257 lines
9.3 KiB
C++
257 lines
9.3 KiB
C++
/*
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**************************************************************************
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* Copyright (C) 1999-2003, International Business Machines Corporation and
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* others. All Rights Reserved.
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**************************************************************************
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* Date Name Description
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* 11/17/99 aliu Creation. Ported from java. Modified to
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* match current UnicodeString API. Forced
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* to use name "handleReplaceBetween" because
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* of existing methods in UnicodeString.
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**************************************************************************
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*/
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#ifndef REP_H
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#define REP_H
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#include "unicode/uobject.h"
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U_NAMESPACE_BEGIN
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class UnicodeString;
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/**
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* <code>Replaceable</code> is an abstract base class representing a
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* string of characters that supports the replacement of a range of
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* itself with a new string of characters. It is used by APIs that
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* change a piece of text while retaining metadata. Metadata is data
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* other than the Unicode characters returned by char32At(). One
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* example of metadata is style attributes; another is an edit
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* history, marking each character with an author and revision number.
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*
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* <p>An implicit aspect of the <code>Replaceable</code> API is that
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* during a replace operation, new characters take on the metadata of
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* the old characters. For example, if the string "the <b>bold</b>
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* font" has range (4, 8) replaced with "strong", then it becomes "the
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* <b>strong</b> font".
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*
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* <p><code>Replaceable</code> specifies ranges using a start
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* offset and a limit offset. The range of characters thus specified
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* includes the characters at offset start..limit-1. That is, the
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* start offset is inclusive, and the limit offset is exclusive.
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*
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* <p><code>Replaceable</code> also includes API to access characters
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* in the string: <code>length()</code>, <code>charAt()</code>,
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* <code>char32At()</code>, and <code>extractBetween()</code>.
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*
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* <p>For a subclass to support metadata, typical behavior of
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* <code>replace()</code> is the following:
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* <ul>
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* <li>Set the metadata of the new text to the metadata of the first
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* character replaced</li>
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* <li>If no characters are replaced, use the metadata of the
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* previous character</li>
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* <li>If there is no previous character (i.e. start == 0), use the
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* following character</li>
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* <li>If there is no following character (i.e. the replaceable was
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* empty), use default metadata.<br>
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* <li>If the code point U+FFFF is seen, it should be interpreted as
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* a special marker having no metadata<li>
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* </li>
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* </ul>
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* If this is not the behavior, the subclass should document any differences.
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* @author Alan Liu
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* @stable ICU 2.0
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*/
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class U_COMMON_API Replaceable : public UObject {
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public:
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/**
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* Destructor.
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* @stable ICU 2.0
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*/
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virtual ~Replaceable();
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/**
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* Returns the number of 16-bit code units in the text.
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* @return number of 16-bit code units in text
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* @stable ICU 1.8
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*/
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inline int32_t length() const;
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/**
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* Returns the 16-bit code unit at the given offset into the text.
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* @param offset an integer between 0 and <code>length()</code>-1
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* inclusive
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* @return 16-bit code unit of text at given offset
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* @stable ICU 1.8
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*/
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inline UChar charAt(int32_t offset) const;
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/**
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* Returns the 32-bit code point at the given 16-bit offset into
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* the text. This assumes the text is stored as 16-bit code units
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* with surrogate pairs intermixed. If the offset of a leading or
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* trailing code unit of a surrogate pair is given, return the
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* code point of the surrogate pair.
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*
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* @param offset an integer between 0 and <code>length()</code>-1
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* inclusive
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* @return 32-bit code point of text at given offset
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* @stable ICU 1.8
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*/
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inline UChar32 char32At(int32_t offset) const;
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/**
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* Copies characters in the range [<tt>start</tt>, <tt>limit</tt>)
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* into the UnicodeString <tt>target</tt>.
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* @param start offset of first character which will be copied
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* @param limit offset immediately following the last character to
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* be copied
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* @param target UnicodeString into which to copy characters.
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* @return A reference to <TT>target</TT>
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* @stable ICU 2.1
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*/
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virtual void extractBetween(int32_t start,
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int32_t limit,
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UnicodeString& target) const = 0;
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/**
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* Replaces a substring of this object with the given text. If the
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* characters being replaced have metadata, the new characters
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* that replace them should be given the same metadata.
