OptionSpec.java

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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * The MIT License
 *
 * Copyright (c) 2004-2015 Paul R. Holser, Jr.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
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package jdk.internal.joptsimple;

import java.util.List;

/**
 * Describes options that an option parser recognizes.
 *
 * <p>Instances of this interface are returned by the "fluent interface" methods to allow retrieval of option arguments
 * in a type-safe manner.  Here's an example:</p>
 *
 * <pre><code>
 *     OptionParser parser = new OptionParser();
 *     <strong>OptionSpec&lt;Integer&gt;</strong> count =
 *         parser.accepts( "count" ).withRequiredArg().ofType( Integer.class );
 *     OptionSet options = parser.parse( "--count", "2" );
 *     assert options.has( count );
 *     int countValue = options.valueOf( count );
 *     assert countValue == count.value( options );
 *     List&lt;Integer&gt; countValues = options.valuesOf( count );
 *     assert countValues.equals( count.values( options ) );
 * </code></pre>
 *
 * @param <V> represents the type of the arguments this option accepts
 * @author <a href="mailto:[email protected]">Paul Holser</a>
 */
public interface OptionSpec<V> {
    /**
     * Gives any arguments associated with the given option in the given set of detected options.
     *
     * <p>Specifying a {@linkplain ArgumentAcceptingOptionSpec#defaultsTo(Object, Object[]) default argument value}
     * for this option will cause this method to return that default value even if this option was not detected on the
     * command line, or if this option can take an optional argument but did not have one on the command line.</p>
     *
     * @param detectedOptions the detected options to search in
     * @return the arguments associated with this option; an empty list if no such arguments are present, or if this
     * option was not detected
     * @throws OptionException if there is a problem converting this option's arguments to the desired type; for
     * example, if the type does not implement a correct conversion constructor or method
     * @throws NullPointerException if {@code detectedOptions} is {@code null}
     * @see OptionSet#valuesOf(OptionSpec)
     */
    List<V> values( OptionSet detectedOptions );

    /**
     * Gives the argument associated with the given option in the given set of detected options.
     *
     * <p>Specifying a {@linkplain ArgumentAcceptingOptionSpec#defaultsTo(Object, Object[]) default argument value}
     * for this option will cause this method to return that default value even if this option was not detected on the
     * command line, or if this option can take an optional argument but did not have one on the command line.</p>
     *
     * @param detectedOptions the detected options to search in
     * @return the argument of the this option; {@code null} if no argument is present, or that option was not detected
     * @throws OptionException if more than one argument was detected for the option
     * @throws NullPointerException if {@code detectedOptions} is {@code null}
     * @throws ClassCastException if the arguments of this option are not of the expected type
     * @see OptionSet#valueOf(OptionSpec)
     */
    V value( OptionSet detectedOptions );

    /**
     * @return the string representations of this option
     */
    List<String> options();

    /**
     * Tells whether this option is designated as a "help" option. The presence of a "help" option on a command line
     * means that missing "required" options will not cause parsing to fail.
     *
     * @return whether this option is designated as a "help" option
     */
    boolean isForHelp();
}