X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=a985021f32a40f2857b6eb4d5e0a59decbc7b376;hb=a06bfbf46ad8e21060b59ed409ba2f87fbfcdc35;hp=9023eb6eb2363edbdb54009c50d4c580005ddaee;hpb=094ce63c66fa8d25297cfc86e6aed299ee830254;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/utf8.pm b/lib/utf8.pm index 9023eb6..a985021 100644 --- a/lib/utf8.pm +++ b/lib/utf8.pm @@ -2,7 +2,7 @@ package utf8; $utf8::hint_bits = 0x00800000; -our $VERSION = '1.00'; +our $VERSION = '1.07'; sub import { $^H |= $utf8::hint_bits; @@ -16,6 +16,7 @@ sub unimport { sub AUTOLOAD { require "utf8_heavy.pl"; goto &$AUTOLOAD if defined &$AUTOLOAD; + require Carp; Carp::croak("Undefined subroutine $AUTOLOAD called"); } @@ -31,23 +32,40 @@ utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code 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 + $flag = utf8::valid(STRING); + =head1 DESCRIPTION The C pragma tells the Perl parser to allow UTF-8 in the program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based -platforms). The C pragma tells Perl to switch back to treating +platforms). The C pragma tells Perl to switch back to treating the source text as literal bytes in the current lexical scope. -This pragma is primarily a compatibility device. Perl versions -earlier than 5.6 allowed arbitrary bytes in source code, whereas -in future we would like to standardize on the UTF-8 encoding for -source text. Until UTF-8 becomes the default format for source -text, this pragma should be used to recognize UTF-8 in the source. +B The utility functions described below are +directly usable without C. + +Because it is not possible to reliably tell UTF-8 from native 8 bit +encodings, you need either a Byte Order Mark at the beginning of your +source code, or C, to instruct perl. + When UTF-8 becomes the standard source format, this pragma will -effectively become a no-op. For convenience in what follows the -term I is used to refer to UTF-8 on ASCII and ISO Latin based +effectively become a no-op. For convenience in what follows the term +I is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms. +See also the effects of the C<-C> switch and its cousin, the +C<$ENV{PERL_UNICODE}>, in L. + Enabling the C pragma has the following effect: =over 4 @@ -55,65 +73,126 @@ Enabling the C pragma has the following effect: =item * 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. On EBCDIC platforms characters -in the Latin 1 character set are treated as being part of a literal -UTF-EBCDIC character. +as being part of a literal UTF-X sequence. This includes most +literals such as identifier names, string constants, and constant +regular expression patterns. + +On EBCDIC platforms characters in the Latin 1 character set are +treated as being part of a literal UTF-EBCDIC character. =back 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-8. If you want to have such bytes and use utf8, you can disable -utf8 until the end the block (or file, if at top level) by C. +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. =head2 Utility functions -The following functions are defined in the C package by the perl core. +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 -=item * $num_octets = utf8::upgrade($string); +=item * $num_octets = utf8::upgrade($string) + +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). + +B +Therefore Encode is recommended for the general purposes; see also +L. + +=item * $success = utf8::downgrade($string[, FAIL_OK]) -Converts internal representation of string to the Perl's internal -I form. Returns the number of octets necessary to represent -the string as I. Note that this should not be used to convert -a legacy byte encoding to Unicode: use Encode for that. Affected -by the encoding pragma. +Converts in-place the internal octet sequence in I to the +equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). +I<$string> already encoded as native 8 bit does no harm. Can be used to +make sure that the UTF-8 flag is off, e.g. when you want to make sure +that the substr() or length() function works with the usually faster +byte algorithm. -=item * utf8::downgrade($string[, CHECK]) +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. -Converts internal representation of string to be un-encoded bytes. -Note that this should not be used to convert Unicode back to a legacy -byte encoding: use Encode for that. B affected by the encoding -pragma. +Returns true on success. + +B +Therefore Encode is recommended for the general purposes; see also +L. =item * utf8::encode($string) -Converts (in-place) I<$string> from logical characters to octet -sequence representing it in Perl's I encoding. Note that this -should not be used to convert a legacy byte encoding to Unicode: use -Encode for that. +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. + +B +Therefore Encode is recommended for the general purposes; see also +L. + +=item * $success = utf8::decode($string) + +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. + +B +Therefore Encode is recommended for the general purposes; see also +L. -=item * $flag = utf8::decode($string) +=item * $flag = utf8::is_utf8(STRING) -Attempts to convert I<$string> in-place from Perl's I encoding -into logical characters. Note that this should not be used to convert -Unicode back to a legacy byte encoding: use Encode for that. +(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) + +[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 -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, +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. +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, L, L =cut