Package com.ibm.icu.text

Class RuleBasedBreakIterator

java.lang.Object

com.ibm.icu.text.BreakIterator

com.ibm.icu.text.RuleBasedBreakIterator

All Implemented Interfaces:

Cloneable

public class RuleBasedBreakIterator
extends BreakIterator

Rule Based Break Iterator This is a port of the C++ class RuleBasedBreakIterator from ICU4C.

Field Summary

Fields inherited from class com.ibm.icu.text.BreakIterator

DONE, KIND_CHARACTER, KIND_LINE, KIND_SENTENCE, KIND_TITLE, KIND_WORD, WORD_IDEO, WORD_IDEO_LIMIT, WORD_KANA, WORD_KANA_LIMIT, WORD_LETTER, WORD_LETTER_LIMIT, WORD_NONE, WORD_NONE_LIMIT, WORD_NUMBER, WORD_NUMBER_LIMIT

Constructor Summary

Constructors

Constructor	Description
RuleBasedBreakIterator(String rules)	Construct a RuleBasedBreakIterator from a set of rules supplied as a string.

Method Summary

Modifier and Type	Method	Description
protected static void	checkOffset(int offset, CharacterIterator text)	Throw IllegalArgumentException unless begin <= offset < end.
Object	clone()	Clones this iterator.
static void	compileRules(String rules, OutputStream ruleBinary)	Compile a set of source break rules into the binary state tables used by the break iterator engine.
int	current()	Returns the current iteration position.
void	dump()	Deprecated. This API is ICU internal only.
boolean	equals(Object that)	Returns true if both BreakIterators are of the same class, have the same rules, and iterate over the same text.
int	first()	Sets the current iteration position to the beginning of the text.
int	following(int offset)	Sets the iterator to refer to the first boundary position following the specified position.
static RuleBasedBreakIterator	getInstanceFromCompiledRules(InputStream is)	Create a break iterator from a precompiled set of break rules.
static RuleBasedBreakIterator	getInstanceFromCompiledRules(ByteBuffer bytes)	Deprecated. This API is ICU internal only.
int	getRuleStatus()	Return the status tag from the break rule that determined the most recently returned break position.
int	getRuleStatusVec(int[] fillInArray)	Get the status (tag) values from the break rule(s) that determined the most recently returned break position.
CharacterIterator	getText()	Return a CharacterIterator over the text being analyzed.
int	hashCode()	Compute a hashcode for this BreakIterator
boolean	isBoundary(int offset)	Returns true if the specified position is a boundary position.
int	last()	Sets the current iteration position to the end of the text.
int	next()	Advances the iterator to the next boundary position.
int	next(int n)	Advances the iterator either forward or backward the specified number of steps.
int	preceding(int offset)	Sets the iterator to refer to the last boundary position before the specified position.
int	previous()	Moves the iterator backwards, to the last boundary preceding this one.
void	setText(CharacterIterator newText)	Set the iterator to analyze a new piece of text.
String	toString()	Returns the description (rules) used to create this iterator.

Methods inherited from class com.ibm.icu.text.BreakIterator

getAvailableLocales, getAvailableULocales, getBreakInstance, getCharacterInstance, getCharacterInstance, getCharacterInstance, getLineInstance, getLineInstance, getLineInstance, getLocale, getSentenceInstance, getSentenceInstance, getSentenceInstance, getTitleInstance, getTitleInstance, getTitleInstance, getWordInstance, getWordInstance, getWordInstance, registerInstance, registerInstance, setText, unregister

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

RuleBasedBreakIterator

public RuleBasedBreakIterator(String rules)

Construct a RuleBasedBreakIterator from a set of rules supplied as a string.

Parameters:

rules - The break rules to be used.

Method Detail

getInstanceFromCompiledRules

public static RuleBasedBreakIterator getInstanceFromCompiledRules(InputStream is)
                                                           throws IOException

Create a break iterator from a precompiled set of break rules. Creating a break iterator from the binary rules is much faster than creating one from source rules. The binary rules are generated by the RuleBasedBreakIterator.compileRules() function. Binary break iterator rules are not guaranteed to be compatible between different versions of ICU.

Parameters:

is - an input stream supplying the compiled binary rules.

Throws:

IOException - if there is an error while reading the rules from the InputStream.

See Also:

compileRules(String, OutputStream)

getInstanceFromCompiledRules

@Deprecated
public static RuleBasedBreakIterator getInstanceFromCompiledRules(ByteBuffer bytes)
                                                           throws IOException

Deprecated.

This API is ICU internal only.

Create a break iterator from a precompiled set of break rules. Creating a break iterator from the binary rules is much faster than creating one from source rules. The binary rules are generated by the RuleBasedBreakIterator.compileRules() function. Binary break iterator rules are not guaranteed to be compatible between different versions of ICU.

Parameters:

bytes - a buffer supplying the compiled binary rules.

Throws:

IOException - if there is an error while reading the rules from the buffer.

See Also:

compileRules(String, OutputStream)

clone

public Object clone()

Clones this iterator.

Overrides:

clone in class BreakIterator

Returns:

A newly-constructed RuleBasedBreakIterator with the same behavior as this one.

equals

public boolean equals(Object that)

Returns true if both BreakIterators are of the same class, have the same rules, and iterate over the same text.

Overrides:

equals in class Object

Parameters:

that - the object to compare this instance with.