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*
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* <p>Subclasses must ensure that if the text between start and
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* limit is equal to the replacement text, that replace has no
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* effect. That is, any metadata
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* should be unaffected. In addition, subclasses are encouraged to
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* check for initial and trailing identical characters, and make a
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* smaller replacement if possible. This will preserve as much
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* metadata as possible.
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* @param start the beginning index, inclusive; <code>0 <= start
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* <= limit</code>.
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* @param limit the ending index, exclusive; <code>start <= limit
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* <= length()</code>.
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* @param text the text to replace characters <code>start</code>
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* to <code>limit - 1</code>
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* @stable ICU 2.0
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*/
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virtual void handleReplaceBetween(int32_t start,
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int32_t limit,
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const UnicodeString& text) = 0;
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// Note: All other methods in this class take the names of
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// existing UnicodeString methods. This method is the exception.
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// It is named differently because all replace methods of
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// UnicodeString return a UnicodeString&. The 'between' is
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// required in order to conform to the UnicodeString naming
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// convention; API taking start/length are named <operation>, and
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// those taking start/limit are named <operationBetween>. The
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// 'handle' is added because 'replaceBetween' and
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// 'doReplaceBetween' are already taken.
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/**
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* Copies a substring of this object, retaining metadata.
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* This method is used to duplicate or reorder substrings.
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* The destination index must not overlap the source range.
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*
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* @param start the beginning index, inclusive; <code>0 <= start <=
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* limit</code>.
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* @param limit the ending index, exclusive; <code>start <= limit <=
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* length()</code>.
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* @param dest the destination index. The characters from
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* <code>start..limit-1</code> will be copied to <code>dest</code>.
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* Implementations of this method may assume that <code>dest <= start ||
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* dest >= limit</code>.
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* @stable ICU 2.0
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*/
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virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0;
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/**
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* Returns true if this object contains metadata. If a
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* Replaceable object has metadata, calls to the Replaceable API
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* must be made so as to preserve metadata. If it does not, calls
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* to the Replaceable API may be optimized to improve performance.
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* The default implementation returns true.
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* @return true if this object contains metadata
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* @stable ICU 2.2
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*/
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virtual UBool hasMetaData() const;
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/**
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* Clone this object, an instance of a subclass of Replaceable.
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* Clones can be used concurrently in multiple threads.
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* If a subclass does not implement clone(), or if an error occurs,
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* then NULL is returned.
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* The clone functions in all subclasses return a pointer to a Replaceable
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* because some compilers do not support covariant (same-as-this)
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* return types; cast to the appropriate subclass if necessary.
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* The caller must delete the clone.
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*
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* @return a clone of this object
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*
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* @see getDynamicClassID
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* @draft ICU 2.6
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*/
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virtual Replaceable *clone() const;
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protected:
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/**
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* Default constructor.
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* @stable ICU 2.4
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*/
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Replaceable();
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/*
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* Assignment operator not declared. The compiler will provide one
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* which does nothing since this class does not contain any data members.
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* API/code coverage may show the assignment operator as present and
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* untested - ignore.
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* Subclasses need this assignment operator if they use compiler-provided
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* assignment operators of their own. An alternative to not declaring one
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* here would be to declare and empty-implement a protected or public one.
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Replaceable &Replaceable::operator=(const Replaceable &);
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*/
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/**
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* Virtual version of length().
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* @stable ICU 2.4
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*/
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virtual int32_t getLength() const = 0;
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/**
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* Virtual version of charAt().
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* @stable ICU 2.4
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*/
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virtual UChar getCharAt(int32_t offset) const = 0;
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/**
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* Virtual version of char32At().
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* @stable ICU 2.4
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*/
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virtual UChar32 getChar32At(int32_t offset) const = 0;
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};
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inline Replaceable::Replaceable() {}
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inline int32_t
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Replaceable::length() const {
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return getLength();
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}
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inline UChar
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Replaceable::charAt(int32_t offset) const {
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return getCharAt(offset);
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}
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inline UChar32
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Replaceable::char32At(int32_t offset) const {
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return getChar32At(offset);
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}
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// There is no rep.cpp, see unistr.cpp for Replaceable function implementations.
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U_NAMESPACE_END
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#endif
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