X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=ac73aa180665c706d72b2150a924e56d7694a5bb;hb=50109ad0d28b27abe5ee82def070e14b4526321c;hp=691de0d6303158f44fe454d1c75846a7d33e2596;hpb=d41ff1b8ad987cfcb928deba4254681c1a4c0e36;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/utf8.pm b/lib/utf8.pm index 691de0d..ac73aa1 100644 --- a/lib/utf8.pm +++ b/lib/utf8.pm @@ -1,19 +1,23 @@ package utf8; -$^U = 1; +$utf8::hint_bits = 0x00800000; + +our $VERSION = '1.06'; sub import { - $^H |= 0x00000008; + $^H |= $utf8::hint_bits; $enc{caller()} = $_[1] if $_[1]; } sub unimport { - $^H &= ~0x00000008; + $^H &= ~$utf8::hint_bits; } sub AUTOLOAD { require "utf8_heavy.pl"; - goto &$AUTOLOAD; + goto &$AUTOLOAD if defined &$AUTOLOAD; + require Carp; + Carp::croak("Undefined subroutine $AUTOLOAD called"); } 1; @@ -21,163 +25,174 @@ __END__ =head1 NAME -utf8 - Perl pragma to turn on UTF-8 and Unicode support +utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code =head1 SYNOPSIS use utf8; no utf8; + # Convert a Perl scalar to/from UTF-8. + $num_octets = utf8::upgrade($string); + $success = utf8::downgrade($string[, FAIL_OK]); + + # Change the native bytes of a Perl scalar to/from UTF-8 bytes. + utf8::encode($string); + utf8::decode($string); + + $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 + $flag = utf8::valid(STRING); + =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. - -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 (allow UTF-EBCDIC on EBCDIC based +platforms). The C pragma tells Perl to switch back to treating +the source text as literal bytes in the current lexical scope. -=over 4 +B The utility functions described below are +directly usable without C. -=item * +Because it is not possible to reliably tell UTF-8 from native 8 bit +encodings, you need either a Byte Order Mark at the beginning of your +source code, or C, to instruct perl. -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 hexadecimal 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 C<-w> is turned on, it will -produce a warning that you might be generating invalid UTF-8. +When UTF-8 becomes the standard source format, this pragma will +effectively become a no-op. For convenience in what follows the term +I is used to refer to UTF-8 on ASCII and ISO Latin based +platforms and UTF-EBCDIC on EBCDIC based platforms. -=item * +See also the effects of the C<-C> switch and its cousin, the +C<$ENV{PERL_UNICODE}>, in L. -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.) +Enabling the C pragma has the following effect: + +=over 4 =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>).) +Bytes in the source text that have their high-bit set will be treated +as being part of a literal UTF-X sequence. This includes most +literals such as identifier names, string constants, and constant +regular expression patterns. -=item * +On EBCDIC platforms characters in the Latin 1 character set are +treated as being part of a literal UTF-EBCDIC character. -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. +=back -=item * +Note that if you have bytes with the eighth bit on in your script +(for example embedded Latin-1 in your string literals), C +will be unhappy since the bytes are most probably not well-formed +UTF-X. If you want to have such bytes under C, you can disable +this pragma until the end the block (or file, if at top level) by +C. -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}>. +=head2 Utility functions -=item * +The following functions are defined in the C package by the +Perl core. You do not need to say C to use these and in fact +you should not say that unless you really want to have UTF-8 source code. + +=over 4 -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 * $num_octets = utf8::upgrade($string) -=item * +Converts in-place the internal octet sequence in the native encoding +(Latin-1 or EBCDIC) to the equivalent character sequence in I. +I<$string> already encoded as characters does no harm. Returns the +number of octets necessary to represent the string as I. Can be +used to make sure that the UTF-8 flag is on, so that C<\w> or C +work as Unicode on strings containing characters in the range 0x80-0xFF +(on ASCII and derivatives). -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: +B +Therefore Encode is recommended for the general purposes; see also +L. - use utf8; - while (<>) { - tr/\0-\xff//CU; # latin1 char to utf8 - ... - } +=item * $success = utf8::downgrade($string[, FAIL_OK]) -Similarly you could translate your output with +Converts in-place the internal octet sequence in I to the +equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). +I<$string> already encoded as native 8 bit does no harm. Can be used to +make sure that the UTF-8 flag is off, e.g. when you want to make sure +that the substr() or length() function works with the usually faster +byte algorithm. - tr/\0-\x{ff}//UC; # utf8 to latin1 char +Fails if the original I sequence cannot be represented in the +native 8 bit encoding. On failure dies or, if the value of C is +true, returns false. -No, C doesn't take /U or /C (yet?). +Returns true on success. -=item * +B +Therefore Encode is recommended for the general purposes; see also +L. -Case translation operators use the Unicode case translation tables. -Note that C translates to uppercase, while C translates -to titlecase (for languages that make the distinction). Naturally -the corresponding backslash sequences have the same semantics. +=item * utf8::encode($string) -=item * +Converts in-place the character sequence to the corresponding octet +sequence in I. The UTF8 flag is turned off, so that after this +operation, the string is a byte string. Returns nothing. -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. +B +Therefore Encode is recommended for the general purposes; see also +L. -=item * +=item * $success = utf8::decode($string) -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.) +Attempts to convert in-place the octet sequence in I to the +corresponding character sequence. The UTF-8 flag is turned on only if +the source string contains multiple-byte I characters. If +I<$string> is invalid as I, returns false; otherwise returns +true. -=item * +B +Therefore Encode is recommended for the general purposes; see also +L. -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 * $flag = utf8::is_utf8(STRING) -=item * +(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. +Functionally the same as Encode::is_utf8(). + +=item * $flag = utf8::valid(STRING) -And finally, C reverses by character rather than by byte. +[INTERNAL] Test whether STRING is in a consistent state regarding +UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag +on B if string is held as bytes (both these states are 'consistent'). +Main reason for this routine is to allow Perl's testsuite to check +that operations have left strings in a consistent state. You most +probably want to use utf8::is_utf8() instead. =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. - -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. +C is like C, but the UTF8 flag is +cleared. See L for more on the UTF8 flag and the C API +functions C, C, C, +and C, which are wrapped by the Perl functions +C, C, C and +C. Also, the functions utf8::is_utf8, utf8::valid, +utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are +actually internal, and thus always available, without a C +statement. + +=head1 BUGS + +One can have Unicode in identifier names, but not in package/class or +subroutine names. While some limited functionality towards this does +exist as of Perl 5.8.0, that is more accidental than designed; use of +Unicode for the said purposes is unsupported. + +One reason of this unfinishedness is its (currently) inherent +unportability: since both package names and subroutine names may need +to be mapped to file and directory names, the Unicode capability of +the filesystem becomes important-- and there unfortunately aren't +portable answers. + +=head1 SEE ALSO + +L, L, L, L, L =cut