Unicode::Normalize(3) Perl Programmers Reference Guide Unicode::Normalize(3)NAMEUnicode::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 perluni‐
code).
$code_point should be an unsigned integer representing a Unicode code
point.
Note: Between XSUB and pure Perl, there is an incompatibility about the
interpretation of $code_point as a decimal number. XSUB converts
$code_point to an unsigned integer, but pure Perl does not. Do not use
a floating point nor a negative sign in $code_point.
Normalization Forms
"$NFD_string = NFD($string)"
It returns the Normalization Form D (formed by canonical decomposi‐
tion).
"$NFC_string = NFC($string)"
It returns the Normalization Form C (formed by canonical decomposi‐
tion followed by canonical composition).
"$NFKD_string = NFKD($string)"
It returns the Normalization Form KD (formed by compatibility
decomposition).
"$NFKC_string = NFKC($string)"
It returns the Normalization Form KC (formed by compatibility
decomposition followed by canonical composition).
"$FCD_string = FCD($string)"
If the given string is in FCD ("Fast C or D" form; cf. UTN #5), it
returns the string without modification; otherwise it returns an
FCD string.
Note: FCD is not always unique, then plural forms may be equivalent
each other. "FCD()" will return one of these equivalent forms.
"$FCC_string = FCC($string)"
It returns the FCC form ("Fast C Contiguous"; cf. UTN #5).
Note: FCC is unique, as well as four normalization forms (NF*).
"$normalized_string = normalize($form_name, $string)"
It returns the normalization form of $form_name.
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 [, $useCompatMapping])"
It returns the concatenation of the decomposition of each character
in the string.
If the second parameter (a boolean) is omitted or false, the decom‐
position is canonical decomposition; if the second parameter (a
boolean) is true, the decomposition is compatibility decomposition.
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)"
It returns the result of reordering the combining characters
according to Canonical Ordering Behavior.
For example, when you have a list of NFD/NFKD strings, you can get
the concatenated NFD/NFKD string from them, by saying
$concat_NFD = reorder(join '', @NFD_strings);
$concat_NFKD = reorder(join '', @NFKD_strings);
"$composed_string = compose($string)"
It returns the result of canonical composition without applying any
decomposition.
For example, when you have a NFD/NFKD string, you can get its
NFC/NFKC string, by 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 normaliza‐
tion form.
The result returned will be one of the following:
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)"
It returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkNFC($string)"
It returns true (1) if "YES"; false ("empty string") if "NO";
"undef" if "MAYBE".
"$result = checkNFKD($string)"
It returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkNFKC($string)"
It returns true (1) if "YES"; false ("empty string") if "NO";
"undef" if "MAYBE".
"$result = checkFCD($string)"
It returns true (1) if "YES"; false ("empty string") if "NO".
"$result = checkFCC($string)"
It returns true (1) if "YES"; false ("empty string") if "NO";
"undef" if "MAYBE".
Note: If a string is not in FCD, it must not be in FCC. So "check‐
FCC($not_FCD_string)" should return "NO".
"$result = check($form_name, $string)"
It returns true (1) if "YES"; false ("empty string") if "NO";
"undef" if "MAYBE".
As $form_name, one of the following names must be given.
'C' or 'NFC' for Normalization Form C (UAX #15)
'D' or 'NFD' for Normalization Form D (UAX #15)
'KC' or 'NFKC' for Normalization Form KC (UAX #15)
'KD' or 'NFKD' for Normalization Form KD (UAX #15)
'FCD' for "Fast C or D" Form (UTN #5)
'FCC' for "Fast C Contiguous" (UTN #5)
Note
In the cases of NFD, NFKD, and FCD, the answer must be either "YES" or
"NO". The answer "MAYBE" may be returned in the cases of NFC, NFKC, and
FCC.
A "MAYBE" string should contain at least one combining character or the
like. For example, "COMBINING ACUTE ACCENT" has the
MAYBE_NFC/MAYBE_NFKC property.
