001/*
002 * Units of Measurement API
003 * Copyright (c) 2014-2019, Jean-Marie Dautelle, Werner Keil, Otavio Santana.
004 *
005 * All rights reserved.
006 *
007 * Redistribution and use in source and binary forms, with or without modification,
008 * are permitted provided that the following conditions are met:
009 *
010 * 1. Redistributions of source code must retain the above copyright notice,
011 *    this list of conditions and the following disclaimer.
012 *
013 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
014 *    and the following disclaimer in the documentation and/or other materials provided with the distribution.
015 *
016 * 3. Neither the name of JSR-385 nor the names of its contributors may be used to endorse or promote products
017 *    derived from this software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
021 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
022 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
023 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
026 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
028 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package javax.measure.format;
031
032import java.io.IOException;
033import java.text.ParsePosition;
034
035import javax.measure.Unit;
036
037/**
038 * Formats instances of {@link Unit} to a {@link String} or {@link Appendable} and parses a {@link CharSequence} to a {@link Unit}.
039 *
040 * <h1><a id="synchronization">Synchronization</a></h1>
041 * <p>
042 * Instances of this class are not required to be thread-safe. It is recommended to use separate format instances for each thread. If multiple threads
043 * access a format concurrently, it must be synchronized externally.
044 * <p>
045 *
046 * @author <a href="mailto:[email protected]">Jean-Marie Dautelle</a>
047 * @author <a href="mailto:[email protected]">Werner Keil</a>
048 *
049 * @version 1.3.2, November 3, 2018
050 * @since 1.0
051 *
052 * @see Unit
053 */
054public interface UnitFormat {
055    /**
056     * Formats the specified {@link Unit}.
057     *
058     * @param unit
059     *            the {@link Unit} to format, not {@code null}
060     * @param appendable
061     *            the appendable destination.
062     * @return the appendable destination passed in with formatted text appended.
063     * @throws IOException
064     *             if an error occurs while writing to the destination.
065     */
066    Appendable format(Unit<?> unit, Appendable appendable) throws IOException;
067
068    /**
069     * Formats the specified {@link Unit}.
070     *
071     * @param unit
072     *            the {@link Unit} to format, not {@code null}
073     * @return the string representation using the settings of this {@link UnitFormat}.
074     */
075    String format(Unit<?> unit);
076
077    /**
078     * Attaches a system-wide label to the specified unit.
079     * <p>
080     * If the specified label is already associated to a unit the previous association can be discarded or ignored. Depending on the
081     * {@link UnitFormat} implementation, this call may be ignored if the particular unit already has a label.
082     * </p>
083     * If a {@link UnitFormat} implementation is explicitly <b>immutable</b>, similar to e.g. the result of <code>Collections.unmodifiableList()</code>,
084     * then an {@linkplain UnsupportedOperationException} may be thrown upon this call.
085     * <p>
086     * Since <code>UnitFormat</code> implementations often apply the Singleton pattern, <b>system-wide</b> means, the label applies to every instance of
087     * <code>UnitFormatA</code> implementing <code>UnitFormat</code> in this case, but not every instance of <code>UnitFormatB</code> or <code>UnitFormatC</code> both
088     * also implementing <code>UnitFormat</code>. If a <code>UnitFormat</code> #isLocaleSensitive() it is up to the implementation, whether the label is
089     * ignored, applied in a local-neutral manner (in addition to its local-sensitive information) or locale-specific.
090     * </p>
091     *
092     * @param unit
093     *            the unit being labeled.
094     * @param label
095     *            the new label for this unit.
096     * @throws IllegalArgumentException
097     *             if the label is not a valid identifier. This may include characters not supported by a particular {@link UnitFormat} implementation
098     *             (e.g. only <b>ASCII</b> characters for certain devices)
099     * @throws UnsupportedOperationException
100     *             if the <code>label</code> operation is not supported by this {@link UnitFormat}
101     */
102    void label(Unit<?> unit, String label);
103
104    /**
105     * Returns <code>true</code> if this {@link UnitFormat} depends on a <code>Locale</code> to perform its tasks.
106     * <p>
107     * In environments that do not support a <code>Locale</code>, e.g. Java ME, this usually returns <code>false</code>.
108     * </p>
109     *
110     * @return Whether this format depends on a locale.
111     */
112    default boolean isLocaleSensitive() {
113        return false;
114    }
115
116    /**
117     * Parses a portion of the specified <code>CharSequence</code> from the specified position to produce a {@link Unit}.
118     * If parsing succeeds, then the index of the <code>pos</code> argument is updated to the index after the last character used.
119     *
120     * @param csq
121     *            the <code>CharSequence</code> to parse.
122     * @param pos
123     *            a ParsePosition object holding the current parsing index and error parsing index information as described above.
124     * @return the unit parsed from the specified character sub-sequence.
125     * @throws IllegalArgumentException
126     *             if any problem occurs while parsing the specified character sequence (e.g. illegal syntax).
127     * @since 2.0
128     */
129    Unit<?> parse(CharSequence csq, ParsePosition pos) throws IllegalArgumentException, MeasurementParseException;
130
131    /**
132     * Parses the text into an instance of {@link Unit}.
133     * <p>
134     * The parse must complete normally and parse the entire text. If the parse completes without reading the entire length of the text, an exception
135     * is thrown. If any other problem occurs during parsing, an exception is thrown.
136     * <p>
137     *
138     * @param csq
139     *            the {@code CharSequence} to parse.
140     * @return the unit parsed from the specified character sequence.
141     * @throws MeasurementParseException
142     *             if any problem occurs while parsing the specified character sequence (e.g. illegal syntax).
143     * @throws UnsupportedOperationException
144     *             if the {@link UnitFormat} is unable to parse.
145     * @since 2.0
146     */
147    Unit<?> parse(CharSequence csq) throws MeasurementParseException;
148}