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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**************************************************************************
* Copyright (C) 1999-2012, International Business Machines Corporation and
* others. All Rights Reserved.
**************************************************************************
* Date Name Description
* 11/17/99 aliu Creation. Ported from java. Modified to
* match current UnicodeString API. Forced
* to use name "handleReplaceBetween" because
* of existing methods in UnicodeString.
**************************************************************************
*/
#ifndef REP_H
#define REP_H
#include "unicode/uobject.h"
/**
* \file
* \brief C++ API: Replaceable String
*/
U_NAMESPACE_BEGIN
class UnicodeString;
/**
* <code>Replaceable</code> is an abstract base class 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.<br>
* <li>If the code point U+FFFF is seen, it should be interpreted as
* a special marker having no metadata<li>
* </li>
* </ul>
* If this is not the behavior, the subclass should document any differences.
* @author Alan Liu
* @stable ICU 2.0
*/
class U_COMMON_API Replaceable : public UObject {
public:
/**
* Destructor.
* @stable ICU 2.0
*/
virtual ~Replaceable();
/**
* Returns the number of 16-bit code units in the text.
* @return number of 16-bit code units in text
* @stable ICU 1.8
*/
inline int32_t length() const;
/**
* 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 1.8
*/
inline char16_t charAt(int32_t offset) const;
/**
* Returns the 32-bit code point at the given 16-bit offset into
* the text. This assumes the text is stored as 16-bit code units
* with surrogate pairs intermixed. If the offset of a leading or
* trailing code unit of a surrogate pair is given, return the
* code point of the surrogate pair.
*
* @param offset an integer between 0 and <code>length()</code>-1
* inclusive
* @return 32-bit code point of text at given offset
* @stable ICU 1.8
*/
inline UChar32 char32At(int32_t offset) const;
/**
* Copies characters in the range [<tt>start</tt>, <tt>limit</tt>)
* into the UnicodeString <tt>target</tt>.
* @param start offset of first character which will be copied
* @param limit offset immediately following the last character to
* be copied
* @param target UnicodeString into which to copy characters.
* @return A reference to <TT>target</TT>
* @stable ICU 2.1
*/
virtual void extractBetween(int32_t start,
int32_t limit,
UnicodeString& target) const = 0;
/**
* Replaces a substring of this object with the given text. If the
* characters being replaced have metadata, the new characters
* that replace them should be given the same metadata.
*
* <p>Subclasses must ensure that if the text between start and
* limit is equal to the replacement text, that replace has no
* effect. That is, any metadata
* should be unaffected. In addition, subclasses are encouraged to
* check for initial and trailing identical characters, and make a
* smaller replacement if possible. This will preserve as much
* metadata as possible.
* @param start the beginning index, inclusive; <code>0 <= start
* <= limit</code>.
* @param limit the ending index, exclusive; <code>start <= limit
* <= length()</code>.
* @param text the text to replace characters <code>start</code>
* to <code>limit - 1</code>
* @stable ICU 2.0
*/
virtual void handleReplaceBetween(int32_t start,
int32_t limit,
const UnicodeString& text) = 0;
// Note: All other methods in this class take the names of
// existing UnicodeString methods. This method is the exception.
// It is named differently because all replace methods of
// UnicodeString return a UnicodeString&. The 'between' is
// required in order to conform to the UnicodeString naming
// convention; API taking start/length are named <operation>, and
// those taking start/limit are named <operationBetween>. The
// 'handle' is added because 'replaceBetween' and
// 'doReplaceBetween' are already taken.
/**
* Copies a substring of this object, retaining metadata.
* This method is used to duplicate or reorder substrings.
* The destination index must not overlap the source range.
*
* @param start the beginning index, inclusive; <code>0 <= start <=
* limit</code>.
* @param limit the ending index, exclusive; <code>start <= limit <=
* length()</code>.
* @param dest the destination index. The characters from
* <code>start..limit-1</code> will be copied to <code>dest</code>.
* Implementations of this method may assume that <code>dest <= start ||
* dest >= limit</code>.
* @stable ICU 2.0
*/
virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0;
/**
* Returns true if this object contains metadata. If a
* Replaceable object has metadata, calls to the Replaceable API
* must be made so as to preserve metadata. If it does not, calls
* to the Replaceable API may be optimized to improve performance.
* The default implementation returns true.
* @return true if this object contains metadata
* @stable ICU 2.2
*/
virtual UBool hasMetaData() const;
/**
* Clone this object, an instance of a subclass of Replaceable.
* Clones can be used concurrently in multiple threads.
* If a subclass does not implement clone(), or if an error occurs,
* then NULL is returned.
* The clone functions in all subclasses return a pointer to a Replaceable
* because some compilers do not support covariant (same-as-this)
* return types; cast to the appropriate subclass if necessary.
* The caller must delete the clone.
*
* @return a clone of this object
*
* @see getDynamicClassID
* @stable ICU 2.6
*/
virtual Replaceable *clone() const;
protected:
/**
* Default constructor.
* @stable ICU 2.4
*/
inline Replaceable();
/*
* Assignment operator not declared. The compiler will provide one
* which does nothing since this class does not contain any data members.
* API/code coverage may show the assignment operator as present and
* untested - ignore.
* Subclasses need this assignment operator if they use compiler-provided
* assignment operators of their own. An alternative to not declaring one
* here would be to declare and empty-implement a protected or public one.
Replaceable &Replaceable::operator=(const Replaceable &);
*/
/**
* Virtual version of length().
* @stable ICU 2.4
*/
virtual int32_t getLength() const = 0;
/**
* Virtual version of charAt().
* @stable ICU 2.4
*/
virtual char16_t getCharAt(int32_t offset) const = 0;
/**
* Virtual version of char32At().
* @stable ICU 2.4
*/
virtual UChar32 getChar32At(int32_t offset) const = 0;
};
inline Replaceable::Replaceable() {}
inline int32_t
Replaceable::length() const {
return getLength();
}
inline char16_t
Replaceable::charAt(int32_t offset) const {
return getCharAt(offset);
}
inline UChar32
Replaceable::char32At(int32_t offset) const {
return getChar32At(offset);
}
// There is no rep.cpp, see unistr.cpp for Replaceable function implementations.
U_NAMESPACE_END
#endif
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