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/usr/include/unicode/rep.h


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     1	// © 2016 and later: Unicode, Inc. and others.
     2	// License & terms of use: http://www.unicode.org/copyright.html
     3	/*
     4	**************************************************************************
     5	* Copyright (C) 1999-2012, International Business Machines Corporation and
     6	* others. All Rights Reserved.
     7	**************************************************************************
     8	*   Date        Name        Description
     9	*   11/17/99    aliu        Creation.  Ported from java.  Modified to
    10	*                           match current UnicodeString API.  Forced
    11	*                           to use name "handleReplaceBetween" because
    12	*                           of existing methods in UnicodeString.
    13	**************************************************************************
    14	*/
    15	
    16	#ifndef REP_H
    17	#define REP_H
    18	
    19	#include "unicode/utypes.h"
    20	
    21	#if U_SHOW_CPLUSPLUS_API
    22	
    23	#include "unicode/uobject.h"
    24	
    25	/**
    26	 * \file 
    27	 * \brief C++ API: Replaceable String
    28	 */
    29	 
    30	U_NAMESPACE_BEGIN
    31	
    32	class UnicodeString;
    33	
    34	/**
    35	 * <code>Replaceable</code> is an abstract base class representing a
    36	 * string of characters that supports the replacement of a range of
    37	 * itself with a new string of characters.  It is used by APIs that
    38	 * change a piece of text while retaining metadata.  Metadata is data
    39	 * other than the Unicode characters returned by char32At().  One
    40	 * example of metadata is style attributes; another is an edit
    41	 * history, marking each character with an author and revision number.
    42	 *
    43	 * <p>An implicit aspect of the <code>Replaceable</code> API is that
    44	 * during a replace operation, new characters take on the metadata of
    45	 * the old characters.  For example, if the string "the <b>bold</b>
    46	 * font" has range (4, 8) replaced with "strong", then it becomes "the
    47	 * <b>strong</b> font".
    48	 *
    49	 * <p><code>Replaceable</code> specifies ranges using a start
    50	 * offset and a limit offset.  The range of characters thus specified
    51	 * includes the characters at offset start..limit-1.  That is, the
    52	 * start offset is inclusive, and the limit offset is exclusive.
    53	 *
    54	 * <p><code>Replaceable</code> also includes API to access characters
    55	 * in the string: <code>length()</code>, <code>charAt()</code>,
    56	 * <code>char32At()</code>, and <code>extractBetween()</code>.
    57	 *
    58	 * <p>For a subclass to support metadata, typical behavior of
    59	 * <code>replace()</code> is the following:
    60	 * <ul>
    61	 *   <li>Set the metadata of the new text to the metadata of the first
    62	 *   character replaced</li>
    63	 *   <li>If no characters are replaced, use the metadata of the
    64	 *   previous character</li>
    65	 *   <li>If there is no previous character (i.e. start == 0), use the
    66	 *   following character</li>
    67	 *   <li>If there is no following character (i.e. the replaceable was
    68	 *   empty), use default metadata.<br>
    69	 *   <li>If the code point U+FFFF is seen, it should be interpreted as
    70	 *   a special marker having no metadata<li>
    71	 *   </li>
    72	 * </ul>
    73	 * If this is not the behavior, the subclass should document any differences.
    74	 * @author Alan Liu
    75	 * @stable ICU 2.0
    76	 */
    77	class U_COMMON_API Replaceable : public UObject {
    78	
    79	public:
    80	    /**
    81	     * Destructor.
    82	     * @stable ICU 2.0
    83	     */
    84	    virtual ~Replaceable();
    85	
    86	    /**
    87	     * Returns the number of 16-bit code units in the text.
    88	     * @return number of 16-bit code units in text
    89	     * @stable ICU 1.8
    90	     */ 
    91	    inline int32_t length() const;
    92	
    93	    /**
    94	     * Returns the 16-bit code unit at the given offset into the text.
    95	     * @param offset an integer between 0 and <code>length()</code>-1
    96	     * inclusive
    97	     * @return 16-bit code unit of text at given offset
    98	     * @stable ICU 1.8
    99	     */
   100	    inline char16_t charAt(int32_t offset) const;
   101	
   102	    /**
   103	     * Returns the 32-bit code point at the given 16-bit offset into
   104	     * the text.  This assumes the text is stored as 16-bit code units
   105	     * with surrogate pairs intermixed.  If the offset of a leading or
   106	     * trailing code unit of a surrogate pair is given, return the
   107	     * code point of the surrogate pair.
   108	     *
   109	     * @param offset an integer between 0 and <code>length()</code>-1
   110	     * inclusive
   111	     * @return 32-bit code point of text at given offset
   112	     * @stable ICU 1.8
   113	     */
   114	    inline UChar32 char32At(int32_t offset) const;
   115	
   116	    /**
   117	     * Copies characters in the range [<tt>start</tt>, <tt>limit</tt>) 
   118	     * into the UnicodeString <tt>target</tt>.
   119	     * @param start offset of first character which will be copied
   120	     * @param limit offset immediately following the last character to
   121	     * be copied
   122	     * @param target UnicodeString into which to copy characters.
