Transliterator is an abstract class that
+ * transliterates text from one format to another. The most common
+ * kind of transliterator is a script, or alphabet, transliterator.
+ * For example, a Russian to Latin transliterator changes Russian text
+ * written in Cyrillic characters to phonetically equivalent Latin
+ * characters. It does not translate Russian to English!
+ * Transliteration, unlike translation, operates on characters, without
+ * reference to the meanings of words and sentences.
+ *
+ * Although script conversion is its most common use, a
+ * transliterator can actually perform a more general class of tasks.
+ * In fact, Transliterator defines a very general API
+ * which specifies only that a segment of the input text is replaced
+ * by new text. The particulars of this conversion are determined
+ * entirely by subclasses of Transliterator.
+ *
+ *
Transliterators are stateless + * + *
Transliterator objects are stateless; they
+ * retain no information between calls to
+ * transliterate(). (However, this does not
+ * mean that threads may share transliterators without synchronizing
+ * them. Transliterators are not immutable, so they must be
+ * synchronized when shared between threads.) This might seem to
+ * limit the complexity of the transliteration operation. In
+ * practice, subclasses perform complex transliterations by delaying
+ * the replacement of text until it is known that no other
+ * replacements are possible. In other words, although the
+ * Transliterator objects are stateless, the source text
+ * itself embodies all the needed information, and delayed operation
+ * allows arbitrary complexity.
+ *
+ *
Batch transliteration + * + *
The simplest way to perform transliteration is all at once, on a
+ * string of existing text. This is referred to as batch
+ * transliteration. For example, given a string input
+ * and a transliterator t, the call
+ *
+ * \htmlonly
\endhtmlonlyString result = t.transliterate(input);
+ * \htmlonly\endhtmlonly
+ *
+ * will transliterate it and return the result. Other methods allow
+ * the client to specify a substring to be transliterated and to use
+ * {@link Replaceable } objects instead of strings, in order to
+ * preserve out-of-band information (such as text styles).
+ *
+ * Keyboard transliteration + * + *
Somewhat more involved is keyboard, or incremental + * transliteration. This is the transliteration of text that is + * arriving from some source (typically the user's keyboard) one + * character at a time, or in some other piecemeal fashion. + * + *
In keyboard transliteration, a Replaceable buffer
+ * stores the text. As text is inserted, as much as possible is
+ * transliterated on the fly. This means a GUI that displays the
+ * contents of the buffer may show text being modified as each new
+ * character arrives.
+ *
+ *
Consider the simple RuleBasedTransliterator:
+ *
+ * \htmlonly
\endhtmlonly
+ * th>{theta}
+ * t>{tau}
+ * \htmlonly\endhtmlonly
+ *
+ * When the user types 't', nothing will happen, since the
+ * transliterator is waiting to see if the next character is 'h'. To
+ * remedy this, we introduce the notion of a cursor, marked by a '|'
+ * in the output string:
+ *
+ * \htmlonly\endhtmlonly
+ * t>|{tau}
+ * {tau}h>{theta}
+ * \htmlonly\endhtmlonly
+ *
+ * Now when the user types 't', tau appears, and if the next character
+ * is 'h', the tau changes to a theta. This is accomplished by
+ * maintaining a cursor position (independent of the insertion point,
+ * and invisible in the GUI) across calls to
+ * transliterate(). Typically, the cursor will
+ * be coincident with the insertion point, but in a case like the one
+ * above, it will precede the insertion point.
+ *
+ * Keyboard transliteration methods maintain a set of three indices
+ * that are updated with each call to
+ * transliterate(), including the cursor, start,
+ * and limit. Since these indices are changed by the method, they are
+ * passed in an int[] array. The START index
+ * marks the beginning of the substring that the transliterator will
+ * look at. It is advanced as text becomes committed (but it is not
+ * the committed index; that's the CURSOR). The
+ * CURSOR index, described above, marks the point at
+ * which the transliterator last stopped, either because it reached
+ * the end, or because it required more characters to disambiguate
+ * between possible inputs. The CURSOR can also be
+ * explicitly set by rules in a RuleBasedTransliterator.
+ * Any characters before the CURSOR index are frozen;
+ * future keyboard transliteration calls within this input sequence
+ * will not change them. New text is inserted at the
+ * LIMIT index, which marks the end of the substring that
+ * the transliterator looks at.
+ *
+ *
Because keyboard transliteration assumes that more characters
+ * are to arrive, it is conservative in its operation. It only
+ * transliterates when it can do so unambiguously. Otherwise it waits
+ * for more characters to arrive. When the client code knows that no
+ * more characters are forthcoming, perhaps because the user has
+ * performed some input termination operation, then it should call
+ * finishTransliteration() to complete any
+ * pending transliterations.
+ *
+ *
Inverses + * + *
Pairs of transliterators may be inverses of one another. For
+ * example, if transliterator A transliterates characters by
+ * incrementing their Unicode value (so "abc" -> "def"), and
+ * transliterator B decrements character values, then A
+ * is an inverse of B and vice versa. If we compose A
+ * with B in a compound transliterator, the result is the
+ * indentity transliterator, that is, a transliterator that does not
+ * change its input text.
