Commit | Line | Data |
---|---|---|
86530b38 AT |
1 | package utf8; |
2 | ||
3 | $utf8::hint_bits = 0x00800000; | |
4 | ||
5 | our $VERSION = '1.00'; | |
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 | Carp::croak("Undefined subroutine $AUTOLOAD called"); | |
20 | } | |
21 | ||
22 | 1; | |
23 | __END__ | |
24 | ||
25 | =head1 NAME | |
26 | ||
27 | utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code | |
28 | ||
29 | =head1 SYNOPSIS | |
30 | ||
31 | use utf8; | |
32 | no utf8; | |
33 | ||
34 | =head1 DESCRIPTION | |
35 | ||
36 | The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the | |
37 | program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based | |
38 | platforms). The C<no utf8> pragma tells Perl to switch back to treating | |
39 | the source text as literal bytes in the current lexical scope. | |
40 | ||
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 | |
47 | effectively become a no-op. For convenience in what follows the | |
48 | term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based | |
49 | platforms and UTF-EBCDIC on EBCDIC based platforms. | |
50 | ||
51 | Enabling the C<utf8> pragma has the following effect: | |
52 | ||
53 | =over 4 | |
54 | ||
55 | =item * | |
56 | ||
57 | Bytes in the source text that have their high-bit set will be treated | |
58 | as being part of a literal UTF-8 character. This includes most | |
59 | literals such as identifier names, string constants, and constant | |
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. | |
64 | ||
65 | =back | |
66 | ||
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 | ||
73 | =head2 Utility functions | |
74 | ||
75 | The following functions are defined in the C<utf8::> package by the perl core. | |
76 | ||
77 | =over 4 | |
78 | ||
79 | =item * $num_octets = utf8::upgrade($string); | |
80 | ||
81 | Converts (in-place) internal representation of string to Perl's internal | |
82 | I<UTF-X> form. Returns the number of octets necessary to represent | |
83 | the string as I<UTF-X>. Can be used to make sure that the | |
84 | UTF-8 flag is on, so that C<\w> or C<lc()> work as expected on strings | |
85 | containing characters in the range 0x80-0xFF. Note that this should | |
86 | not be used to convert | |
87 | a legacy byte encoding to Unicode: use Encode for that. Affected | |
88 | by the encoding pragma. | |
89 | ||
90 | =item * utf8::downgrade($string[, FAIL_OK]) | |
91 | ||
92 | Converts (in-place) internal representation of string to be un-encoded | |
93 | bytes. Returns true on success. On failure dies or, if the value of | |
94 | FAIL_OK is true, returns false. Can be used to make sure that the | |
95 | UTF-8 flag is off, e.g. when you want to make sure that the substr() | |
96 | or length() function works with the usually faster byte algorithm. | |
97 | Note that this should not be used to convert Unicode back to a legacy | |
98 | byte encoding: use Encode for that. B<Not> affected by the encoding | |
99 | pragma. | |
100 | ||
101 | =item * utf8::encode($string) | |
102 | ||
103 | Converts (in-place) I<$string> from logical characters to octet | |
104 | sequence representing it in Perl's I<UTF-X> encoding. Same as | |
105 | Encode::encode_utf8(). Note that this should not be used to convert | |
106 | a legacy byte encoding to Unicode: use Encode for that. | |
107 | ||
108 | =item * $flag = utf8::decode($string) | |
109 | ||
110 | Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding | |
111 | into logical characters. Same as Encode::decode_utf8(). Note that this | |
112 | should not be used to convert Unicode back to a legacy byte encoding: | |
113 | use Encode for that. | |
114 | ||
115 | =item * $flag = utf8::valid(STRING) | |
116 | ||
117 | [INTERNAL] Test whether STRING is in a consistent state. Will return | |
118 | true if string is held as bytes, or is well-formed UTF-8 and has the | |
119 | UTF-8 flag on. Main reason for this routine is to allow Perl's | |
120 | testsuite to check that operations have left strings in a consistent | |
121 | state. | |
122 | ||
123 | =back | |
124 | ||
125 | C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is | |
126 | cleared. See L<perlunicode> for more on the UTF8 flag and the C API | |
127 | functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, | |
128 | and C<sv_utf8_decode>, which are wrapped by the Perl functions | |
129 | C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and | |
130 | C<utf8::decode>. Note that in the Perl 5.8.0 implementation the | |
131 | functions utf8::valid, utf8::encode, utf8::decode, utf8::upgrade, | |
132 | and utf8::downgrade are always available, without a C<require utf8> | |
133 | statement-- this may change in future releases. | |
134 | ||
135 | =head1 BUGS | |
136 | ||
137 | One can have Unicode in identifier names, but not in package/class or | |
138 | subroutine names. While some limited functionality towards this does | |
139 | exist as of Perl 5.8.0, that is more accidental than designed; use of | |
140 | Unicode for the said purposes is unsupported. | |
141 | ||
142 | One reason of this unfinishedness is its (currently) inherent | |
143 | unportability: since both package names and subroutine names may need | |
144 | to be mapped to file and directory names, the Unicode capability of | |
145 | the filesystem becomes important-- and there unfortunately aren't | |
146 | portable answers. | |
147 | ||
148 | =head1 SEE ALSO | |
149 | ||
150 | L<perlunicode>, L<bytes> | |
151 | ||
152 | =cut |