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icu::Transliterator Class Reference

Transliterator is an abstract class that transliterates text from one format to another. More...

#include <translit.h>

Inheritance diagram for icu::Transliterator:
icu::UObject icu::UMemory

Data Structures

union  Token
 A context integer or pointer for a factory function, passed by value. More...

Public Types

typedef Transliterator *(* Factory )(const UnicodeString &ID, Token context)
 A function that creates and returns a Transliterator.

Public Member Functions

virtual ~Transliterator ()
 Destructor.
virtual Transliteratorclone () const
 Implements Cloneable.
virtual int32_t transliterate (Replaceable &text, int32_t start, int32_t limit) const
 Transliterates a segment of a string, with optional filtering.
virtual void transliterate (Replaceable &text) const
 Transliterates an entire string in place.
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 new text has been inserted, typically as a result of a keyboard event.
virtual void transliterate (Replaceable &text, UTransPosition &index, UChar32 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.
virtual void transliterate (Replaceable &text, UTransPosition &index, UErrorCode &status) const
 Transliterates the portion of the text buffer that can be transliterated unambiguosly.
virtual void finishTransliteration (Replaceable &text, UTransPosition &index) const
 Finishes any pending transliterations that were waiting for more characters.
virtual void filteredTransliterate (Replaceable &text, UTransPosition &index, UBool incremental) const
 Transliterate a substring of text, as specified by index, taking filters into account.
int32_t getMaximumContextLength (void) const
 Returns the length of the longest context required by this transliterator.
virtual const UnicodeStringgetID (void) const
 Returns a programmatic identifier for this transliterator.
const UnicodeFiltergetFilter (void) const
 Returns the filter used by this transliterator, or NULL if this transliterator uses no filter.
UnicodeFilterorphanFilter (void)
 Returns the filter used by this transliterator, or NULL if this transliterator uses no filter.
void adoptFilter (UnicodeFilter *adoptedFilter)
 Changes the filter used by this transliterator.
TransliteratorcreateInverse (UErrorCode &status) const
 Returns this transliterator's inverse.
virtual UnicodeStringtoRules (UnicodeString &result, UBool escapeUnprintable) const
 Create a rule string that can be passed to createFromRules() to recreate this transliterator.
int32_t countElements () const
 Return the number of elements that make up this transliterator.
const TransliteratorgetElement (int32_t index, UErrorCode &ec) const
 Return an element that makes up this transliterator.
UnicodeSetgetSourceSet (UnicodeSet &result) const
 Returns the set of all characters that may be modified in the input text by this Transliterator.
virtual void handleGetSourceSet (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.
virtual UnicodeSetgetTargetSet (UnicodeSet &result) const
 Returns the set of all characters that may be generated as replacement text by this transliterator.
virtual UClassID getDynamicClassID (void) const =0
 Returns a unique class ID polymorphically.
- Public Member Functions inherited from icu::UObject
virtual ~UObject ()
 Destructor.

Static Public Member Functions

static Token integerToken (int32_t)
 Return a token containing an integer.
static Token pointerToken (void *)
 Return a token containing a pointer.
static UnicodeStringgetDisplayName (const UnicodeString &ID, UnicodeString &result)
 Returns a name for this transliterator that is appropriate for display to the user in the default locale.
static UnicodeStringgetDisplayName (const UnicodeString &ID, const Locale &inLocale, UnicodeString &result)
 Returns a name for this transliterator that is appropriate for display to the user in the given locale.
static TransliteratorcreateInstance (const UnicodeString &ID, UTransDirection dir, UParseError &parseError, UErrorCode &status)
 Returns a Transliterator object given its ID.
static TransliteratorcreateInstance (const UnicodeString &ID, UTransDirection dir, UErrorCode &status)
 Returns a Transliterator object given its ID.
static TransliteratorcreateFromRules (const UnicodeString &ID, const UnicodeString &rules, UTransDirection dir, UParseError &parseError, UErrorCode &status)
 Returns a Transliterator object constructed from the given rule string.
static void registerFactory (const UnicodeString &id, Factory factory, Token context)
 Registers a factory function that creates transliterators of a given ID.
static void registerInstance (Transliterator *adoptedObj)
 Registers an instance obj of a subclass of Transliterator with the system.
static void registerAlias (const UnicodeString &aliasID, const UnicodeString &realID)
 Registers an ID string as an alias of another ID string.
static void unregister (const UnicodeString &ID)
 Unregisters a transliterator or class.
static StringEnumerationgetAvailableIDs (UErrorCode &ec)
 Return a StringEnumeration over the IDs available at the time of the call, including user-registered IDs.
static int32_t countAvailableSources (void)
 Return the number of registered source specifiers.
static UnicodeStringgetAvailableSource (int32_t index, UnicodeString &result)
 Return a registered source specifier.
static int32_t countAvailableTargets (const UnicodeString &source)
 Return the number of registered target specifiers for a given source specifier.
static UnicodeStringgetAvailableTarget (int32_t index, const UnicodeString &source, UnicodeString &result)
 Return a registered target specifier for a given source.
static int32_t countAvailableVariants (const UnicodeString &source, const UnicodeString &target)
 Return the number of registered variant specifiers for a given source-target pair.
static UnicodeStringgetAvailableVariant (int32_t index, const UnicodeString &source, const UnicodeString &target, UnicodeString &result)
 Return a registered variant specifier for a given source-target pair.
static UClassID getStaticClassID (void)
 Return the class ID for this class.
static int32_t countAvailableIDs (void)
 Return the number of IDs currently registered with the system.
static const UnicodeStringgetAvailableID (int32_t index)
 Return the index-th available ID.

