/*
 ********************************************************************************
 * Copyright (C) 2009, Yahoo! Inc., International Business Machines Corporation *
 * and others. All Rights Reserved.                                             *
 ********************************************************************************
 */

package com.ibm.icu.text;

import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;

/**
 * <p><code>SelectFormat</code> supports the creation of  internationalized
 * messages by selecting phrases based on keywords. The pattern  specifies
 * how to map keywords to phrases and provides a default phrase. The
 * object provided to the format method is a string that's matched
 * against the keywords. If there is a match, the corresponding phrase
 * is selected; otherwise, the default phrase is used.</p>
 *
 * <h4>Using <code>SelectFormat</code> for Gender Agreement</h4>
 *
 * <p>The main use case for the select format is gender based inflection.
 * When names or nouns are inserted into sentences, their gender can  affect pronouns,
 * verb forms, articles, and adjectives. Special care needs to be
 * taken for the case where the gender cannot be determined.
 * The impact varies between languages:</p>
 *
 * <ul>
 * <li>English has three genders, and unknown gender is handled as a  special
 * case. Names use the gender of the named person (if known), nouns  referring
 * to people use natural gender, and inanimate objects are usually  neutral.
 * The gender only affects pronouns: "he", "she", "it", "they".
 *
 * <li>German differs from English in that the gender of nouns is  rather
 * arbitrary, even for nouns referring to people ("M&auml;dchen", girl, is  neutral).
 * The gender affects pronouns ("er", "sie", "es"), articles ("der",  "die",
 * "das"), and adjective forms ("guter Mann", "gute Frau", "gutes  M&auml;dchen").
 *
 * <li>French has only two genders; as in German the gender of nouns
 * is rather arbitrary &#8211; for sun and moon, the genders
 * are the opposite of those in German. The gender affects
 * pronouns ("il", "elle"), articles ("le", "la"),
 * adjective forms ("bon", "bonne"), and sometimes
 * verb forms ("all&eacute;", "all&eacute;e").
 *
 * <li>Polish distinguishes five genders (or noun classes),
 * human masculine, animate non-human masculine, inanimate masculine,
 * feminine, and neuter.
 * </ul>
 *
 * <p>Some other languages have noun classes that are not related to  gender,
 * but similar in grammatical use.
 * Some African languages have around 20 noun classes.</p>
 *
 * <p>To enable localizers to create sentence patterns that take their
 * language's gender dependencies into consideration, software has to  provide
 * information about the gender associated with a noun or name to
 * <code>MessageFormat</code>.
 * Two main cases can be distinguished:</p>
 *
 * <ul>
 * <li>For people, natural gender information should be maintained  for each person.
 * The keywords "male", "female", "mixed" (for groups of people)
 * and "unknown" are used.
 *
 * <li>For nouns, grammatical gender information should be maintained  for
 * each noun and per language, e.g., in resource bundles.
 * The keywords "masculine", "feminine", and "neuter" are commonly  used,
 * but some languages may require other keywords.
 * </ul>
 *
 * <p>The resulting keyword is provided to <code>MessageFormat</code>  as a
 * parameter separate from the name or noun it's associated with. For  example,
 * to generate a message such as "Jean went to Paris", three separate  arguments
 * would be provided: The name of the person as argument 0, the  gender of
 * the person as argument 1, and the name of the city as argument 2.
 * The sentence pattern for English, where the gender of the person has
 * no impact on this simple sentence, would not refer to argument 1  at all:</p>
 *
 * <pre>{0} went to {2}.</pre>
 *
 * <p>The sentence pattern for French, where the gender of the person affects
 * the form of the participle, uses a select format based on argument 1:</p>
 *
 * <pre>{0} est {1, select, female {all&eacute;e} other {all&eacute;}} &agrave; {2}.</pre>
 *
 * <p>Patterns can be nested, so that it's possible to handle  interactions of
 * number and gender where necessary. For example, if the above  sentence should
 * allow for the names of several people to be inserted, the  following sentence
 * pattern can be used (with argument 0 the list of people's names,  
 * argument 1 the number of people, argument 2 their combined gender, and  
 * argument 3 the city name):</p>
 *
 * <pre>{0} {1, plural, 
 * one {est {2, select, female {all&eacute;e} other  {all&eacute;}}}
 * other {sont {2, select, female {all&eacute;es} other {all&eacute;s}}}
 * }&agrave; {3}.</pre>
 *
 * <h4>Patterns and Their Interpretation</h4>
 *
 * <p>The <code>SelectFormat</code> pattern text defines the phrase  output
 * for each user-defined keyword.
 * The pattern is a sequence of <code><i>keyword</i>{<i>phrase</i>}</code>
 * clauses, separated by white space characters.
 * Each clause assigns the phrase <code><i>phrase</i></code>
 * to the user-defined <code><i>keyword</i></code>.</p>
 *
 * <p>Keywords must match the pattern [a-zA-Z][a-zA-Z0-9_-]*; keywords
 * that don't match this pattern result in the error code
 * <code>U_ILLEGAL_CHARACTER</code>.
 * You always have to define a phrase for the default keyword
 * <code>other</code>; this phrase is returned when the keyword  
 * provided to
 * the <code>format</code> method matches no other keyword.
 * If a pattern does not provide a phrase for <code>other</code>, the  method
 * it's provided to returns the error  <code>U_DEFAULT_KEYWORD_MISSING</code>.
 * If a pattern provides more than one phrase for the same keyword, the
 * error <code>U_DUPLICATE_KEYWORD</code> is returned.
 * <br/>
 * Spaces between <code><i>keyword</i></code> and
 * <code>{<i>phrase</i>}</code>  will be ignored; spaces within
 * <code>{<i>phrase</i>}</code> will be preserved.<p>
 *
 * <p>The phrase for a particular select case may contain other message
 * format patterns. <code>SelectFormat</code> preserves these so that  you
 * can use the strings produced by <code>SelectFormat</code> with other
 * formatters. If you are using <code>SelectFormat</code> inside a
 * <code>MessageFormat</code> pattern, <code>MessageFormat</code> will
 * automatically evaluate the resulting format pattern.
 * Thus, curly braces (<code>{</code>, <code>}</code>) are <i>only</i> allowed
 * in phrases to define a nested format pattern.</p>
 *
 * <p>Example:
 * <pre>
 * MessageFormat msgFmt = new MessageFormat("{0} est " +
 *     "{1, select, female {all&eacute;e} other {all&eacute;}} &agrave; Paris.",
 *     new ULocale("fr"));
 * Object args[] = {"Kirti","female"};
 * System.out.println(msgFmt.format(args));
 * </pre>
 * Produces the output:
 * <pre>
 * Kirti est all&eacute;e &agrave; Paris.
 * </pre>
 * 
 * @draft ICU 4.4
 * @provisional This API might change or be removed in a future release.
 */

