com.ibm.icu.text

Class ComposedCharIter

public final class ComposedCharIter extends Object

Deprecated: ICU 2.2

ComposedCharIter is an iterator class that returns all of the precomposed characters defined in the Unicode standard, along with their decomposed forms. This is often useful when building data tables (e.g. collation tables) which need to treat composed and decomposed characters equivalently.

For example, imagine that you have built a collation table with ordering rules for the {@link Normalizer#DECOMP canonically decomposed} forms of all characters used in a particular language. When you process input text using this table, the text must first be decomposed so that it matches the form used in the table. This can impose a performance penalty that may be unacceptable in some situations.

You can avoid this problem by ensuring that the collation table contains rules for both the decomposed and composed versions of each character. To do so, use a ComposedCharIter to iterate through all of the composed characters in Unicode. If the decomposition for that character consists solely of characters that are listed in your ruleset, you can add a new rule for the composed character that makes it equivalent to its decomposition sequence.

Note that ComposedCharIter iterates over a static table of the composed characters in Unicode. If you want to iterate over the composed characters in a particular string, use {@link Normalizer} instead.

When constructing a ComposedCharIter there is one optional feature that you can enable or disable:

ComposedCharIter is currently based on version 2.1.8 of the Unicode Standard. It will be updated as later versions of Unicode are released.

Field Summary
static charDONE
Constant that indicates the iteration has completed.
Constructor Summary
ComposedCharIter()
Construct a new ComposedCharIter.
ComposedCharIter(boolean compat, int options)
Constructs a non-default ComposedCharIter with optional behavior.
Method Summary
Stringdecomposition()
Returns the Unicode decomposition of the current character.
booleanhasNext()
Determines whether there any precomposed Unicode characters not yet returned by {@link #next}.
charnext()
Returns the next precomposed Unicode character.

Field Detail

DONE

public static final char DONE

Deprecated: ICU 2.2

Constant that indicates the iteration has completed. {@link #next} returns this value when there are no more composed characters over which to iterate.

Constructor Detail

ComposedCharIter

public ComposedCharIter()

Deprecated: ICU 2.2

Construct a new ComposedCharIter. The iterator will return all Unicode characters with canonical decompositions, including Korean Hangul characters.

ComposedCharIter

public ComposedCharIter(boolean compat, int options)

Deprecated: ICU 2.2

Constructs a non-default ComposedCharIter with optional behavior.

Parameters: compat false for canonical decompositions only; true for both canonical and compatibility decompositions. options Optional decomposition features. Currently, the only supported option is {@link Normalizer#IGNORE_HANGUL}, which causes this ComposedCharIter not to iterate over the Hangul characters and their corresponding Jamo decompositions.

Method Detail

decomposition

public String decomposition()

Deprecated: ICU 2.2

Returns the Unicode decomposition of the current character. This method returns the decomposition of the precomposed character most recently returned by {@link #next}. The resulting decomposition is affected by the settings of the options passed to the constructor.

hasNext

public boolean hasNext()

Deprecated: ICU 2.2

Determines whether there any precomposed Unicode characters not yet returned by {@link #next}.

next

public char next()

Deprecated: ICU 2.2

Returns the next precomposed Unicode character. Repeated calls to next return all of the precomposed characters defined by Unicode, in ascending order. After all precomposed characters have been returned, {@link #hasNext} will return false and further calls to next will return {@link #DONE}.
Copyright (c) 2006 IBM Corporation and others.