Unicod...ingprep(3pm)

✨ NAME ✨

okay so bestie, welcome to Unicod...ingprep(3pm) 💖 — this is Unicode::Stringprep — Preparation of Internationalized Strings (RFC 3454). that's the whole vibe. we prep strings. we make them behave. periodt.

---

🌸 SYNOPSIS 🌸

use Unicode::Stringprep;
use Unicode::Stringprep::Mapping;
use Unicode::Stringprep::Prohibited;

my $prepper = Unicode::Stringprep->new(
  3.2,
  [ { 32 => '<SPACE>'},  ],
  'KC',
  [ @Unicode::Stringprep::Prohibited::C12, @Unicode::Stringprep::Prohibited::C22,
    @Unicode::Stringprep::Prohibited::C3, @Unicode::Stringprep::Prohibited::C4,
    @Unicode::Stringprep::Prohibited::C5, @Unicode::Stringprep::Prohibited::C6,
    @Unicode::Stringprep::Prohibited::C7, @Unicode::Stringprep::Prohibited::C8,
    @Unicode::Stringprep::Prohibited::C9 ],
  1, 0 );
$output = $prepper->($input)

like. look at that. iconic. no notes. 🫶

---

🦋 DESCRIPTION 🦋

So this module implements the stringprep framework — that's the whole "get your Unicode text strings ready" pipeline, and the point of it is to increase the likelihood that string input and string comparison work in ways that make sense for typical users throughout the world. literally a global-vibes-compatibility situation. 💅

The stringprep protocol is useful for protocol identifier values, company and personal names, internationalized domain names, and other text strings. so basically, everything that has a name and travels the earth.

Here's the thing though: the stringprep framework does not specify how protocols should prepare text strings. nope. Protocols have to create profiles of stringprep in order to fully specify the processing options. so this module gives you the machinery, and your protocol decides the settings. main character energy, but the protocol is the main character. 😭

---

🔥 FUNCTIONS 🔥

This module provides a single function, new, that creates a perl function implementing a stringprep profile.

not me telling you that this module exports nothing. fr fr, nothing comes out of it automatically. you call new yourself like a grown-up. 🎀

• new($unicode_version, $mapping_tables, $unicode_normalization, $prohibited_tables, $bidi_check, $unassigned_check) — Creates a blessed function reference that implements a stringprep profile.

This function takes the following parameters:

• $unicode_version — The Unicode version specified by the stringprep profile.

Currently, this parameter must be 3.2 (numeric). no other number. just that one. 😌

• $mapping_tables — The mapping tables used for stringprep.

The parameter may be a reference to a hash or an array, or undef. A hash must map Unicode codepoints (as integers, e. g. 0x0020 for U+0020) to replacement strings (as perl strings). An array may contain pairs of Unicode codepoints and replacement strings as well as references to nested hashes and arrays.

Unicode::Stringprep::Mapping provides the tables from RFC 3454, Appendix B.

For further information on the mapping step, see RFC 3454, section 3.

• $unicode_normalization — The Unicode normalization to be used.

Currently, undef/'' (no normalization) and 'KC' (compatibility composed) are specified for stringprep.

For further information on the normalization step, see RFC 3454, section 4.

Normalization form KC will also enable checks for some problem sequences for which the normalization can't be implemented in an interoperable way. 👀

For more information, see "CAVEATS" below.

• $prohibited_tables — The list of prohibited output characters for stringprep.

The parameter may be a reference to an array, or undef. The array contains pairs of codepoints, which define the start and end of a Unicode character range (as integers). The end character may be undef, specifying a single-character range. The array may also contain references to nested arrays.

Unicode::Stringprep::Prohibited provides the tables from RFC 3454, Appendix C.

For further information on the prohibition checking step, see RFC 3454, section 5.

• $bidi_check — Whether to employ checks for confusing bidirectional text. A boolean value.

For further information on the bidi checking step, see RFC 3454, section 6.

• $unassigned_check — Whether to check for and prohibit unassigned characters. A boolean value.

The check must be used when creating stored strings. It should not be used for query strings, increasing the chance that newly assigned characters work as expected. 🍓

For further information on stored and query strings, see RFC 3454, section 7.

