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version 1.1, 2012/02/21 23:05:52
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version 1.1.1.2, 2012/02/21 23:50:25
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Line 29 If you are not using any private character tables (see
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Line 29 If you are not using any private character tables (see
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| <a href="pcre_maketables.html"><b>pcre_maketables()</b></a> |
<a href="pcre_maketables.html"><b>pcre_maketables()</b></a> |
| documentation), this is relatively straightforward. If you are using private |
documentation), this is relatively straightforward. If you are using private |
| tables, it is a little bit more complicated. However, if you are using the |
tables, it is a little bit more complicated. However, if you are using the |
| just-in-time optimization feature of <b>pcre_study()</b>, it is not possible to | just-in-time optimization feature, it is not possible to save and reload the |
| save and reload the JIT data. | JIT data. |
| </P> |
</P> |
| <P> |
<P> |
| If you save compiled patterns to a file, you can copy them to a different host |
If you save compiled patterns to a file, you can copy them to a different host |
| and run them there. This works even if the new host has the opposite endianness | and run them there. If the two hosts have different endianness (byte order), |
| to the one on which the patterns were compiled. There may be a small | you should run the <b>pcre[16]_pattern_to_host_byte_order()</b> function on the |
| performance penalty, but it should be insignificant. However, compiling regular | new host before trying to match the pattern. The matching functions return |
| expressions with one version of PCRE for use with a different version is not | PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness. |
| guaranteed to work and may cause crashes, and saving and restoring a compiled | |
| pattern loses any JIT optimization data. | |
| </P> |
</P> |
| |
<P> |
| |
Compiling regular expressions with one version of PCRE for use with a different |
| |
version is not guaranteed to work and may cause crashes, and saving and |
| |
restoring a compiled pattern loses any JIT optimization data. |
| |
</P> |
| <br><a name="SEC2" href="#TOC1">SAVING A COMPILED PATTERN</a><br> |
<br><a name="SEC2" href="#TOC1">SAVING A COMPILED PATTERN</a><br> |
| <P> |
<P> |
| The value returned by <b>pcre_compile()</b> points to a single block of memory | The value returned by <b>pcre[16]_compile()</b> points to a single block of |
| that holds the compiled pattern and associated data. You can find the length of | memory that holds the compiled pattern and associated data. You can find the |
| this block in bytes by calling <b>pcre_fullinfo()</b> with an argument of | length of this block in bytes by calling <b>pcre[16]_fullinfo()</b> with an |
| PCRE_INFO_SIZE. You can then save the data in any appropriate manner. Here is | argument of PCRE_INFO_SIZE. You can then save the data in any appropriate |
| sample code that compiles a pattern and writes it to a file. It assumes that | manner. Here is sample code for the 8-bit library that compiles a pattern and |
| the variable <i>fd</i> refers to a file that is open for output: | writes it to a file. It assumes that the variable <i>fd</i> refers to a file |
| | that is open for output: |
| <pre> |
<pre> |
| int erroroffset, rc, size; |
int erroroffset, rc, size; |
| char *error; |
char *error; |
|
Line 83 If the pattern has been studied, it is also possible t
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Line 87 If the pattern has been studied, it is also possible t
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| data in a similar way to the compiled pattern itself. However, if the |
data in a similar way to the compiled pattern itself. However, if the |
| PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is created cannot |
PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is created cannot |
| be saved because it is too dependent on the current environment. When studying |
be saved because it is too dependent on the current environment. When studying |
| generates additional information, <b>pcre_study()</b> returns a pointer to a | generates additional information, <b>pcre[16]_study()</b> returns a pointer to a |
| <b>pcre_extra</b> data block. Its format is defined in the | <b>pcre[16]_extra</b> data block. Its format is defined in the |
| <a href="pcreapi.html#extradata">section on matching a pattern</a> |
<a href="pcreapi.html#extradata">section on matching a pattern</a> |
| in the |
in the |
| <a href="pcreapi.html"><b>pcreapi</b></a> |
<a href="pcreapi.html"><b>pcreapi</b></a> |
| documentation. The <i>study_data</i> field points to the binary study data, and |
documentation. The <i>study_data</i> field points to the binary study data, and |
