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version 1.1.1.3, 2012/10/09 09:19:17	version 1.1.1.4, 2013/07/22 08:25:56
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.TH PCREUNICODE 3 "14 April 2012" "PCRE 8.30"	.TH PCREUNICODE 3 "27 February 2013" "PCRE 8.33"
.SH NAME	.SH NAME
PCRE - Perl-compatible regular expressions	PCRE - Perl-compatible regular expressions
.SH "UTF-8, UTF-16, AND UNICODE PROPERTY SUPPORT"	.SH "UTF-8, UTF-16, UTF-32, AND UNICODE PROPERTY SUPPORT"
.rs	.rs
.sp	.sp
From Release 8.30, in addition to its previous UTF-8 support, PCRE also	As well as UTF-8 support, PCRE also supports UTF-16 (from release 8.30) and
supports UTF-16 by means of a separate 16-bit library. This can be built as	UTF-32 (from release 8.32), by means of two additional libraries. They can be
well as, or instead of, the 8-bit library.	built as well as, or instead of, the 8-bit library.
.	.
.	.
.SH "UTF-8 SUPPORT"	.SH "UTF-8 SUPPORT"
Line 18 support, and, in addition, you must call	Line 18 support, and, in addition, you must call
\fBpcre_compile()\fP	\fBpcre_compile()\fP
.\"	.\"
with the PCRE_UTF8 option flag, or the pattern must start with the sequence	with the PCRE_UTF8 option flag, or the pattern must start with the sequence
(*UTF8). When either of these is the case, both the pattern and any subject	(UTF8) or (UTF). When either of these is the case, both the pattern and any
strings that are matched against it are treated as UTF-8 strings instead of	subject strings that are matched against it are treated as UTF-8 strings
strings of 1-byte characters.	instead of strings of individual 1-byte characters.
.	.
.	.
.SH "UTF-16 SUPPORT"	.SH "UTF-16 AND UTF-32 SUPPORT"
.rs	.rs
.sp	.sp
In order process UTF-16 strings, you must build PCRE's 16-bit library with UTF	In order process UTF-16 or UTF-32 strings, you must build PCRE's 16-bit or
support, and, in addition, you must call	32-bit library with UTF support, and, in addition, you must call
.\" HTML <a href="pcre_compile.html">	.\" HREF
.\" </a>
\fBpcre16_compile()\fP	\fBpcre16_compile()\fP
.\"	.\"
with the PCRE_UTF16 option flag, or the pattern must start with the sequence	or
(*UTF16). When either of these is the case, both the pattern and any subject	.\" HREF
strings that are matched against it are treated as UTF-16 strings instead of	\fBpcre32_compile()\fP
strings of 16-bit characters.	.\"
	with the PCRE_UTF16 or PCRE_UTF32 option flag, as appropriate. Alternatively,
	the pattern must start with the sequence (UTF16), (UTF32), as appropriate, or
	(*UTF), which can be used with either library. When UTF mode is set, both the
	pattern and any subject strings that are matched against it are treated as
	UTF-16 or UTF-32 strings instead of strings of individual 16-bit or 32-bit
	characters.
.	.
.	.
.SH "UTF SUPPORT OVERHEAD"	.SH "UTF SUPPORT OVERHEAD"
Line 43 strings of 16-bit characters.	Line 48 strings of 16-bit characters.
.sp	.sp
If you compile PCRE with UTF support, but do not use it at run time, the	If you compile PCRE with UTF support, but do not use it at run time, the
library will be a bit bigger, but the additional run time overhead is limited	library will be a bit bigger, but the additional run time overhead is limited
to testing the PCRE_UTF8/16 flag occasionally, so should not be very big.	to testing the PCRE_UTF[8\|16\|32] flag occasionally, so should not be very big.
.	.
.	.
.SH "UNICODE PROPERTY SUPPORT"	.SH "UNICODE PROPERTY SUPPORT"
Line 54 support), the escape sequences \ep{..}, \eP{..}, and \	Line 59 support), the escape sequences \ep{..}, \eP{..}, and \
The available properties that can be tested are limited to the general	The available properties that can be tested are limited to the general
category properties such as Lu for an upper case letter or Nd for a decimal	category properties such as Lu for an upper case letter or Nd for a decimal
number, the Unicode script names such as Arabic or Han, and the derived	number, the Unicode script names such as Arabic or Han, and the derived
properties Any and L&. A full list is given in the	properties Any and L&. Full lists is given in the
.\" HREF	.\" HREF
\fBpcrepattern\fP	\fBpcrepattern\fP
.\"	.\"
	and
	.\" HREF
	\fBpcresyntax\fP
	.\"
documentation. Only the short names for properties are supported. For example,	documentation. Only the short names for properties are supported. For example,
\ep{L} matches a letter. Its Perl synonym, \ep{Letter}, is not supported.	\ep{L} matches a letter. Its Perl synonym, \ep{Letter}, is not supported.
