Transliterator
public
abstract
class
Transliterator
extends Object
| java.lang.Object | |
| ↳ | android.icu.text.Transliterator |
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(). As a result, threads may share transliterators without synchronizing them. 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);
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 rule-based Transliterator:
th>{theta}
t>{tau}
t>|{tau}
{tau}h>{theta}
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. These indices are changed by the method, and
they are passed in and out via a Position object. 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.
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 identity 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"where 'x' represents transliteration. However,
"B" x BA -> "A"
"ABCD" x AB -> "BBCD"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"
.getInverse() could legitimately return
BA.
Filtering
Each transliterator has a filter, which restricts changes to those characters selected by the filter. The filter affects just the characters that are changed -- the characters outside of the filter are still part of the context for the filter. For example, in the following even though 'x' is filtered out, and doesn't convert to y, it does affect the conversion of 'a'.
String rules = "x > y; x{a} > b; ";
Transliterator tempTrans = Transliterator.createFromRules("temp", rules, Transliterator.FORWARD);
tempTrans.setFilter(new UnicodeSet("[a]"));
String tempResult = tempTrans.transform("xa");
// results in "xb"
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(String).
Composed transliterators
In addition to built-in system transliterators like "Latin-Greek", there are also built-in composed transliterators. These are implemented by composing two or more component transliterators. For example, if we have scripts "A", "B", "C", and "D", and we want to transliterate between all pairs of them, then we need to write 12 transliterators: "A-B", "A-C", "A-D", "B-A",..., "D-A", "D-B", "D-C". If it is possible to convert all scripts to an intermediate script "M", then instead of writing 12 rule sets, we only need to write 8: "A~M", "B~M", "C~M", "D~M", "M~A", "M~B", "M~C", "M~D". (This might not seem like a big win, but it's really 2n vs. n 2 - n, so as n gets larger the gain becomes significant. With 9 scripts, it's 18 vs. 72 rule sets, a big difference.) Note the use of "~" rather than "-" for the script separator here; this indicates that the given transliterator is intended to be composed with others, rather than be used as is.
Composed transliterators can be instantiated as usual. For example, the system transliterator "Devanagari-Gujarati" is a composed transliterator built internally as "Devanagari~InterIndic;InterIndic~Gujarati". When this transliterator is instantiated, it appears externally to be a standard transliterator (e.g., getID() returns "Devanagari-Gujarati").
Rule syntax
A set of rules determines how to perform translations. Rules within a rule set are separated by semicolons (';'). To include a literal semicolon, prefix it with a backslash ('\'). Unicode Pattern_White_Space is ignored. If the first non-blank character on a line is '#', the entire line is ignored as a comment.
Each set of rules consists of two groups, one forward, and one reverse. This is a convention that is not enforced; rules for one direction may be omitted, with the result that translations in that direction will not modify the source text. In addition, bidirectional forward-reverse rules may be specified for symmetrical transformations.
Note: Another description of the Transliterator rule syntax is available in section Transform Rules Syntax of UTS #35: Unicode LDML. The rules are shown there using arrow symbols \u2190 and \u2192 and \u2194. ICU supports both those and the equivalent ASCII symbols < and > and <>.
Rule statements take one of the following forms:
$alefmadda=\\u0622;- Variable definition. The name on the
left is assigned the text on the right. In this example,
after this statement, instances of the left hand name,
"
$alefmadda", will be replaced by the Unicode character U+0622. Variable names must begin with a letter and consist only of letters, digits, and underscores. Case is significant. Duplicate names cause an exception to be thrown, that is, variables cannot be redefined. The right hand side may contain well-formed text of any length, including no text at all ("$empty=;"). The right hand side may contain embeddedUnicodeSetpatterns, for example, "$softvowel=[eiyEIY]". ai>$alefmadda;- Forward translation rule. This rule states that the string on the left will be changed to the string on the right when performing forward transliteration.
ai<$alefmadda;- Reverse translation rule. This rule states that the string on the right will be changed to the string on the left when performing reverse transliteration.
ai<>$alefmadda;- Bidirectional translation rule. This rule states that the string on the right will be changed to the string on the left when performing forward transliteration, and vice versa when performing reverse transliteration.
Translation rules consist of a match pattern and an output
string. The match pattern consists of literal characters,
optionally preceded by context, and optionally followed by
context. Context characters, like literal pattern characters,
must be matched in the text being transliterated. However, unlike
literal pattern characters, they are not replaced by the output
text. For example, the pattern "abc{def}"
indicates the characters "def" must be
preceded by "abc" for a successful match.
