tor-browser

rep.h (9602B)

---

// © 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/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#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 nullptr is returned.
    * 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 /* U_SHOW_CPLUSPLUS_API */

#endif