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1 | package utf8; |
2 | |
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3 | $utf8::hint_bits = 0x00800000; |
4 | |
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5 | our $VERSION = '1.00'; |
6 | |
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7 | sub import { |
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8 | $^H |= $utf8::hint_bits; |
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9 | $enc{caller()} = $_[1] if $_[1]; |
10 | } |
11 | |
12 | sub unimport { |
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13 | $^H &= ~$utf8::hint_bits; |
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14 | } |
15 | |
16 | sub AUTOLOAD { |
17 | require "utf8_heavy.pl"; |
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18 | goto &$AUTOLOAD if defined &$AUTOLOAD; |
19 | Carp::croak("Undefined subroutine $AUTOLOAD called"); |
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20 | } |
21 | |
22 | 1; |
23 | __END__ |
24 | |
25 | =head1 NAME |
26 | |
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27 | utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code |
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28 | |
29 | =head1 SYNOPSIS |
30 | |
31 | use utf8; |
32 | no utf8; |
33 | |
34 | =head1 DESCRIPTION |
35 | |
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36 | The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the |
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37 | program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based |
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38 | platforms). The C<no utf8> pragma tells Perl to switch back to treating |
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39 | the source text as literal bytes in the current lexical scope. |
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40 | |
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41 | This pragma is primarily a compatibility device. Perl versions |
42 | earlier than 5.6 allowed arbitrary bytes in source code, whereas |
43 | in future we would like to standardize on the UTF-8 encoding for |
44 | source text. Until UTF-8 becomes the default format for source |
45 | text, this pragma should be used to recognize UTF-8 in the source. |
46 | When UTF-8 becomes the standard source format, this pragma will |
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47 | effectively become a no-op. For convenience in what follows the |
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48 | term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based |
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49 | platforms and UTF-EBCDIC on EBCDIC based platforms. |
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50 | |
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51 | Enabling the C<utf8> pragma has the following effect: |
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52 | |
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53 | =over 4 |
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54 | |
55 | =item * |
56 | |
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57 | Bytes in the source text that have their high-bit set will be treated |
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58 | as being part of a literal UTF-8 character. This includes most |
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59 | literals such as identifier names, string constants, and constant |
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60 | regular expression patterns. |
61 | |
62 | On EBCDIC platforms characters in the Latin 1 character set are |
63 | treated as being part of a literal UTF-EBCDIC character. |
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64 | |
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65 | =back |
66 | |
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67 | Note that if you have bytes with the eighth bit on in your script |
68 | (for example embedded Latin-1 in your string literals), C<use utf8> |
69 | will be unhappy since the bytes are most probably not well-formed |
70 | UTF-8. If you want to have such bytes and use utf8, you can disable |
71 | utf8 until the end the block (or file, if at top level) by C<no utf8;>. |
72 | |
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73 | =head2 Utility functions |
74 | |
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75 | The following functions are defined in the C<utf8::> package by the |
76 | Perl core. You do not need to say C<use utf8> to use these and in fact |
77 | you should not unless you really want to have UTF-8 source code. |
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78 | |
79 | =over 4 |
80 | |
81 | =item * $num_octets = utf8::upgrade($string); |
82 | |
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83 | Converts (in-place) internal representation of string to Perl's |
84 | internal I<UTF-X> form. Returns the number of octets necessary to |
85 | represent the string as I<UTF-X>. Can be used to make sure that the |
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86 | UTF-8 flag is on, so that C<\w> or C<lc()> work as expected on strings |
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87 | containing characters in the range 0x80-0xFF (oon ASCII and |
88 | derivatives). Note that this should not be used to convert a legacy |
89 | byte encoding to Unicode: use Encode for that. Affected by the |
90 | encoding pragma. |
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91 | |
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92 | =item * utf8::downgrade($string[, FAIL_OK]) |
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93 | |
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94 | Converts (in-place) internal representation of string to be un-encoded |
95 | bytes. Returns true on success. On failure dies or, if the value of |
96 | FAIL_OK is true, returns false. Can be used to make sure that the |
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97 | UTF-8 flag is off, e.g. when you want to make sure that the substr() |
98 | or length() function works with the usually faster byte algorithm. |
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99 | Note that this should not be used to convert Unicode back to a legacy |
100 | byte encoding: use Encode for that. B<Not> affected by the encoding |
101 | pragma. |
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102 | |
103 | =item * utf8::encode($string) |
104 | |
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105 | Converts (in-place) I<$string> from logical characters to octet |
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106 | sequence representing it in Perl's I<UTF-X> encoding. Returns |
107 | nothing. Same as Encode::encode_utf8(). Note that this should not be |
108 | used to convert a legacy byte encoding to Unicode: use Encode for |
109 | that. |
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110 | |
111 | =item * $flag = utf8::decode($string) |
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112 | |
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113 | Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding |
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114 | into logical characters. Returns nothing. Same as Encode::decode_utf8(). |
115 | Note that this should not be used to convert Unicode back to a legacy |
116 | byte encoding: use Encode for that. |
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117 | |
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118 | =item * $flag = utf8::is_utf8(STRING) |
119 | |
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120 | Test whether STRING is in UTF-8. Same as Encode::is_utf8(). |
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121 | |
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122 | =item * $flag = utf8::valid(STRING) |
123 | |
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124 | [INTERNAL] Test whether STRING is in a consistent state regarding |
125 | UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag |
126 | on B<or> if string is held as bytes (both these states are 'consistent'). |
127 | Main reason for this routine is to allow Perl's testsuite to check |
128 | that operations have left strings in a consistent state. You most |
129 | probably want to use utf8::is_utf8() instead. |
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130 | |
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131 | =back |
132 | |
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133 | C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is |
134 | cleared. See L<perlunicode> for more on the UTF8 flag and the C API |
135 | functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, |
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136 | and C<sv_utf8_decode>, which are wrapped by the Perl functions |
137 | C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and |
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138 | C<utf8::decode>. Note that in the Perl 5.8.0 implementation the |
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139 | functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode, |
140 | utf8::upgrade, and utf8::downgrade are always available, without a |
141 | C<require utf8> statement-- this may change in future releases. |
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142 | |
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143 | =head1 BUGS |
144 | |
145 | One can have Unicode in identifier names, but not in package/class or |
146 | subroutine names. While some limited functionality towards this does |
147 | exist as of Perl 5.8.0, that is more accidental than designed; use of |
148 | Unicode for the said purposes is unsupported. |
149 | |
150 | One reason of this unfinishedness is its (currently) inherent |
151 | unportability: since both package names and subroutine names may need |
152 | to be mapped to file and directory names, the Unicode capability of |
153 | the filesystem becomes important-- and there unfortunately aren't |
154 | portable answers. |
155 | |
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156 | =head1 SEE ALSO |
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157 | |
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158 | L<perlunicode>, L<bytes> |
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159 | |
160 | =cut |