If there is a successful match, "def" will
be replaced, but not "abc". The final '}'
is optional, so "abc{def" is equivalent to
"abc{def}". Another example is "{123}456"
(or "123}456") in which the literal
pattern "123" must be followed by "456".
The output string of a forward or reverse rule consists of
characters to replace the literal pattern characters. If the
output string contains the character '|', this is
taken to indicate the location of the cursor after
replacement. The cursor is the point in the text at which the
next replacement, if any, will be applied. The cursor is usually
placed within the replacement text; however, it can actually be
placed into the precending or following context by using the
special character '@'. Examples:
a {foo} z > | @ bar; # foo -> bar, move cursor before a
{foo} xyz > bar @@|; # foo -> bar, cursor between y and z
UnicodeSet
UnicodeSet patterns may appear anywhere that
makes sense. They may appear in variable definitions.
Contrariwise, UnicodeSet patterns may themselves
contain variable references, such as "$a=[a-z];$not_a=[^$a]",
or "$range=a-z;$ll=[$range]".
UnicodeSet patterns may also be embedded directly
into rule strings. Thus, the following two rules are equivalent:
$vowel=[aeiou]; $vowel>'*'; # One way to do this
[aeiou]>'*'; # Another way
See UnicodeSet for more documentation and examples.
Segments
Segments of the input string can be matched and copied to the output string. This makes certain sets of rules simpler and more general, and makes reordering possible. For example:
([a-z]) > $1 $1; # double lowercase letters
([:Lu:]) ([:Ll:]) > $2 $1; # reverse order of Lu-Ll pairs
The segment of the input string to be copied is delimited by
"(" and ")". Up to
nine segments may be defined. Segments may not overlap. In the
output string, "$1" through "$9"
represent the input string segments, in left-to-right order of
definition.
Anchors
Patterns can be anchored to the beginning or the end of the text. This is done with the
special characters '^' and '$'. For example:
^ a > 'BEG_A'; # match 'a' at start of text a > 'A'; # match other instances of 'a' z $ > 'END_Z'; # match 'z' at end of text z > 'Z'; # match other instances of 'z'
It is also possible to match the beginning or the end of the text using a UnicodeSet.
This is done by including a virtual anchor character '$' at the end of the
set pattern. Although this is usually the match character for the end anchor, the set will
match either the beginning or the end of the text, depending on its placement. For
example:
$x = [a-z$]; # match 'a' through 'z' OR anchor $x 1 > 2; # match '1' after a-z or at the start 3 $x > 4; # match '3' before a-z or at the end
Example
The following example rules illustrate many of the features of the rule language.
| Rule 1. | abc{def}>x|y |
| Rule 2. | xyz>r |
| Rule 3. | yz>q |
Applying these rules to the string "adefabcdefz"
yields the following results:
|adefabcdefz |
Initial state, no rules match. Advance cursor. |
a|defabcdefz |
Still no match. Rule 1 does not match because the preceding context is not present. |
ad|efabcdefz |
Still no match. Keep advancing until there is a match... |
ade|fabcdefz |
... |
adef|abcdefz |
... |
adefa|bcdefz |
... |
adefab|cdefz |
... |
adefabc|defz |
Rule 1 matches; replace "def"
with "xy" and back up the cursor
to before the 'y'. |
adefabcx|yz |
Although "xyz" is
present, rule 2 does not match because the cursor is
before the 'y', not before the 'x'.
Rule 3 does match. Replace "yz"
with "q". |
adefabcxq| |
The cursor is at the end; transliteration is complete. |
The order of rules is significant. If multiple rules may match at some point, the first matching rule is applied.
Forward and reverse rules may have an empty output string. Otherwise, an empty left or right hand side of any statement is a syntax error.
Single quotes are used to quote any character other than a
digit or letter. To specify a single quote itself, inside or
outside of quotes, use two single quotes in a row. For example,
the rule "'>'>o''clock" changes the
string ">" to the string "o'clock".
Notes
While a Transliterator is being built from rules, it checks that the rules are added in proper order. For example, if the rule "a>x" is followed by the rule "ab>y", then the second rule will throw an exception. The reason is that the second rule can never be triggered, since the first rule always matches anything it matches. In other words, the first rule masks the second rule.
