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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/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