Protected Member Functions

 Transliterator (const UnicodeString &ID, UnicodeFilter *adoptedFilter)
 Default constructor.
 Transliterator (const Transliterator &)
 Copy constructor.
Transliteratoroperator= (const Transliterator &)
 Assignment operator.
virtual void handleTransliterate (Replaceable &text, UTransPosition &pos, UBool incremental) const =0
 Abstract method that concrete subclasses define to implement their transliteration algorithm.
void setMaximumContextLength (int32_t maxContextLength)
 Method for subclasses to use to set the maximum context length.
void setID (const UnicodeString &id)
 Set the ID of this transliterators.

Static Protected Member Functions

static TransliteratorcreateBasicInstance (const UnicodeString &id, const UnicodeString *canon)
 Create a transliterator from a basic ID.
static void _registerFactory (const UnicodeString &id, Factory factory, Token context)
static void _registerInstance (Transliterator *adoptedObj)
static void _registerAlias (const UnicodeString &aliasID, const UnicodeString &realID)
static void _registerSpecialInverse (const UnicodeString &target, const UnicodeString &inverseTarget, UBool bidirectional)
 Register two targets as being inverses of one another.
static int32_t _countAvailableSources (void)
 Non-mutexed internal method.
static UnicodeString_getAvailableSource (int32_t index, UnicodeString &result)
 Non-mutexed internal method.
static int32_t _countAvailableTargets (const UnicodeString &source)
 Non-mutexed internal method.
static UnicodeString_getAvailableTarget (int32_t index, const UnicodeString &source, UnicodeString &result)
 Non-mutexed internal method.
static int32_t _countAvailableVariants (const UnicodeString &source, const UnicodeString &target)
 Non-mutexed internal method.
static UnicodeString_getAvailableVariant (int32_t index, const UnicodeString &source, const UnicodeString &target, UnicodeString &result)
 Non-mutexed internal method.

Friends

class TransliteratorParser
class TransliteratorIDParser
class TransliteratorAlias

Detailed Description

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

String result = t.transliterate(input);

will transliterate it and return the result. Other methods allow the client to specify a substring to be transliterated and to use 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:

th>{theta}
t>{tau}

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:

t>|{tau}
{tau}h>{theta}

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

"A" x AB -> "B"
"B" x BA -> "A"

where 'x' represents transliteration. However,

"ABCD" x AB -> "BBCD"
"BBCD" x BA -> "AACD"

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.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 getDisplayName.

Factory methods and registration

In general, client code should use the factory method 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 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 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 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

Definition at line 241 of file translit.h.

Member Typedef Documentation

typedef Transliterator*( * icu::Transliterator::Factory)(const UnicodeString &ID, Token context)

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.

Parameters
IDthe string identifier for this transliterator
contexta 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

Definition at line 311 of file translit.h.

Constructor & Destructor Documentation

icu::Transliterator::Transliterator ( const UnicodeString ID,
UnicodeFilter adoptedFilter 
)
protected

Default constructor.

