perlreapi.1

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "PERLREAPI 1"
.TH PERLREAPI 1 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
perlreapi \- perl regular expression plugin interface
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
As of Perl 5.9.5 there is a new interface for plugging and using other
regular expression engines than the default one.
.PP
Each engine is supposed to provide access to a constant structure of the
following format:
.PP
.Vb 10
\&    typedef struct regexp_engine {
\&        REGEXP* (*comp) (pTHX_ const SV * const pattern, const U32 flags);
\&        I32     (*exec) (pTHX_ REGEXP * const rx, char* stringarg, char* strend,
\&                         char* strbeg, I32 minend, SV* screamer,
\&                         void* data, U32 flags);
\&        char*   (*intuit) (pTHX_ REGEXP * const rx, SV *sv, char *strpos,
\&                           char *strend, U32 flags,
\&                           struct re_scream_pos_data_s *data);
\&        SV*     (*checkstr) (pTHX_ REGEXP * const rx);
\&        void    (*free) (pTHX_ REGEXP * const rx);
\&        void    (*numbered_buff_FETCH) (pTHX_ REGEXP * const rx, const I32 paren,
\&                                 SV * const sv);
\&        void    (*numbered_buff_STORE) (pTHX_ REGEXP * const rx, const I32 paren,
\&                                       SV const * const value);
\&        I32     (*numbered_buff_LENGTH) (pTHX_ REGEXP * const rx, const SV * const sv,
\&                                        const I32 paren);
\&        SV*     (*named_buff) (pTHX_ REGEXP * const rx, SV * const key,
\&                               SV * const value, U32 flags);
\&        SV*     (*named_buff_iter) (pTHX_ REGEXP * const rx, const SV * const lastkey,
\&                                    const U32 flags);
\&        SV*     (*qr_package)(pTHX_ REGEXP * const rx);
\&    #ifdef USE_ITHREADS
\&        void*   (*dupe) (pTHX_ REGEXP * const rx, CLONE_PARAMS *param);
\&    #endif
.Ve
.PP
When a regexp is compiled, its \f(CW\*(C`engine\*(C'\fR field is then set to point at
the appropriate structure, so that when it needs to be used Perl can find
the right routines to do so.
.PP
In order to install a new regexp handler, \f(CW$^H{regcomp}\fR is set
to an integer which (when casted appropriately) resolves to one of these
structures. When compiling, the \f(CW\*(C`comp\*(C'\fR method is executed, and the
resulting regexp structure's engine field is expected to point back at
the same structure.
.PP
The pTHX_ symbol in the definition is a macro used by perl under threading
to provide an extra argument to the routine holding a pointer back to
the interpreter that is executing the regexp. So under threading all
routines get an extra argument.
.SH "Callbacks"
.IX Header "Callbacks"
.Sh "comp"
.IX Subsection "comp"
.Vb 1
\&    REGEXP* comp(pTHX_ const SV * const pattern, const U32 flags);
.Ve
.PP
Compile the pattern stored in \f(CW\*(C`pattern\*(C'\fR using the given \f(CW\*(C`flags\*(C'\fR and
return a pointer to a prepared \f(CW\*(C`REGEXP\*(C'\fR structure that can perform
the match. See \*(L"The \s-1REGEXP\s0 structure\*(R" below for an explanation of
the individual fields in the \s-1REGEXP\s0 struct.
.PP
The \f(CW\*(C`pattern\*(C'\fR parameter is the scalar that was used as the
pattern. previous versions of perl would pass two \f(CW\*(C`char*\*(C'\fR indicating
the start and end of the stringified pattern, the following snippet can
be used to get the old parameters:
.PP
.Vb 3
\&    STRLEN plen;
\&    char*  exp = SvPV(pattern, plen);
\&    char* xend = exp + plen;
.Ve
.PP
Since any scalar can be passed as a pattern it's possible to implement
an engine that does something with an array (\f(CW\*(C`"ook" =~ [ qw/ eek
hlagh / ]\*(C'\fR) or with the non-stringified form of a compiled regular
expression (\f(CW\*(C`"ook" =~ qr/eek/\*(C'\fR). perl's own engine will always
stringify everything using the snippet above but that doesn't mean
other engines have to.
