Unicode::Normalize(3pm) Perl Programmers Reference Guide Unicode::Normalize(3pm)
NAME
Unicode::Normalize - Unicode Normalization Forms
SYNOPSIS
(1) using function names exported by default:
use Unicode::Normalize;
$NFD_string = NFD($string); # Normalization Form D
$NFC_string = NFC($string); # Normalization Form C
$NFKD_string = NFKD($string); # Normalization Form KD
$NFKC_string = NFKC($string); # Normalization Form KC
(2) using function names exported on request:
use Unicode::Normalize 'normalize';
$NFD_string = normalize('D', $string); # Normalization Form D
$NFC_string = normalize('C', $string); # Normalization Form C
$NFKD_string = normalize('KD', $string); # Normalization Form KD
$NFKC_string = normalize('KC', $string); # Normalization Form KC
DESCRIPTION
Parameters:
$string is used as a string under character semantics (see perlunicode).
$codepoint should be an unsigned integer representing a Unicode code point.
Note: Between XSUB and pure Perl, there is an incompatibility about the interpretation of $codepoint
as a decimal number. XSUB converts $codepoint to an unsigned integer, but pure Perl does not. Do
not use a floating point nor a negative sign in $codepoint.
Normalization Forms
"$NFD_string = NFD($string)"
returns the Normalization Form D (formed by canonical decomposition).
"$NFC_string = NFC($string)"
returns the Normalization Form C (formed by canonical decomposition followed by canonical compo-sition). composition).
sition).
"$NFKD_string = NFKD($string)"
returns the Normalization Form KD (formed by compatibility decomposition).
"$NFKC_string = NFKC($string)"
returns the Normalization Form KC (formed by compatibility decomposition followed by canonical
composition).
"$FCD_string = FCD($string)"
If the given string is in FCD ("Fast C or D" form; cf. UTN #5), returns it without modification;
otherwise returns an FCD string.
Note: FCD is not always unique, then plural forms may be equivalent each other. "FCD()" will
return one of these equivalent forms.
"$FCC_string = FCC($string)"
returns the FCC form ("Fast C Contiguous"; cf. UTN #5).
Note: FCC is unique, as well as four normalization forms (NF*).
"$normalized_string = normalize($form_name, $string)"
As $form_name, one of the following names must be given.
'C' or 'NFC' for Normalization Form C (UAX #15)
'D' or 'NFD' for Normalization Form D (UAX #15)
'KC' or 'NFKC' for Normalization Form KC (UAX #15)
'KD' or 'NFKD' for Normalization Form KD (UAX #15)
'FCD' for "Fast C or D" Form (UTN #5)
'FCC' for "Fast C Contiguous" (UTN #5)
Decomposition and Composition
"$decomposed_string = decompose($string)"
"$decomposed_string = decompose($string, $useCompatMapping)"
Decomposes the specified string and returns the result.
If the second parameter (a boolean) is omitted or false, decomposes it using the Canonical Decom-position Decomposition
position Mapping. If true, decomposes it using the Compatibility Decomposition Mapping.
The string returned is not always in NFD/NFKD. Reordering may be required.
$NFD_string = reorder(decompose($string)); # eq. to NFD()
$NFKD_string = reorder(decompose($string, TRUE)); # eq. to NFKD()
"$reordered_string = reorder($string)"
Reorders the combining characters and the like in the canonical ordering and returns the result.
E.g., when you have a list of NFD/NFKD strings, you can get the concatenated NFD/NFKD string from
them, saying
$concat_NFD = reorder(join '', @NFD_strings);
$concat_NFKD = reorder(join '', @NFKD_strings);
"$composed_string = compose($string)"
Returns the string where composable pairs are composed.
E.g., when you have a NFD/NFKD string, you can get its NFC/NFKC string, saying
$NFC_string = compose($NFD_string);
$NFKC_string = compose($NFKD_string);
Quick Check
(see Annex 8, UAX #15; and DerivedNormalizationProps.txt)
The following functions check whether the string is in that normalization form.
The result returned will be:
YES The string is in that normalization form.
NO The string is not in that normalization form.
MAYBE Dubious. Maybe yes, maybe no.
"$result = checkNFD($string)"
returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkNFC($string)"
returns true (1) if "YES"; false ("empty string") if "NO"; "undef" if "MAYBE".
"$result = checkNFKD($string)"
returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkNFKC($string)"
returns true (1) if "YES"; false ("empty string") if "NO"; "undef" if "MAYBE".
"$result = checkFCD($string)"
returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkFCC($string)"
returns true (1) if "YES"; false ("empty string") if "NO"; "undef" if "MAYBE".
If a string is not in FCD, it must not be in FCC. So "checkFCC($not_FCD_string)" should return
"NO".
"$result = check($form_name, $string)"
returns true (1) if "YES"; false ("empty string") if "NO"; "undef" if "MAYBE".
As $form_name, one of the following names must be given.
'C' or 'NFC' for Normalization Form C (UAX #15)
'D' or 'NFD' for Normalization Form D (UAX #15)
'KC' or 'NFKC' for Normalization Form KC (UAX #15)
'KD' or 'NFKD' for Normalization Form KD (UAX #15)
'FCD' for "Fast C or D" Form (UTN #5)
'FCC' for "Fast C Contiguous" (UTN #5)
Note
In the cases of NFD, NFKD, and FCD, the answer must be either "YES" or "NO". The answer "MAYBE" may
be returned in the cases of NFC, NFKC, and FCC.
