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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 = '1.02'; |
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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 | |
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34 | $num_octets = utf8::upgrade($string); |
35 | $success = utf8::downgrade($string[, FAIL_OK]); |
36 | |
37 | utf8::encode($string); |
38 | utf8::decode($string); |
39 | |
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40 | $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 |
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41 | $flag = utf8::valid(STRING); |
42 | |
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43 | =head1 DESCRIPTION |
44 | |
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45 | The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the |
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46 | program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based |
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47 | platforms). The C<no utf8> pragma tells Perl to switch back to treating |
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48 | the source text as literal bytes in the current lexical scope. |
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49 | |
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50 | This pragma is primarily a compatibility device. Perl versions |
51 | earlier than 5.6 allowed arbitrary bytes in source code, whereas |
52 | in future we would like to standardize on the UTF-8 encoding for |
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53 | source text. |
54 | |
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55 | B<Do not use this pragma for anything else than telling Perl that your |
56 | script is written in UTF-8.> The utility functions described below are |
57 | useful for their own purposes, but they are not really part of the |
58 | "pragmatic" effect. |
59 | |
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60 | Until UTF-8 becomes the default format for source text, either this |
61 | pragma or the L</encoding> pragma should be used to recognize UTF-8 |
62 | in the source. When UTF-8 becomes the standard source format, this |
63 | pragma will effectively become a no-op. For convenience in what |
64 | follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO |
65 | Latin based platforms and UTF-EBCDIC on EBCDIC based platforms. |
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66 | |
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67 | See also the effects of the C<-C> switch and its cousin, the |
68 | C<$ENV{PERL_UNICODE}>, in L<perlrun>. |
69 | |
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70 | Enabling the C<utf8> pragma has the following effect: |
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71 | |
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72 | =over 4 |
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73 | |
74 | =item * |
75 | |
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76 | Bytes in the source text that have their high-bit set will be treated |
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77 | as being part of a literal UTF-8 character. This includes most |
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78 | literals such as identifier names, string constants, and constant |
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79 | regular expression patterns. |
80 | |
81 | On EBCDIC platforms characters in the Latin 1 character set are |
82 | treated as being part of a literal UTF-EBCDIC character. |
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83 | |
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84 | =back |
85 | |
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86 | Note that if you have bytes with the eighth bit on in your script |
87 | (for example embedded Latin-1 in your string literals), C<use utf8> |
88 | will be unhappy since the bytes are most probably not well-formed |
89 | UTF-8. If you want to have such bytes and use utf8, you can disable |
90 | utf8 until the end the block (or file, if at top level) by C<no utf8;>. |
91 | |
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92 | If you want to automatically upgrade your 8-bit legacy bytes to UTF-8, |
93 | use the L</encoding> pragma instead of this pragma. For example, if |
94 | you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8 |
95 | as used in e.g. C<chr()> and C<\x{...}>, try this: |
96 | |
97 | use encoding "latin-1"; |
98 | my $c = chr(0xc4); |
99 | my $x = "\x{c5}"; |
100 | |
101 | In case you are wondering: yes, C<use encoding 'utf8';> works much |
102 | the same as C<use utf8;>. |
103 | |
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104 | =head2 Utility functions |
105 | |
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106 | The following functions are defined in the C<utf8::> package by the |
107 | Perl core. You do not need to say C<use utf8> to use these and in fact |
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108 | you should not say that unless you really want to have UTF-8 source code. |
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109 | |
110 | =over 4 |
111 | |
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112 | =item * $num_octets = utf8::upgrade($string) |
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113 | |
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114 | Converts (in-place) internal representation of string to Perl's |
115 | internal I<UTF-X> form. Returns the number of octets necessary to |
116 | represent the string as I<UTF-X>. Can be used to make sure that the |
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117 | UTF-8 flag is on, so that C<\w> or C<lc()> work as expected on strings |
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118 | containing characters in the range 0x80-0xFF (oon ASCII and |
119 | derivatives). Note that this should not be used to convert a legacy |
120 | byte encoding to Unicode: use Encode for that. Affected by the |
121 | encoding pragma. |
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122 | |
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123 | =item * $success = utf8::downgrade($string[, FAIL_OK]) |
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124 | |
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125 | Converts (in-place) internal representation of string to be un-encoded |
126 | bytes. Returns true on success. On failure dies or, if the value of |
127 | FAIL_OK is true, returns false. Can be used to make sure that the |
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128 | UTF-8 flag is off, e.g. when you want to make sure that the substr() |
129 | or length() function works with the usually faster byte algorithm. |
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130 | Note that this should not be used to convert Unicode back to a legacy |
131 | byte encoding: use Encode for that. B<Not> affected by the encoding |
132 | pragma. |
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133 | |
134 | =item * utf8::encode($string) |
135 | |
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136 | Converts (in-place) I<$string> from logical characters to octet |
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137 | sequence representing it in Perl's I<UTF-X> encoding. Returns |
138 | nothing. Same as Encode::encode_utf8(). Note that this should not be |
139 | used to convert a legacy byte encoding to Unicode: use Encode for |
140 | that. |
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141 | |
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142 | =item * utf8::decode($string) |
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143 | |
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144 | Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding |
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145 | into logical characters. Returns nothing. Same as Encode::decode_utf8(). |
146 | Note that this should not be used to convert Unicode back to a legacy |
147 | byte encoding: use Encode for that. |
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148 | |
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149 | =item * $flag = utf8::is_utf8(STRING) |
150 | |
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151 | (Since Perl 5.8.1) Test whether STRING is in UTF-8. Functionally |
152 | the same as Encode::is_utf8(). |
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153 | |
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154 | =item * $flag = utf8::valid(STRING) |
155 | |
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156 | [INTERNAL] Test whether STRING is in a consistent state regarding |
157 | UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag |
158 | on B<or> if string is held as bytes (both these states are 'consistent'). |
159 | Main reason for this routine is to allow Perl's testsuite to check |
160 | that operations have left strings in a consistent state. You most |
161 | probably want to use utf8::is_utf8() instead. |
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162 | |
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163 | =back |
164 | |
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165 | C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is |
166 | cleared. See L<perlunicode> for more on the UTF8 flag and the C API |
167 | functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, |
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168 | and C<sv_utf8_decode>, which are wrapped by the Perl functions |
169 | C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and |
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170 | C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation |
171 | the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode, |
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172 | utf8::upgrade, and utf8::downgrade are always available, without a |
173 | C<require utf8> statement-- this may change in future releases. |
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174 | |
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175 | =head1 BUGS |
176 | |
177 | One can have Unicode in identifier names, but not in package/class or |
178 | subroutine names. While some limited functionality towards this does |
179 | exist as of Perl 5.8.0, that is more accidental than designed; use of |
180 | Unicode for the said purposes is unsupported. |
181 | |
182 | One reason of this unfinishedness is its (currently) inherent |
183 | unportability: since both package names and subroutine names may need |
184 | to be mapped to file and directory names, the Unicode capability of |
185 | the filesystem becomes important-- and there unfortunately aren't |
186 | portable answers. |
187 | |
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188 | =head1 SEE ALSO |
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189 | |
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190 | L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode> |
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191 | |
192 | =cut |