Summary
Nested classes | |
|---|---|
class |
Transliterator.Position
Position structure for incremental transliteration. |
Constants | |
|---|---|
int |
FORWARD
Direction constant indicating the forward direction in a transliterator, e.g., the forward rules of a rule-based Transliterator. |
int |
REVERSE
Direction constant indicating the reverse direction in a transliterator, e.g., the reverse rules of a rule-based Transliterator. |
Public methods | |
|---|---|
static
final
Transliterator
|
createFromRules(String ID, String rules, int dir)
Returns a |
void
|
filteredTransliterate(Replaceable text, Transliterator.Position index, boolean incremental)
Transliterate a substring of text, as specified by index, taking filters into account. |
final
void
|
finishTransliteration(Replaceable text, Transliterator.Position index)
Finishes any pending transliterations that were waiting for more characters. |
static
final
Enumeration<String>
|
getAvailableIDs()
Returns an enumeration over the programmatic names of registered
|
static
final
Enumeration<String>
|
getAvailableSources()
Returns an enumeration over the source names of registered transliterators. |
static
final
Enumeration<String>
|
getAvailableTargets(String source)
Returns an enumeration over the target names of registered transliterators having a given source name. |
static
final
Enumeration<String>
|
getAvailableVariants(String source, String target)
Returns an enumeration over the variant names of registered transliterators having a given source name and target name. |
static
String
|
getDisplayName(String id, Locale inLocale)
Returns a name for this transliterator that is appropriate for display to the user in the given locale. |
static
final
String
|
getDisplayName(String ID)
Returns a name for this transliterator that is appropriate for
display to the user in the default |
static
String
|
getDisplayName(String id, ULocale inLocale)
Returns a name for this transliterator that is appropriate for display to the user in the given locale. |
Transliterator[]
|
getElements()
Return the elements that make up this transliterator. |
final
UnicodeFilter
|
getFilter()
Returns the filter used by this transliterator, or null if this transliterator uses no filter. |
final
String
|
getID()
Returns a programmatic identifier for this transliterator. |
static
Transliterator
|
getInstance(String ID, int dir)
Returns a |
static
final
Transliterator
|
getInstance(String ID)
Returns a |
final
Transliterator
|
getInverse()
Returns this transliterator's inverse. |
final
int
|
getMaximumContextLength()
Returns the length of the longest context required by this transliterator. |
final
UnicodeSet
|
getSourceSet()
Returns the set of all characters that may be modified in the input text by this Transliterator. |
UnicodeSet
|
getTargetSet()
Returns the set of all characters that may be generated as replacement text by this transliterator. |
void
|
setFilter(UnicodeFilter filter)
Changes the filter used by this transliterator. |
String
|
toRules(boolean escapeUnprintable)
Returns a rule string for this transliterator. |
final
int
|
transliterate(Replaceable text, int start, int limit)
Transliterates a segment of a string, with optional filtering. |
final
void
|
transliterate(Replaceable text)
Transliterates an entire string in place. |
final
void
|
transliterate(Replaceable text, Transliterator.Position index)
Transliterates the portion of the text buffer that can be transliterated unambiguosly. |
final
String
|
transliterate(String text)
Transliterate an entire string and returns the result. |
final
void
|
transliterate(Replaceable text, Transliterator.Position index, String insertion)
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. |
final
void
|
transliterate(Replaceable text, Transliterator.Position index, int insertion)
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. |
Inherited methods | |
|---|---|
Constants
FORWARD
public static final int FORWARD
Direction constant indicating the forward direction in a transliterator, e.g., the forward rules of a rule-based Transliterator. An "A-B" transliterator transliterates A to B when operating in the forward direction, and B to A when operating in the reverse direction.
Constant Value: 0 (0x00000000)
REVERSE
public static final int REVERSE
Direction constant indicating the reverse direction in a transliterator, e.g., the reverse rules of a rule-based Transliterator. An "A-B" transliterator transliterates A to B when operating in the forward direction, and B to A when operating in the reverse direction.
Constant Value: 1 (0x00000001)
Public methods
createFromRules
public static final Transliterator createFromRules (String ID, String rules, int dir)
Returns a Transliterator object constructed from
the given rule string. This will be a rule-based Transliterator,
if the rule string contains only rules, or a
compound Transliterator, if it contains ID blocks, or a
null Transliterator, if it contains ID blocks which parse as
empty for the given direction.
| Parameters | |
|---|---|
ID |
String: the id for the transliterator. |
rules |
String: rules, separated by ';' |
dir |
int: either FORWARD or REVERSE. |
| Returns | |
|---|---|
Transliterator |
a newly created Transliterator |
| Throws | |
|---|---|
IllegalArgumentException |
if there is a problem with the ID or the rules |
filteredTransliterate
public void filteredTransliterate (Replaceable text, Transliterator.Position index, boolean incremental)
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.
