Normalize(3) User Contributed Perl Documentation Normalize(3)
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).
$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($string)"
It returns the Normalization Form D (formed by canonical
decomposition).
"$NFC_string = NFC($string)"
It returns the Normalization Form C (formed by canonical
decomposition followed by canonical composition).
"$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
decomposition 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);
"($processed, $unprocessed) = splitOnLastStarter($normalized)"
It returns two strings: the first one, $processed, is a part before
the last starter, and the second one, $unprocessed is another part
after the first part. A starter is a character having a combining
class of zero (see UAX #15).
Note that $processed may be empty (when $normalized contains no
starter or starts with the last starter), and then $unprocessed
should be equal to the entire $normalized.
When you have a $normalized string and an $unnormalized string
following it, a simple concatenation is wrong:
$concat = $normalized . normalize($form, $unnormalized); # wrong!
Instead of it, do like this:
($processed, $unprocessed) = splitOnLastStarter($normalized);
$concat = $processed . normalize($form, $unprocessed.$unnormalized);
"splitOnLastStarter()" should be called with a pre-normalized
parameter $normalized, that is in the same form as $form you want.
If you have an array of @string that should be concatenated and
then normalized, you can do like this:
my $result = "";
my $unproc = "";
foreach my $str (@string) {
$unproc .= $str;
my $n = normalize($form, $unproc);
my($p, $u) = splitOnLastStarter($n);
$result .= $p;
$unproc = $u;
}
$result .= $unproc;
# instead of normalize($form, join('', @string))
"$processed = normalize_partial($form, $unprocessed)"
A wrapper for the combination of "normalize()" and
"splitOnLastStarter()". Note that $unprocessed will be modified as
a side-effect.
If you have an array of @string that should be concatenated and
then normalized, you can do like this:
my $result = "";
my $unproc = "";
foreach my $str (@string) {
$unproc .= $str;
$result .= normalize_partial($form, $unproc);
}
$result .= $unproc;
# instead of normalize($form, join('', @string))
"$processed = NFD_partial($unprocessed)"
It does like "normalize_partial('NFD', $unprocessed)". Note that
$unprocessed will be modified as a side-effect.
"$processed = NFC_partial($unprocessed)"
It does like "normalize_partial('NFC', $unprocessed)". Note that
$unprocessed will be modified as a side-effect.
"$processed = NFKD_partial($unprocessed)"
It does like "normalize_partial('NFKD', $unprocessed)". Note that
$unprocessed will be modified as a side-effect.
"$processed = NFKC_partial($unprocessed)"
It does like "normalize_partial('NFKC', $unprocessed)". Note that
$unprocessed will be modified as a side-effect.
Quick Check
(see Annex 8, UAX #15; and DerivedNormalizationProps.txt)
The following functions check whether the string is in that
normalization form.
The result returned will be one of the following:
YES The string is in that normalization form.
NO The string is not in that normalization form.
MAYBE Dubious. Maybe yes, maybe no.
"$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($string)"
It returns true (1) if "YES"; false ("empty string") if "NO";
"undef" if "MAYBE".
Note: If a string is not in FCD, it must not be in FCC. So
"checkFCC($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 $form_name, one of the following names must be given.
'C' or 'NFC' for Normalization Form C (UAX #15)
'D' or 'NFD' for Normalization Form D (UAX #15)
'KC' or 'NFKC' for Normalization Form KC (UAX #15)
'KD' or 'NFKD' for Normalization Form KD (UAX #15)
'FCD' for "Fast C or D" Form (UTN #5)
'FCC' for "Fast C Contiguous" (UTN #5)
Note
In the cases of NFD, NFKD, and FCD, the answer must be either "YES" or
"NO". The answer "MAYBE" may be returned in the cases of NFC, NFKC, and
FCC.
A "MAYBE" string should contain at least one combining character or the
like. For example, "COMBINING ACUTE ACCENT" has the
MAYBE_NFC/MAYBE_NFKC property.
Both "checkNFC("A\N{COMBINING ACUTE ACCENT}")" and
"checkNFC("B\N{COMBINING ACUTE ACCENT}")" will return "MAYBE".
"A\N{COMBINING ACUTE ACCENT}" is not in NFC (its NFC is "\N{LATIN
CAPITAL LETTER A WITH ACUTE}"), while "B\N{COMBINING ACUTE ACCENT}" is
in NFC.
If you want to check exactly, compare the string with its NFC/NFKC/FCC.
if ($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_decomposition = getCanon($code_point)"
If the character is canonically decomposable (including Hangul
Syllables), it returns the (full) canonical decomposition as a
string. Otherwise it returns "undef".
Note: According to the Unicode standard, the canonical
decomposition of the character that is not canonically decomposable
is same as the character itself.
"$compatibility_decomposition = getCompat($code_point)"
If the character is compatibility decomposable (including Hangul
Syllables), it returns the (full) compatibility decomposition as a
string. Otherwise it returns "undef".
Note: According to the Unicode standard, the compatibility
decomposition of the character that is not compatibility
decomposable is same as the character itself.
"$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($code_point)"
It returns a boolean whether the character of the specified
codepoint may be composed with the previous one in a certain
composition (including Hangul Compositions, but excluding
Composition Exclusions and Non-Starter Decompositions).
"$is_exclusion = isExclusion($code_point)"
It returns a boolean whether the code point is a composition
exclusion.
"$is_singleton = isSingleton($code_point)"
It returns a boolean whether the code point is a singleton
"$is_non_starter_decomposition = isNonStDecomp($code_point)"
It returns a boolean whether the code point has Non-Starter
Decomposition.
"$is_Full_Composition_Exclusion = isComp_Ex($code_point)"
It returns a boolean of the derived property Comp_Ex
(Full_Composition_Exclusion). This property is generated from
Composition Exclusions + Singletons + Non-Starter Decompositions.
"$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
version of normalization implemented by this module depends on what
has been compiled into your perl. The following table lists the
default Unicode version that comes with various perl versions. (It
is possible to change the Unicode version in any perl version to be
any earlier Unicode version, so one could cause Unicode 3.2 to be
used in any perl version starting with 5.8.0. See
$Config{privlib}/unicore/README.perl.
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
5.10.0 5.0.0
5.8.9, 5.10.1 5.1.0
5.12.x 5.2.0
5.14.x 6.0.0
5.16.x 6.1.0
5.18.x 6.2.0
5.20.x 6.3.0
5.22.x 7.0.0
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
NormalizationCorrections.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 will not
support 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 AT cpan.org>
Currently maintained by <perl5-porters AT perl.org>
Copyright(C) 2001-2012, SADAHIRO Tomoyuki. Japan. All rights reserved.
LICENSE
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 v5.26.3 2015-12-16 Normalize(3)
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