaces.
    102     *
    103     * @param seq  the string to handle, not null
    104     * @param formatter  the destination formatter, not null
    105     * @param flags  the flags for formatting, see {@code Formattable}
    106     * @param width  the width of the output, see {@code Formattable}
    107     * @param precision  the precision of the output, see {@code Formattable}
    108     * @param ellipsis  the ellipsis to use when precision dictates truncation, null or
    109     *  empty causes a hard truncation
    110     * @return the {@code formatter} instance, not null
    111     */
    112    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    113            final int precision, final CharSequence ellipsis) {
    114        return append(seq, formatter, flags, width, precision, ' ', ellipsis);
    115    }
    116
    117    /**
    118     * Handles the common {@link Formattable} operations of truncate-pad-append.
    119     *
    120     * @param seq  the string to handle, not null
    121     * @param formatter  the destination formatter, not null
    122     * @param flags  the flags for formatting, see {@code Formattable}
    123     * @param width  the width of the output, see {@code Formattable}
    124     * @param precision  the precision of the output, see {@code Formattable}
    125     * @param padChar  the pad character to use
    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     */
    130    public static Formatter append(final CharSequence seq, final Formatter formatter, final int flags, final int width,
    131            final int precision, final char padChar, final CharSequence ellipsis) {
    132        if (!(ellipsis == null || precision < 0 || ellipsis.length() <= precision)) {
    133            throw new IllegalArgumentException(
    134                    String.format("Specified ellipsis '%s' exceeds precision of %s",
    135                            ellipsis,
    136                            precision));
    137        }
    138        final StringBuilder buf = new StringBuilder(seq);
    139        if (precision >= 0 && precision < seq.length()) {
    140            final CharSequence _ellipsis;
    141            if (ellipsis == null) {
    142                _ellipsis = "";
    143            } else {
    144                _ellipsis = ellipsis;
    145            }
    146            buf.replace(precision - _ellipsis.length(), seq.length(), _ellipsis.toString());
    147        }
    148        final boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
    149        for (int i = buf.length(); i < width; i++) {
    150            buf.insert(leftJustify ? i : 0, padChar);
    151        }
    152        formatter.format(buf.toString());
    153        return formatter;
    154    }
    155
    156}