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   1  package utf8;
   2  
   3  $utf8::hint_bits = 0x00800000;
   4  
   5  our $VERSION = '1.07';
   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 a Perl scalar to/from UTF-8.
  36      $num_octets = utf8::upgrade($string);
  37      $success    = utf8::downgrade($string[, FAIL_OK]);
  38  
  39      # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
  40      utf8::encode($string);
  41      utf8::decode($string);
  42  
  43      $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
  44      $flag = utf8::valid(STRING);
  45  
  46  =head1 DESCRIPTION
  47  
  48  The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
  49  program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
  50  platforms).  The C<no utf8> pragma tells Perl to switch back to treating
  51  the source text as literal bytes in the current lexical scope.
  52  
  53  B<Do not use this pragma for anything else than telling Perl that your
  54  script is written in UTF-8.> The utility functions described below are
  55  directly usable without C<use utf8;>.
  56  
  57  Because it is not possible to reliably tell UTF-8 from native 8 bit
  58  encodings, you need either a Byte Order Mark at the beginning of your
  59  source code, or C<use utf8;>, to instruct perl.
  60  
  61  When UTF-8 becomes the standard source format, this pragma will
  62  effectively become a no-op.  For convenience in what follows the term
  63  I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
  64  platforms and UTF-EBCDIC on EBCDIC based platforms.
  65  
  66  See also the effects of the C<-C> switch and its cousin, the
  67  C<$ENV{PERL_UNICODE}>, in L<perlrun>.
  68  
  69  Enabling the C<utf8> pragma has the following effect:
  70  
  71  =over 4
  72  
  73  =item *
  74  
  75  Bytes in the source text that have their high-bit set will be treated
  76  as being part of a literal UTF-X sequence.  This includes most
  77  literals such as identifier names, string constants, and constant
  78  regular expression patterns.
  79  
  80  On EBCDIC platforms characters in the Latin 1 character set are
  81  treated as being part of a literal UTF-EBCDIC character.
  82  
  83  =back
  84  
  85  Note that if you have bytes with the eighth bit on in your script
  86  (for example embedded Latin-1 in your string literals), C<use utf8>
  87  will be unhappy since the bytes are most probably not well-formed
  88  UTF-X.  If you want to have such bytes under C<use utf8>, you can disable
  89  this pragma until the end the block (or file, if at top level) by
  90  C<no utf8;>.
  91  
  92  =head2 Utility functions
  93  
  94  The following functions are defined in the C<utf8::> package by the
  95  Perl core.  You do not need to say C<use utf8> to use these and in fact
  96  you should not say that  unless you really want to have UTF-8 source code.
  97  
  98  =over 4
  99  
 100  =item * $num_octets = utf8::upgrade($string)
 101  
 102  Converts in-place the internal octet sequence in the native encoding
 103  (Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
 104  I<$string> already encoded as characters does no harm.  Returns the
 105  number of octets necessary to represent the string as I<UTF-X>.  Can be
 106  used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
 107  work as Unicode on strings containing characters in the range 0x80-0xFF
 108  (on ASCII and derivatives).
 109  
 110  B<Note that this function does not handle arbitrary encodings.>
 111  Therefore Encode is recommended for the general purposes; see also
 112  L<Encode>.
 113  
 114  =item * $success = utf8::downgrade($string[, FAIL_OK])
 115  
 116  Converts in-place the internal octet sequence in I<UTF-X> to the
 117  equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
 118  I<$string> already encoded as native 8 bit does no harm.  Can be used to
 119  make sure that the UTF-8 flag is off, e.g. when you want to make sure
 120  that the substr() or length() function works with the usually faster
 121  byte algorithm.
 122  
 123  Fails if the original I<UTF-X> sequence cannot be represented in the
 124  native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
 125  true, returns false. 
 126  
 127  Returns true on success.
 128  
 129  B<Note that this function does not handle arbitrary encodings.>
 130  Therefore Encode is recommended for the general purposes; see also
 131  L<Encode>.
 132  
 133  =item * utf8::encode($string)
 134  
 135  Converts in-place the character sequence to the corresponding octet
 136  sequence in I<UTF-X>.  The UTF8 flag is turned off, so that after this
 137  operation, the string is a byte string.  Returns nothing.
 138  
 139  B<Note that this function does not handle arbitrary encodings.>
 140  Therefore Encode is recommended for the general purposes; see also
 141  L<Encode>.
 142  
 143  =item * $success = utf8::decode($string)
 144  
 145  Attempts to convert in-place the octet sequence in I<UTF-X> to the
 146  corresponding character sequence.  The UTF-8 flag is turned on only if
 147  the source string contains multiple-byte I<UTF-X> characters.  If
 148  I<$string> is invalid as I<UTF-X>, returns false; otherwise returns
 149  true.
 150  
 151  B<Note that this function does not handle arbitrary encodings.>
 152  Therefore Encode is recommended for the general purposes; see also
 153  L<Encode>.
 154  
 155  =item * $flag = utf8::is_utf8(STRING)
 156  
 157  (Since Perl 5.8.1)  Test whether STRING is in UTF-8 internally.
 158  Functionally the same as Encode::is_utf8().
 159  
 160  =item * $flag = utf8::valid(STRING)
 161  
 162  [INTERNAL] Test whether STRING is in a consistent state regarding
 163  UTF-8.  Will return true is well-formed UTF-8 and has the UTF-8 flag
 164  on B<or> if string is held as bytes (both these states are 'consistent').
 165  Main reason for this routine is to allow Perl's testsuite to check
 166  that operations have left strings in a consistent state.  You most
 167  probably want to use utf8::is_utf8() instead.
 168  
 169  =back
 170  
 171  C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
 172  cleared.  See L<perlunicode> for more on the UTF8 flag and the C API
 173  functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
 174  and C<sv_utf8_decode>, which are wrapped by the Perl functions
 175  C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
 176  C<utf8::decode>.  Also, the functions utf8::is_utf8, utf8::valid,
 177  utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are
 178  actually internal, and thus always available, without a C<require utf8>
 179  statement.
 180  
 181  =head1 BUGS
 182  
 183  One can have Unicode in identifier names, but not in package/class or
 184  subroutine names.  While some limited functionality towards this does
 185  exist as of Perl 5.8.0, that is more accidental than designed; use of
 186  Unicode for the said purposes is unsupported.
 187  
 188  One reason of this unfinishedness is its (currently) inherent
 189  unportability: since both package names and subroutine names may need
 190  to be mapped to file and directory names, the Unicode capability of
 191  the filesystem becomes important-- and there unfortunately aren't
 192  portable answers.
 193  
 194  =head1 SEE ALSO
 195  
 196  L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
 197  
 198  =cut