public class SelectFormat extends Format {
    private static final long serialVersionUID = 1L;

    /**
     * Creates a new <code>SelectFormat</code> 
     * 
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public SelectFormat() {
        throw new UnsupportedOperationException("Constructor SelectFormat() is not implemented yet.");
    }

    /**
     * Creates a new <code>SelectFormat</code> for a given pattern string.
     * 
     * @param  pattern the pattern for this <code>SelectFormat</code>.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public SelectFormat(String pattern) {
        throw new UnsupportedOperationException("Constructor SelectFormat(String) is not implemented yet.");
    }

    /**
     * Sets the pattern used by this select format.
     * Patterns and their interpretation are specified in the class description.
     *
     * @param pattern the pattern for this select format.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public void applyPattern(String pattern) {
        throw new UnsupportedOperationException("SelectFormat.applyPattern(String) is not implemented yet.");
    }

    /**
     * Returns the pattern for this <code>SelectFormat</code>
     *
     * @return the pattern string
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public String toPattern() {
        throw new UnsupportedOperationException("SelectFormat.toPattern() is not implemented yet.");
    }

    /**
     * Formats a select message for a given keyword.
     *
     * @param keyword a keyword for which the select message should be formatted.
     * @return the string containing the formatted select message.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public final String format(String keyword) {
        throw new UnsupportedOperationException("SelectFormat.format(String) is not implemented yet.");
    }

    /**
     * Formats a select message for a given keyword and appends the formatted
     * message to the given <code>StringBuffer</code>.
     * 
     * @param keyword a keyword for which the select message should be formatted.
     * @param toAppendTo the formatted message will be appended to this
     *        <code>StringBuffer</code>.
     * @param pos will be ignored by this method.
     * @return the string buffer passed in as toAppendTo, with formatted text
     *         appended.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public StringBuffer format(Object keyword, StringBuffer toAppendTo,
            FieldPosition pos) {
        throw new UnsupportedOperationException("SelectFormat.format( Object, StringBuffer,FieldPosition) is not implemented yet.");
    }

    /**
     * This method is not yet supported by <code>SelectFormat</code>.
     * 
     * @param source the string to be parsed.
     * @param pos defines the position where parsing is to begin,
     * and upon return, the position where parsing left off.  If the position
     * has not changed upon return, then parsing failed.
     * @return nothing because this method is not yet implemented.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public Object parseObject(String source, ParsePosition pos) {
        throw new UnsupportedOperationException();
    }

    /**
     * {@inheritDoc}
     * 
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public boolean equals(Object rhs) {
        throw new UnsupportedOperationException("SelectFormat.equals(Object) is not implemented yet.");
    }

    /**
     * Returns true if this equals the provided <code>SelectFormat<code>.
     * 
     * @param rhs the SelectFormat to compare against
     * @return true if this equals <code>rhs</code>
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public boolean equals(SelectFormat rhs) {
        throw new UnsupportedOperationException("SelectFormat.equals(SelectFormat) is not implemented yet.");
    }

    /**
     * {@inheritDoc}
     * 
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public int hashCode() {
        throw new UnsupportedOperationException("SelectFormat.hashCode() is not implemented yet.");
    }

    /**
     * Returns a string representation of the object
     * 
     * @return a text representation of the format object.
     * The result string includes the class name and
     * the pattern string returned by <code>toPattern()</code>.
     * @draft ICU 4.4
     * @provisional This API might change or be removed in a future release.
     */
    public String toString() {
        throw new UnsupportedOperationException("SelectFormat.toString() is not implemented yet.");
    }
}