choicfmt.h | Explore in Territory

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
********************************************************************************
*   Copyright (C) 1997-2013, International Business Machines
*   Corporation and others.  All Rights Reserved.
********************************************************************************
*
* File CHOICFMT.H
*
* Modification History:
*
*   Date        Name        Description
*   02/19/97    aliu        Converted from java.
*   03/20/97    helena      Finished first cut of implementation and got rid
*                           of nextDouble/previousDouble and replaced with
*                           boolean array.
*   4/10/97     aliu        Clean up.  Modified to work on AIX.
*   8/6/97      nos         Removed overloaded constructor, member var 'buffer'.
*   07/22/98    stephen     Removed operator!= (implemented in Format)
********************************************************************************
*/

#ifndef CHOICFMT_H
#define CHOICFMT_H

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

/**
 * \file
 * \brief C++ API: Choice Format.
 */

#if !UCONFIG_NO_FORMATTING

#include "unicode/fieldpos.h"
#include "unicode/format.h"
#include "unicode/messagepattern.h"
#include "unicode/numfmt.h"
#include "unicode/unistr.h"

#ifndef U_HIDE_DEPRECATED_API

U_NAMESPACE_BEGIN

class MessageFormat;

/**
 * ChoiceFormat converts between ranges of numeric values and strings for those ranges.
 * The strings must conform to the MessageFormat pattern syntax.
 *
 * <p><em><code>ChoiceFormat</code> is probably not what you need.
 * Please use <code>MessageFormat</code>
 * with <code>plural</code> arguments for proper plural selection,
 * and <code>select</code> arguments for simple selection among a fixed set of choices!</em></p>
 *
 * <p>A <code>ChoiceFormat</code> splits
 * the real number line \htmlonly<code>-&#x221E;</code> to
 * <code>+&#x221E;</code>\endhtmlonly into two
 * or more contiguous ranges. Each range is mapped to a
 * string.</p>
 *
 * <p><code>ChoiceFormat</code> was originally intended
 * for displaying grammatically correct
 * plurals such as &quot;There is one file.&quot; vs. &quot;There are 2 files.&quot;
 * <em>However,</em> plural rules for many languages
 * are too complex for the capabilities of ChoiceFormat,
 * and its requirement of specifying the precise rules for each message
 * is unmanageable for translators.</p>
 *
 * <p>There are two methods of defining a <code>ChoiceFormat</code>; both
 * are equivalent.  The first is by using a string pattern. This is the
 * preferred method in most cases.  The second method is through direct
 * specification of the arrays that logically make up the
 * <code>ChoiceFormat</code>.</p>
 *
 * <p>Note: Typically, choice formatting is done (if done at all) via <code>MessageFormat</code>
 * with a <code>choice</code> argument type,
 * rather than using a stand-alone <code>ChoiceFormat</code>.</p>
 *
 * <h5>Patterns and Their Interpretation</h5>
 *
 * <p>The pattern string defines the range boundaries and the strings for each number range.
 * Syntax:
 * <pre>
 * choiceStyle = number separator message ('|' number separator message)*
 * number = normal_number | ['-'] \htmlonly&#x221E;\endhtmlonly (U+221E, infinity)
 * normal_number = double value (unlocalized ASCII string)
 * separator = less_than | less_than_or_equal
 * less_than = '<'
 * less_than_or_equal = '#' | \htmlonly&#x2264;\endhtmlonly (U+2264)
 * message: see {@link MessageFormat}
 * </pre>
 * Pattern_White_Space between syntax elements is ignored, except
 * around each range's sub-message.</p>
 *
 * <p>Each numeric sub-range extends from the current range's number
 * to the next range's number.
 * The number itself is included in its range if a <code>less_than_or_equal</code> sign is used,
 * and excluded from its range (and instead included in the previous range)
 * if a <code>less_than</code> sign is used.</p>
 *
 * <p>When a <code>ChoiceFormat</code> is constructed from
 * arrays of numbers, closure flags and strings,
 * they are interpreted just like
 * the sequence of <code>(number separator string)</code> in an equivalent pattern string.
 * <code>closure[i]==true</code> corresponds to a <code>less_than</code> separator sign.
 * The equivalent pattern string will be constructed automatically.</p>
 *
 * <p>During formatting, a number is mapped to the first range
 * where the number is not greater than the range's upper limit.
 * That range's message string is returned. A NaN maps to the very first range.</p>
 *
 * <p>During parsing, a range is selected for the longest match of
 * any range's message. That range's number is returned, ignoring the separator/closure.
 * Only a simple string match is performed, without parsing of arguments that
 * might be specified in the message strings.</p>
 *
 * <p>Note that the first range's number is ignored in formatting
 * but may be returned from parsing.</p>
 *
 * <h5>Examples</h5>
 *
 * <p>Here is an example of two arrays that map the number
 * <code>1..7</code> to the English day of the week abbreviations
 * <code>Sun..Sat</code>. No closures array is given; this is the same as
 * specifying all closures to be <code>false</code>.</p>
 *
 * <pre>    {1,2,3,4,5,6,7},
 *     {&quot;Sun&quot;,&quot;Mon&quot;,&quot;Tue&quot;,&quot;Wed&quot;,&quot;Thur&quot;,&quot;Fri&quot;,&quot;Sat&quot;}</pre>
 *
 * <p>Here is an example that maps the ranges [-Inf, 1), [1, 1], and (1,
 * +Inf] to three strings. That is, the number line is split into three
 * ranges: x &lt; 1.0, x = 1.0, and x &gt; 1.0.
 * (The round parentheses in the notation above indicate an exclusive boundary,
 * like the turned bracket in European notation: [-Inf, 1) == [-Inf, 1[  )</p>
 *
 * <pre>    {0, 1, 1},
 *     {false, false, true},
 *     {&quot;no files&quot;, &quot;one file&quot;, &quot;many files&quot;}</pre>
 *
 * <p>Here is an example that shows formatting and parsing: </p>
 *
 * \code
 *   #include <unicode/choicfmt.h>
 *   #include <unicode/unistr.h>
 *   #include <iostream.h>
 *
 *   int main(int argc, char *argv[]) {
 *       double limits[] = {1,2,3,4,5,6,7};
 *       UnicodeString monthNames[] = {
 *           "Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
 *       ChoiceFormat fmt(limits, monthNames, 7);
 *       UnicodeString str;
 *       char buf[256];
 *       for (double x = 1.0; x <= 8.0; x += 1.0) {
 *           fmt.format(x, str);
 *           str.extract(0, str.length(), buf, 256, "");
 *           str.truncate(0);
 *           cout << x << " -> "
 *                << buf << endl;
 *       }
 *       cout << endl;
 *       return 0;
 *   }
 * \endcode
 *
 * <p><em>User subclasses are not supported.</em> While clients may write
 * subclasses, such code will not necessarily work and will not be
 * guaranteed to work stably from release to release.
 *
 * @deprecated ICU 49 Use MessageFormat instead, with plural and select arguments.
 */
class U_I18N_API ChoiceFormat: public NumberFormat { … };


U_NAMESPACE_END

#endif  // U_HIDE_DEPRECATED_API
#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // CHOICFMT_H
//eof
chromium/third_party/icu/source/i18n/unicode/choicfmt.h