+ *
+ * The Transliterator method getInverse()
+ * returns a transliterator's inverse, if one exists, or
+ * null otherwise. However, the result of
+ * getInverse() usually will not be a true
+ * mathematical inverse. This is because true inverse transliterators
+ * are difficult to formulate. For example, consider two
+ * transliterators: AB, which transliterates the character 'A'
+ * to 'B', and BA, which transliterates 'B' to 'A'. It might
+ * seem that these are exact inverses, since
+ *
+ * \htmlonly
\endhtmlonly"A" x AB -> "B"\endhtmlonly + * + * where 'x' represents transliteration. However, + * + * \htmlonly
+ * "B" x BA -> "A"\htmlonly
\endhtmlonly"ABCD" x AB -> "BBCD"\endhtmlonly + * + * so AB composed with BA is not the + * identity. Nonetheless, BA may be usefully considered to be + * AB's inverse, and it is on this basis that + * AB
+ * "BBCD" x BA -> "AACD"\htmlonly
.getInverse() could legitimately return
+ * BA.
+ *
+ * IDs and display names + * + *
A transliterator is designated by a short identifier string or + * ID. IDs follow the format source-destination, + * where source describes the entity being replaced, and + * destination describes the entity replacing + * source. The entities may be the names of scripts, + * particular sequences of characters, or whatever else it is that the + * transliterator converts to or from. For example, a transliterator + * from Russian to Latin might be named "Russian-Latin". A + * transliterator from keyboard escape sequences to Latin-1 characters + * might be named "KeyboardEscape-Latin1". By convention, system + * entity names are in English, with the initial letters of words + * capitalized; user entity names may follow any format so long as + * they do not contain dashes. + * + *
In addition to programmatic IDs, transliterator objects have + * display names for presentation in user interfaces, returned by + * {@link #getDisplayName }. + * + *
Factory methods and registration + * + *
In general, client code should use the factory method
+ * {@link #createInstance } to obtain an instance of a
+ * transliterator given its ID. Valid IDs may be enumerated using
+ * getAvailableIDs(). Since transliterators are mutable,
+ * multiple calls to {@link #createInstance } with the same ID will
+ * return distinct objects.
+ *
+ *
In addition to the system transliterators registered at startup,
+ * user transliterators may be registered by calling
+ * registerInstance() at run time. A registered instance
+ * acts a template; future calls to {@link #createInstance } with the ID
+ * of the registered object return clones of that object. Thus any
+ * object passed to registerInstance() must implement
+ * clone() propertly. To register a transliterator subclass
+ * without instantiating it (until it is needed), users may call
+ * {@link #registerFactory }. In this case, the objects are
+ * instantiated by invoking the zero-argument public constructor of
+ * the class.
+ *
+ *
Subclassing
+ *
+ * Subclasses must implement the abstract method
+ * handleTransliterate().
Subclasses should override
+ * the transliterate() method taking a
+ * Replaceable and the transliterate()
+ * method taking a String and StringBuffer
+ * if the performance of these methods can be improved over the
+ * performance obtained by the default implementations in this class.
+ *
+ * @author Alan Liu
+ * @stable ICU 2.0
+ */
+class U_I18N_API Transliterator : public UObject {
+
+private:
+
+ /**
+ * Programmatic name, e.g., "Latin-Arabic".
+ */
+ UnicodeString ID;
+
+ /**
+ * This transliterator's filter. Any character for which
+ * filter.contains() returns false will not be
+ * altered by this transliterator. If filter is
+ * null then no filtering is applied.
+ */
+ UnicodeFilter* filter;
+
+ int32_t maximumContextLength;
+
+ public:
+
+ /**
+ * A context integer or pointer for a factory function, passed by
+ * value.
+ * @stable ICU 2.4
+ */
+ union Token {
+ /**
+ * This token, interpreted as a 32-bit integer.
+ * @stable ICU 2.4
+ */
+ int32_t integer;
+ /**
+ * This token, interpreted as a native pointer.
+ * @stable ICU 2.4
+ */
+ void* pointer;
+ };
+
+#ifndef U_HIDE_INTERNAL_API
+ /**
+ * Return a token containing an integer.
+ * @return a token containing an integer.
+ * @internal
+ */
+ inline static Token integerToken(int32_t);
+
+ /**
+ * Return a token containing a pointer.
+ * @return a token containing a pointer.
+ * @internal
+ */
+ inline static Token pointerToken(void*);
+#endif /* U_HIDE_INTERNAL_API */
+
+ /**
+ * A function that creates and returns a Transliterator. When
+ * invoked, it will be passed the ID string that is being
+ * instantiated, together with the context pointer that was passed
+ * in when the factory function was first registered. Many
+ * factory functions will ignore both parameters, however,
+ * functions that are registered to more than one ID may use the
+ * ID or the context parameter to parameterize the transliterator
+ * they create.
+ * @param ID the string identifier for this transliterator
+ * @param context a context pointer that will be stored and
+ * later passed to the factory function when an ID matching
+ * the registration ID is being instantiated with this factory.
+ * @stable ICU 2.4
+ */
+ typedef Transliterator* (U_EXPORT2 *Factory)(const UnicodeString& ID, Token context);
+
+protected:
+
+ /**
+ * Default constructor.
+ * @param ID the string identifier for this transliterator
+ * @param adoptedFilter the filter. Any character for which
+ * filter.contains() returns false will not be
+ * altered by this transliterator. If filter is
+ * null then no filtering is applied.
+ * @stable ICU 2.4
+ */
+ Transliterator(const UnicodeString& ID, UnicodeFilter* adoptedFilter);
+
+ /**
+ * Copy constructor.
+ * @stable ICU 2.4
+ */
+ Transliterator(const Transliterator&);
+
+ /**
+ * Assignment operator.
+ * @stable ICU 2.4
+ */
+ Transliterator& operator=(const Transliterator&);
+
+ /**
+ * Create a transliterator from a basic ID. This is an ID
+ * containing only the forward direction source, target, and
+ * variant.