Furthermore, in Perl, many properties may optionally be prefixed by "Is", for	Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
Line 75 place. From release 7.3 of PCRE, the check is accordin	Line 84 place. From release 7.3 of PCRE, the check is accordin
which are themselves derived from the Unicode specification. Earlier releases	which are themselves derived from the Unicode specification. Earlier releases
of PCRE followed the rules of RFC 2279, which allows the full range of 31-bit	of PCRE followed the rules of RFC 2279, which allows the full range of 31-bit
values (0 to 0x7FFFFFFF). The current check allows only values in the range U+0	values (0 to 0x7FFFFFFF). The current check allows only values in the range U+0
to U+10FFFF, excluding U+D800 to U+DFFF.	to U+10FFFF, excluding the surrogate area. (From release 8.33 the so-called
	"non-character" code points are no longer excluded because Unicode corrigendum
	#9 makes it clear that they should not be.)
.P	.P
The excluded code points are the "Surrogate Area" of Unicode. They are reserved	Characters in the "Surrogate Area" of Unicode are reserved for use by UTF-16,
for use by UTF-16, where they are used in pairs to encode codepoints with	where they are used in pairs to encode codepoints with values greater than
values greater than 0xFFFF. The code points that are encoded by UTF-16 pairs	0xFFFF. The code points that are encoded by UTF-16 pairs are available
are available independently in the UTF-8 encoding. (In other words, the whole	independently in the UTF-8 and UTF-32 encodings. (In other words, the whole
surrogate thing is a fudge for UTF-16 which unfortunately messes up UTF-8.)	surrogate thing is a fudge for UTF-16 which unfortunately messes up UTF-8 and
	UTF-32.)
.P	.P
If an invalid UTF-8 string is passed to PCRE, an error return is given. At	If an invalid UTF-8 string is passed to PCRE, an error return is given. At
compile time, the only additional information is the offset to the first byte	compile time, the only additional information is the offset to the first byte
Line 91 detailed reason code if the caller has provided memory	Line 103 detailed reason code if the caller has provided memory
.P	.P
In some situations, you may already know that your strings are valid, and	In some situations, you may already know that your strings are valid, and
therefore want to skip these checks in order to improve performance, for	therefore want to skip these checks in order to improve performance, for
example in the case of a long subject string that is being scanned repeatedly	example in the case of a long subject string that is being scanned repeatedly.
with different patterns. If you set the PCRE_NO_UTF8_CHECK flag at compile time	If you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time, PCRE
or at run time, PCRE assumes that the pattern or subject it is given	assumes that the pattern or subject it is given (respectively) contains only
(respectively) contains only valid UTF-8 codes. In this case, it does not	valid UTF-8 codes. In this case, it does not diagnose an invalid UTF-8 string.
diagnose an invalid UTF-8 string.
.P	.P
If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, what	Note that passing PCRE_NO_UTF8_CHECK to \fBpcre_compile()\fP just disables the
happens depends on why the string is invalid. If the string conforms to the	check for the pattern; it does not also apply to subject strings. If you want
"old" definition of UTF-8 (RFC 2279), it is processed as a string of characters	to disable the check for a subject string you must pass this option to
in the range 0 to 0x7FFFFFFF by \fBpcre_dfa_exec()\fP and the interpreted	\fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP.
version of \fBpcre_exec()\fP. In other words, apart from the initial validity
test, these functions (when in UTF-8 mode) handle strings according to the more
liberal rules of RFC 2279. However, the just-in-time (JIT) optimization for
\fBpcre_exec()\fP supports only RFC 3629. If you are using JIT optimization, or
if the string does not even conform to RFC 2279, the result is undefined. Your
program may crash.
.P	.P
If you want to process strings of values in the full range 0 to 0x7FFFFFFF,	If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, the result
encoded in a UTF-8-like manner as per the old RFC, you can set	is undefined and your program may crash.
PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in this
situation, you will have to apply your own validity check, and avoid the use of
JIT optimization.
.	.
.	.
.\" HTML <a name="utf16strings"></a>	.\" HTML <a name="utf16strings"></a>
Line 136 therefore want to skip these checks in order to improv	Line 138 therefore want to skip these checks in order to improv
the PCRE_NO_UTF16_CHECK flag at compile time or at run time, PCRE assumes that	the PCRE_NO_UTF16_CHECK flag at compile time or at run time, PCRE assumes that
the pattern or subject it is given (respectively) contains only valid UTF-16	the pattern or subject it is given (respectively) contains only valid UTF-16
sequences. In this case, it does not diagnose an invalid UTF-16 string.	sequences. In this case, it does not diagnose an invalid UTF-16 string.
	However, if an invalid string is passed, the result is undefined.
.	.
.	.
	.\" HTML <a name="utf32strings"></a>
	.SS "Validity of UTF-32 strings"
	.rs
	.sp
	When you set the PCRE_UTF32 flag, the strings of 32-bit data units that are
	passed as patterns and subjects are (by default) checked for validity on entry
	to the relevant functions. This check allows only values in the range U+0
	to U+10FFFF, excluding the surrogate area U+D800 to U+DFFF.
