X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=3098fe21bd3d562ddcbaf4996d948e276514a50a;hb=46726cbe13a1bbdca5ff648034840cd7466b80c5;hp=35a478d10dcfde1a85c5253bf4e0e370e6d4603e;hpb=22244bdbbe5e55ece3797eb1c4fed22e93953c4c;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/utf8.pm b/lib/utf8.pm index 35a478d..3098fe2 100644 --- a/lib/utf8.pm +++ b/lib/utf8.pm @@ -1,12 +1,12 @@ package utf8; sub import { - $^H |= 0x00000008; + $^H |= 0x00800000; $enc{caller()} = $_[1] if $_[1]; } sub unimport { - $^H &= ~0x00000008; + $^H &= ~0x00800000; } sub AUTOLOAD { @@ -19,7 +19,7 @@ __END__ =head1 NAME -utf8 - Perl pragma to turn on UTF-8 and Unicode support +utf8 - Perl pragma to enable/disable UTF-8 in source code =head1 SYNOPSIS @@ -28,154 +28,48 @@ utf8 - Perl pragma to turn on UTF-8 and Unicode support =head1 DESCRIPTION -The utf8 pragma tells Perl to use UTF-8 as its internal string -representation for the rest of the enclosing block. (The "no utf8" -pragma tells Perl to switch back to ordinary byte-oriented processing -for the rest of the enclosing block.) Under utf8, many operations that -formerly operated on bytes change to operating on characters. For -ASCII data this makes no difference, because UTF-8 stores ASCII in -single bytes, but for any character greater than C, the -character is stored in a sequence of two or more bytes, all of which -have the high bit set. But by and large, the user need not worry about -this, because the utf8 pragma hides it from the user. A character -under utf8 is logically just a number ranging from 0 to 2**32 or so. -Larger characters encode to longer sequences of bytes, but again, this -is hidden. +WARNING: The implementation of Unicode support in Perl is incomplete. +Expect sudden and unannounced changes! -Use of the utf8 pragma has the following effects: +The C pragma tells the Perl parser to allow UTF-8 in the +program text in the current lexical scope. The C pragma +tells Perl to switch back to treating the source text as literal +bytes in the current lexical scope. -=over 4 +This pragma is primarily a compatibility device. Perl versions +earlier than 5.6 allowed arbitrary bytes in source code, whereas +in future we would like to standardize on the UTF-8 encoding for +source text. Until UTF-8 becomes the default format for source +text, this pragma should be used to recognize UTF-8 in the source. +When UTF-8 becomes the standard source format, this pragma will +effectively become a no-op. -=item * - -Strings and patterns may contain characters that have an ordinal value -larger than 255. Presuming you use a Unicode editor to edit your -program, these will typically occur directly within the literal strings -as UTF-8 characters, but you can also specify a particular character -with an extension of the C<\x> notation. UTF-8 characters are -specified by putting the hexidecimal code within curlies after the -C<\x>. For instance, a Unicode smiley face is C<\x{263A}>. A -character in the Latin-1 range (128..255) should be written C<\x{ab}> -rather than C<\xab>, since the former will turn into a two-byte UTF-8 -code, while the latter will continue to be interpreted as generating a -8-bit byte rather than a character. In fact, if -w is turned on, it will -produce a warning that you might be generating invalid UTF-8. - -=item * - -Identifiers within the Perl script may contain Unicode alphanumeric -characters, including ideographs. (You are currently on your own when -it comes to using the canonical forms of characters--Perl doesn't (yet) -attempt to canonicalize variable names for you.) - -=item * - -Regular expressions match characters instead of bytes. For instance, -"." matches a character instead of a byte. (However, the C<\C> pattern -is provided to force a match a single byte ("C" in C, hence -C<\C>).) - -=item * +Enabling the C pragma has the following effects: -Character classes in regular expressions match characters instead of -bytes, and match against the character properties specified in the -Unicode properties database. So C<\w> can be used to match an ideograph, -for instance. +=over =item * -Named Unicode properties and block ranges make be used as character -classes via the new C<\p{}> (matches property) and C<\P{}> (doesn't -match property) constructs. For instance, C<\p{Lu}> matches any -character with the Unicode uppercase property, while C<\p{M}> matches -any mark character. Single letter properties may omit the brackets, so -that can be written C<\pM> also. Many predefined character classes are -available, such as C<\p{IsMirrored}> and C<\p{InTibetan}>. +Bytes in the source text that have their high-bit set will be treated +as being part of a literal UTF-8 character. This includes most literals +such as identifiers, string constants, constant regular expression patterns +and package names. =item * -The special pattern C<\X> match matches any extended Unicode sequence -(a "combining character sequence" in Standardese), where the first -character is a base character and subsequent characters are mark -characters that apply to the base character. It is equivalent to -C<(?:\PM\pM*)>. - -=item * +In the absence of inputs marked as UTF-8, regular expressions within the +scope of this pragma will default to using character semantics instead +of byte semantics. -The C operator translates characters instead of bytes. It can also -be forced to translate between 8-bit codes and UTF-8 regardless of the -surrounding utf8 state. For instance, if you know your input in Latin-1, -you can say: - - use utf8; - while (<>) { - tr/\0-\xff//CU; # latin1 char to utf8 - ... + @bytes_or_chars = split //, $data; # may split to bytes if data + # $data isn't UTF-8 + { + use utf8; # force char semantics + @chars = split //, $data; # splits characters } -Similarly you could translate your output with - - tr/\0-\x{ff}//UC; # utf8 to latin1 char - -No, C doesn't take /U or /C (yet?). - -=item * - -Case translation operators use the Unicode case translation tables. -Note that C translates to uppercase, while C translates -to titlecase (for languages that make the distinction). Naturally -the corresponding backslash sequences have the same semantics. - -=item * - -Most operators that deal with positions or lengths in the string will -automatically switch to using character positions, including C, -C, C, C, C, C, -C, and C. Operators that specifically don't switch -include C, C, and C. Operators that really -don't care include C, as well as any other operator that -treats a string as a bucket of bits, such as C, and the -operators dealing with filenames. - -=item * - -The C/C letters "C" and "C" do I change, -since they're often used for byte-oriented formats. (Again, think -"C" in the C language.) However, there is a new "C" specifier -that will convert between UTF-8 characters and integers. (It works -outside of the utf8 pragma too.) - -=item * - -The C and C functions work on characters. This is like -C and C, not like C and -C. In fact, the latter are how you now emulate -byte-oriented C and C under utf8. - -=item * - -And finally, C reverses by character rather than by byte. - -=back - -=head1 CAVEATS - -As of yet, there is no method for automatically coercing input and -output to some encoding other than UTF-8. This is planned in the near -future, however. - -In any event, you'll need to keep track of whether interfaces to other -modules expect UTF-8 data or something else. The utf8 pragma does not -magically mark strings for you in order to remember their encoding, nor -will any automatic coercion happen (other than that eventually planned -for I/O). If you want such automatic coercion, you can build yourself -a set of pretty object-oriented modules. Expect it to run considerably -slower than than this low-level support. +=head1 SEE ALSO -Use of locales with utf8 may lead to odd results. Currently there is -some attempt to apply 8-bit locale info to characters in the range -0..255, but this is demonstrably incorrect for locales that use -characters above that range (when mapped into Unicode). It will also -tend to run slower. Avoidance of locales is strongly encouraged. +L, L =cut