+ * @param id a basic ID of the form S-T or S-T/V.
+ * @param canon canonical ID to assign to the object, or
+ * NULL to leave the ID unchanged
+ * @return a newly created Transliterator or null if the ID is
+ * invalid.
+ * @stable ICU 2.4
+ */
+ static Transliterator* createBasicInstance(const UnicodeString& id,
+ const UnicodeString* canon);
+
+ friend class TransliteratorParser; // for parseID()
+ friend class TransliteratorIDParser; // for createBasicInstance()
+ friend class TransliteratorAlias; // for setID()
+
+public:
+
+ /**
+ * Destructor.
+ * @stable ICU 2.0
+ */
+ virtual ~Transliterator();
+
+ /**
+ * Implements Cloneable.
+ * All subclasses are encouraged to implement this method if it is
+ * possible and reasonable to do so. Subclasses that are to be
+ * registered with the system using registerInstance()
+ * are required to implement this method. If a subclass does not
+ * implement clone() properly and is registered with the system
+ * using registerInstance(), then the default clone() implementation
+ * will return null, and calls to createInstance() will fail.
+ *
+ * @return a copy of the object.
+ * @see #registerInstance
+ * @stable ICU 2.0
+ */
+ virtual Transliterator* clone() const;
+
+ /**
+ * Transliterates a segment of a string, with optional filtering.
+ *
+ * @param text the string to be transliterated
+ * @param start the beginning index, inclusive; 0 <= start
+ * <= limit.
+ * @param limit the ending index, exclusive; start <= limit
+ * <= text.length().
+ * @return The new limit index. The text previously occupying [start,
+ * limit) has been transliterated, possibly to a string of a different
+ * length, at [start, new-limit), where
+ * new-limit is the return value. If the input offsets are out of bounds,
+ * the returned value is -1 and the input string remains unchanged.
+ * @stable ICU 2.0
+ */
+ virtual int32_t transliterate(Replaceable& text,
+ int32_t start, int32_t limit) const;
+
+ /**
+ * Transliterates an entire string in place. Convenience method.
+ * @param text the string to be transliterated
+ * @stable ICU 2.0
+ */
+ virtual void transliterate(Replaceable& text) const;
+
+ /**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly after new text has been inserted,
+ * typically as a result of a keyboard event. The new text in
+ * insertion will be inserted into text
+ * at index.limit, advancing
+ * index.limit by insertion.length().
+ * Then the transliterator will try to transliterate characters of
+ * text between index.cursor and
+ * index.limit. Characters before
+ * index.cursor will not be changed.
+ *
+ *
Upon return, values in index will be updated.
+ * index.start will be advanced to the first
+ * character that future calls to this method will read.
+ * index.cursor and index.limit will
+ * be adjusted to delimit the range of text that future calls to
+ * this method may change.
+ *
+ *
Typical usage of this method begins with an initial call
+ * with index.start and index.limit
+ * set to indicate the portion of text to be
+ * transliterated, and index.cursor == index.start.
+ * Thereafter, index can be used without
+ * modification in future calls, provided that all changes to
+ * text are made via this method.
+ *
+ *
This method assumes that future calls may be made that will + * insert new text into the buffer. As a result, it only performs + * unambiguous transliterations. After the last call to this + * method, there may be untransliterated text that is waiting for + * more input to resolve an ambiguity. In order to perform these + * pending transliterations, clients should call {@link + * #finishTransliteration } after the last call to this + * method has been made. + * + * @param text the buffer holding transliterated and untransliterated text + * @param index an array of three integers. + * + *
index.start: the beginning index,
+ * inclusive; 0 <= index.start <= index.limit.
+ *
+ * index.limit: the ending index, exclusive;
+ * index.start <= index.limit <= text.length().
+ * insertion is inserted at
+ * index.limit.
+ *
+ * index.cursor: the next character to be
+ * considered for transliteration; index.start <=
+ * index.cursor <= index.limit. Characters before
+ * index.cursor will not be changed by future calls
+ * to this method.index.limit. If null then no text
+ * is inserted.
+ * @param status Output param to filled in with a success or an error.
+ * @see #handleTransliterate
+ * @exception IllegalArgumentException if index
+ * is invalid
+ * @see UTransPosition
+ * @stable ICU 2.0
+ */
+ virtual void transliterate(Replaceable& text, UTransPosition& index,
+ const UnicodeString& insertion,
+ UErrorCode& status) const;
+
+ /**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly after a new character has been
+ * inserted, typically as a result of a keyboard event. This is a
+ * convenience method.
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ * @param index an array of three integers.
+ * @param insertion text to be inserted and possibly
+ * transliterated into the translation buffer at
+ * index.limit.
+ * @param status Output param to filled in with a success or an error.
+ * @see #transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const
+ * @stable ICU 2.0
+ */
+ virtual void transliterate(Replaceable& text, UTransPosition& index,
+ UChar32 insertion,
+ UErrorCode& status) const;
+
+ /**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly. This is a convenience method; see
+ * {@link
+ * #transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const }
+ * for details.
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ * @param index an array of three integers. See {@link #transliterate(Replaceable&, UTransPosition&, const UnicodeString*, UErrorCode&) const }.
+ * @param status Output param to filled in with a success or an error.
+ * @see #transliterate(Replaceable, int[], String)
+ * @stable ICU 2.0
+ */
+ virtual void transliterate(Replaceable& text, UTransPosition& index,
+ UErrorCode& status) const;
+
+ /**
+ * Finishes any pending transliterations that were waiting for
+ * more characters. Clients should call this method as the last
+ * call after a sequence of one or more calls to
+ * transliterate().
