i18n::langtags.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "I18N::LangTags 3"
.TH I18N::LangTags 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
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.SH "NAME"
I18N::LangTags \- functions for dealing with RFC3066\-style language tags
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use I18N::LangTags();
.Ve
.PP
\&...or specify whichever of those functions you want to import, like so:
.PP
.Vb 1
\&  use I18N::LangTags qw(implicate_supers similarity_language_tag);
.Ve
.PP
All the exportable functions are listed below \*(-- you're free to import
only some, or none at all.  By default, none are imported.  If you
say:
.PP
.Vb 1
\&    use I18N::LangTags qw(:ALL)
.Ve
.PP
\&...then all are exported.  (This saves you from having to use
something less obvious like \f(CW\*(C`use I18N::LangTags qw(/./)\*(C'\fR.)
.PP
If you don't import any of these functions, assume a \f(CW&I18N::LangTags::\fR
in front of all the function names in the following examples.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Language tags are a formalism, described in \s-1RFC\s0 3066 (obsoleting
1766), for declaring what language form (language and possibly
dialect) a given chunk of information is in.
.PP
This library provides functions for common tasks involving language
tags as they are needed in a variety of protocols and applications.
.PP
Please see the \*(L"See Also\*(R" references for a thorough explanation
of how to correctly use language tags.
.IP "\(bu" 4
the function is_language_tag($lang1)
.Sp
Returns true iff \f(CW$lang1\fR is a formally valid language tag.
.Sp
.Vb 3
\&   is_language_tag("fr")            is TRUE
\&   is_language_tag("x\-jicarilla")   is FALSE
\&       (Subtags can be 8 chars long at most \-\- \*(Aqjicarilla\*(Aq is 9)
\&
\&   is_language_tag("sgn\-US")    is TRUE
\&       (That\*(Aqs American Sign Language)
\&
\&   is_language_tag("i\-Klikitat")    is TRUE
\&       (True without regard to the fact noone has actually
\&        registered Klikitat \-\- it\*(Aqs a formally valid tag)
\&
\&   is_language_tag("fr\-patois")     is TRUE
\&       (Formally valid \-\- altho descriptively weak!)
\&
\&   is_language_tag("Spanish")       is FALSE
\&   is_language_tag("french\-patois") is FALSE
\&       (No good \-\- first subtag has to match
\&        /^([xXiI]|[a\-zA\-Z]{2,3})$/ \-\- see RFC3066)
\&
\&   is_language_tag("x\-borg\-prot2532") is TRUE
\&       (Yes, subtags can contain digits, as of RFC3066)
.Ve
.IP "\(bu" 4
the function extract_language_tags($whatever)
.Sp
Returns a list of whatever looks like formally valid language tags
in \f(CW$whatever\fR.  Not very smart, so don't get too creative with
what you want to feed it.
.Sp
.Vb 2
\&  extract_language_tags("fr, fr\-ca, i\-mingo")
\&    returns:   (\*(Aqfr\*(Aq, \*(Aqfr\-ca\*(Aq, \*(Aqi\-mingo\*(Aq)
\&
\&  extract_language_tags("It\*(Aqs like this: I\*(Aqm in fr \-\- French!")
\&    returns:   (\*(AqIt\*(Aq, \*(Aqin\*(Aq, \*(Aqfr\*(Aq)
\&  (So don\*(Aqt just feed it any old thing.)
.Ve
.Sp
The output is untainted.  If you don't know what tainting is,
don't worry about it.
.IP "\(bu" 4
the function same_language_tag($lang1, \f(CW$lang2\fR)
.Sp
Returns true iff \f(CW$lang1\fR and \f(CW$lang2\fR are acceptable variant tags
representing the same language-form.
.Sp
.Vb 10
\&   same_language_tag(\*(Aqx\-kadara\*(Aq, \*(Aqi\-kadara\*(Aq)  is TRUE
\&      (The x/i\- alternation doesn\*(Aqt matter)
\&   same_language_tag(\*(AqX\-KADARA\*(Aq, \*(Aqi\-kadara\*(Aq)  is TRUE
\&      (...and neither does case)
\&   same_language_tag(\*(Aqen\*(Aq,       \*(Aqen\-US\*(Aq)     is FALSE
\&      (all\-English is not the SAME as US English)
\&   same_language_tag(\*(Aqx\-kadara\*(Aq, \*(Aqx\-kadar\*(Aq)   is FALSE
\&      (these are totally unrelated tags)
\&   same_language_tag(\*(Aqno\-bok\*(Aq,    \*(Aqnb\*(Aq)       is TRUE
\&      (no\-bok is a legacy tag for nb (Norwegian Bokmal))
.Ve
.Sp
\&\f(CW\*(C`same_language_tag\*(C'\fR works by just seeing whether
\&\f(CW\*(C`encode_language_tag($lang1)\*(C'\fR is the same as
\&\f(CW\*(C`encode_language_tag($lang2)\*(C'\fR.
