perldebguts.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.

\&
\& Enter h or \`h h\*(Aq for help.
\&
\& main::(\-e:1):   0
\&   DB<1> sub foo { 14 }
\&
\&   DB<2> sub bar { 3 }
\&
\&   DB<3> t print foo() * bar()
\& main::((eval 172):3):   print foo() + bar();
\& main::foo((eval 168):2):
\& main::bar((eval 170):2):
\& 42
.Ve
.PP
with this one, once the \f(CW\*(C`o\*(C'\fRption \f(CW\*(C`frame=2\*(C'\fR has been set:
.PP
.Vb 11
\&   DB<4> o f=2
\&                frame = \*(Aq2\*(Aq
\&   DB<5> t print foo() * bar()
\& 3:      foo() * bar()
\& entering main::foo
\&  2:     sub foo { 14 };
\& exited main::foo
\& entering main::bar
\&  2:     sub bar { 3 };
\& exited main::bar
\& 42
.Ve
.PP
By way of demonstration, we present below a laborious listing
resulting from setting your \f(CW\*(C`PERLDB_OPTS\*(C'\fR environment variable to
the value \f(CW\*(C`f=n N\*(C'\fR, and running \fIperl \-d \-V\fR from the command line.
Examples use various values of \f(CW\*(C`n\*(C'\fR are shown to give you a feel
for the difference between settings.  Long those it may be, this
is not a complete listing, but only excerpts.
.IP "1." 4
.Vb 10
\&  entering main::BEGIN
\&   entering Config::BEGIN
\&    Package lib/Exporter.pm.
\&    Package lib/Carp.pm.
\&   Package lib/Config.pm.
\&   entering Config::TIEHASH
\&   entering Exporter::import
\&    entering Exporter::export
\&  entering Config::myconfig
\&   entering Config::FETCH
\&   entering Config::FETCH
\&   entering Config::FETCH
\&   entering Config::FETCH
.Ve
.IP "2." 4
.Vb 10
\&  entering main::BEGIN
\&   entering Config::BEGIN
\&    Package lib/Exporter.pm.
\&    Package lib/Carp.pm.
\&   exited Config::BEGIN
\&   Package lib/Config.pm.
\&   entering Config::TIEHASH
\&   exited Config::TIEHASH
\&   entering Exporter::import
\&    entering Exporter::export
\&    exited Exporter::export
\&   exited Exporter::import
\&  exited main::BEGIN
\&  entering Config::myconfig
\&   entering Config::FETCH
\&   exited Config::FETCH
\&   entering Config::FETCH
\&   exited Config::FETCH
\&   entering Config::FETCH
.Ve
.IP "3." 4
.Vb 10
\&  in  $=main::BEGIN() from /dev/null:0
\&   in  $=Config::BEGIN() from lib/Config.pm:2
\&    Package lib/Exporter.pm.
\&    Package lib/Carp.pm.
\&   Package lib/Config.pm.
\&   in  $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:644
\&   in  $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&    in  $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from li
\&  in  @=Config::myconfig() from /dev/null:0
\&   in  $=Config::FETCH(ref(Config), \*(Aqpackage\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(Aqbaserev\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(AqPERL_VERSION\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(AqPERL_SUBVERSION\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(Aqosname\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(Aqosvers\*(Aq) from lib/Config.pm:574
.Ve
.IP "4." 4
.Vb 10
\&  in  $=main::BEGIN() from /dev/null:0
\&   in  $=Config::BEGIN() from lib/Config.pm:2
\&    Package lib/Exporter.pm.
\&    Package lib/Carp.pm.
\&   out $=Config::BEGIN() from lib/Config.pm:0
\&   Package lib/Config.pm.