+ * @param text the buffer holding transliterated and
+ * untransliterated text.
+ * @param index the array of indices previously passed to {@link
+ * #transliterate }
+ * @stable ICU 2.0
+ */
+ virtual void finishTransliteration(Replaceable& text,
+ UTransPosition& index) const;
+
+private:
+
+ /**
+ * This internal method does incremental transliteration. If the
+ * 'insertion' is non-null then we append it to 'text' before
+ * proceeding. This method calls through to the pure virtual
+ * framework method handleTransliterate() to do the actual
+ * work.
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ * @param index an array of three integers. See {@link
+ * #transliterate(Replaceable, int[], String)}.
+ * @param insertion text to be inserted and possibly
+ * transliterated into the translation buffer at
+ * index.limit.
+ * @param status Output param to filled in with a success or an error.
+ */
+ void _transliterate(Replaceable& text,
+ UTransPosition& index,
+ const UnicodeString* insertion,
+ UErrorCode &status) const;
+
+protected:
+
+ /**
+ * Abstract method that concrete subclasses define to implement
+ * their transliteration algorithm. This method handles both
+ * incremental and non-incremental transliteration. Let
+ * originalStart refer to the value of
+ * pos.start upon entry.
+ *
+ * incremental is false, then this method
+ * should transliterate all characters between
+ * pos.start and pos.limit. Upon return
+ * pos.start must == pos.limit.incremental is true, then this method
+ * should transliterate all characters between
+ * pos.start and pos.limit that can be
+ * unambiguously transliterated, regardless of future insertions
+ * of text at pos.limit. Upon return,
+ * pos.start should be in the range
+ * [originalStart, pos.limit).
+ * pos.start should be positioned such that
+ * characters [originalStart,
+ * pos.start) will not be changed in the future by this
+ * transliterator and characters [pos.start,
+ * pos.limit) are unchanged.Implementations of this method should also obey the + * following invariants:
+ * + *pos.limit and pos.contextLimit
+ * should be updated to reflect changes in length of the text
+ * between pos.start and pos.limit. The
+ * difference pos.contextLimit - pos.limit should
+ * not change.pos.contextStart should not change.pos.start nor
+ * pos.limit should be less than
+ * originalStart.originalStart and text after
+ * pos.limit should not change.pos.contextStart and text after
+ * pos.contextLimit should be ignored.Subclasses may safely assume that all characters in
+ * [pos.start, pos.limit) are filtered.
+ * In other words, the filter has already been applied by the time
+ * this method is called. See
+ * filteredTransliterate().
+ *
+ *
This method is not for public consumption. Calling
+ * this method directly will transliterate
+ * [pos.start, pos.limit) without
+ * applying the filter. End user code should call
+ * transliterate() instead of this method. Subclass code
+ * and wrapping transliterators should call
+ * filteredTransliterate() instead of this method.
+ *
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ *
+ * @param pos the indices indicating the start, limit, context
+ * start, and context limit of the text.
+ *
+ * @param incremental if true, assume more text may be inserted at
+ * pos.limit and act accordingly. Otherwise,
+ * transliterate all text between pos.start and
+ * pos.limit and move pos.start up to
+ * pos.limit.
+ *
+ * @see #transliterate
+ * @stable ICU 2.4
+ */
+ virtual void handleTransliterate(Replaceable& text,
+ UTransPosition& pos,
+ UBool incremental) const = 0;
+
+public:
+ /**
+ * Transliterate a substring of text, as specified by index, taking filters
+ * into account. This method is for subclasses that need to delegate to
+ * another transliterator, such as CompoundTransliterator.
+ * @param text the text to be transliterated
+ * @param index the position indices
+ * @param incremental if TRUE, then assume more characters may be inserted
+ * at index.limit, and postpone processing to accomodate future incoming
+ * characters
+ * @stable ICU 2.4
+ */
+ virtual void filteredTransliterate(Replaceable& text,
+ UTransPosition& index,
+ UBool incremental) const;
+
+private:
+
+ /**
+ * Top-level transliteration method, handling filtering, incremental and
+ * non-incremental transliteration, and rollback. All transliteration
+ * public API methods eventually call this method with a rollback argument
+ * of TRUE. Other entities may call this method but rollback should be
+ * FALSE.
+ *
+ *
If this transliterator has a filter, break up the input text into runs + * of unfiltered characters. Pass each run to + * subclass.handleTransliterate(). + * + *
In incremental mode, if rollback is TRUE, perform a special
+ * incremental procedure in which several passes are made over the input
+ * text, adding one character at a time, and committing successful
+ * transliterations as they occur. Unsuccessful transliterations are rolled
+ * back and retried with additional characters to give correct results.
+ *
+ * @param text the text to be transliterated
+ * @param index the position indices
+ * @param incremental if TRUE, then assume more characters may be inserted
+ * at index.limit, and postpone processing to accomodate future incoming
+ * characters
+ * @param rollback if TRUE and if incremental is TRUE, then perform special
+ * incremental processing, as described above, and undo partial
+ * transliterations where necessary. If incremental is FALSE then this
+ * parameter is ignored.
+ */
+ virtual void filteredTransliterate(Replaceable& text,
+ UTransPosition& index,
+ UBool incremental,
+ UBool rollback) const;
+
+public:
+
+ /**
+ * Returns the length of the longest context required by this transliterator.