Parameters
IDthe string identifier for this transliterator
adoptedFilterthe 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
icu::Transliterator::Transliterator ( const Transliterator )
protected

Copy constructor.

Stable:
ICU 2.4
virtual icu::Transliterator::~Transliterator ( )
virtual

Destructor.

Stable:
ICU 2.0

Member Function Documentation

static int32_t icu::Transliterator::_countAvailableSources ( void  )
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static int32_t icu::Transliterator::_countAvailableTargets ( const UnicodeString source)
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static int32_t icu::Transliterator::_countAvailableVariants ( const UnicodeString source,
const UnicodeString target 
)
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static UnicodeString& icu::Transliterator::_getAvailableSource ( int32_t  index,
UnicodeString result 
)
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static UnicodeString& icu::Transliterator::_getAvailableTarget ( int32_t  index,
const UnicodeString source,
UnicodeString result 
)
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static UnicodeString& icu::Transliterator::_getAvailableVariant ( int32_t  index,
const UnicodeString source,
const UnicodeString target,
UnicodeString result 
)
staticprotected

Non-mutexed internal method.

Internal:
Do not use. This API is for internal use only.
static void icu::Transliterator::_registerAlias ( const UnicodeString aliasID,
const UnicodeString realID 
)
staticprotected
Internal:
Do not use. This API is for internal use only.
static void icu::Transliterator::_registerFactory ( const UnicodeString id,
Factory  factory,
Token  context 
)
staticprotected
Parameters
idthe ID being registered
factorya function pointer that will be copied and called later when the given ID is passed to createInstance()
contexta 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.
Internal:
Do not use. This API is for internal use only.
static void icu::Transliterator::_registerInstance ( Transliterator adoptedObj)
staticprotected
Internal:
Do not use. This API is for internal use only.
static void icu::Transliterator::_registerSpecialInverse ( const UnicodeString target,
const UnicodeString inverseTarget,
UBool  bidirectional 
)
staticprotected

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.

Parameters
targetthe target against which to register the inverse
inverseTargetthe inverse of target, that is Any-target.getInverse() => Any-inverseTarget
bidirectionalif true, register the reverse relation as well, that is, Any-inverseTarget.getInverse() => Any-target
Internal:
Do not use. This API is for internal use only.
void icu::Transliterator::adoptFilter ( UnicodeFilter adoptedFilter)

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.

Parameters
adoptedFilterthe new filter to be adopted.
Stable:
ICU 2.0
virtual Transliterator* icu::Transliterator::clone ( ) const
virtual

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.

Returns
a copy of the object.
See Also
registerInstance
Stable:
ICU 2.0
static int32_t icu::Transliterator::countAvailableIDs ( void  )
static

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.

Returns
the number of IDs currently registered with the system.
Obsolete:
ICU 3.4 use getAvailableIDs() instead
static int32_t icu::Transliterator::countAvailableSources ( void  )
static

Return the number of registered source specifiers.

Returns
the number of registered source specifiers.
Stable:
ICU 2.0
static int32_t icu::Transliterator::countAvailableTargets ( const UnicodeString source)
static

Return the number of registered target specifiers for a given source specifier.

Parameters
sourcethe given source specifier.
Returns
the number of registered target specifiers for a given source specifier.
Stable:
ICU 2.0
static int32_t icu::Transliterator::countAvailableVariants ( const UnicodeString source,
const UnicodeString target 
)
static

Return the number of registered variant specifiers for a given source-target pair.

Parameters
sourcethe source specifiers.
targetthe target specifiers.
Stable:
ICU 2.0
int32_t icu::Transliterator::countElements ( ) 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.

Returns
the number of transliterators that compose this transliterator, or 1 if this transliterator is not composed of multiple transliterators
Stable:
ICU 3.0
static Transliterator* icu::Transliterator::createBasicInstance ( const UnicodeString id,
const UnicodeString canon 
)
staticprotected

Create a transliterator from a basic ID.

This is an ID containing only the forward direction source, target, and variant.

Parameters
ida basic ID of the form S-T or S-T/V.
canoncanonical ID to assign to the object, or NULL to leave the ID unchanged
Returns
a newly created Transliterator or null if the ID is invalid.
Stable:
ICU 2.4
static Transliterator* icu::Transliterator::createFromRules ( const UnicodeString ID,
const UnicodeString rules,
UTransDirection  dir,
UParseError parseError,
UErrorCode status 
)
static

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.

