Unicode::Normalize - Unicode Normalization Forms

AUTHOR
SEE ALSO

NAME

Unicode::Normalize - Unicode Normalization Forms

SYNOPSIS

  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

or

  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 XS edition and pure Perl edition, interpretation of $codepoint as a decimal number has incompatibility. XS 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).

$normalized_string = normalize($form_name, $string)

As $form_name, one of the following names must be given.

  'C'  or 'NFC'  for Normalization Form C
  'D'  or 'NFD'  for Normalization Form D
  'KC' or 'NFKC' for Normalization Form KC
  'KD' or 'NFKD' for Normalization Form KD

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 YES (1) or NO (empty string).
$result = checkNFC($string): returns YES (1), NO (empty string), or MAYBE (undef).
$result = checkNFKD($string): returns YES (1) or NO (empty string).
$result = checkNFKC($string): returns YES (1), NO (empty string), or MAYBE (undef).
$result = check($form_name, $string): returns YES (1), NO (empty string), or MAYBE (undef).; $form_name is alike to that for normalize().

Note

In the cases of NFD and NFKD, the answer must be either YES or NO. The answer MAYBE may be returned in the cases of NFC and NFKC.

A MAYBE-NFC/NFKC 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; i.e.,

    $string eq NFC($string)    # more thorough than checkNFC($string)
    $string eq NFKC($string)   # more thorough than checkNFKC($string)

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.

AUTHOR

SADAHIRO Tomoyuki, <SADAHIRO@cpan.org>

  http://homepage1.nifty.com/nomenclator/perl/

  Copyright(C) 2001-2003, 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.