+ * This is preceding context. The default implementation supplied
+ * by Transliterator returns zero; subclasses
+ * that use preceding context should override this method to return the
+ * correct value. For example, if a transliterator translates "ddd" (where
+ * d is any digit) to "555" when preceded by "(ddd)", then the preceding
+ * context length is 5, the length of "(ddd)".
+ *
+ * @return The maximum number of preceding context characters this
+ * transliterator needs to examine
+ * @stable ICU 2.0
+ */
+ int32_t getMaximumContextLength(void) const;
+
+protected:
+
+ /**
+ * Method for subclasses to use to set the maximum context length.
+ * @param maxContextLength the new value to be set.
+ * @see #getMaximumContextLength
+ * @stable ICU 2.4
+ */
+ void setMaximumContextLength(int32_t maxContextLength);
+
+public:
+
+ /**
+ * Returns a programmatic identifier for this transliterator.
+ * If this identifier is passed to createInstance(), it
+ * will return this object, if it has been registered.
+ * @return a programmatic identifier for this transliterator.
+ * @see #registerInstance
+ * @see #registerFactory
+ * @see #getAvailableIDs
+ * @stable ICU 2.0
+ */
+ virtual const UnicodeString& getID(void) const;
+
+ /**
+ * Returns a name for this transliterator that is appropriate for
+ * display to the user in the default locale. See {@link
+ * #getDisplayName } for details.
+ * @param ID the string identifier for this transliterator
+ * @param result Output param to receive the display name
+ * @return A reference to 'result'.
+ * @stable ICU 2.0
+ */
+ static UnicodeString& U_EXPORT2 getDisplayName(const UnicodeString& ID,
+ UnicodeString& result);
+
+ /**
+ * Returns a name for this transliterator that is appropriate for
+ * display to the user in the given locale. This name is taken
+ * from the locale resource data in the standard manner of the
+ * java.text package.
+ *
+ *
If no localized names exist in the system resource bundles,
+ * a name is synthesized using a localized
+ * MessageFormat pattern from the resource data. The
+ * arguments to this pattern are an integer followed by one or two
+ * strings. The integer is the number of strings, either 1 or 2.
+ * The strings are formed by splitting the ID for this
+ * transliterator at the first '-'. If there is no '-', then the
+ * entire ID forms the only string.
+ * @param ID the string identifier for this transliterator
+ * @param inLocale the Locale in which the display name should be
+ * localized.
+ * @param result Output param to receive the display name
+ * @return A reference to 'result'.
+ * @stable ICU 2.0
+ */
+ static UnicodeString& U_EXPORT2 getDisplayName(const UnicodeString& ID,
+ const Locale& inLocale,
+ UnicodeString& result);
+
+ /**
+ * Returns the filter used by this transliterator, or NULL
+ * if this transliterator uses no filter.
+ * @return the filter used by this transliterator, or NULL
+ * if this transliterator uses no filter.
+ * @stable ICU 2.0
+ */
+ const UnicodeFilter* getFilter(void) const;
+
+ /**
+ * Returns the filter used by this transliterator, or NULL if this
+ * transliterator uses no filter. The caller must eventually delete the
+ * result. After this call, this transliterator's filter is set to
+ * NULL.
+ * @return the filter used by this transliterator, or NULL if this
+ * transliterator uses no filter.
+ * @stable ICU 2.4
+ */
+ UnicodeFilter* orphanFilter(void);
+
+ /**
+ * Changes the filter used by this transliterator. If the filter
+ * is set to null then no filtering will occur.
+ *
+ *
Callers must take care if a transliterator is in use by
+ * multiple threads. The filter should not be changed by one
+ * thread while another thread may be transliterating.
+ * @param adoptedFilter the new filter to be adopted.
+ * @stable ICU 2.0
+ */
+ void adoptFilter(UnicodeFilter* adoptedFilter);
+
+ /**
+ * Returns this transliterator's inverse. See the class
+ * documentation for details. This implementation simply inverts
+ * the two entities in the ID and attempts to retrieve the
+ * resulting transliterator. That is, if getID()
+ * returns "A-B", then this method will return the result of
+ * createInstance("B-A"), or null if that
+ * call fails.
+ *
+ *
Subclasses with knowledge of their inverse may wish to
+ * override this method.
+ *
+ * @param status Output param to filled in with a success or an error.
+ * @return a transliterator that is an inverse, not necessarily
+ * exact, of this transliterator, or null if no such
+ * transliterator is registered.
+ * @see #registerInstance
+ * @stable ICU 2.0
+ */
+ Transliterator* createInverse(UErrorCode& status) const;
+
+ /**
+ * Returns a Transliterator object given its ID.
+ * The ID must be either a system transliterator ID or a ID registered
+ * using registerInstance().
+ *
+ * @param ID a valid ID, as enumerated by getAvailableIDs()
+ * @param dir either FORWARD or REVERSE.
+ * @param parseError Struct to recieve information on position
+ * of error if an error is encountered
+ * @param status Output param to filled in with a success or an error.
+ * @return A Transliterator object with the given ID
+ * @see #registerInstance
+ * @see #getAvailableIDs
+ * @see #getID
+ * @stable ICU 2.0
+ */
+ static Transliterator* U_EXPORT2 createInstance(const UnicodeString& ID,
+ UTransDirection dir,
+ UParseError& parseError,
+ UErrorCode& status);
+
+ /**
+ * Returns a Transliterator object given its ID.
+ * The ID must be either a system transliterator ID or a ID registered
+ * using registerInstance().