Parameters
IDthe id for the transliterator.
rulesrules, separated by ';'
direither FORWARD or REVERSE.
parseErrorStruct to recieve information on position of error if an error is encountered
statusOutput param set to success/failure code.
Stable:
ICU 2.0
static Transliterator* icu::Transliterator::createInstance ( const UnicodeString ID,
UTransDirection  dir,
UParseError parseError,
UErrorCode status 
)
static

Returns a Transliterator object given its ID.

The ID must be either a system transliterator ID or a ID registered using registerInstance().

Parameters
IDa valid ID, as enumerated by getAvailableIDs()
direither FORWARD or REVERSE.
parseErrorStruct to recieve information on position of error if an error is encountered
statusOutput param to filled in with a success or an error.
Returns
A Transliterator object with the given ID
See Also
registerInstance
getAvailableIDs
getID
Stable:
ICU 2.0
static Transliterator* icu::Transliterator::createInstance ( const UnicodeString ID,
UTransDirection  dir,
UErrorCode status 
)
static

Returns a Transliterator object given its ID.

The ID must be either a system transliterator ID or a ID registered using registerInstance().

Parameters
IDa valid ID, as enumerated by getAvailableIDs()
direither FORWARD or REVERSE.
statusOutput param to filled in with a success or an error.
Returns
A Transliterator object with the given ID
Stable:
ICU 2.0
Transliterator* icu::Transliterator::createInverse ( UErrorCode status) const

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.

Parameters
statusOutput param to filled in with a success or an error.
Returns
a transliterator that is an inverse, not necessarily exact, of this transliterator, or null if no such transliterator is registered.
See Also
registerInstance
Stable:
ICU 2.0
virtual void icu::Transliterator::filteredTransliterate ( Replaceable text,
UTransPosition index,
UBool  incremental 
) const
virtual

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.

Parameters
textthe text to be transliterated
indexthe position indices
incrementalif 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 icu::Transliterator::finishTransliteration ( Replaceable text,
UTransPosition index 
) const
virtual

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().

Parameters
textthe buffer holding transliterated and untransliterated text.
indexthe array of indices previously passed to transliterate
Stable:
ICU 2.0
static const UnicodeString& icu::Transliterator::getAvailableID ( int32_t  index)
static

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.

Parameters
indexthe given ID index.
Returns
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 StringEnumeration* icu::Transliterator::getAvailableIDs ( UErrorCode ec)
static

Return a StringEnumeration over the IDs available at the time of the call, including user-registered IDs.

Parameters
ecinput-output error code
Returns
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 UnicodeString& icu::Transliterator::getAvailableSource ( int32_t  index,
UnicodeString result 
)
static

Return a registered source specifier.

Parameters
indexwhich specifier to return, from 0 to n-1, where n = countAvailableSources()
resultfill-in paramter to receive the source specifier. If index is out of range, result will be empty.
Returns
reference to result
Stable:
ICU 2.0
static UnicodeString& icu::Transliterator::getAvailableTarget ( int32_t  index,
const UnicodeString source,
UnicodeString result 
)
static

Return a registered target specifier for a given source.

Parameters
indexwhich specifier to return, from 0 to n-1, where n = countAvailableTargets(source)
sourcethe source specifier
resultfill-in paramter to receive the target specifier. If source is invalid or if index is out of range, result will be empty.
Returns
reference to result
Stable:
ICU 2.0
static UnicodeString& icu::Transliterator::getAvailableVariant ( int32_t  index,
const UnicodeString source,
const UnicodeString target,
UnicodeString result 
)
static

Return a registered variant specifier for a given source-target pair.

Parameters
indexwhich specifier to return, from 0 to n-1, where n = countAvailableVariants(source, target)
sourcethe source specifier
targetthe target specifier
resultfill-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.
Returns
reference to result
Stable:
ICU 2.0
static UnicodeString& icu::Transliterator::getDisplayName ( const UnicodeString ID,
UnicodeString result 
)
static

Returns a name for this transliterator that is appropriate for display to the user in the default locale.

See getDisplayName for details.

Parameters
IDthe string identifier for this transliterator
resultOutput param to receive the display name
Returns
A reference to 'result'.
Stable:
ICU 2.0
static UnicodeString& icu::Transliterator::getDisplayName ( const UnicodeString ID,
const Locale inLocale,
UnicodeString result 
)
static

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.