	.P
	If an invalid UTF-32 string is passed to PCRE, an error return is given. At
	compile time, the only additional information is the offset to the first data
	unit of the failing character. The run-time functions \fBpcre32_exec()\fP and
	\fBpcre32_dfa_exec()\fP also pass back this information, as well as a more
	detailed reason code if the caller has provided memory in which to do this.
	.P
	In some situations, you may already know that your strings are valid, and
	therefore want to skip these checks in order to improve performance. If you set
	the PCRE_NO_UTF32_CHECK flag at compile time or at run time, PCRE assumes that
	the pattern or subject it is given (respectively) contains only valid UTF-32
	sequences. In this case, it does not diagnose an invalid UTF-32 string.
	However, if an invalid string is passed, the result is undefined.
	.
	.
.SS "General comments about UTF modes"	.SS "General comments about UTF modes"
.rs	.rs
.sp	.sp
1. Codepoints less than 256 can be specified by either braced or unbraced	1. Codepoints less than 256 can be specified in patterns by either braced or
hexadecimal escape sequences (for example, \ex{b3} or \exb3). Larger values	unbraced hexadecimal escape sequences (for example, \ex{b3} or \exb3). Larger
have to use braced sequences.	values have to use braced sequences.
.P	.P
2. Octal numbers up to \e777 are recognized, and in UTF-8 mode, they match	2. Octal numbers up to \e777 are recognized, and in UTF-8 mode they match
two-byte characters for values greater than \e177.	two-byte characters for values greater than \e177.
.P	.P
3. Repeat quantifiers apply to complete UTF characters, not to individual	3. Repeat quantifiers apply to complete UTF characters, not to individual
Line 155 data units, for example: \ex{100}{3}.	Line 181 data units, for example: \ex{100}{3}.
unit.	unit.
.P	.P
5. The escape sequence \eC can be used to match a single byte in UTF-8 mode, or	5. The escape sequence \eC can be used to match a single byte in UTF-8 mode, or
a single 16-bit data unit in UTF-16 mode, but its use can lead to some strange	a single 16-bit data unit in UTF-16 mode, or a single 32-bit data unit in
effects because it breaks up multi-unit characters (see the description of \eC	UTF-32 mode, but its use can lead to some strange effects because it breaks up
in the	multi-unit characters (see the description of \eC in the
.\" HREF	.\" HREF
\fBpcrepattern\fP	\fBpcrepattern\fP
.\"	.\"
documentation). The use of \eC is not supported in the alternative matching	documentation). The use of \eC is not supported in the alternative matching
function \fBpcre[16]_dfa_exec()\fP, nor is it supported in UTF mode by the JIT	function \fBpcre[16\|32]_dfa_exec()\fP, nor is it supported in UTF mode by the
optimization of \fBpcre[16]_exec()\fP. If JIT optimization is requested for a	JIT optimization of \fBpcre[16\|32]_exec()\fP. If JIT optimization is requested
UTF pattern that contains \eC, it will not succeed, and so the matching will	for a UTF pattern that contains \eC, it will not succeed, and so the matching
be carried out by the normal interpretive function.	will be carried out by the normal interpretive function.
.P	.P
6. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly	6. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly
test characters of any code value, but, by default, the characters that PCRE	test characters of any code value, but, by default, the characters that PCRE
Line 197 low-valued characters, unless the PCRE_UCP option is s	Line 223 low-valued characters, unless the PCRE_UCP option is s
PCRE_UCP is set.	PCRE_UCP is set.
.P	.P
9. Case-insensitive matching applies only to characters whose values are less	9. Case-insensitive matching applies only to characters whose values are less
than 128, unless PCRE is built with Unicode property support. Even when Unicode	than 128, unless PCRE is built with Unicode property support. A few Unicode
property support is available, PCRE still uses its own character tables when	characters such as Greek sigma have more than two codepoints that are
checking the case of low-valued characters, so as not to degrade performance.	case-equivalent. Up to and including PCRE release 8.31, only one-to-one case
The Unicode property information is used only for characters with higher	mappings were supported, but later releases (with Unicode property support) do
values. Furthermore, PCRE supports case-insensitive matching only when there is	treat as case-equivalent all versions of characters such as Greek sigma.
a one-to-one mapping between a letter's cases. There are a small number of
many-to-one mappings in Unicode; these are not supported by PCRE.
.	.
.	.
.SH AUTHOR	.SH AUTHOR
Line 220 Cambridge CB2 3QH, England.	Line 244 Cambridge CB2 3QH, England.
.rs	.rs
.sp	.sp
.nf	.nf
Last updated: 14 April 2012	Last updated: 27 February 2013
Copyright (c) 1997-2012 University of Cambridge.	Copyright (c) 1997-2013 University of Cambridge.
.fi	.fi

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