+ * @param ID a valid ID, as enumerated by getAvailableIDs()
+ * @param dir either FORWARD or REVERSE.
+ * @param status Output param to filled in with a success or an error.
+ * @return A Transliterator object with the given ID
+ * @stable ICU 2.0
+ */
+ static Transliterator* U_EXPORT2 createInstance(const UnicodeString& ID,
+ UTransDirection dir,
+ UErrorCode& status);
+
+ /**
+ * Returns a Transliterator object constructed from
+ * the given rule string. This will be a RuleBasedTransliterator,
+ * if the rule string contains only rules, or a
+ * CompoundTransliterator, if it contains ID blocks, or a
+ * NullTransliterator, if it contains ID blocks which parse as
+ * empty for the given direction.
+ * @param ID the id for the transliterator.
+ * @param rules rules, separated by ';'
+ * @param dir either FORWARD or REVERSE.
+ * @param parseError Struct to recieve information on position
+ * of error if an error is encountered
+ * @param status Output param set to success/failure code.
+ * @stable ICU 2.0
+ */
+ static Transliterator* U_EXPORT2 createFromRules(const UnicodeString& ID,
+ const UnicodeString& rules,
+ UTransDirection dir,
+ UParseError& parseError,
+ UErrorCode& status);
+
+ /**
+ * Create a rule string that can be passed to createFromRules()
+ * to recreate this transliterator.
+ * @param result the string to receive the rules. Previous
+ * contents will be deleted.
+ * @param escapeUnprintable if TRUE then convert unprintable
+ * character to their hex escape representations, \\uxxxx or
+ * \\Uxxxxxxxx. Unprintable characters are those other than
+ * U+000A, U+0020..U+007E.
+ * @stable ICU 2.0
+ */
+ virtual UnicodeString& toRules(UnicodeString& result,
+ UBool escapeUnprintable) const;
+
+ /**
+ * Return the number of elements that make up this transliterator.
+ * For example, if the transliterator "NFD;Jamo-Latin;Latin-Greek"
+ * were created, the return value of this method would be 3.
+ *
+ *
If this transliterator is not composed of other + * transliterators, then this method returns 1. + * @return the number of transliterators that compose this + * transliterator, or 1 if this transliterator is not composed of + * multiple transliterators + * @stable ICU 3.0 + */ + int32_t countElements() const; + + /** + * Return an element that makes up this transliterator. For + * example, if the transliterator "NFD;Jamo-Latin;Latin-Greek" + * were created, the return value of this method would be one + * of the three transliterator objects that make up that + * transliterator: [NFD, Jamo-Latin, Latin-Greek]. + * + *
If this transliterator is not composed of other
+ * transliterators, then this method will return a reference to
+ * this transliterator when given the index 0.
+ * @param index a value from 0..countElements()-1 indicating the
+ * transliterator to return
+ * @param ec input-output error code
+ * @return one of the transliterators that makes up this
+ * transliterator, if this transliterator is made up of multiple
+ * transliterators, otherwise a reference to this object if given
+ * an index of 0
+ * @stable ICU 3.0
+ */
+ const Transliterator& getElement(int32_t index, UErrorCode& ec) const;
+
+ /**
+ * Returns the set of all characters that may be modified in the
+ * input text by this Transliterator. This incorporates this
+ * object's current filter; if the filter is changed, the return
+ * value of this function will change. The default implementation
+ * returns an empty set. Some subclasses may override {@link
+ * #handleGetSourceSet } to return a more precise result. The
+ * return result is approximate in any case and is intended for
+ * use by tests, tools, or utilities.
+ * @param result receives result set; previous contents lost
+ * @return a reference to result
+ * @see #getTargetSet
+ * @see #handleGetSourceSet
+ * @stable ICU 2.4
+ */
+ UnicodeSet& getSourceSet(UnicodeSet& result) const;
+
+ /**
+ * Framework method that returns the set of all characters that
+ * may be modified in the input text by this Transliterator,
+ * ignoring the effect of this object's filter. The base class
+ * implementation returns the empty set. Subclasses that wish to
+ * implement this should override this method.
+ * @return the set of characters that this transliterator may
+ * modify. The set may be modified, so subclasses should return a
+ * newly-created object.
+ * @param result receives result set; previous contents lost
+ * @see #getSourceSet
+ * @see #getTargetSet
+ * @stable ICU 2.4
+ */
+ virtual void handleGetSourceSet(UnicodeSet& result) const;
+
+ /**
+ * Returns the set of all characters that may be generated as
+ * replacement text by this transliterator. The default
+ * implementation returns the empty set. Some subclasses may
+ * override this method to return a more precise result. The
+ * return result is approximate in any case and is intended for
+ * use by tests, tools, or utilities requiring such
+ * meta-information.
+ * @param result receives result set; previous contents lost
+ * @return a reference to result
+ * @see #getTargetSet
+ * @stable ICU 2.4
+ */
+ virtual UnicodeSet& getTargetSet(UnicodeSet& result) const;
+
+public:
+
+ /**
+ * Registers a factory function that creates transliterators of
+ * a given ID.
+ * @param id the ID being registered
+ * @param factory a function pointer that will be copied and
+ * called later when the given ID is passed to createInstance()
+ * @param context a context pointer that will be stored and
+ * later passed to the factory function when an ID matching
+ * the registration ID is being instantiated with this factory.
+ * @stable ICU 2.0
+ */
+ static void U_EXPORT2 registerFactory(const UnicodeString& id,
+ Factory factory,
+ Token context);
+
+ /**
+ * Registers an instance obj of a subclass of
+ * Transliterator with the system. When
+ * createInstance() is called with an ID string that is
+ * equal to obj->getID(), then obj->clone() is
+ * returned.