The function returned can be called with a single parameter, the string to be prepared, and returns the prepared string. It will die if the input string cannot be successfully prepared because it would contain invalid output (so use eval if necessary). 💀

For performance reasons, it is strongly recommended to call the new function as few times as possible, i. e. exactly once per stringprep profile. It might also be better not to use this module directly but to use (or write) a module implementing a profile, such as Authen::SASL::SASLprep. like, build it once, reuse it forever. that's the slay strategy. ✨

---

👑 IMPLEMENTING PROFILES 👑

You can easily implement a stringprep profile without subclassing:

package ACME::ExamplePrep;

use Unicode::Stringprep;

use Unicode::Stringprep::Mapping;
use Unicode::Stringprep::Prohibited;

*exampleprep = Unicode::Stringprep->new(
  3.2,
  [ \@Unicode::Stringprep::Mapping::B1, ],
  '',
  [ \@Unicode::Stringprep::Prohibited::C12,
    \@Unicode::Stringprep::Prohibited::C22, ],
  1,
);

This binds ACME::ExamplePrep::exampleprep to the function created by Unicode::Stringprep->new.

Usually, it is not necessary to subclass this module. Subclassing this module is not recommended. 🙈 like please don't. just don't do it. you don't need to. trust.

---

🌈 DATA TABLES 🌈

The following modules contain the data tables from RFC 3454. These modules are automatically loaded when loading Unicode::Stringprep.

• Unicode::Stringprep::Unassigned

@Unicode::Stringprep::Unassigned::A1  # Appendix A.1

• Unicode::Stringprep::Mapping

@Unicode::Stringprep::Mapping::B1     # Appendix B.1
@Unicode::Stringprep::Mapping::B2     # Appendix B.2
@Unicode::Stringprep::Mapping::B2     # Appendix B.3

• Unicode::Stringprep::Prohibited

@Unicode::Stringprep::Prohibited::C11 # Appendix C.1.1
@Unicode::Stringprep::Prohibited::C12 # Appendix C.1.2
@Unicode::Stringprep::Prohibited::C21 # Appendix C.2.1
@Unicode::Stringprep::Prohibited::C22 # Appendix C.2.2
@Unicode::Stringprep::Prohibited::C3  # Appendix C.3
@Unicode::Stringprep::Prohibited::C4  # Appendix C.4
@Unicode::Stringprep::Prohibited::C5  # Appendix C.5
@Unicode::Stringprep::Prohibited::C6  # Appendix C.6
@Unicode::Stringprep::Prohibited::C7  # Appendix C.7
@Unicode::Stringprep::Prohibited::C8  # Appendix C.8
@Unicode::Stringprep::Prohibited::C9  # Appendix C.9

• Unicode::Stringprep::BiDi

@Unicode::Stringprep::BiDi::D1        # Appendix D.1
@Unicode::Stringprep::BiDi::D2        # Appendix D.2

---

💀 CAVEATS 💀

okay bestie, sit down, this one's a whole saga. 😭

In Unicode 3.2 to 4.0.1, the specification of UAX #15: Unicode Normalization Forms for forms NFC and NFKC is not logically self-consistent. This has been fixed in Corrigendum #5 (http://unicode.org/versions/corrigendum5.html).

Unfortunately, this yields two ways to implement NFC and NFKC in Unicode 3.2, on which the Stringprep standard is based: one based on a literal interpretation of the original specification and one based on the corrected specification. The output of these implementations differs for a small class of strings, all of which can't appear in meaningful text. See UAX #15, section 19 (http://unicode.org/reports/tr15/#Stability_Prior_to_Unicode41) for details.

This module will check for these strings and, if normalization is done, prohibit them in output as it is not possible to interoperate under these circumstandes.

Please note that due to this, the normalization step may cause the preparation to fail. That is, the preparation function may die even if there are no prohibited characters and no checks for bidi sequences and unassigned characters, which may be surprising. like. yes. it's surprising. it's giving "why is my string mad at me". 🫠 but that's just how it is.

---

💖 AUTHOR 💖

Claus Faerber <CFAERBER@cpan.org> — thank you for your service, king 👑

---

🎀 LICENSE 🎀

Copyright 2007-2009 Claus Faerber.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. so, free. use it. remix it. 🦋

---

⭐ SEE ALSO ⭐

• Unicode::Normalize
• RFC 3454 (http://www.ietf.org/rfc/rfc3454.txt)

---

and that's the whole page, bestie!! 💜 go prep some strings, stay interoperable, and remember: this was perl v5.36.0, dated 2022-10-15, page Unicod...ingprep(3pm). mwah 💅✨🎀