Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/rep.h

+/*
+**************************************************************************
+* Copyright (C) 1999-2005, 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 UChar 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
+     */
+    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 UChar getCharAt(int32_t offset) const = 0;
+
+    /**
+     * Virtual version of char32At().
+     * @stable ICU 2.4
+     */
+    virtual UChar32 getChar32At(int32_t offset) const = 0;
+};
+
+inline int32_t
+Replaceable::length() const {
+    return getLength();
+}
+
+inline UChar
+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