.PP
The \f(CW\*(C`flags\*(C'\fR parameter is a bitfield which indicates which of the
\&\f(CW\*(C`msixp\*(C'\fR flags the regex was compiled with. It also contains
additional info such as whether \f(CW\*(C`use locale\*(C'\fR is in effect.
.PP
The \f(CW\*(C`eogc\*(C'\fR flags are stripped out before being passed to the comp
routine. The regex engine does not need to know whether any of these
are set as those flags should only affect what perl does with the
pattern and its match variables, not how it gets compiled and
executed.
.PP
By the time the comp callback is called, some of these flags have
already had effect (noted below where applicable). However most of
their effect occurs after the comp callback has run in routines that
read the \f(CW\*(C`rx\->extflags\*(C'\fR field which it populates.
.PP
In general the flags should be preserved in \f(CW\*(C`rx\->extflags\*(C'\fR after
compilation, although the regex engine might want to add or delete
some of them to invoke or disable some special behavior in perl. The
flags along with any special behavior they cause are documented below:
.PP
The pattern modifiers:
.ie n .IP """/m"" \- RXf_PMf_MULTILINE" 4
.el .IP "\f(CW/m\fR \- RXf_PMf_MULTILINE" 4
.IX Item "/m - RXf_PMf_MULTILINE"
If this is in \f(CW\*(C`rx\->extflags\*(C'\fR it will be passed to
\&\f(CW\*(C`Perl_fbm_instr\*(C'\fR by \f(CW\*(C`pp_split\*(C'\fR which will treat the subject string
as a multi-line string.
.ie n .IP """/s"" \- RXf_PMf_SINGLELINE" 4
.el .IP "\f(CW/s\fR \- RXf_PMf_SINGLELINE" 4
.IX Item "/s - RXf_PMf_SINGLELINE"
.PD 0
.ie n .IP """/i"" \- RXf_PMf_FOLD" 4
.el .IP "\f(CW/i\fR \- RXf_PMf_FOLD" 4
.IX Item "/i - RXf_PMf_FOLD"
.ie n .IP """/x"" \- RXf_PMf_EXTENDED" 4
.el .IP "\f(CW/x\fR \- RXf_PMf_EXTENDED" 4
.IX Item "/x - RXf_PMf_EXTENDED"
.PD
If present on a regex \f(CW\*(C`#\*(C'\fR comments will be handled differently by the
tokenizer in some cases.
.Sp
\&\s-1TODO:\s0 Document those cases.
.ie n .IP """/p"" \- RXf_PMf_KEEPCOPY" 4
.el .IP "\f(CW/p\fR \- RXf_PMf_KEEPCOPY" 4
.IX Item "/p - RXf_PMf_KEEPCOPY"
.PP
Additional flags:
.IP "RXf_PMf_LOCALE" 4
.IX Item "RXf_PMf_LOCALE"
Set if \f(CW\*(C`use locale\*(C'\fR is in effect. If present in \f(CW\*(C`rx\->extflags\*(C'\fR
\&\f(CW\*(C`split\*(C'\fR will use the locale dependent definition of whitespace under
when RXf_SKIPWHITE or RXf_WHITE are in effect. Under \s-1ASCII\s0 whitespace
is defined as per isSPACE, and by the internal
macros \f(CW\*(C`is_utf8_space\*(C'\fR under \s-1UTF\-8\s0 and \f(CW\*(C`isSPACE_LC\*(C'\fR under \f(CW\*(C`use
locale\*(C'\fR.
.IP "RXf_UTF8" 4
.IX Item "RXf_UTF8"
Set if the pattern is \fISvUTF8()\fR, set by Perl_pmruntime.
.Sp
A regex engine may want to set or disable this flag during
compilation. The perl engine for instance may upgrade non\-UTF\-8
strings to \s-1UTF\-8\s0 if the pattern includes constructs such as \f(CW\*(C`\ex{...}\*(C'\fR
that can only match Unicode values.
.IP "RXf_SPLIT" 4
.IX Item "RXf_SPLIT"
If \f(CW\*(C`split\*(C'\fR is invoked as \f(CW\*(C`split \*(Aq \*(Aq\*(C'\fR or with no arguments (which
really means \f(CW\*(C`split(\*(Aq \*(Aq, $_)\*(C'\fR, see split), perl will
set this flag. The regex engine can then check for it and set the
\&\s-1SKIPWHITE\s0 and \s-1WHITE\s0 extflags. To do this the perl engine does:
.Sp