Both "checkNFC("A\N{COMBINING ACUTE ACCENT}")" and "checkNFC("B\N{COM‐
BINING ACUTE ACCENT}")" will return "MAYBE". "A\N{COMBINING ACUTE
ACCENT}" is not in NFC (its NFC is "\N{LATIN CAPITAL LETTER A WITH
ACUTE}"), while "B\N{COMBINING ACUTE ACCENT}" is in NFC.
If you want to check exactly, compare the string with its NFC/NFKC/FCC.
if ($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_decomposition = getCanon($code_point)"
If the character is canonically decomposable (including Hangul Syl‐
lables), it returns the (full) canonical decomposition as a string.
Otherwise it returns "undef".
Note: According to the Unicode standard, the canonical decomposi‐
tion of the character that is not canonically decomposable is same
as the character itself.
"$compatibility_decomposition = getCompat($code_point)"
If the character is compatibility decomposable (including Hangul
Syllables), it returns the (full) compatibility decomposition as a
string. Otherwise it returns "undef".
Note: According to the Unicode standard, the compatibility decompo‐
sition of the character that is not compatibility decomposable is
same as the character itself.
"$code_point_composite = getComposite($code_point_here,
$code_point_next)"
If two characters here and next (as code points) are composable
(including Hangul Jamo/Syllables and Composition Exclusions), it
returns the code point of the composite.
If they are not composable, it returns "undef".
"$combining_class = getCombinClass($code_point)"
It returns the combining class (as an integer) of the character.
"$may_be_composed_with_prev_char = isComp2nd($code_point)"
It returns a boolean whether the character of the specified code‐
point may be composed with the previous one in a certain composi‐
tion (including Hangul Compositions, but excluding Composition
Exclusions and Non-Starter Decompositions).
"$is_exclusion = isExclusion($code_point)"
It returns a boolean whether the code point is a composition exclu‐
sion.
"$is_singleton = isSingleton($code_point)"
It returns a boolean whether the code point is a singleton
"$is_non_starter_decomposition = isNonStDecomp($code_point)"
It returns a boolean whether the code point has Non-Starter Decom‐
position.
"$is_Full_Composition_Exclusion = isComp_Ex($code_point)"
It returns a boolean of the derived property Comp_Ex (Full_Composi‐
tion_Exclusion). This property is generated from Composition Exclu‐
sions + Singletons + Non-Starter Decompositions.
"$NFD_is_NO = isNFD_NO($code_point)"
It returns a boolean of the derived property NFD_NO
(NFD_Quick_Check=No).
"$NFC_is_NO = isNFC_NO($code_point)"
It returns a boolean of the derived property NFC_NO
(NFC_Quick_Check=No).
"$NFC_is_MAYBE = isNFC_MAYBE($code_point)"
It returns a boolean of the derived property NFC_MAYBE
(NFC_Quick_Check=Maybe).
"$NFKD_is_NO = isNFKD_NO($code_point)"
It returns a boolean of the derived property NFKD_NO
(NFKD_Quick_Check=No).
"$NFKC_is_NO = isNFKC_NO($code_point)"
It returns a boolean of the derived property NFKC_NO
(NFKC_Quick_Check=No).
"$NFKC_is_MAYBE = isNFKC_MAYBE($code_point)"
It returns a boolean of the derived property NFKC_MAYBE
(NFKC_Quick_Check=Maybe).
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 formerly /lib/unicode), the Unicode ver‐
sion 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 (normalization is same as 3.1.0)
5.8.0 3.2.0
5.8.1-5.8.3 4.0.0
5.8.4-5.8.6 4.0.1 (normalization is same as 4.0.0)
5.8.7-5.8.8 4.1.0
Correction of decomposition mapping
In older Unicode versions, a small number of characters (all of
which are CJK compatibility ideographs as far as they have been
found) may have an erroneous decomposition mapping (see Normaliza‐
tionCorrections.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 map‐
ping 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 will not sup‐
port the 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) 2001-2007, 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/CompositionExclusions.txt
Composition Exclusion Table
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 2008-09-19 Unicode::Normalize(3)
