X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/4ac9195fe27b27610b09db5d1e9a4a36a7b59787..0c50e9158896a33f8e2c4ec35ba33d7eff021f08:/lib/utf8.pm diff --git a/lib/utf8.pm b/lib/utf8.pm index f9055b5..9d56095 100644 --- a/lib/utf8.pm +++ b/lib/utf8.pm @@ -1,14 +1,11 @@ package utf8; -if (ord('A') != 193) { # make things more pragmatic for EBCDIC folk - $utf8::hint_bits = 0x00800000; -our $VERSION = '1.00'; +our $VERSION = '1.21'; sub import { $^H |= $utf8::hint_bits; - $enc{caller()} = $_[1] if $_[1]; } sub unimport { @@ -18,71 +15,273 @@ sub unimport { sub AUTOLOAD { require "utf8_heavy.pl"; goto &$AUTOLOAD if defined &$AUTOLOAD; + require Carp; Carp::croak("Undefined subroutine $AUTOLOAD called"); } -} - 1; __END__ =head1 NAME -utf8 - Perl pragma to enable/disable UTF-8 in source code +utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code =head1 SYNOPSIS - use utf8; - no utf8; + use utf8; + no utf8; -=head1 DESCRIPTION + # 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}" + + # Convert a code point from the platform native character set to + # Unicode, and vice-versa. + $unicode = utf8::native_to_unicode(ord('A')); # returns 65 on both + # ASCII and EBCDIC + # platforms + $native = utf8::unicode_to_native(65); # returns 65 on ASCII + # platforms; 193 on + # EBCDIC -WARNING: The implementation of Unicode support in Perl is incomplete. -See L for the exact details. + $flag = utf8::is_utf8($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. 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. +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. (On EBCDIC platforms, technically it is allowing UTF-EBCDIC, +and not UTF-8, but this distinction is academic, so in this document the term +UTF-8 is used to mean both). + +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. This pragma already is a no-op on -EBCDIC platforms (where it is alright to code perl in EBCDIC -rather than UTF-8). +effectively become a no-op. + +See also the effects of the C<-C> switch and its cousin, the +C environment variable, in L. -Enabling the C pragma has the following effects: +Enabling the C pragma has the following effect: =over 4 =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. +Bytes in the source text that are not in the ASCII character set will be +treated as being part of a literal UTF-8 sequence. This includes most +literals such as identifier names, string constants, and constant +regular expression patterns. -=item * +=back + +Note that if you have non-ASCII, non-UTF-8 bytes in your script (for example +embedded Latin-1 in your string literals), C will be unhappy. 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. 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 * C<$num_octets = utf8::upgrade($string)> + +(Since Perl v5.8.0) +Converts in-place the internal representation of the string from an octet +sequence in the native encoding (Latin-1 or EBCDIC) to UTF-8. The +logical character sequence itself is unchanged. If I<$string> is already +upgraded, then this is a no-op. Returns the +number of octets necessary to represent the string as UTF-8. + +If your code needs to be compatible with versions of perl without +C, you can force Unicode semantics on +a given string: + + # force unicode semantics for $string without the + # "unicode_strings" feature + utf8::upgrade($string); + +For example: + + # without explicit or implicit use feature 'unicode_strings' + my $x = "\xDF"; # LATIN SMALL LETTER SHARP S + $x =~ /ss/i; # won't match + my $y = uc($x); # won't convert + utf8::upgrade($x); + $x =~ /ss/i; # matches + my $z = uc($x); # converts to "SS" + +B; +use L instead. + +=item * C<$success = utf8::downgrade($string[, $fail_ok])> + +(Since Perl v5.8.0) +Converts in-place the internal representation of the string from UTF-8 to the +equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The +logical character sequence itself is unchanged. If I<$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. + +Fails if the original UTF-8 sequence cannot be represented in the +native 8 bit encoding. On failure dies or, if the value of I<$fail_ok> is +true, returns false. + +Returns true on success. -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. +If your code expects an octet sequence this can be used to validate +that you've received one: - @bytes_or_chars = split //, $data; # may split to bytes if data - # $data isn't UTF-8 - { - use utf8; # force char semantics - @chars = split //, $data; # splits characters - } + # throw an exception if not representable as octets + utf8::downgrade($string) + + # or do your own error handling + utf8::downgrade($string, 1) or die "string must be octets"; + +B; +use L instead. + +=item * C + +(Since Perl v5.8.0) +Converts in-place the character sequence to the corresponding octet +sequence in Perl's extended UTF-8. That is, every (possibly wide) character +gets replaced with a sequence of one or more characters that represent the +individual UTF-8 bytes of the character. The UTF8 flag is turned off. +Returns nothing. + + my $x = "\x{100}"; # $x contains one character, with ord 0x100 + utf8::encode($x); # $x contains two characters, with ords (on + # ASCII platforms) 0xc4 and 0x80. On EBCDIC + # 1047, this would instead be 0x8C and 0x41. + +Similar to: + + use Encode; + $x = Encode::encode("utf8", $x); + +B; +use L instead. + +=item * C<$success = utf8::decode($string)> + +(Since Perl v5.8.0) +Attempts to convert in-place the octet sequence encoded in Perl's extended +UTF-8 to the corresponding character sequence. That is, it replaces each +sequence of characters in the string whose ords represent a valid (extended) +UTF-8 byte sequence, with the corresponding single character. The UTF-8 flag +is turned on only if the source string contains multiple-byte UTF-8 +characters. If I<$string> is invalid as extended UTF-8, returns false; +otherwise returns true. + + my $x = "\xc4\x80"; # $x contains two characters, with ords + # 0xc4 and 0x80 + utf8::decode($x); # On ASCII platforms, $x contains one char, + # with ord 0x100. Since these bytes aren't + # legal UTF-EBCDIC, on EBCDIC platforms, $x is + # unchanged and the function returns FALSE. + +B; +use L instead. + +=item * C<$unicode = utf8::native_to_unicode($code_point)> + +(Since Perl v5.8.0) +This takes an unsigned integer (which represents the ordinal number of a +character (or a code point) on the platform the program is being run on) and +returns its Unicode equivalent value. Since ASCII platforms natively use the +Unicode code points, this function returns its input on them. On EBCDIC +platforms it converts from EBCDIC to Unicode. + +A meaningless value will currently be returned if the input is not an unsigned +integer. + +Since Perl v5.22.0, calls to this function are optimized out on ASCII +platforms, so there is no performance hit in using it there. + +=item * C<$native = utf8::unicode_to_native($code_point)> + +(Since Perl v5.8.0) +This is the inverse of C, converting the other +direction. Again, on ASCII platforms, this returns its input, but on EBCDIC +platforms it will find the native platform code point, given any Unicode one. + +A meaningless value will currently be returned if the input is not an unsigned +integer. + +Since Perl v5.22.0, calls to this function are optimized out on ASCII +platforms, so there is no performance hit in using it there. + +=item * C<$flag = utf8::is_utf8($string)> + +(Since Perl 5.8.1) Test whether I<$string> is marked internally as encoded in +UTF-8. Functionally the same as C. + +Typically only necessary for debugging and testing, if you need to +dump the internals of an SV, L Dump() +provides more detail in a compact form. + +If you still think you need this outside of debugging, testing or +dealing with filenames, you should probably read L and +L. + +Don't use this flag as a marker to distinguish character and binary +data: that should be decided for each variable when you write your +code. + +To force unicode semantics in code portable to perl 5.8 and 5.10, call +C unconditionally. + +=item * C<$flag = utf8::valid($string)> + +[INTERNAL] Test whether I<$string> is in a consistent state regarding +UTF-8. Will return true if it is well-formed Perl extended UTF-8 and has the +UTF-8 flag +on B if I<$string> is held as bytes (both these states are 'consistent'). +The main reason for this routine is to allow Perl's test suite to check +that operations have left strings in a consistent state. =back +C is like C, but the UTF8 flag is +cleared. See L, 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 C, C, +C, C, C, and C are +actually internal, and thus always available, without a C +statement. + +=head1 BUGS + +Some filesystems may not support UTF-8 file names, or they may be supported +incompatibly with Perl. Therefore UTF-8 names that are visible to the +filesystem, such as module names may not work. + =head1 SEE ALSO -L, L +L, L, L, L, L =cut