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Unicode::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).
$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($string)"
returns the Normalization Form C (formed by canonical decomposition
followed by canonical composition).
"$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 Decomposition 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($codepoint)"
If the character of the specified codepoint is canonically decomposable
(including Hangul Syllables), returns the completely decomposed string
canonically equivalent to it.
If it is not decomposable, returns "undef".
"$compatibility_decomposed = getCompat($codepoint)"
If the character of the specified codepoint is compatibility
decomposable (including Hangul Syllables), returns the completely
decomposed string compatibility equivalent to it.
If it is not decomposable, returns "undef".
"$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 previous 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 formerly /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 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 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
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