   123	     * @return A reference to <TT>target</TT>
   124	     * @stable ICU 2.1
   125	     */
   126	    virtual void extractBetween(int32_t start,
   127	                                int32_t limit,
   128	                                UnicodeString& target) const = 0;
   129	
   130	    /**
   131	     * Replaces a substring of this object with the given text.  If the
   132	     * characters being replaced have metadata, the new characters
   133	     * that replace them should be given the same metadata.
   134	     *
   135	     * <p>Subclasses must ensure that if the text between start and
   136	     * limit is equal to the replacement text, that replace has no
   137	     * effect. That is, any metadata
   138	     * should be unaffected. In addition, subclasses are encouraged to
   139	     * check for initial and trailing identical characters, and make a
   140	     * smaller replacement if possible. This will preserve as much
   141	     * metadata as possible.
   142	     * @param start the beginning index, inclusive; <code>0 <= start
   143	     * <= limit</code>.
   144	     * @param limit the ending index, exclusive; <code>start <= limit
   145	     * <= length()</code>.
   146	     * @param text the text to replace characters <code>start</code>
   147	     * to <code>limit - 1</code> 
   148	     * @stable ICU 2.0
   149	     */
   150	    virtual void handleReplaceBetween(int32_t start,
   151	                                      int32_t limit,
   152	                                      const UnicodeString& text) = 0;
   153	    // Note: All other methods in this class take the names of
   154	    // existing UnicodeString methods.  This method is the exception.
   155	    // It is named differently because all replace methods of
   156	    // UnicodeString return a UnicodeString&.  The 'between' is
   157	    // required in order to conform to the UnicodeString naming
   158	    // convention; API taking start/length are named <operation>, and
   159	    // those taking start/limit are named <operationBetween>.  The
   160	    // 'handle' is added because 'replaceBetween' and
   161	    // 'doReplaceBetween' are already taken.
   162	
   163	    /**
   164	     * Copies a substring of this object, retaining metadata.
   165	     * This method is used to duplicate or reorder substrings.
   166	     * The destination index must not overlap the source range.
   167	     * 
   168	     * @param start the beginning index, inclusive; <code>0 <= start <=
   169	     * limit</code>.
   170	     * @param limit the ending index, exclusive; <code>start <= limit <=
   171	     * length()</code>.
   172	     * @param dest the destination index.  The characters from
   173	     * <code>start..limit-1</code> will be copied to <code>dest</code>.
   174	     * Implementations of this method may assume that <code>dest <= start ||
   175	     * dest >= limit</code>.
   176	     * @stable ICU 2.0
   177	     */
   178	    virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0;
   179	
   180	    /**
   181	     * Returns true if this object contains metadata.  If a
   182	     * Replaceable object has metadata, calls to the Replaceable API
   183	     * must be made so as to preserve metadata.  If it does not, calls
   184	     * to the Replaceable API may be optimized to improve performance.
   185	     * The default implementation returns true.
   186	     * @return true if this object contains metadata
   187	     * @stable ICU 2.2
   188	     */
   189	    virtual UBool hasMetaData() const;
   190	
   191	    /**
   192	     * Clone this object, an instance of a subclass of Replaceable.
   193	     * Clones can be used concurrently in multiple threads.
   194	     * If a subclass does not implement clone(), or if an error occurs,
   195	     * then nullptr is returned.
   196	     * The caller must delete the clone.
   197	     *
   198	     * @return a clone of this object
   199	     *
   200	     * @see getDynamicClassID
   201	     * @stable ICU 2.6
   202	     */
   203	    virtual Replaceable *clone() const;
   204	
   205	protected:
   206	
   207	    /**
   208	     * Default constructor.
   209	     * @stable ICU 2.4
   210	     */
   211	    inline Replaceable();
   212	
   213	    /*
   214	     * Assignment operator not declared. The compiler will provide one
   215	     * which does nothing since this class does not contain any data members.
   216	     * API/code coverage may show the assignment operator as present and
   217	     * untested - ignore.
   218	     * Subclasses need this assignment operator if they use compiler-provided
   219	     * assignment operators of their own. An alternative to not declaring one
   220	     * here would be to declare and empty-implement a protected or public one.
   221	    Replaceable &Replaceable::operator=(const Replaceable &);
   222	     */
   223	
   224	    /**
   225	     * Virtual version of length().
   226	     * @stable ICU 2.4
   227	     */ 
   228	    virtual int32_t getLength() const = 0;
   229	
   230	    /**
   231	     * Virtual version of charAt().
   232	     * @stable ICU 2.4
   233	     */
   234	    virtual char16_t getCharAt(int32_t offset) const = 0;
   235	
   236	    /**
   237	     * Virtual version of char32At().
   238	     * @stable ICU 2.4
   239	     */
   240	    virtual UChar32 getChar32At(int32_t offset) const = 0;
   241	};
   242	
   243	inline Replaceable::Replaceable() {}
   244	
   245	inline int32_t
   246	Replaceable::length() const {
   247	    return getLength();
   248	}
   249	
   250	inline char16_t
   251	Replaceable::charAt(int32_t offset) const {
   252	    return getCharAt(offset);
   253	}
   254	
   255	inline UChar32
   256	Replaceable::char32At(int32_t offset) const {
   257	    return getChar32At(offset);
   258	}
   259	
   260	// There is no rep.cpp, see unistr.cpp for Replaceable function implementations.
   261	
   262	U_NAMESPACE_END
   263	
   264	#endif /* U_SHOW_CPLUSPLUS_API */
   265	
   266	#endif