+ *
+ * After this call the Transliterator class owns the adoptedObj
+ * and will delete it.
+ *
+ * @param adoptedObj an instance of subclass of
+ * Transliterator that defines clone()
+ * @see #createInstance
+ * @see #registerFactory
+ * @see #unregister
+ * @stable ICU 2.0
+ */
+ static void U_EXPORT2 registerInstance(Transliterator* adoptedObj);
+
+ /**
+ * Registers an ID string as an alias of another ID string.
+ * That is, after calling this function, createInstance(aliasID)
+ * will return the same thing as createInstance(realID).
+ * This is generally used to create shorter, more mnemonic aliases
+ * for long compound IDs.
+ *
+ * @param aliasID The new ID being registered.
+ * @param realID The ID that the new ID is to be an alias for.
+ * This can be a compound ID and can include filters and should
+ * refer to transliterators that have already been registered with
+ * the framework, although this isn't checked.
+ * @stable ICU 3.6
+ */
+ static void U_EXPORT2 registerAlias(const UnicodeString& aliasID,
+ const UnicodeString& realID);
+
+protected:
+
+#ifndef U_HIDE_INTERNAL_API
+ /**
+ * @internal
+ * @param id the ID being registered
+ * @param factory a function pointer that will be copied and
+ * called later when the given ID is passed to createInstance()
+ * @param context a context pointer that will be stored and
+ * later passed to the factory function when an ID matching
+ * the registration ID is being instantiated with this factory.
+ */
+ static void _registerFactory(const UnicodeString& id,
+ Factory factory,
+ Token context);
+
+ /**
+ * @internal
+ */
+ static void _registerInstance(Transliterator* adoptedObj);
+
+ /**
+ * @internal
+ */
+ static void _registerAlias(const UnicodeString& aliasID, const UnicodeString& realID);
+
+ /**
+ * Register two targets as being inverses of one another. For
+ * example, calling registerSpecialInverse("NFC", "NFD", true) causes
+ * Transliterator to form the following inverse relationships:
+ *
+ *
NFC => NFD + * Any-NFC => Any-NFD + * NFD => NFC + * Any-NFD => Any-NFC+ * + * (Without the special inverse registration, the inverse of NFC + * would be NFC-Any.) Note that NFD is shorthand for Any-NFD, but + * that the presence or absence of "Any-" is preserved. + * + *
The relationship is symmetrical; registering (a, b) is + * equivalent to registering (b, a). + * + *
The relevant IDs must still be registered separately as + * factories or classes. + * + *
Only the targets are specified. Special inverses always
+ * have the form Any-Target1 <=> Any-Target2. The target should
+ * have canonical casing (the casing desired to be produced when
+ * an inverse is formed) and should contain no whitespace or other
+ * extraneous characters.
+ *
+ * @param target the target against which to register the inverse
+ * @param inverseTarget the inverse of target, that is
+ * Any-target.getInverse() => Any-inverseTarget
+ * @param bidirectional if true, register the reverse relation
+ * as well, that is, Any-inverseTarget.getInverse() => Any-target
+ * @internal
+ */
+ static void _registerSpecialInverse(const UnicodeString& target,
+ const UnicodeString& inverseTarget,
+ UBool bidirectional);
+#endif /* U_HIDE_INTERNAL_API */
+
+public:
+
+ /**
+ * Unregisters a transliterator or class. This may be either
+ * a system transliterator or a user transliterator or class.
+ * Any attempt to construct an unregistered transliterator based
+ * on its ID will fail.
+ *
+ * @param ID the ID of the transliterator or class
+ * @return the Object that was registered with
+ * ID, or null if none was
+ * @see #registerInstance
+ * @see #registerFactory
+ * @stable ICU 2.0
+ */
+ static void U_EXPORT2 unregister(const UnicodeString& ID);
+
+public:
+
+ /**
+ * Return a StringEnumeration over the IDs available at the time of the
+ * call, including user-registered IDs.
+ * @param ec input-output error code
+ * @return a newly-created StringEnumeration over the transliterators
+ * available at the time of the call. The caller should delete this object
+ * when done using it.
+ * @stable ICU 3.0
+ */
+ static StringEnumeration* U_EXPORT2 getAvailableIDs(UErrorCode& ec);
+
+ /**
+ * Return the number of registered source specifiers.
+ * @return the number of registered source specifiers.
+ * @stable ICU 2.0
+ */
+ static int32_t U_EXPORT2 countAvailableSources(void);
+
+ /**
+ * Return a registered source specifier.
+ * @param index which specifier to return, from 0 to n-1, where
+ * n = countAvailableSources()
+ * @param result fill-in paramter to receive the source specifier.
+ * If index is out of range, result will be empty.
+ * @return reference to result
+ * @stable ICU 2.0
+ */
+ static UnicodeString& U_EXPORT2 getAvailableSource(int32_t index,
+ UnicodeString& result);
+
+ /**
+ * Return the number of registered target specifiers for a given
+ * source specifier.
+ * @param source the given source specifier.
+ * @return the number of registered target specifiers for a given
+ * source specifier.
+ * @stable ICU 2.0
+ */
+ static int32_t U_EXPORT2 countAvailableTargets(const UnicodeString& source);
+
+ /**
+ * Return a registered target specifier for a given source.
+ * @param index which specifier to return, from 0 to n-1, where
+ * n = countAvailableTargets(source)
+ * @param source the source specifier
+ * @param result fill-in paramter to receive the target specifier.