Parameters
IDthe string identifier for this transliterator
inLocalethe Locale in which the display name should be localized.
resultOutput param to receive the display name
Returns
A reference to 'result'.
Stable:
ICU 2.0
virtual UClassID icu::Transliterator::getDynamicClassID ( void  ) const
pure virtual

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.

Returns
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

Reimplemented from icu::UObject.

const Transliterator& icu::Transliterator::getElement ( int32_t  index,
UErrorCode ec 
) 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.

Parameters
indexa value from 0..countElements()-1 indicating the transliterator to return
ecinput-output error code
Returns
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 UnicodeFilter* icu::Transliterator::getFilter ( void  ) const

Returns the filter used by this transliterator, or NULL if this transliterator uses no filter.

Returns
the filter used by this transliterator, or NULL if this transliterator uses no filter.
Stable:
ICU 2.0
virtual const UnicodeString& icu::Transliterator::getID ( void  ) const
virtual

Returns a programmatic identifier for this transliterator.

If this identifier is passed to createInstance(), it will return this object, if it has been registered.

Returns
a programmatic identifier for this transliterator.
See Also
registerInstance
registerFactory
getAvailableIDs
Stable:
ICU 2.0
int32_t icu::Transliterator::getMaximumContextLength ( void  ) const
inline

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)".

Returns
The maximum number of preceding context characters this transliterator needs to examine
Stable:
ICU 2.0

Definition at line 1313 of file translit.h.

UnicodeSet& icu::Transliterator::getSourceSet ( UnicodeSet result) 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 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.

Parameters
resultreceives result set; previous contents lost
Returns
a reference to result
See Also
getTargetSet
handleGetSourceSet
Stable:
ICU 2.4
static UClassID icu::Transliterator::getStaticClassID ( void  )
static

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().

Returns
The class ID for class Transliterator.
Stable:
ICU 2.0
virtual UnicodeSet& icu::Transliterator::getTargetSet ( UnicodeSet result) const
virtual

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.

Parameters
resultreceives result set; previous contents lost
Returns
a reference to result
See Also
getTargetSet
Stable:
ICU 2.4
virtual void icu::Transliterator::handleGetSourceSet ( UnicodeSet result) const
virtual

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.

Returns
the set of characters that this transliterator may modify. The set may be modified, so subclasses should return a newly-created object.
Parameters
resultreceives result set; previous contents lost
See Also
getSourceSet
getTargetSet
Stable:
ICU 2.4
virtual void icu::Transliterator::handleTransliterate ( Replaceable text,
UTransPosition pos,
UBool  incremental 
) const
protectedpure virtual

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.

  • If incremental is false, then this method should transliterate all characters between pos.start and pos.limit. Upon return pos.start must == pos.limit.

  • If 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.

  • Upon return, neither pos.start nor pos.limit should be less than originalStart.

  • Text before originalStart and text after pos.limit should not change.

  • Text before 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.

Parameters
textthe buffer holding transliterated and untransliterated text
posthe indices indicating the start, limit, context start, and context limit of the text.
incrementalif 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 Also
transliterate
Stable:
ICU 2.4
Transliterator::Token icu::Transliterator::integerToken ( int32_t  i)
inlinestatic

Return a token containing an integer.

Returns
a token containing an integer.
Internal:
Do not use. This API is for internal use only.

Definition at line 1325 of file translit.h.

References icu::Transliterator::Token::integer.

Transliterator& icu::Transliterator::operator= ( const Transliterator )
protected

Assignment operator.

Stable:
ICU 2.4
UnicodeFilter* icu::Transliterator::orphanFilter ( void  )

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.

Returns
the filter used by this transliterator, or NULL if this transliterator uses no filter.
Stable:
ICU 2.4
Transliterator::Token icu::Transliterator::pointerToken ( void *  p)
inlinestatic

Return a token containing a pointer.

Returns
a token containing a pointer.
Internal:
Do not use. This API is for internal use only.

Definition at line 1331 of file translit.h.

References icu::Transliterator::Token::pointer.

static void icu::Transliterator::registerAlias ( const UnicodeString aliasID,
const UnicodeString realID 
)
static

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.

