| 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
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
Normalizer instead.
When constructing a ComposedCharIter there is one
optional feature that you can enable or disable:
-
Normalizer.IGNORE_HANGUL - Do not iterate over the Hangul
characters and their corresponding Jamo decompositions.
This option is off by default (i.e. Hangul processing is enabled)
since the Unicode standard specifies that Hangul to Jamo
is a canonical decomposition.
ComposedCharIter is currently based on version 2.1.8 of the
Unicode Standard.
It will be updated as later versions of Unicode are released.
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