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