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/*

 *******************************************************************************

 * (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved                     *

 *                                                                             *

 * The original version of this source code and documentation is copyrighted   *

 * and owned by IBM, These materials are provided under terms of a License     *

 * Agreement between IBM and Sun. This technology is protected by multiple     *

 * US and International patents. This notice and attribution to IBM may not    *

 * to removed.                                                                 *

 *******************************************************************************

 */

package jdk.internal.icu.text;

/**

 * <code>Replaceable</code> is an interface representing a

 * string of characters that supports the replacement of a range of

 * itself with a new string of characters.  It is used by APIs that

 * change a piece of text while retaining metadata.  Metadata is data

 * other than the Unicode characters returned by char32At().  One

 * example of metadata is style attributes; another is an edit

 * history, marking each character with an author and revision number.

 *

 * <p>An implicit aspect of the <code>Replaceable</code> API is that

 * during a replace operation, new characters take on the metadata of

 * the old characters.  For example, if the string "the <b>bold</b>

 * font" has range (4, 8) replaced with "strong", then it becomes "the

 * <b>strong</b> font".

 *

 * <p><code>Replaceable</code> specifies ranges using a start

 * offset and a limit offset.  The range of characters thus specified

 * includes the characters at offset start..limit-1.  That is, the

 * start offset is inclusive, and the limit offset is exclusive.

 *

 * <p><code>Replaceable</code> also includes API to access characters

 * in the string: <code>length()</code>, <code>charAt()</code>,

 * <code>char32At()</code>, and <code>extractBetween()</code>.

 *

 * <p>For a subclass to support metadata, typical behavior of

 * <code>replace()</code> is the following:

 * <ul>

 *   <li>Set the metadata of the new text to the metadata of the first

 *   character replaced</li>

 *   <li>If no characters are replaced, use the metadata of the

 *   previous character</li>

 *   <li>If there is no previous character (i.e. start == 0), use the

 *   following character</li>

 *   <li>If there is no following character (i.e. the replaceable was

 *   empty), use default metadata</li>

 *   <li>If the code point U+FFFF is seen, it should be interpreted as

 *   a special marker having no metadata</li>

 * </ul>

 * If this is not the behavior, the subclass should document any differences.

 *

 * <p>Copyright &copy; IBM Corporation 1999.  All rights reserved.

 *

 * @author Alan Liu

 * @stable ICU 2.0

 */

public interface Replaceable {

    /**

     * Returns the number of 16-bit code units in the text.

     * @return number of 16-bit code units in text

     * @stable ICU 2.0

     */

    int length();

    /**

     * Returns the 16-bit code unit at the given offset into the text.

     * @param offset an integer between 0 and <code>length()</code>-1

     * inclusive

     * @return 16-bit code unit of text at given offset

     * @stable ICU 2.0

     */

    char charAt(int offset);

    /**

     * Copies characters from this object into the destination

     * character array.  The first character to be copied is at index

     * <code>srcStart</code>; the last character to be copied is at

     * index <code>srcLimit-1</code> (thus the total number of

     * characters to be copied is <code>srcLimit-srcStart</code>). The

     * characters are copied into the subarray of <code>dst</code>

     * starting at index <code>dstStart</code> and ending at index

     * <code>dstStart + (srcLimit-srcStart) - 1</code>.

     *

     * @param srcStart the beginning index to copy, inclusive;

     *        {@code 0 <= start <= limit}.

     * @param srcLimit the ending index to copy, exclusive;

     *        {@code start <= limit <= length()}.

     * @param dst the destination array.

     * @param dstStart the start offset in the destination array.

     * @stable ICU 2.0

     */

    void getChars(int srcStart, int srcLimit, char dst[], int dstStart);

}