\&   in  $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:644
\&   out $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:644
\&   in  $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&    in  $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/
\&    out $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/
\&   out $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&  out $=main::BEGIN() from /dev/null:0
\&  in  @=Config::myconfig() from /dev/null:0
\&   in  $=Config::FETCH(ref(Config), \*(Aqpackage\*(Aq) from lib/Config.pm:574
\&   out $=Config::FETCH(ref(Config), \*(Aqpackage\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(Aqbaserev\*(Aq) from lib/Config.pm:574
\&   out $=Config::FETCH(ref(Config), \*(Aqbaserev\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(AqPERL_VERSION\*(Aq) from lib/Config.pm:574
\&   out $=Config::FETCH(ref(Config), \*(AqPERL_VERSION\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(ref(Config), \*(AqPERL_SUBVERSION\*(Aq) from lib/Config.pm:574
.Ve
.IP "5." 4
.Vb 10
\&  in  $=main::BEGIN() from /dev/null:0
\&   in  $=Config::BEGIN() from lib/Config.pm:2
\&    Package lib/Exporter.pm.
\&    Package lib/Carp.pm.
\&   out $=Config::BEGIN() from lib/Config.pm:0
\&   Package lib/Config.pm.
\&   in  $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:644
\&   out $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:644
\&   in  $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&    in  $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/E
\&    out $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/E
\&   out $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&  out $=main::BEGIN() from /dev/null:0
\&  in  @=Config::myconfig() from /dev/null:0
\&   in  $=Config::FETCH(\*(AqConfig=HASH(0x1aa444)\*(Aq, \*(Aqpackage\*(Aq) from lib/Config.pm:574
\&   out $=Config::FETCH(\*(AqConfig=HASH(0x1aa444)\*(Aq, \*(Aqpackage\*(Aq) from lib/Config.pm:574
\&   in  $=Config::FETCH(\*(AqConfig=HASH(0x1aa444)\*(Aq, \*(Aqbaserev\*(Aq) from lib/Config.pm:574
\&   out $=Config::FETCH(\*(AqConfig=HASH(0x1aa444)\*(Aq, \*(Aqbaserev\*(Aq) from lib/Config.pm:574
.Ve
.IP "6." 4
.Vb 10
\&  in  $=CODE(0x15eca4)() from /dev/null:0
\&   in  $=CODE(0x182528)() from lib/Config.pm:2
\&    Package lib/Exporter.pm.
\&   out $=CODE(0x182528)() from lib/Config.pm:0
\&   scalar context return from CODE(0x182528): undef
\&   Package lib/Config.pm.
\&   in  $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:628
\&   out $=Config::TIEHASH(\*(AqConfig\*(Aq) from lib/Config.pm:628
\&   scalar context return from Config::TIEHASH:   empty hash
\&   in  $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&    in  $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/Exporter.pm:171
\&    out $=Exporter::export(\*(AqConfig\*(Aq, \*(Aqmain\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from lib/Exporter.pm:171
\&    scalar context return from Exporter::export: \*(Aq\*(Aq
\&   out $=Exporter::import(\*(AqConfig\*(Aq, \*(Aqmyconfig\*(Aq, \*(Aqconfig_vars\*(Aq) from /dev/null:0
\&   scalar context return from Exporter::import: \*(Aq\*(Aq
.Ve
.PP
In all cases shown above, the line indentation shows the call tree.
If bit 2 of \f(CW\*(C`frame\*(C'\fR is set, a line is printed on exit from a
subroutine as well.  If bit 4 is set, the arguments are printed
along with the caller info.  If bit 8 is set, the arguments are
printed even if they are tied or references.  If bit 16 is set, the
return value is printed, too.
.PP
When a package is compiled, a line like this
.PP
.Vb 1
\&    Package lib/Carp.pm.
.Ve
.PP
is printed with proper indentation.
.SH "Debugging regular expressions"
.IX Header "Debugging regular expressions"
There are two ways to enable debugging output for regular expressions.
.PP
If your perl is compiled with \f(CW\*(C`\-DDEBUGGING\*(C'\fR, you may use the
\&\fB\-Dr\fR flag on the command line.
