X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/7d865a9101bac3fd36e6d9d186fde02f53394ed4..0320cda07264be63db1ffb5e9512ee11cad682e8:/lib/utf8.pm diff --git a/lib/utf8.pm b/lib/utf8.pm index c748a49..ed0a4d8 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 = '1.08'; 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"); } @@ -31,6 +32,20 @@ utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code use utf8; no utf8; + # Convert the internal representation of a Perl scalar to/from UTF-8. + + $num_octets = utf8::upgrade($string); + $success = utf8::downgrade($string[, FAIL_OK]); + + # Change each character of a Perl scalar to/from a series of + # characters that represent the UTF-8 bytes of each original character. + + utf8::encode($string); # "\x{100}" becomes "\xc4\x80" + utf8::decode($string); # "\xc4\x80" becomes "\x{100}" + + $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 + $flag = utf8::valid(STRING); + =head1 DESCRIPTION The C pragma tells the Perl parser to allow UTF-8 in the @@ -38,16 +53,22 @@ program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based platforms). The C pragma tells Perl to switch back to treating the source text as literal bytes in the current lexical scope. -This pragma is primarily a compatibility device. Perl versions -earlier than 5.6 allowed arbitrary bytes in source code, whereas -in future we would like to standardize on the UTF-8 encoding for -source text. Until UTF-8 becomes the default format for source -text, this pragma should be used to recognize UTF-8 in the source. +B The utility functions described below are +directly usable without C. + +Because it is not possible to reliably tell UTF-8 from native 8 bit +encodings, you need either a Byte Order Mark at the beginning of your +source code, or C, to instruct perl. + When UTF-8 becomes the standard source format, this pragma will -effectively become a no-op. For convenience in what follows the -term I is used to refer to UTF-8 on ASCII and ISO Latin based +effectively become a no-op. For convenience in what follows the term +I is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms. +See also the effects of the C<-C> switch and its cousin, the +C<$ENV{PERL_UNICODE}>, in L. + Enabling the C pragma has the following effect: =over 4 @@ -55,69 +76,111 @@ 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 representation of the string from an octet +sequence in the native encoding (Latin-1 or EBCDIC) to I. The +logical character sequence itself is unchanged. If I<$string> is already +stored as I, then this is a no-op. 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. -Converts (in-place) internal representation of string to Perl's internal -I form. 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 expected on strings -containing characters in the range 0x80-0xFF. Note that this should -not be used to convert -a legacy byte encoding to Unicode: use Encode for that. Affected -by the encoding pragma. +=item * $success = utf8::downgrade($string[, FAIL_OK]) -=item * utf8::downgrade($string[, FAIL_OK]) +Converts in-place the the internal representation of the string from +I to the equivalent octet sequence in the native encoding (Latin-1 +or EBCDIC). The logical character sequence itself is unchanged. If +I<$string> is already stored as native 8 bit, then this is a no-op. 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. -Converts (in-place) internal representation of string to be un-encoded -bytes. Returns true on success. On failure dies or, if the value of -FAIL_OK is true, returns false. 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. -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. +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. + +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. Same as -Encode::encode_utf8(). 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. That is, every (possibly wide) character gets +replaced with a sequence of one or more characters that represent the +individual I bytes of the character. The UTF8 flag is turned off. +Returns nothing. + + my $a = "\x{100}"; # $a contains one character, with ord 0x100 + utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80 + +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. That is, it replaces each sequence of +characters in the string whose ords represent a valid UTF-X byte +sequence, with the corresponding single character. 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 * $flag = utf8::decode($string) + my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80 + utf8::decode($a); # $a contains one character, with ord 0x100 -Attempts to convert I<$string> in-place from Perl's I encoding -into logical characters. Same as Encode::decode_utf8(). Note that this -should not be used to convert Unicode back to a legacy byte encoding: -use Encode for that. +B +Therefore Encode is recommended for the general purposes; see also +L. + +=item * $flag = utf8::is_utf8(STRING) + +(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. Will return -true if string is held as bytes, or is well-formed UTF-8 and has the -UTF-8 flag on. Main reason for this routine is to allow Perl's -testsuite to check that operations have left strings in a consistent -state. +[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 @@ -126,13 +189,26 @@ 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. Note that in the Perl 5.8.0 implementation the -functions utf8::valid, utf8::encode, utf8::decode, utf8::upgrade, -and utf8::downgrade are always available, without a C -statement-- this may change in future releases. +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