A "MAYBE" string should contain at least one combining character or the like. For example, "COMBINING
ACUTE ACCENT" has the MAYBE_NFC/MAYBE_NFKC property.
Both "checkNFC("A\N{COMBINING ACUTE ACCENT}")" and "checkNFC("B\N{COMBINING ACUTE ACCENT}")" will
return "MAYBE". "A\N{COMBINING ACUTE ACCENT}" is not in NFC (its NFC is "\N{LATIN CAPITAL LETTER A
WITH ACUTE}"), while "B\N{COMBINING ACUTE ACCENT}" is in NFC.
If you want to check exactly, compare the string with its NFC/NFKC/FCC.
if ($string eq NFC($string)) {
# $string is exactly normalized in NFC;
} else {
# $string is not normalized in NFC;
}
if ($string eq NFKC($string)) {
# $string is exactly normalized in NFKC;
} else {
# $string is not normalized in NFKC;
}
Character Data
These functions are interface of character data used internally. If you want only to get Unicode
normalization forms, you don't need call them yourself.
"$canonical_decomposed = getCanon($codepoint)"
If the character of the specified codepoint is canonically decomposable (including Hangul Sylla-bles), Syllables),
bles), returns the completely decomposed string canonically equivalent to it.
If it is not decomposable, returns "undef".
"$compatibility_decomposed = getCompat($codepoint)"
If the character of the specified codepoint is compatibility decomposable (including Hangul Syl-lables), Syllables),
lables), returns the completely decomposed string compatibility equivalent to it.
If it is not decomposable, returns "undef".
"$codepoint_composite = getComposite($codepoint_here, $codepoint_next)"
If two characters here and next (as codepoints) are composable (including Hangul Jamo/Syllables
and Composition Exclusions), returns the codepoint of the composite.
If they are not composable, returns "undef".
"$combining_class = getCombinClass($codepoint)"
Returns the combining class of the character as an integer.
"$is_exclusion = isExclusion($codepoint)"
Returns a boolean whether the character of the specified codepoint is a composition exclusion.
"$is_singleton = isSingleton($codepoint)"
Returns a boolean whether the character of the specified codepoint is a singleton.
"$is_non_starter_decomposition = isNonStDecomp($codepoint)"
Returns a boolean whether the canonical decomposition of the character of the specified codepoint
is a Non-Starter Decomposition.
"$may_be_composed_with_prev_char = isComp2nd($codepoint)"
Returns a boolean whether the character of the specified codepoint may be composed with the pre-vious previous
vious one in a certain composition (including Hangul Compositions, but excluding Composition
Exclusions and Non-Starter Decompositions).
EXPORT
"NFC", "NFD", "NFKC", "NFKD": by default.
"normalize" and other some functions: on request.
CAVEATS
Perl's version vs. Unicode version
Since this module refers to perl core's Unicode database in the directory /lib/unicore (or for-merly formerly
merly /lib/unicode), the Unicode version of normalization implemented by this module depends on
your perl's version.
perl's version implemented Unicode version
5.6.1 3.0.1
5.7.2 3.1.0
5.7.3 3.1.1 (same normalized form as that of 3.1.0)
5.8.0 3.2.0
5.8.1-5.8.3 4.0.0
5.8.4-5.8.6 (latest) 4.0.1 (same normalized form as that of 4.0.0)
Correction of decomposition mapping
In older Unicode versions, a small number of characters (all of which are CJK compatibility ideo-graphs ideographs
graphs as far as they have been found) may have an erroneous decomposition mapping (see Normal-izationCorrections.txt). NormalizationCorrections.txt).
izationCorrections.txt). Anyhow, this module will neither refer to NormalizationCorrections.txt
nor provide any specific version of normalization. Therefore this module running on an older perl
with an older Unicode database may use the erroneous decomposition mapping blindly conforming to
the Unicode database.
Revised definition of canonical composition
In Unicode 4.1.0, the definition D2 of canonical composition (which affects NFC and NFKC) has
been changed (see Public Review Issue #29 and recent UAX #15). This module has used the newer
definition since the version 0.07 (Oct 31, 2001). This module does not support normalization
according to the older definition, even if the Unicode version implemented by perl is lower than
4.1.0.
AUTHOR
SADAHIRO Tomoyuki <SADAHIRO@cpan.org>
Copyright(C) 2001-2005, SADAHIRO Tomoyuki. Japan. All rights reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl
itself.
SEE ALSO
http://www.unicode.org/reports/tr15/
Unicode Normalization Forms - UAX #15
http://www.unicode.org/Public/UNIDATA/DerivedNormalizationProps.txt
Derived Normalization Properties
http://www.unicode.org/Public/UNIDATA/NormalizationCorrections.txt
Normalization Corrections
http://www.unicode.org/review/pr-29.html
Public Review Issue #29: Normalization Issue
http://www.unicode.org/notes/tn5/
Canonical Equivalence in Applications - UTN #5
perl v5.8.8 2001-09-21 Unicode::Normalize(3pm)
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