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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 = '1.06'; |
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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; |
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19 | require Carp; |
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20 | Carp::croak("Undefined subroutine $AUTOLOAD called"); |
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21 | } |
22 | |
23 | 1; |
24 | __END__ |
25 | |
26 | =head1 NAME |
27 | |
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28 | utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code |
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29 | |
30 | =head1 SYNOPSIS |
31 | |
32 | use utf8; |
33 | no utf8; |
34 | |
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35 | # Convert a Perl scalar to/from UTF-8. |
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36 | $num_octets = utf8::upgrade($string); |
37 | $success = utf8::downgrade($string[, FAIL_OK]); |
38 | |
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39 | # Change the native bytes of a Perl scalar to/from UTF-8 bytes. |
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40 | utf8::encode($string); |
41 | utf8::decode($string); |
42 | |
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43 | $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 |
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44 | $flag = utf8::valid(STRING); |
45 | |
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46 | =head1 DESCRIPTION |
47 | |
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48 | The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the |
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49 | program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based |
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50 | platforms). The C<no utf8> pragma tells Perl to switch back to treating |
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51 | the source text as literal bytes in the current lexical scope. |
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52 | |
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53 | B<Do not use this pragma for anything else than telling Perl that your |
54 | script is written in UTF-8.> The utility functions described below are |
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55 | directly usable without C<use utf8;>. |
56 | |
57 | Because it is not possible to reliably tell UTF-8 from native 8 bit |
58 | encodings, you need either a Byte Order Mark at the beginning of your |
59 | source code, or C<use utf8;>, to instruct perl. |
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60 | |
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61 | When UTF-8 becomes the standard source format, this pragma will |
62 | effectively become a no-op. For convenience in what follows the term |
63 | I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based |
64 | platforms and UTF-EBCDIC on EBCDIC based platforms. |
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65 | |
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66 | See also the effects of the C<-C> switch and its cousin, the |
67 | C<$ENV{PERL_UNICODE}>, in L<perlrun>. |
68 | |
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69 | Enabling the C<utf8> pragma has the following effect: |
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70 | |
4ac9195f |
71 | =over 4 |
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72 | |
73 | =item * |
74 | |
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75 | Bytes in the source text that have their high-bit set will be treated |
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76 | as being part of a literal UTF-X sequence. This includes most |
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77 | literals such as identifier names, string constants, and constant |
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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. |
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82 | |
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83 | =back |
84 | |
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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 |
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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;>. |
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91 | |
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92 | =head2 Utility functions |
93 | |
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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 |
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96 | you should not say that unless you really want to have UTF-8 source code. |
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97 | |
98 | =over 4 |
99 | |
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100 | =item * $num_octets = utf8::upgrade($string) |
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101 | |
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102 | Converts in-place the internal octet sequence in the native encoding |
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103 | (Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>. |
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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). |
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109 | |
110 | B<Note that this function does not handle arbitrary encodings.> |
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111 | Therefore Encode is recommended for the general purposes; see also |
112 | L<Encode>. |
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113 | |
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114 | =item * $success = utf8::downgrade($string[, FAIL_OK]) |
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115 | |
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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<$string> already encoded as native 8 bit does no harm. Can be used to |
119 | make sure that the UTF-8 flag is off, e.g. when you want to make sure |
120 | that the substr() or length() function works with the usually faster |
121 | byte algorithm. |
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122 | |
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123 | Fails if the original I<UTF-X> sequence cannot be represented in the |
124 | native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is |
125 | true, returns false. |
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126 | |
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127 | Returns true on success. |
128 | |
129 | B<Note that this function does not handle arbitrary encodings.> |
130 | Therefore Encode is recommended for the general purposes; see also |
131 | L<Encode>. |
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132 | |
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133 | B<NOTE:> this function is experimental and may change or be removed |
134 | without notice. |
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135 | |
136 | =item * utf8::encode($string) |
137 | |
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138 | Converts in-place the character sequence to the corresponding octet |
139 | sequence in I<UTF-X>. The UTF8 flag is turned off, so that after this |
140 | operation, the string is a byte string. Returns nothing. |
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141 | |
142 | B<Note that this function does not handle arbitrary encodings.> |
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143 | Therefore Encode is recommended for the general purposes; see also |
144 | L<Encode>. |
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145 | |
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146 | =item * $success = utf8::decode($string) |
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147 | |
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148 | Attempts to convert in-place the octet sequence in I<UTF-X> to the |
149 | corresponding character sequence. The UTF-8 flag is turned on only if |
150 | the source string contains multiple-byte I<UTF-X> characters. If |
151 | I<$string> is invalid as I<UTF-X>, returns false; otherwise returns |
152 | true. |
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153 | |
154 | B<Note that this function does not handle arbitrary encodings.> |
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155 | Therefore Encode is recommended for the general purposes; see also |
156 | L<Encode>. |
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157 | |
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158 | B<NOTE:> this function is experimental and may change or be removed |
159 | without notice. |
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160 | |
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161 | =item * $flag = utf8::is_utf8(STRING) |
162 | |
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163 | (Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. |
164 | Functionally the same as Encode::is_utf8(). |
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165 | |
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166 | =item * $flag = utf8::valid(STRING) |
167 | |
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168 | [INTERNAL] Test whether STRING is in a consistent state regarding |
169 | UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag |
170 | on B<or> if string is held as bytes (both these states are 'consistent'). |
171 | Main reason for this routine is to allow Perl's testsuite to check |
172 | that operations have left strings in a consistent state. You most |
173 | probably want to use utf8::is_utf8() instead. |
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174 | |
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175 | =back |
176 | |
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177 | C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is |
178 | cleared. See L<perlunicode> for more on the UTF8 flag and the C API |
179 | functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, |
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180 | and C<sv_utf8_decode>, which are wrapped by the Perl functions |
181 | C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and |
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182 | C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation |
183 | the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode, |
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184 | utf8::upgrade, and utf8::downgrade are always available, without a |
185 | C<require utf8> statement-- this may change in future releases. |
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186 | |
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187 | =head1 BUGS |
188 | |
189 | One can have Unicode in identifier names, but not in package/class or |
190 | subroutine names. While some limited functionality towards this does |
191 | exist as of Perl 5.8.0, that is more accidental than designed; use of |
192 | Unicode for the said purposes is unsupported. |
193 | |
194 | One reason of this unfinishedness is its (currently) inherent |
195 | unportability: since both package names and subroutine names may need |
196 | to be mapped to file and directory names, the Unicode capability of |
197 | the filesystem becomes important-- and there unfortunately aren't |
198 | portable answers. |
199 | |
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200 | =head1 SEE ALSO |
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201 | |
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202 | L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> |
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203 | |
204 | =cut |