1package utf8; 2 3use strict; 4use warnings; 5 6our $hint_bits = 0x00800000; 7 8our $VERSION = '1.24'; 9our $AUTOLOAD; 10 11sub import { 12 $^H |= $hint_bits; 13} 14 15sub unimport { 16 $^H &= ~$hint_bits; 17} 18 19sub AUTOLOAD { 20 goto &$AUTOLOAD if defined &$AUTOLOAD; 21 require Carp; 22 Carp::croak("Undefined subroutine $AUTOLOAD called"); 23} 24 251; 26__END__ 27 28=head1 NAME 29 30utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code 31 32=head1 SYNOPSIS 33 34 use utf8; 35 no utf8; 36 37 # Convert the internal representation of a Perl scalar to/from UTF-8. 38 39 $num_octets = utf8::upgrade($string); 40 $success = utf8::downgrade($string[, $fail_ok]); 41 42 # Change each character of a Perl scalar to/from a series of 43 # characters that represent the UTF-8 bytes of each original character. 44 45 utf8::encode($string); # "\x{100}" becomes "\xc4\x80" 46 utf8::decode($string); # "\xc4\x80" becomes "\x{100}" 47 48 # Convert a code point from the platform native character set to 49 # Unicode, and vice-versa. 50 $unicode = utf8::native_to_unicode(ord('A')); # returns 65 on both 51 # ASCII and EBCDIC 52 # platforms 53 $native = utf8::unicode_to_native(65); # returns 65 on ASCII 54 # platforms; 193 on 55 # EBCDIC 56 57 $flag = utf8::is_utf8($string); # since Perl 5.8.1 58 $flag = utf8::valid($string); 59 60=head1 DESCRIPTION 61 62The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the 63program text in the current lexical scope. The C<no utf8> pragma tells Perl 64to switch back to treating the source text as literal bytes in the current 65lexical scope. (On EBCDIC platforms, technically it is allowing UTF-EBCDIC, 66and not UTF-8, but this distinction is academic, so in this document the term 67UTF-8 is used to mean both). 68 69B<Do not use this pragma for anything else than telling Perl that your 70script is written in UTF-8.> The utility functions described below are 71directly usable without C<use utf8;>. 72 73Because it is not possible to reliably tell UTF-8 from native 8 bit 74encodings, you need either a Byte Order Mark at the beginning of your 75source code, or C<use utf8;>, to instruct perl. 76 77When UTF-8 becomes the standard source format, this pragma will 78effectively become a no-op. 79 80See also the effects of the C<-C> switch and its cousin, the 81C<PERL_UNICODE> environment variable, in L<perlrun>. 82 83Enabling the C<utf8> pragma has the following effect: 84 85=over 4 86 87=item * 88 89Bytes in the source text that are not in the ASCII character set will be 90treated as being part of a literal UTF-8 sequence. This includes most 91literals such as identifier names, string constants, and constant 92regular expression patterns. 93 94=back 95 96Note that if you have non-ASCII, non-UTF-8 bytes in your script (for example 97embedded Latin-1 in your string literals), C<use utf8> will be unhappy. If 98you want to have such bytes under C<use utf8>, you can disable this pragma 99until the end the block (or file, if at top level) by C<no utf8;>. 100 101=head2 Utility functions 102 103The following functions are defined in the C<utf8::> package by the 104Perl core. You do not need to say C<use utf8> to use these and in fact 105you should not say that unless you really want to have UTF-8 source code. 106 107=over 4 108 109=item * C<$num_octets = utf8::upgrade($string)> 110 111(Since Perl v5.8.0) 112Converts in-place the internal representation of the string from an octet 113sequence in the native encoding (Latin-1 or EBCDIC) to UTF-8. The 114logical character sequence itself is unchanged. If I<$string> is already 115upgraded, then this is a no-op. Returns the 116number of octets necessary to represent the string as UTF-8. 117 118If your code needs to be compatible with versions of perl without 119C<use feature 'unicode_strings';>, you can force Unicode semantics on 120a given string: 121 122 # force unicode semantics for $string without the 123 # "unicode_strings" feature 124 utf8::upgrade($string); 125 126For example: 127 128 # without explicit or implicit use feature 'unicode_strings' 129 my $x = "\xDF"; # LATIN SMALL LETTER SHARP S 130 $x =~ /ss/i; # won't match 131 my $y = uc($x); # won't convert 132 utf8::upgrade($x); 133 $x =~ /ss/i; # matches 134 my $z = uc($x); # converts to "SS" 135 136B<Note that this function does not handle arbitrary encodings>; 137use L<Encode> instead. 138 139=item * C<$success = utf8::downgrade($string[, $fail_ok])> 140 141(Since Perl v5.8.0) 142Converts in-place the internal representation of the string from UTF-8 to the 143equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The 144logical character sequence itself is unchanged. If I<$string> is already 145stored as native 8 bit, then this is a no-op. Can be used to make sure that 146the UTF-8 flag is off, e.g. when you want to make sure that the substr() or 147length() function works with the usually faster byte algorithm. 148 149Fails if the original UTF-8 sequence cannot be represented in the 150native 8 bit encoding. On failure dies or, if the value of I<$fail_ok> is 151true, returns false. 152 153Returns true on success. 154 155If your code expects an octet sequence this can be used to validate 156that you've received one: 157 158 # throw an exception if not representable as octets 159 utf8::downgrade($string) 160 161 # or do your own error handling 162 utf8::downgrade($string, 1) or die "string must be octets"; 163 164B<Note that this function does not handle arbitrary encodings>; 165use L<Encode> instead. 166 167=item * C<utf8::encode($string)> 168 169(Since Perl v5.8.0) 170Converts in-place the character sequence to the corresponding octet 171sequence in Perl's extended UTF-8. That is, every (possibly wide) character 172gets replaced with a sequence of one or more characters that represent the 173individual UTF-8 bytes of the character. The UTF8 flag is turned off. 174Returns nothing. 175 176 my $x = "\x{100}"; # $x contains one character, with ord 0x100 177 utf8::encode($x); # $x contains two characters, with ords (on 178 # ASCII platforms) 0xc4 and 0x80. On EBCDIC 179 # 1047, this would instead be 0x8C and 0x41. 180 181Similar to: 182 183 use Encode; 184 $x = Encode::encode("utf8", $x); 185 186B<Note that this function does not handle arbitrary encodings>; 187use L<Encode> instead. 188 189=item * C<$success = utf8::decode($string)> 190 191(Since Perl v5.8.0) 192Attempts to convert in-place the octet sequence encoded in Perl's extended 193UTF-8 to the corresponding character sequence. That is, it replaces each 194sequence of characters in the string whose ords represent a valid (extended) 195UTF-8 byte sequence, with the corresponding single character. The UTF-8 flag 196is turned on only if the source string contains multiple-byte UTF-8 197characters. If I<$string> is invalid as extended UTF-8, returns false; 198otherwise returns true. 199 200 my $x = "\xc4\x80"; # $x contains two characters, with ords 201 # 0xc4 and 0x80 202 utf8::decode($x); # On ASCII platforms, $x contains one char, 203 # with ord 0x100. Since these bytes aren't 204 # legal UTF-EBCDIC, on EBCDIC platforms, $x is 205 # unchanged and the function returns FALSE. 206 my $y = "\xc3\x83\xc2\xab"; This has been encoded twice; this 207 # example is only for ASCII platforms 208 utf8::decode($y); # Converts $y to \xc3\xab, returns TRUE; 209 utf8::decode($y); # Further converts to \xeb, returns TRUE; 210 utf8::decode($y); # Returns FALSE, leaves $y unchanged 211 212B<Note that this function does not handle arbitrary encodings>; 213use L<Encode> instead. 214 215=item * C<$unicode = utf8::native_to_unicode($code_point)> 216 217(Since Perl v5.8.0) 218This takes an unsigned integer (which represents the ordinal number of a 219character (or a code point) on the platform the program is being run on) and 220returns its Unicode equivalent value. Since ASCII platforms natively use the 221Unicode code points, this function returns its input on them. On EBCDIC 222platforms it converts from EBCDIC to Unicode. 223 224A meaningless value will currently be returned if the input is not an unsigned 225integer. 226 227Since Perl v5.22.0, calls to this function are optimized out on ASCII 228platforms, so there is no performance hit in using it there. 229 230=item * C<$native = utf8::unicode_to_native($code_point)> 231 232(Since Perl v5.8.0) 233This is the inverse of C<utf8::native_to_unicode()>, converting the other 234direction. Again, on ASCII platforms, this returns its input, but on EBCDIC 235platforms it will find the native platform code point, given any Unicode one. 236 237A meaningless value will currently be returned if the input is not an unsigned 238integer. 239 240Since Perl v5.22.0, calls to this function are optimized out on ASCII 241platforms, so there is no performance hit in using it there. 242 243=item * C<$flag = utf8::is_utf8($string)> 244 245(Since Perl 5.8.1) Test whether I<$string> is marked internally as encoded in 246UTF-8. Functionally the same as C<Encode::is_utf8($string)>. 247 248Typically only necessary for debugging and testing, if you need to 249dump the internals of an SV, L<Devel::Peek's|Devel::Peek> Dump() 250provides more detail in a compact form. 251 252If you still think you need this outside of debugging, testing or 253dealing with filenames, you should probably read L<perlunitut> and 254L<perlunifaq/What is "the UTF8 flag"?>. 255 256Don't use this flag as a marker to distinguish character and binary 257data: that should be decided for each variable when you write your 258code. 259 260To force unicode semantics in code portable to perl 5.8 and 5.10, call 261C<utf8::upgrade($string)> unconditionally. 262 263=item * C<$flag = utf8::valid($string)> 264 265[INTERNAL] Test whether I<$string> is in a consistent state regarding 266UTF-8. Will return true if it is well-formed Perl extended UTF-8 and has the 267UTF-8 flag 268on B<or> if I<$string> is held as bytes (both these states are 'consistent'). 269The main reason for this routine is to allow Perl's test suite to check 270that operations have left strings in a consistent state. 271 272=back 273 274C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is 275cleared. See L<perlunicode>, and the C API 276functions C<L<sv_utf8_upgrade|perlapi/sv_utf8_upgrade>>, 277C<L<perlapi/sv_utf8_downgrade>>, C<L<perlapi/sv_utf8_encode>>, 278and C<L<perlapi/sv_utf8_decode>>, which are wrapped by the Perl functions 279C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and 280C<utf8::decode>. Also, the functions C<utf8::is_utf8>, C<utf8::valid>, 281C<utf8::encode>, C<utf8::decode>, C<utf8::upgrade>, and C<utf8::downgrade> are 282actually internal, and thus always available, without a C<require utf8> 283statement. 284 285=head1 BUGS 286 287Some filesystems may not support UTF-8 file names, or they may be supported 288incompatibly with Perl. Therefore UTF-8 names that are visible to the 289filesystem, such as module names may not work. 290 291=head1 SEE ALSO 292 293L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> 294 295=cut 296