Parameters
aliasIDThe new ID being registered.
realIDThe 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 icu::Transliterator::registerFactory ( const UnicodeString id,
Factory  factory,
Token  context 
)
static

Registers a factory function that creates transliterators of a given ID.

Because ICU may choose to cache Transliterators internally, this must be called at application startup, prior to any calls to Transliterator::createXXX to avoid undefined behavior.

Parameters
idthe ID being registered
factorya function pointer that will be copied and called later when the given ID is passed to createInstance()
contexta 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 icu::Transliterator::registerInstance ( Transliterator adoptedObj)
static

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.

Because ICU may choose to cache Transliterators internally, this must be called at application startup, prior to any calls to Transliterator::createXXX to avoid undefined behavior.

Parameters
adoptedObjan instance of subclass of Transliterator that defines clone()
See Also
createInstance
registerFactory
unregister
Stable:
ICU 2.0
void icu::Transliterator::setID ( const UnicodeString id)
inlineprotected

Set the ID of this transliterators.

Subclasses shouldn't do this, unless the underlying script behavior has changed.

Parameters
idthe new id t to be set.
Stable:
ICU 2.4

Definition at line 1317 of file translit.h.

References icu::UnicodeString::append(), and icu::UnicodeString::truncate().

void icu::Transliterator::setMaximumContextLength ( int32_t  maxContextLength)
protected

Method for subclasses to use to set the maximum context length.

Parameters
maxContextLengththe new value to be set.
See Also
getMaximumContextLength
Stable:
ICU 2.4
virtual UnicodeString& icu::Transliterator::toRules ( UnicodeString result,
UBool  escapeUnprintable 
) const
virtual

Create a rule string that can be passed to createFromRules() to recreate this transliterator.

Parameters
resultthe string to receive the rules. Previous contents will be deleted.
escapeUnprintableif 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 int32_t icu::Transliterator::transliterate ( Replaceable text,
int32_t  start,
int32_t  limit 
) const
virtual

Transliterates a segment of a string, with optional filtering.

Parameters
textthe string to be transliterated
startthe beginning index, inclusive; 0 <= start <= limit.
limitthe ending index, exclusive; start <= limit <= text.length().
Returns
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 void icu::Transliterator::transliterate ( Replaceable text) const
virtual

Transliterates an entire string in place.

Convenience method.

Parameters
textthe string to be transliterated
Stable:
ICU 2.0
virtual void icu::Transliterator::transliterate ( Replaceable text,
UTransPosition index,
const UnicodeString insertion,
UErrorCode status 
) const
virtual

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 finishTransliteration after the last call to this method has been made.

Parameters
textthe buffer holding transliterated and untransliterated text
indexan 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.
Parameters
insertiontext to be inserted and possibly transliterated into the translation buffer at index.limit. If null then no text is inserted.
statusOutput param to filled in with a success or an error.
See Also
handleTransliterate
Exceptions
IllegalArgumentExceptionif index is invalid
See Also
UTransPosition
Stable:
ICU 2.0
virtual void icu::Transliterator::transliterate ( Replaceable text,
UTransPosition index,
UChar32  insertion,
UErrorCode status 
) const
virtual

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.

Parameters
textthe buffer holding transliterated and untransliterated text
indexan array of three integers.
insertiontext to be inserted and possibly transliterated into the translation buffer at index.limit.
statusOutput param to filled in with a success or an error.
See Also
transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const
Stable:
ICU 2.0
virtual void icu::Transliterator::transliterate ( Replaceable text,
UTransPosition index,
UErrorCode status 
) const
virtual

Transliterates the portion of the text buffer that can be transliterated unambiguosly.

This is a convenience method; see transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const for details.

Parameters
textthe buffer holding transliterated and untransliterated text
indexan array of three integers. See transliterate(Replaceable&, UTransPosition&, const UnicodeString*, UErrorCode&) const .
statusOutput param to filled in with a success or an error.
See Also
#transliterate(Replaceable, int[], String)
Stable:
ICU 2.0
static void icu::Transliterator::unregister ( const UnicodeString ID)
static

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.

Because ICU may choose to cache Transliterators internally, this should be called during application shutdown, after all calls to Transliterator::createXXX to avoid undefined behavior.

Parameters
IDthe ID of the transliterator or class
Returns
the Object that was registered with ID, or null if none was
See Also
registerInstance
registerFactory
Stable:
ICU 2.0

The documentation for this class was generated from the following file: