| 1 | package utf8; |
| 2 | |
| 3 | $utf8::hint_bits = 0x00800000; |
| 4 | |
| 5 | our $VERSION = '1.08'; |
| 6 | |
| 7 | sub import { |
| 8 | $^H |= $utf8::hint_bits; |
| 9 | $enc{caller()} = $_[1] if $_[1]; |
| 10 | } |
| 11 | |
| 12 | sub unimport { |
| 13 | $^H &= ~$utf8::hint_bits; |
| 14 | } |
| 15 | |
| 16 | sub AUTOLOAD { |
| 17 | require "utf8_heavy.pl"; |
| 18 | goto &$AUTOLOAD if defined &$AUTOLOAD; |
| 19 | require Carp; |
| 20 | Carp::croak("Undefined subroutine $AUTOLOAD called"); |
| 21 | } |
| 22 | |
| 23 | 1; |
| 24 | __END__ |
| 25 | |
| 26 | =head1 NAME |
| 27 | |
| 28 | utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code |
| 29 | |
| 30 | =head1 SYNOPSIS |
| 31 | |
| 32 | use utf8; |
| 33 | no utf8; |
| 34 | |
| 35 | # Convert the internal representation of a Perl scalar to/from UTF-8. |
| 36 | |
| 37 | $num_octets = utf8::upgrade($string); |
| 38 | $success = utf8::downgrade($string[, FAIL_OK]); |
| 39 | |
| 40 | # Change each character of a Perl scalar to/from a series of |
| 41 | # characters that represent the UTF-8 bytes of each original character. |
| 42 | |
| 43 | utf8::encode($string); # "\x{100}" becomes "\xc4\x80" |
| 44 | utf8::decode($string); # "\xc4\x80" becomes "\x{100}" |
| 45 | |
| 46 | $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 |
| 47 | $flag = utf8::valid(STRING); |
| 48 | |
| 49 | =head1 DESCRIPTION |
| 50 | |
| 51 | The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the |
| 52 | program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based |
| 53 | platforms). The C<no utf8> pragma tells Perl to switch back to treating |
| 54 | the source text as literal bytes in the current lexical scope. |
| 55 | |
| 56 | B<Do not use this pragma for anything else than telling Perl that your |
| 57 | script is written in UTF-8.> The utility functions described below are |
| 58 | directly usable without C<use utf8;>. |
| 59 | |
| 60 | Because it is not possible to reliably tell UTF-8 from native 8 bit |
| 61 | encodings, you need either a Byte Order Mark at the beginning of your |
| 62 | source code, or C<use utf8;>, to instruct perl. |
| 63 | |
| 64 | When UTF-8 becomes the standard source format, this pragma will |
| 65 | effectively become a no-op. For convenience in what follows the term |
| 66 | I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based |
| 67 | platforms and UTF-EBCDIC on EBCDIC based platforms. |
| 68 | |
| 69 | See also the effects of the C<-C> switch and its cousin, the |
| 70 | C<$ENV{PERL_UNICODE}>, in L<perlrun>. |
| 71 | |
| 72 | Enabling the C<utf8> pragma has the following effect: |
| 73 | |
| 74 | =over 4 |
| 75 | |
| 76 | =item * |
| 77 | |
| 78 | Bytes in the source text that have their high-bit set will be treated |
| 79 | as being part of a literal UTF-X sequence. This includes most |
| 80 | literals such as identifier names, string constants, and constant |
| 81 | regular expression patterns. |
| 82 | |
| 83 | On EBCDIC platforms characters in the Latin 1 character set are |
| 84 | treated as being part of a literal UTF-EBCDIC character. |
| 85 | |
| 86 | =back |
| 87 | |
| 88 | Note that if you have bytes with the eighth bit on in your script |
| 89 | (for example embedded Latin-1 in your string literals), C<use utf8> |
| 90 | will be unhappy since the bytes are most probably not well-formed |
| 91 | UTF-X. If you want to have such bytes under C<use utf8>, you can disable |
| 92 | this pragma until the end the block (or file, if at top level) by |
| 93 | C<no utf8;>. |
| 94 | |
| 95 | =head2 Utility functions |
| 96 | |
| 97 | The following functions are defined in the C<utf8::> package by the |
| 98 | Perl core. You do not need to say C<use utf8> to use these and in fact |
| 99 | you should not say that unless you really want to have UTF-8 source code. |
| 100 | |
| 101 | =over 4 |
| 102 | |
| 103 | =item * $num_octets = utf8::upgrade($string) |
| 104 | |
| 105 | Converts in-place the internal representation of the string from an octet |
| 106 | sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The |
| 107 | logical character sequence itself is unchanged. If I<$string> is already |
| 108 | stored as I<UTF-X>, then this is a no-op. Returns the |
| 109 | number of octets necessary to represent the string as I<UTF-X>. Can be |
| 110 | used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()> |
| 111 | work as Unicode on strings containing characters in the range 0x80-0xFF |
| 112 | (on ASCII and derivatives). |
| 113 | |
| 114 | B<Note that this function does not handle arbitrary encodings.> |
| 115 | Therefore Encode is recommended for the general purposes; see also |
| 116 | L<Encode>. |
| 117 | |
| 118 | =item * $success = utf8::downgrade($string[, FAIL_OK]) |
| 119 | |
| 120 | Converts in-place the the internal representation of the string from |
| 121 | I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1 |
| 122 | or EBCDIC). The logical character sequence itself is unchanged. If |
| 123 | I<$string> is already stored as native 8 bit, then this is a no-op. Can |
| 124 | be used to |
| 125 | make sure that the UTF-8 flag is off, e.g. when you want to make sure |
| 126 | that the substr() or length() function works with the usually faster |
| 127 | byte algorithm. |
| 128 | |
| 129 | Fails if the original I<UTF-X> sequence cannot be represented in the |
| 130 | native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is |
| 131 | true, returns false. |
| 132 | |
| 133 | Returns true on success. |
| 134 | |
| 135 | B<Note that this function does not handle arbitrary encodings.> |
| 136 | Therefore Encode is recommended for the general purposes; see also |
| 137 | L<Encode>. |
| 138 | |
| 139 | =item * utf8::encode($string) |
| 140 | |
| 141 | Converts in-place the character sequence to the corresponding octet |
| 142 | sequence in I<UTF-X>. That is, every (possibly wide) character gets |
| 143 | replaced with a sequence of one or more characters that represent the |
| 144 | individual I<UTF-X> bytes of the character. The UTF8 flag is turned off. |
| 145 | Returns nothing. |
| 146 | |
| 147 | my $a = "\x{100}"; # $a contains one character, with ord 0x100 |
| 148 | utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80 |
| 149 | |
| 150 | B<Note that this function does not handle arbitrary encodings.> |
| 151 | Therefore Encode is recommended for the general purposes; see also |
| 152 | L<Encode>. |
| 153 | |
| 154 | =item * $success = utf8::decode($string) |
| 155 | |
| 156 | Attempts to convert in-place the octet sequence in I<UTF-X> to the |
| 157 | corresponding character sequence. That is, it replaces each sequence of |
| 158 | characters in the string whose ords represent a valid UTF-X byte |
| 159 | sequence, with the corresponding single character. The UTF-8 flag is |
| 160 | turned on only if the source string contains multiple-byte I<UTF-X> |
| 161 | characters. If I<$string> is invalid as I<UTF-X>, returns false; |
| 162 | otherwise returns true. |
| 163 | |
| 164 | my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80 |
| 165 | utf8::decode($a); # $a contains one character, with ord 0x100 |
| 166 | |
| 167 | B<Note that this function does not handle arbitrary encodings.> |
| 168 | Therefore Encode is recommended for the general purposes; see also |
| 169 | L<Encode>. |
| 170 | |
| 171 | =item * $flag = utf8::is_utf8(STRING) |
| 172 | |
| 173 | (Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. |
| 174 | Functionally the same as Encode::is_utf8(). |
| 175 | |
| 176 | =item * $flag = utf8::valid(STRING) |
| 177 | |
| 178 | [INTERNAL] Test whether STRING is in a consistent state regarding |
| 179 | UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag |
| 180 | on B<or> if string is held as bytes (both these states are 'consistent'). |
| 181 | Main reason for this routine is to allow Perl's testsuite to check |
| 182 | that operations have left strings in a consistent state. You most |
| 183 | probably want to use utf8::is_utf8() instead. |
| 184 | |
| 185 | =back |
| 186 | |
| 187 | C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is |
| 188 | cleared. See L<perlunicode> for more on the UTF8 flag and the C API |
| 189 | functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, |
| 190 | and C<sv_utf8_decode>, which are wrapped by the Perl functions |
| 191 | C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and |
| 192 | C<utf8::decode>. Also, the functions utf8::is_utf8, utf8::valid, |
| 193 | utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are |
| 194 | actually internal, and thus always available, without a C<require utf8> |
| 195 | statement. |
| 196 | |
| 197 | =head1 BUGS |
| 198 | |
| 199 | One can have Unicode in identifier names, but not in package/class or |
| 200 | subroutine names. While some limited functionality towards this does |
| 201 | exist as of Perl 5.8.0, that is more accidental than designed; use of |
| 202 | Unicode for the said purposes is unsupported. |
| 203 | |
| 204 | One reason of this unfinishedness is its (currently) inherent |
| 205 | unportability: since both package names and subroutine names may need |
| 206 | to be mapped to file and directory names, the Unicode capability of |
| 207 | the filesystem becomes important-- and there unfortunately aren't |
| 208 | portable answers. |
| 209 | |
| 210 | =head1 SEE ALSO |
| 211 | |
| 212 | L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> |
| 213 | |
| 214 | =cut |