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