| Parameters | |
|---|---|
text |
Replaceable: the text to be transliterated |
index |
Transliterator.Position: the position indices |
incremental |
boolean: if true, then assume more characters may be inserted
at index.limit, and postpone processing to accommodate future incoming
characters |
finishTransliteration
public final void finishTransliteration (Replaceable text, Transliterator.Position index)
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 | |
|---|---|
text |
Replaceable: the buffer holding transliterated and
untransliterated text. |
index |
Transliterator.Position: the array of indices previously passed to transliterate(Replaceable) |
getAvailableIDs
public static final Enumeration<String> getAvailableIDs ()
Returns an enumeration over the programmatic names of registered
Transliterator objects. This includes both system
transliterators and user transliterators registered using
registerClass(). The enumerated names may be
passed to getInstance().
| Returns | |
|---|---|
Enumeration<String> |
An Enumeration over String objects |
See also:
getAvailableSources
public static final Enumeration<String> getAvailableSources ()
Returns an enumeration over the source names of registered transliterators. Source names may be passed to getAvailableTargets() to obtain available targets for each source.
| Returns | |
|---|---|
Enumeration<String> |
|
getAvailableTargets
public static final Enumeration<String> getAvailableTargets (String source)
Returns an enumeration over the target names of registered transliterators having a given source name. Target names may be passed to getAvailableVariants() to obtain available variants for each source and target pair.
| Parameters | |
|---|---|
source |
String |
| Returns | |
|---|---|
Enumeration<String> |
|
getAvailableVariants
public static final Enumeration<String> getAvailableVariants (String source, String target)
Returns an enumeration over the variant names of registered transliterators having a given source name and target name.
| Parameters | |
|---|---|
source |
String |
target |
String |
| Returns | |
|---|---|
Enumeration<String> |
|
getDisplayName
public static String getDisplayName (String id, Locale inLocale)
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 | |
|---|---|
id |
String |
inLocale |
Locale: the Locale in which the display name should be
localized. |
| Returns | |
|---|---|
String |
|
See also:
getDisplayName
public static final String getDisplayName (String ID)
Returns a name for this transliterator that is appropriate for
display to the user in the default DISPLAY locale. See getDisplayName(java.lang.String, java.util.Locale) for details.
| Parameters | |
|---|---|
ID |
String |
| Returns | |
|---|---|
String |
|
See also:
getDisplayName
public static String getDisplayName (String id, ULocale inLocale)
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 | |
|---|---|
id |
String |
inLocale |
ULocale: the ULocale in which the display name should be
localized. |
| Returns | |
|---|---|
String |
|
See also:
getElements
public Transliterator[] getElements ()
Return the 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 an array 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 an array of length one containing a reference to this transliterator.
| Returns | |
|---|---|
Transliterator[] |
an array of one or more transliterators that make up this transliterator |
getFilter
public final UnicodeFilter getFilter ()
Returns the filter used by this transliterator, or null if this transliterator uses no filter.
| Returns | |
|---|---|
UnicodeFilter |
|
getID
public final String getID ()
Returns a programmatic identifier for this transliterator.
If this identifier is passed to getInstance(), it
will return this object, if it has been registered.
| Returns | |
|---|---|
String |
|
See also:
getInstance
public static Transliterator getInstance (String ID, int dir)
Returns a Transliterator object given its ID.
The ID must be a system transliterator ID.
| Parameters | |
|---|---|
ID |
String: a valid ID, as enumerated by getAvailableIDs() |
dir |
int: either FORWARD or REVERSE. If REVERSE then the
inverse of the given ID is instantiated. |
| Returns | |
|---|---|
Transliterator |
A Transliterator object with the given ID |
| Throws | |
|---|---|
IllegalArgumentException |
if the given ID is invalid. |
See also:
getInstance
public static final Transliterator getInstance (String ID)
Returns a Transliterator object given its ID.
The ID must be a system transliterator ID.
| Parameters | |
|---|---|
ID |
String: a valid ID, as enumerated by getAvailableIDs() |
| Returns | |
|---|---|
Transliterator |
A Transliterator object with the given ID |
| Throws | |
|---|---|
IllegalArgumentException |
if the given ID is invalid. |
getInverse
public final Transliterator getInverse ()
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
getInstance("B-A"), or null if that
call fails.