.PP
Otherwise, one can \f(CW\*(C`use re \*(Aqdebug\*(Aq\*(C'\fR, which has effects at
compile time and run time.  It is not lexically scoped.
.Sh "Compile-time output"
.IX Subsection "Compile-time output"
The debugging output at compile time looks like this:
.PP
.Vb 10
\&  Compiling REx \`[bc]d(ef*g)+h[ij]k$\*(Aq
\&  size 45 Got 364 bytes for offset annotations.
\&  first at 1
\&  rarest char g at 0
\&  rarest char d at 0
\&     1: ANYOF[bc](12)
\&    12: EXACT <d>(14)
\&    14: CURLYX[0] {1,32767}(28)
\&    16:   OPEN1(18)
\&    18:     EXACT <e>(20)
\&    20:     STAR(23)
\&    21:       EXACT <f>(0)
\&    23:     EXACT <g>(25)
\&    25:   CLOSE1(27)
\&    27:   WHILEM[1/1](0)
\&    28: NOTHING(29)
\&    29: EXACT <h>(31)
\&    31: ANYOF[ij](42)
\&    42: EXACT <k>(44)
\&    44: EOL(45)
\&    45: END(0)
\&  anchored \`de\*(Aq at 1 floating \`gh\*(Aq at 3..2147483647 (checking floating) 
\&        stclass \`ANYOF[bc]\*(Aq minlen 7 
\&  Offsets: [45]
\&        1[4] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 5[1]
\&        0[0] 12[1] 0[0] 6[1] 0[0] 7[1] 0[0] 9[1] 8[1] 0[0] 10[1] 0[0]
\&        11[1] 0[0] 12[0] 12[0] 13[1] 0[0] 14[4] 0[0] 0[0] 0[0] 0[0]
\&        0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 18[1] 0[0] 19[1] 20[0]  
\&  Omitting $\` $& $\*(Aq support.
.Ve
.PP
The first line shows the pre-compiled form of the regex.  The second
shows the size of the compiled form (in arbitrary units, usually
4\-byte words) and the total number of bytes allocated for the
offset/length table, usually 4+\f(CW\*(C`size\*(C'\fR*8.  The next line shows the
label \fIid\fR of the first node that does a match.
.PP
The
.PP
.Vb 2
\&  anchored \`de\*(Aq at 1 floating \`gh\*(Aq at 3..2147483647 (checking floating) 
\&        stclass \`ANYOF[bc]\*(Aq minlen 7
.Ve
.PP
line (split into two lines above) contains optimizer
information.  In the example shown, the optimizer found that the match 
should contain a substring \f(CW\*(C`de\*(C'\fR at offset 1, plus substring \f(CW\*(C`gh\*(C'\fR
at some offset between 3 and infinity.  Moreover, when checking for
these substrings (to abandon impossible matches quickly), Perl will check
for the substring \f(CW\*(C`gh\*(C'\fR before checking for the substring \f(CW\*(C`de\*(C'\fR.  The
optimizer may also use the knowledge that the match starts (at the
\&\f(CW\*(C`first\*(C'\fR \fIid\fR) with a character class, and no string 
shorter than 7 characters can possibly match.
.PP
The fields of interest which may appear in this line are
.ie n .IP """anchored""\fR \fI\s-1STRING\s0\fR \f(CW""at""\fR \fI\s-1POS\s0" 4
.el .IP "\f(CWanchored\fR \fI\s-1STRING\s0\fR \f(CWat\fR \fI\s-1POS\s0\fR" 4
.IX Item "anchored STRING at POS"
.PD 0
.ie n .IP """floating""\fR \fI\s-1STRING\s0\fR \f(CW""at""\fR \fI\s-1POS1\s0..POS2" 4
.el .IP "\f(CWfloating\fR \fI\s-1STRING\s0\fR \f(CWat\fR \fI\s-1POS1\s0..POS2\fR" 4
.IX Item "floating STRING at POS1..POS2"
.PD
See above.
