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version 1.1.1.3, 2012/10/09 09:19:17
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version 1.1.1.4, 2013/07/22 08:25:57
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Line 13 from the original man page. If there is any nonsense i
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Line 13 from the original man page. If there is any nonsense i
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| man page, in case the conversion went wrong. |
man page, in case the conversion went wrong. |
| <br> |
<br> |
| <br><b> |
<br><b> |
| UTF-8, UTF-16, AND UNICODE PROPERTY SUPPORT | UTF-8, UTF-16, UTF-32, AND UNICODE PROPERTY SUPPORT |
| </b><br> |
</b><br> |
| <P> |
<P> |
| 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. |
| </P> |
</P> |
| <br><b> |
<br><b> |
| UTF-8 SUPPORT |
UTF-8 SUPPORT |
|
Line 28 In order process UTF-8 strings, you must build PCRE's
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Line 28 In order process UTF-8 strings, you must build PCRE's
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| support, and, in addition, you must call |
support, and, in addition, you must call |
| <a href="pcre_compile.html"><b>pcre_compile()</b></a> |
<a href="pcre_compile.html"><b>pcre_compile()</b></a> |
| 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. |
| </P> |
</P> |
| <br><b> |
<br><b> |
| UTF-16 SUPPORT | UTF-16 AND UTF-32 SUPPORT |
| </b><br> |
</b><br> |
| <P> |
<P> |
| 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 |
| <a href="pcre_compile.html"><b>pcre16_compile()</b></a> | <a href="pcre16_compile.html"><b>pcre16_compile()</b></a> |
| 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 | <a href="pcre32_compile.html"><b>pcre32_compile()</b></a> |
| strings that are matched against it are treated as UTF-16 strings instead of | with the PCRE_UTF16 or PCRE_UTF32 option flag, as appropriate. Alternatively, |
| strings of 16-bit characters. | 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. |
| </P> |
</P> |
| <br><b> |
<br><b> |
| UTF SUPPORT OVERHEAD |
UTF SUPPORT OVERHEAD |
|
Line 50 UTF SUPPORT OVERHEAD
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Line 54 UTF SUPPORT OVERHEAD
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| <P> |
<P> |
| 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. |
| </P> |
</P> |
| <br><b> |
<br><b> |
| UNICODE PROPERTY SUPPORT |
UNICODE PROPERTY SUPPORT |
|
Line 61 support), the escape sequences \p{..}, \P{..}, and \X
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Line 65 support), the escape sequences \p{..}, \P{..}, and \X
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| 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 |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
<a href="pcrepattern.html"><b>pcrepattern</b></a> |
| |
and |
| |
<a href="pcresyntax.html"><b>pcresyntax</b></a> |
| documentation. Only the short names for properties are supported. For example, |
documentation. Only the short names for properties are supported. For example, |
| \p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported. |
\p{L} matches a letter. Its Perl synonym, \p{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 79 place. From release 7.3 of PCRE, the check is accordin
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Line 85 place. From release 7.3 of PCRE, the check is accordin
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| 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> |
| <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> |
| <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 |
|
Line 98 detailed reason code if the caller has provided memory
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Line 107 detailed reason code if the caller has provided memory
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| <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> |
| <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 <b>pcre_compile()</b> 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 <b>pcre_dfa_exec()</b> and the interpreted | <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. |
| version of <b>pcre_exec()</b>. 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 | |
| <b>pcre_exec()</b> 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> |
| <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. | |
| <a name="utf16strings"></a></P> |
<a name="utf16strings"></a></P> |
| <br><b> |
<br><b> |
| Validity of UTF-16 strings |
Validity of UTF-16 strings |
|
Line 146 therefore want to skip these checks in order to improv
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Line 145 therefore want to skip these checks in order to improv
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| 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. |
| |
<a name="utf32strings"></a></P> |
| |
<br><b> |
| |
Validity of UTF-32 strings |
| |
</b><br> |
| |
<P> |
| |
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> |
</P> |
| |
<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 <b>pcre32_exec()</b> and |
| |
<b>pcre32_dfa_exec()</b> 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> |
| |
<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. |
| |
</P> |
| <br><b> |
<br><b> |
| General comments about UTF modes |
General comments about UTF modes |
| </b><br> |
</b><br> |
| <P> |
<P> |
| 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, \x{b3} or \xb3). Larger values | unbraced hexadecimal escape sequences (for example, \x{b3} or \xb3). Larger |
| have to use braced sequences. | values have to use braced sequences. |
| </P> |
</P> |
| <P> |
<P> |
| 2. Octal numbers up to \777 are recognized, and in UTF-8 mode, they match | 2. Octal numbers up to \777 are recognized, and in UTF-8 mode they match |
| two-byte characters for values greater than \177. |
two-byte characters for values greater than \177. |
| </P> |
</P> |
| <P> |
<P> |
|
Line 169 unit.
|
Line 193 unit.
|
| </P> |
</P> |
| <P> |
<P> |
| 5. The escape sequence \C can be used to match a single byte in UTF-8 mode, or |
5. The escape sequence \C 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 \C | 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 \C in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
<a href="pcrepattern.html"><b>pcrepattern</b></a> |
| documentation). The use of \C is not supported in the alternative matching |
documentation). The use of \C is not supported in the alternative matching |
| function <b>pcre[16]_dfa_exec()</b>, nor is it supported in UTF mode by the JIT | function <b>pcre[16|32]_dfa_exec()</b>, nor is it supported in UTF mode by the |
| optimization of <b>pcre[16]_exec()</b>. If JIT optimization is requested for a | JIT optimization of <b>pcre[16|32]_exec()</b>. If JIT optimization is requested |
| UTF pattern that contains \C, it will not succeed, and so the matching will | for a UTF pattern that contains \C, 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> |
| <P> |
<P> |
| 6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly |
6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly |
|
Line 208 PCRE_UCP is set.
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Line 232 PCRE_UCP is set.
|
| </P> |
</P> |
| <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. | |
| </P> |
</P> |
| <br><b> |
<br><b> |
| AUTHOR |
AUTHOR |
|
Line 231 Cambridge CB2 3QH, England.
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Line 253 Cambridge CB2 3QH, England.
|
| REVISION |
REVISION |
| </b><br> |
</b><br> |
| <P> |
<P> |
| Last updated: 14 April 2012 | Last updated: 27 February 2013 |
| <br> |
<br> |
| Copyright © 1997-2012 University of Cambridge. | Copyright © 1997-2013 University of Cambridge. |
| <br> |
<br> |
| <p> |
<p> |
| Return to the <a href="index.html">PCRE index page</a>. |
Return to the <a href="index.html">PCRE index page</a>. |
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