Subclasses with knowledge of their inverse may wish to override this method.
| Returns | |
|---|---|
Transliterator |
a transliterator that is an inverse, not necessarily
exact, of this transliterator, or null if no such
transliterator is registered. |
getMaximumContextLength
public final int getMaximumContextLength ()
Returns the length of the longest context required by this transliterator.
This is preceding context. The default value is zero, but
subclasses can change this by calling setMaximumContextLength().
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 | |
|---|---|
int |
The maximum number of preceding context characters this transliterator needs to examine |
getSourceSet
public final UnicodeSet getSourceSet ()
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. The return result is approximate in any case and is intended for use by tests, tools, or utilities.
| Returns | |
|---|---|
UnicodeSet |
|
See also:
getTargetSet
public UnicodeSet getTargetSet ()
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.
Warning. You might expect an empty filter to always produce an empty target. However, consider the following:
[Pp]{}[\u03a3\u03c2\u03c3\u03f7\u03f8\u03fa\u03fb] > \';
With a filter of [], you still get some elements in the target set, because this rule will still match. It could
be recast to the following if it were important.
[Pp]{([\u03a3\u03c2\u03c3\u03f7\u03f8\u03fa\u03fb])} > \' | $1;
| Returns | |
|---|---|
UnicodeSet |
|
See also:
setFilter
public void setFilter (UnicodeFilter filter)
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 | |
|---|---|
filter |
UnicodeFilter |
toRules
public String toRules (boolean escapeUnprintable)
Returns a rule string for this transliterator.
| Parameters | |
|---|---|
escapeUnprintable |
boolean: if true, then unprintable characters
will be converted to escape form backslash-'u' or
backslash-'U'. |
| Returns | |
|---|---|
String |
|
transliterate
public final int transliterate (Replaceable text, int start, int limit)
Transliterates a segment of a string, with optional filtering.
| Parameters | |
|---|---|
text |
Replaceable: the string to be transliterated |
start |
int: the beginning index, inclusive; 0 <= start
<= limit. |
limit |
int: the ending index, exclusive; start <= limit
<= text.length(). |
| Returns | |
|---|---|
int |
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. |
transliterate
public final void transliterate (Replaceable text)
Transliterates an entire string in place. Convenience method.
| Parameters | |
|---|---|
text |
Replaceable: the string to be transliterated |
transliterate
public final void transliterate (Replaceable text, Transliterator.Position index)
Transliterates the portion of the text buffer that can be
transliterated unambiguosly. This is a convenience method; see
transliterate(android.icu.text.Replaceable, android.icu.text.Transliterator.Position, java.lang.String) for details.
| Parameters | |
|---|---|
text |
Replaceable: the buffer holding transliterated and
untransliterated text |
index |
Transliterator.Position: the start and limit of the text, the position
of the cursor, and the start and limit of transliteration. |
transliterate
public final String transliterate (String text)
Transliterate an entire string and returns the result. Convenience method.
| Parameters | |
|---|---|
text |
String: the string to be transliterated |
| Returns | |
|---|---|
String |
The transliterated text |
transliterate
public final void transliterate (Replaceable text, Transliterator.Position index, String insertion)
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.contextLimit, advancing
index.contextLimit by insertion.length().
Then the transliterator will try to transliterate characters of
text between index.start and
index.contextLimit. Characters before
index.start will not be changed.
Upon return, values in index will be updated.
index.contextStart will be advanced to the first
character that future calls to this method will read.
index.start and index.contextLimit 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.contextStart and index.contextLimit
set to indicate the portion of text to be
transliterated, and index.start == index.contextStart.
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(Replaceable, Position) after the last call to this
method has been made.
| Parameters | |
|---|---|
text |
Replaceable: the buffer holding transliterated and untransliterated text |
index |
Transliterator.Position: the start and limit of the text, the position
of the cursor, and the start and limit of transliteration. |
insertion |
String: text to be inserted and possibly
transliterated into the translation buffer at
index.contextLimit. If null then no text
is inserted. |
| Throws | |
|---|---|
IllegalArgumentException |
if index
is invalid |
transliterate
public final void transliterate (Replaceable text, Transliterator.Position index, int insertion)
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; see transliterate(android.icu.text.Replaceable, android.icu.text.Transliterator.Position, java.lang.String) for details.
| Parameters | |
|---|---|
text |
Replaceable: the buffer holding transliterated and
untransliterated text |
index |
Transliterator.Position: the start and limit of the text, the position
of the cursor, and the start and limit of transliteration. |
insertion |
int: text to be inserted and possibly
transliterated into the translation buffer at
index.contextLimit. |
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Last updated 2024-04-04 UTC.