.ie n .IP """matching floating/anchored""" 4
.el .IP "\f(CWmatching floating/anchored\fR" 4
.IX Item "matching floating/anchored"
Which substring to check first.
.ie n .IP """minlen""" 4
.el .IP "\f(CWminlen\fR" 4
.IX Item "minlen"
The minimal length of the match.
.ie n .IP """stclass""\fR \fI\s-1TYPE\s0" 4
.el .IP "\f(CWstclass\fR \fI\s-1TYPE\s0\fR" 4
.IX Item "stclass TYPE"
Type of first matching node.
.ie n .IP """noscan""" 4
.el .IP "\f(CWnoscan\fR" 4
.IX Item "noscan"
Don't scan for the found substrings.
.ie n .IP """isall""" 4
.el .IP "\f(CWisall\fR" 4
.IX Item "isall"
Means that the optimizer information is all that the regular
expression contains, and thus one does not need to enter the regex engine at
all.
.ie n .IP """GPOS""" 4
.el .IP "\f(CWGPOS\fR" 4
.IX Item "GPOS"
Set if the pattern contains \f(CW\*(C`\eG\*(C'\fR.
.ie n .IP """plus""" 4
.el .IP "\f(CWplus\fR" 4
.IX Item "plus"
Set if the pattern starts with a repeated char (as in \f(CW\*(C`x+y\*(C'\fR).
.ie n .IP """implicit""" 4
.el .IP "\f(CWimplicit\fR" 4
.IX Item "implicit"
Set if the pattern starts with \f(CW\*(C`.*\*(C'\fR.
.ie n .IP """with eval""" 4
.el .IP "\f(CWwith eval\fR" 4
.IX Item "with eval"
Set if the pattern contain eval-groups, such as \f(CW\*(C`(?{ code })\*(C'\fR and
\&\f(CW\*(C`(??{ code })\*(C'\fR.
.ie n .IP """anchored(TYPE)""" 4
.el .IP "\f(CWanchored(TYPE)\fR" 4
.IX Item "anchored(TYPE)"
If the pattern may match only at a handful of places, (with \f(CW\*(C`TYPE\*(C'\fR
being \f(CW\*(C`BOL\*(C'\fR, \f(CW\*(C`MBOL\*(C'\fR, or \f(CW\*(C`GPOS\*(C'\fR.  See the table below.
.PP
If a substring is known to match at end-of-line only, it may be
followed by \f(CW\*(C`$\*(C'\fR, as in \f(CW\*(C`floating \`k\*(Aq$\*(C'\fR.
.PP
The optimizer-specific information is used to avoid entering (a slow) regex
engine on strings that will not definitely match.  If the \f(CW\*(C`isall\*(C'\fR flag
is set, a call to the regex engine may be avoided even when the optimizer
found an appropriate place for the match.
.PP
Above the optimizer section is the list of \fInodes\fR of the compiled
form of the regex.  Each line has format
.PP
\&\f(CW\*(C`\*(C'\fR
.Sh "Types of nodes"
.IX Subsection "Types of nodes"
Here are the possible types, with short descriptions:
.PP
.Vb 1
\&    # TYPE arg\-description [num\-args] [longjump\-len] DESCRIPTION
\&
\&    # Exit points
\&    END         no      End of program.
\&    SUCCEED     no      Return from a subroutine, basically.
\&
\&    # Anchors:
\&    BOL         no      Match "" at beginning of line.
\&    MBOL        no      Same, assuming multiline.
\&    SBOL        no      Same, assuming singleline.
\&    EOS         no      Match "" at end of string.
\&    EOL         no      Match "" at end of line.
\&    MEOL        no      Same, assuming multiline.
\&    SEOL        no      Same, assuming singleline.
\&    BOUND       no      Match "" at any word boundary
\&    BOUNDL      no      Match "" at any word boundary
\&    NBOUND      no      Match "" at any word non\-boundary
\&    NBOUNDL     no      Match "" at any word non\-boundary
\&    GPOS        no      Matches where last m//g left off.
\&