| this is what you must save (not the <b>pcre_extra</b> block itself). The length | this is what you must save (not the <b>pcre[16]_extra</b> block itself). The |
| of the study data can be obtained by calling <b>pcre_fullinfo()</b> with an | length of the study data can be obtained by calling <b>pcre[16]_fullinfo()</b> |
| argument of PCRE_INFO_STUDYSIZE. Remember to check that <b>pcre_study()</b> did | with an argument of PCRE_INFO_STUDYSIZE. Remember to check that |
| return a non-NULL value before trying to save the study data. | <b>pcre[16]_study()</b> did return a non-NULL value before trying to save the |
| | study data. |
| </P> |
</P> |
| <br><a name="SEC3" href="#TOC1">RE-USING A PRECOMPILED PATTERN</a><br> |
<br><a name="SEC3" href="#TOC1">RE-USING A PRECOMPILED PATTERN</a><br> |
| <P> |
<P> |
| Re-using a precompiled pattern is straightforward. Having reloaded it into main |
Re-using a precompiled pattern is straightforward. Having reloaded it into main |
| memory, you pass its pointer to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> in | memory, called <b>pcre[16]_pattern_to_host_byte_order()</b> if necessary, |
| the usual way. This should work even on another host, and even if that host has | you pass its pointer to <b>pcre[16]_exec()</b> or <b>pcre[16]_dfa_exec()</b> in |
| the opposite endianness to the one where the pattern was compiled. | the usual way. |
| </P> |
</P> |
| <P> |
<P> |
| However, if you passed a pointer to custom character tables when the pattern |
However, if you passed a pointer to custom character tables when the pattern |
| was compiled (the <i>tableptr</i> argument of <b>pcre_compile()</b>), you must | was compiled (the <i>tableptr</i> argument of <b>pcre[16]_compile()</b>), you |
| now pass a similar pointer to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>, | must now pass a similar pointer to <b>pcre[16]_exec()</b> or |
| because the value saved with the compiled pattern will obviously be nonsense. A | <b>pcre[16]_dfa_exec()</b>, because the value saved with the compiled pattern |
| field in a <b>pcre_extra()</b> block is used to pass this data, as described in | will obviously be nonsense. A field in a <b>pcre[16]_extra()</b> block is used |
| the | to pass this data, as described in the |
| <a href="pcreapi.html#extradata">section on matching a pattern</a> |
<a href="pcreapi.html#extradata">section on matching a pattern</a> |
| in the |
in the |
| <a href="pcreapi.html"><b>pcreapi</b></a> |
<a href="pcreapi.html"><b>pcreapi</b></a> |
|
Line 115 documentation.
|
Line 120 documentation.
|
| </P> |
</P> |
| <P> |
<P> |
| If you did not provide custom character tables when the pattern was compiled, |
If you did not provide custom character tables when the pattern was compiled, |
| the pointer in the compiled pattern is NULL, which causes <b>pcre_exec()</b> to | the pointer in the compiled pattern is NULL, which causes the matching |
| use PCRE's internal tables. Thus, you do not need to take any special action at | functions to use PCRE's internal tables. Thus, you do not need to take any |
| run time in this case. | special action at run time in this case. |
| </P> |
</P> |
| <P> |
<P> |
| If you saved study data with the compiled pattern, you need to create your own |
If you saved study data with the compiled pattern, you need to create your own |
| <b>pcre_extra</b> data block and set the <i>study_data</i> field to point to the | <b>pcre[16]_extra</b> data block and set the <i>study_data</i> field to point to the |
| reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the |
reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the |
| <i>flags</i> field to indicate that study data is present. Then pass the |
<i>flags</i> field to indicate that study data is present. Then pass the |
| <b>pcre_extra</b> block to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> in the | <b>pcre[16]_extra</b> block to the matching function in the usual way. If the |
| usual way. If the pattern was studied for just-in-time optimization, that data | pattern was studied for just-in-time optimization, that data cannot be saved, |
| cannot be saved, and so is lost by a save/restore cycle. | and so is lost by a save/restore cycle. |
| </P> |
</P> |
| <br><a name="SEC4" href="#TOC1">COMPATIBILITY WITH DIFFERENT PCRE RELEASES</a><br> |
<br><a name="SEC4" href="#TOC1">COMPATIBILITY WITH DIFFERENT PCRE RELEASES</a><br> |
| <P> |
<P> |
|
Line 144 Cambridge CB2 3QH, England.
|
Line 149 Cambridge CB2 3QH, England.
|
| </P> |
</P> |
| <br><a name="SEC6" href="#TOC1">REVISION</a><br> |
<br><a name="SEC6" href="#TOC1">REVISION</a><br> |
| <P> |
<P> |
| Last updated: 26 August 2011 | Last updated: 10 January 2012 |
| <br> |
<br> |
| Copyright © 1997-2011 University of Cambridge. | Copyright © 1997-2012 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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