Returns:

true if the specified object is equal to this Object; false otherwise.

See Also:

Object.hashCode()

toString

public String toString()

Returns the description (rules) used to create this iterator. (In ICU4C, the same function is RuleBasedBreakIterator::getRules())

Overrides:

toString in class Object

Returns:

a printable representation of this object.

hashCode

public int hashCode()

Compute a hashcode for this BreakIterator

Overrides:

hashCode in class Object

Returns:

A hash code

See Also:

Object.equals(java.lang.Object)

dump

@Deprecated
public void dump()

Deprecated.

This API is ICU internal only.

Dump the contents of the state table and character classes for this break iterator. For debugging only.

compileRules

public static void compileRules(String rules,
                                OutputStream ruleBinary)
                         throws IOException

Compile a set of source break rules into the binary state tables used by the break iterator engine. Creating a break iterator from precompiled rules is much faster than creating one from source rules. Binary break rules are not guaranteed to be compatible between different versions of ICU.

Parameters:

rules - The source form of the break rules

ruleBinary - An output stream to receive the compiled rules.

Throws:

IOException - If there is an error writing the output.

See Also:

getInstanceFromCompiledRules(InputStream)

first

public int first()

Sets the current iteration position to the beginning of the text. (i.e., the CharacterIterator's starting offset).

Specified by:

first in class BreakIterator

Returns:

The offset of the beginning of the text.

last

public int last()

Sets the current iteration position to the end of the text. (i.e., the CharacterIterator's ending offset).

Specified by:

last in class BreakIterator

Returns:

The text's past-the-end offset.

next

public int next(int n)

Advances the iterator either forward or backward the specified number of steps. Negative values move backward, and positive values move forward. This is equivalent to repeatedly calling next() or previous().

Specified by:

next in class BreakIterator

Parameters:

n - The number of steps to move. The sign indicates the direction (negative is backwards, and positive is forwards).

Returns:

The character offset of the boundary position n boundaries away from the current one.

next

public int next()

Advances the iterator to the next boundary position.

Specified by:

next in class BreakIterator

Returns:

The position of the first boundary after this one.

previous

public int previous()

Moves the iterator backwards, to the last boundary preceding this one.

Specified by:

previous in class BreakIterator

Returns:

The position of the last boundary position preceding this one.

following

public int following(int offset)

Sets the iterator to refer to the first boundary position following the specified position.

Specified by:

following in class BreakIterator

Parameters:

offset - The position from which to begin searching for a break position.

Returns:

The position of the first break after the current position.

preceding

public int preceding(int offset)

Sets the iterator to refer to the last boundary position before the specified position.

Overrides:

preceding in class BreakIterator

Parameters:

offset - The position to begin searching for a break from.

Returns:

The position of the last boundary before the starting position.

checkOffset

protected static final void checkOffset(int offset,
                                        CharacterIterator text)

Throw IllegalArgumentException unless begin <= offset < end.

isBoundary

public boolean isBoundary(int offset)

Returns true if the specified position is a boundary position. As a side effect, leaves the iterator pointing to the first boundary position at or after "offset".

Overrides:

isBoundary in class BreakIterator

Parameters:

offset - the offset to check.

Returns:

True if "offset" is a boundary position.

current

public int current()

Returns the current iteration position.

Specified by:

current in class BreakIterator

Returns:

The current iteration position.

getRuleStatus

public int getRuleStatus()

Return the status tag from the break rule that determined the most recently returned break position. The values appear in the rule source within brackets, {123}, for example. For rules that do not specify a status, a default value of 0 is returned. If more than one rule applies, the numerically largest of the possible status values is returned.

Of the standard types of ICU break iterators, only the word break iterator provides status values. The values are defined in class RuleBasedBreakIterator, and allow distinguishing between words that contain alphabetic letters, "words" that appear to be numbers, punctuation and spaces, words containing ideographic characters, and more. Call getRuleStatus after obtaining a boundary position from next(), previous(), or any other break iterator functions that returns a boundary position.

Overrides:

getRuleStatus in class BreakIterator

Returns:

the status from the break rule that determined the most recently returned break position.

getRuleStatusVec

public int getRuleStatusVec(int[] fillInArray)

Get the status (tag) values from the break rule(s) that determined the most recently returned break position. The values appear in the rule source within brackets, {123}, for example. The default status value for rules that do not explicitly provide one is zero.

The status values used by the standard ICU break rules are defined as public constants in class RuleBasedBreakIterator.

If the size of the output array is insufficient to hold the data, the output will be truncated to the available length. No exception will be thrown.

Overrides:

getRuleStatusVec in class BreakIterator

Parameters:

fillInArray - an array to be filled in with the status values.

Returns:

The number of rule status values from rules that determined the most recent boundary returned by the break iterator. In the event that the array is too small, the return value is the total number of status values that were available, not the reduced number that were actually returned.

getText

public CharacterIterator getText()

Return a CharacterIterator over the text being analyzed. This version of this method returns the actual CharacterIterator we're using internally. Changing the state of this iterator can have undefined consequences. If you need to change it, clone it first.

Specified by:

getText in class BreakIterator

Returns:

An iterator over the text being analyzed.

setText

public void setText(CharacterIterator newText)

Set the iterator to analyze a new piece of text. This function resets the current iteration position to the beginning of the text.

Specified by:

setText in class BreakIterator

Parameters:

newText - An iterator over the text to analyze.