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.TH PCREPRECOMPILE 3 | .TH PCREPRECOMPILE 3 "12 November 2013" "PCRE 8.34" |
.SH NAME |
.SH NAME |
PCRE - Perl-compatible regular expressions |
PCRE - Perl-compatible regular expressions |
.SH "SAVING AND RE-USING PRECOMPILED PCRE PATTERNS" |
.SH "SAVING AND RE-USING PRECOMPILED PCRE PATTERNS" |
Line 18 JIT data.
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Line 18 JIT data.
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.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. If the two hosts have different endianness (byte order), |
and run them there. If the two hosts have different endianness (byte order), |
you should run the \fBpcre[16]_pattern_to_host_byte_order()\fP function on the | you should run the \fBpcre[16|32]_pattern_to_host_byte_order()\fP function on the |
new host before trying to match the pattern. The matching functions return |
new host before trying to match the pattern. The matching functions return |
PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness. |
PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness. |
.P |
.P |
Line 30 restoring a compiled pattern loses any JIT optimizatio
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Line 30 restoring a compiled pattern loses any JIT optimizatio
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.SH "SAVING A COMPILED PATTERN" |
.SH "SAVING A COMPILED PATTERN" |
.rs |
.rs |
.sp |
.sp |
The value returned by \fBpcre[16]_compile()\fP points to a single block of | The value returned by \fBpcre[16|32]_compile()\fP points to a single block of |
memory that holds the compiled pattern and associated data. You can find the |
memory that holds the compiled pattern and associated data. You can find the |
length of this block in bytes by calling \fBpcre[16]_fullinfo()\fP with an | length of this block in bytes by calling \fBpcre[16|32]_fullinfo()\fP with an |
argument of PCRE_INFO_SIZE. You can then save the data in any appropriate |
argument of PCRE_INFO_SIZE. You can then save the data in any appropriate |
manner. Here is sample code for the 8-bit library that compiles a pattern and |
manner. Here is sample code for the 8-bit library that compiles a pattern and |
writes it to a file. It assumes that the variable \fIfd\fP refers to a file |
writes it to a file. It assumes that the variable \fIfd\fP refers to a file |
Line 68 If the pattern has been studied, it is also possible t
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Line 68 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, \fBpcre[16]_study()\fP returns a pointer to a | generates additional information, \fBpcre[16|32]_study()\fP returns a pointer to a |
\fBpcre[16]_extra\fP data block. Its format is defined in the | \fBpcre[16|32]_extra\fP data block. Its format is defined in the |
.\" HTML <a href="pcreapi.html#extradata"> |
.\" HTML <a href="pcreapi.html#extradata"> |
.\" </a> |
.\" </a> |
section on matching a pattern |
section on matching a pattern |
Line 79 in the
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Line 79 in the
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\fBpcreapi\fP |
\fBpcreapi\fP |
.\" |
.\" |
documentation. The \fIstudy_data\fP field points to the binary study data, and |
documentation. The \fIstudy_data\fP field points to the binary study data, and |
this is what you must save (not the \fBpcre[16]_extra\fP block itself). The | this is what you must save (not the \fBpcre[16|32]_extra\fP block itself). The |
length of the study data can be obtained by calling \fBpcre[16]_fullinfo()\fP | length of the study data can be obtained by calling \fBpcre[16|32]_fullinfo()\fP |
with an argument of PCRE_INFO_STUDYSIZE. Remember to check that |
with an argument of PCRE_INFO_STUDYSIZE. Remember to check that |
\fBpcre[16]_study()\fP did return a non-NULL value before trying to save the | \fBpcre[16|32]_study()\fP did return a non-NULL value before trying to save the |
study data. |
study data. |
. |
. |
. |
. |
Line 90 study data.
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Line 90 study data.
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.rs |
.rs |
.sp |
.sp |
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, called \fBpcre[16]_pattern_to_host_byte_order()\fP if necessary, | memory, called \fBpcre[16|32]_pattern_to_host_byte_order()\fP if necessary, you |
you pass its pointer to \fBpcre[16]_exec()\fP or \fBpcre[16]_dfa_exec()\fP in | pass its pointer to \fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP in |
the usual way. |
the usual way. |
.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 \fItableptr\fP argument of \fBpcre[16]_compile()\fP), you | was compiled (the \fItableptr\fP argument of \fBpcre[16|32]_compile()\fP), you |
must now pass a similar pointer to \fBpcre[16]_exec()\fP or | must now pass a similar pointer to \fBpcre[16|32]_exec()\fP or |
\fBpcre[16]_dfa_exec()\fP, because the value saved with the compiled pattern | \fBpcre[16|32]_dfa_exec()\fP, because the value saved with the compiled pattern |
will obviously be nonsense. A field in a \fBpcre[16]_extra()\fP block is used | will obviously be nonsense. A field in a \fBpcre[16|32]_extra()\fP block is used |
to pass this data, as described in the |
to pass this data, as described in the |
.\" HTML <a href="pcreapi.html#extradata"> |
.\" HTML <a href="pcreapi.html#extradata"> |
.\" </a> |
.\" </a> |
Line 110 in the
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Line 110 in the
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.\" |
.\" |
documentation. |
documentation. |
.P |
.P |
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\fBWarning:\fP The tables that \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP use |
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must be the same as those that were used when the pattern was compiled. If this |
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is not the case, the behaviour is undefined. |
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.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 the matching |
the pointer in the compiled pattern is NULL, which causes the matching |
functions to use PCRE's internal tables. Thus, you do not need to take any |
functions to use PCRE's internal tables. Thus, you do not need to take any |
special action at run time in this case. |
special action at run time in this case. |
.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 |
\fBpcre[16]_extra\fP data block and set the \fIstudy_data\fP field to point to the | \fBpcre[16|32]_extra\fP data block and set the \fIstudy_data\fP field to point |
reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the | to the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in |
\fIflags\fP field to indicate that study data is present. Then pass the | the \fIflags\fP field to indicate that study data is present. Then pass the |
\fBpcre[16]_extra\fP block to the matching function in the usual way. If the | \fBpcre[16|32]_extra\fP block to the matching function in the usual way. If the |
pattern was studied for just-in-time optimization, that data cannot be saved, |
pattern was studied for just-in-time optimization, that data cannot be saved, |
and so is lost by a save/restore cycle. |
and so is lost by a save/restore cycle. |
. |
. |
Line 146 Cambridge CB2 3QH, England.
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Line 150 Cambridge CB2 3QH, England.
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.rs |
.rs |
.sp |
.sp |
.nf |
.nf |
Last updated: 10 January 2012 | Last updated: 12 November 2013 |
Copyright (c) 1997-2012 University of Cambridge. | Copyright (c) 1997-2013 University of Cambridge. |
.fi |
.fi |