.Sp
(Yes, I know this function is named a bit oddly.  Call it historic
reasons.)
.IP "\(bu" 4
the function similarity_language_tag($lang1, \f(CW$lang2\fR)
.Sp
Returns an integer representing the degree of similarity between
tags \f(CW$lang1\fR and \f(CW$lang2\fR (the order of which does not matter), where
similarity is the number of common elements on the left,
without regard to case and to x/i\- alternation.
.Sp
.Vb 4
\&   similarity_language_tag(\*(Aqfr\*(Aq, \*(Aqfr\-ca\*(Aq)           is 1
\&      (one element in common)
\&   similarity_language_tag(\*(Aqfr\-ca\*(Aq, \*(Aqfr\-FR\*(Aq)        is 1
\&      (one element in common)
\&
\&   similarity_language_tag(\*(Aqfr\-CA\-joual\*(Aq,
\&                           \*(Aqfr\-CA\-PEI\*(Aq)             is 2
\&   similarity_language_tag(\*(Aqfr\-CA\-joual\*(Aq, \*(Aqfr\-CA\*(Aq)  is 2
\&      (two elements in common)
\&
\&   similarity_language_tag(\*(Aqx\-kadara\*(Aq, \*(Aqi\-kadara\*(Aq)  is 1
\&      (x/i\- doesn\*(Aqt matter)
\&
\&   similarity_language_tag(\*(Aqen\*(Aq,       \*(Aqx\-kadar\*(Aq)   is 0
\&   similarity_language_tag(\*(Aqx\-kadara\*(Aq, \*(Aqx\-kadar\*(Aq)   is 0
\&      (unrelated tags \-\- no similarity)
\&
\&   similarity_language_tag(\*(Aqi\-cree\-syllabic\*(Aq,
\&                           \*(Aqi\-cherokee\-syllabic\*(Aq)   is 0
\&      (no B<leftmost> elements in common!)
.Ve
.IP "\(bu" 4
the function is_dialect_of($lang1, \f(CW$lang2\fR)
.Sp
Returns true iff language tag \f(CW$lang1\fR represents a subform of
language tag \f(CW$lang2\fR.
.Sp
\&\fBGet the order right!  It doesn't work the other way around!\fR
.Sp
.Vb 2
\&   is_dialect_of(\*(Aqen\-US\*(Aq, \*(Aqen\*(Aq)            is TRUE
\&     (American English IS a dialect of all\-English)
\&
\&   is_dialect_of(\*(Aqfr\-CA\-joual\*(Aq, \*(Aqfr\-CA\*(Aq)   is TRUE
\&   is_dialect_of(\*(Aqfr\-CA\-joual\*(Aq, \*(Aqfr\*(Aq)      is TRUE
\&     (Joual is a dialect of (a dialect of) French)
\&
\&   is_dialect_of(\*(Aqen\*(Aq, \*(Aqen\-US\*(Aq)            is FALSE
\&     (all\-English is a NOT dialect of American English)
\&
\&   is_dialect_of(\*(Aqfr\*(Aq, \*(Aqen\-CA\*(Aq)            is FALSE
\&
\&   is_dialect_of(\*(Aqen\*(Aq,    \*(Aqen\*(Aq   )         is TRUE
\&   is_dialect_of(\*(Aqen\-US\*(Aq, \*(Aqen\-US\*(Aq)         is TRUE
\&     (B<Note:> these are degenerate cases)
\&
\&   is_dialect_of(\*(Aqi\-mingo\-tom\*(Aq, \*(Aqx\-Mingo\*(Aq) is TRUE
\&     (the x/i thing doesn\*(Aqt matter, nor does case)
\&
\&   is_dialect_of(\*(Aqnn\*(Aq, \*(Aqno\*(Aq)               is TRUE
\&     (because \*(Aqnn\*(Aq (New Norse) is aliased to \*(Aqno\-nyn\*(Aq,
\&      as a special legacy case, and \*(Aqno\-nyn\*(Aq is a
\&      subform of \*(Aqno\*(Aq (Norwegian))
.Ve
.IP "\(bu" 4
the function super_languages($lang1)
.Sp
Returns a list of language tags that are superordinate tags to \f(CW$lang1\fR
\&\*(-- it gets this by removing subtags from the end of \f(CW$lang1\fR until
nothing (or just \*(L"i\*(R" or \*(L"x\*(R") is left.
.Sp
.Vb 1
\&   super_languages("fr\-CA\-joual")  is  ("fr\-CA", "fr")
\&
\&   super_languages("en\-AU")  is  ("en")
\&
\&   super_languages("en")  is  empty\-list, ()
\&
\&   super_languages("i\-cherokee")  is  empty\-list, ()
\&    ...not ("i"), which would be illegal as well as pointless.
.Ve
.Sp
If \f(CW$lang1\fR is not a valid language tag, returns empty-list in
a list context, undef in a scalar context.
.Sp