+ * If source is invalid or if index is out of range, result will
+ * be empty.
+ * @return reference to result
+ * @stable ICU 2.0
+ */
+ static UnicodeString& U_EXPORT2 getAvailableTarget(int32_t index,
+ const UnicodeString& source,
+ UnicodeString& result);
+
+ /**
+ * Return the number of registered variant specifiers for a given
+ * source-target pair.
+ * @param source the source specifiers.
+ * @param target the target specifiers.
+ * @stable ICU 2.0
+ */
+ static int32_t U_EXPORT2 countAvailableVariants(const UnicodeString& source,
+ const UnicodeString& target);
+
+ /**
+ * Return a registered variant specifier for a given source-target
+ * pair.
+ * @param index which specifier to return, from 0 to n-1, where
+ * n = countAvailableVariants(source, target)
+ * @param source the source specifier
+ * @param target the target specifier
+ * @param result fill-in paramter to receive the variant
+ * specifier. If source is invalid or if target is invalid or if
+ * index is out of range, result will be empty.
+ * @return reference to result
+ * @stable ICU 2.0
+ */
+ static UnicodeString& U_EXPORT2 getAvailableVariant(int32_t index,
+ const UnicodeString& source,
+ const UnicodeString& target,
+ UnicodeString& result);
+
+protected:
+
+#ifndef U_HIDE_INTERNAL_API
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static int32_t _countAvailableSources(void);
+
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static UnicodeString& _getAvailableSource(int32_t index,
+ UnicodeString& result);
+
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static int32_t _countAvailableTargets(const UnicodeString& source);
+
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static UnicodeString& _getAvailableTarget(int32_t index,
+ const UnicodeString& source,
+ UnicodeString& result);
+
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static int32_t _countAvailableVariants(const UnicodeString& source,
+ const UnicodeString& target);
+
+ /**
+ * Non-mutexed internal method
+ * @internal
+ */
+ static UnicodeString& _getAvailableVariant(int32_t index,
+ const UnicodeString& source,
+ const UnicodeString& target,
+ UnicodeString& result);
+#endif /* U_HIDE_INTERNAL_API */
+
+protected:
+
+ /**
+ * Set the ID of this transliterators. Subclasses shouldn't do
+ * this, unless the underlying script behavior has changed.
+ * @param id the new id t to be set.
+ * @stable ICU 2.4
+ */
+ void setID(const UnicodeString& id);
+
+public:
+
+ /**
+ * Return the class ID for this class. This is useful only for
+ * comparing to a return value from getDynamicClassID().
+ * Note that Transliterator is an abstract base class, and therefor
+ * no fully constructed object will have a dynamic
+ * UCLassID that equals the UClassID returned from
+ * TRansliterator::getStaticClassID().
+ * @return The class ID for class Transliterator.
+ * @stable ICU 2.0
+ */
+ static UClassID U_EXPORT2 getStaticClassID(void);
+
+ /**
+ * Returns a unique class ID polymorphically. This method
+ * is to implement a simple version of RTTI, since not all C++
+ * compilers support genuine RTTI. Polymorphic operator==() and
+ * clone() methods call this method.
+ *
+ *
Concrete subclasses of Transliterator must use the + * UOBJECT_DEFINE_RTTI_IMPLEMENTATION macro from + * uobject.h to provide the RTTI functions. + * + * @return The class ID for this object. All objects of a given + * class have the same class ID. Objects of other classes have + * different class IDs. + * @stable ICU 2.0 + */ + virtual UClassID getDynamicClassID(void) const = 0; + +private: + static UBool initializeRegistry(UErrorCode &status); + +public: +#ifndef U_HIDE_OBSOLETE_API + /** + * Return the number of IDs currently registered with the system. + * To retrieve the actual IDs, call getAvailableID(i) with + * i from 0 to countAvailableIDs() - 1. + * @return the number of IDs currently registered with the system. + * @obsolete ICU 3.4 use getAvailableIDs() instead + */ + static int32_t U_EXPORT2 countAvailableIDs(void); + + /** + * Return the index-th available ID. index must be between 0 + * and countAvailableIDs() - 1, inclusive. If index is out of + * range, the result of getAvailableID(0) is returned. + * @param index the given ID index. + * @return the index-th available ID. index must be between 0 + * and countAvailableIDs() - 1, inclusive. If index is out of + * range, the result of getAvailableID(0) is returned. + * @obsolete ICU 3.4 use getAvailableIDs() instead; this function + * is not thread safe, since it returns a reference to storage that + * may become invalid if another thread calls unregister + */ + static const UnicodeString& U_EXPORT2 getAvailableID(int32_t index); +#endif /* U_HIDE_OBSOLETE_API */ +}; + +inline int32_t Transliterator::getMaximumContextLength(void) const { + return maximumContextLength; +} + +inline void Transliterator::setID(const UnicodeString& id) { + ID = id; + // NUL-terminate the ID string, which is a non-aliased copy. + ID.append((UChar)0); + ID.truncate(ID.length()-1); +} + +#ifndef U_HIDE_INTERNAL_API +inline Transliterator::Token Transliterator::integerToken(int32_t i) { + Token t; + t.integer = i; + return t; +} + +inline Transliterator::Token Transliterator::pointerToken(void* p) { + Token t; + t.pointer = p; + return t; +} +#endif /* U_HIDE_INTERNAL_API */ + +U_NAMESPACE_END + +#endif /* #if !UCONFIG_NO_TRANSLITERATION */ + +#endif