From: Ilya Zakharevich Date: Thu, 9 Jul 1998 21:39:40 +0000 (-0400) Subject: applied patch, tweaked doc and code that does labels/indentation X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=54dc92de45fcd4ecd424e5092d7d46275547e13a;p=p5sagit%2Fp5-mst-13.2.git applied patch, tweaked doc and code that does labels/indentation Message-Id: <199807100139.VAA08617@monk.mps.ohio-state.edu> Subject: [PATCH 5.004_71] perldebug.pod and RE p4raw-id: //depot/perl@1429 --- diff --git a/pod/perldebug.pod b/pod/perldebug.pod index 888ad7f..7a6e814 100644 --- a/pod/perldebug.pod +++ b/pod/perldebug.pod @@ -1382,4 +1382,280 @@ print nonempty categories, print the absolute values of counts and totals. If an extension or an external library does not use Perl API to allocate memory, these allocations are not counted. +=head1 Debugging regular expressions + +There are two ways to enable debugging output for regular expressions. + +If your perl is compiled with C<-DDEBUGGING>, you may use the +B<-Dr> flag on the command line. + +Otherwise, one can C, which has effects both at +compile time, and at run time (and is I lexically scoped). + +=head2 Compile-time output + +The debugging output for the compile time looks like this: + + compiling RE `[bc]d(ef*g)+h[ij]k$' + size 43 first at 1 + 1: ANYOF(11) + 11: EXACT (13) + 13: CURLYX {1,32767}(27) + 15: OPEN1(17) + 17: EXACT (19) + 19: STAR(22) + 20: EXACT (0) + 22: EXACT (24) + 24: CLOSE1(26) + 26: WHILEM(0) + 27: NOTHING(28) + 28: EXACT (30) + 30: ANYOF(40) + 40: EXACT (42) + 42: EOL(43) + 43: END(0) + anchored `de' at 1 floating `gh' at 3..2147483647 (checking floating) + stclass `ANYOF' minlen 7 + +The first line shows the pre-compiled form of the regexp, and the +second shows the size of the compiled form (in arbitrary units, +usually 4-byte words) and the label I of the first node which +does a match. + +The last line (split into two lines in the above) contains the optimizer +info. In the example shown, the optimizer found that the match +should contain a substring C at the offset 1, and substring C +at some offset between 3 and infinity. Moreover, when checking for +these substrings (to abandon impossible matches quickly) it will check +for the substring C before checking for the substring C. The +optimizer may also use the knowledge that the match starts (at the +C I) with a character class, and the match cannot be +shorter than 7 chars. + +The fields of interest which may appear in the last line are + +=over + +=item C I C I + +=item C I C I + +see above; + +=item C + +which substring to check first; + +=item C + +the minimal length of the match; + +=item C I + +The type of the first matching node. + +=item C + +which advises to not scan for the found substrings; + +=item C + +which says that the optimizer info is in fact all that the regular +expression contains (thus one does not need to enter the RE engine at +all); + +=item C + +if the pattern contains C<\G>; + +=item C + +if the pattern starts with a repeated char (as in C); + +=item C + +if the pattern starts with C<.*>; + +=item C + +if the pattern contain eval-groups (see L); + +=item C + +if the pattern may +match only at a handful of places (with C being +C, C, or C, see the table below). + +=back + +If a substring is known to match at end-of-line only, it may be +followed by C<$>, as in C. + +The optimizer-specific info is used to avoid entering (a slow) RE +engine on strings which will definitely not match. If C flag +is set, a call to the RE engine may be avoided even when optimizer +found an appropriate place for the match. + +The rest of the output contains the list of I of the compiled +form of the RE. Each line has format + +C< >I: I I (I) + +=head2 Types of nodes + +Here is the list of possible types with short descriptions: + + # 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. + + # [Special] alternatives + ANY no Match any one character (except newline). + SANY no Match any one character. + ANYOF sv Match character in (or not in) this class. + ALNUM no Match any alphanumeric character + ALNUML no Match any alphanumeric char in locale + NALNUM no Match any non-alphanumeric character + NALNUML no Match any non-alphanumeric char in locale + SPACE no Match any whitespace character + SPACEL no Match any whitespace char in locale + NSPACE no Match any non-whitespace character + NSPACEL no Match any non-whitespace char in locale + DIGIT no Match any numeric character + NDIGIT no Match any non-numeric character + + # BRANCH The set of branches constituting a single choice are hooked + # together with their "next" pointers, since precedence prevents + # anything being concatenated to any individual branch. The + # "next" pointer of the last BRANCH in a choice points to the + # thing following the whole choice. This is also where the + # final "next" pointer of each individual branch points; each + # branch starts with the operand node of a BRANCH node. + # + BRANCH node Match this alternative, or the next... + + # BACK Normal "next" pointers all implicitly point forward; BACK + # exists to make loop structures possible. + # not used + BACK no Match "", "next" ptr points backward. + + # Literals + EXACT sv Match this string (preceded by length). + EXACTF sv Match this string, folded (prec. by length). + EXACTFL sv Match this string, folded in locale (w/len). + + # Do nothing + NOTHING no Match empty string. + # A variant of above which delimits a group, thus stops optimizations + TAIL no Match empty string. Can jump here from outside. + + # STAR,PLUS '?', and complex '*' and '+', are implemented as circular + # BRANCH structures using BACK. Simple cases (one character + # per match) are implemented with STAR and PLUS for speed + # and to minimize recursive plunges. + # + STAR node Match this (simple) thing 0 or more times. + PLUS node Match this (simple) thing 1 or more times. + + CURLY sv 2 Match this simple thing {n,m} times. + CURLYN no 2 Match next-after-this simple thing + # {n,m} times, set parenths. + CURLYM no 2 Match this medium-complex thing {n,m} times. + CURLYX sv 2 Match this complex thing {n,m} times. + + # This terminator creates a loop structure for CURLYX + WHILEM no Do curly processing and see if rest matches. + + # OPEN,CLOSE,GROUPP ...are numbered at compile time. + OPEN num 1 Mark this point in input as start of #n. + CLOSE num 1 Analogous to OPEN. + + REF num 1 Match some already matched string + REFF num 1 Match already matched string, folded + REFFL num 1 Match already matched string, folded in loc. + + # grouping assertions + IFMATCH off 1 2 Succeeds if the following matches. + UNLESSM off 1 2 Fails if the following matches. + SUSPEND off 1 1 "Independent" sub-RE. + IFTHEN off 1 1 Switch, should be preceeded by switcher . + GROUPP num 1 Whether the group matched. + + # Support for long RE + LONGJMP off 1 1 Jump far away. + BRANCHJ off 1 1 BRANCH with long offset. + + # The heavy worker + EVAL evl 1 Execute some Perl code. + + # Modifiers + MINMOD no Next operator is not greedy. + LOGICAL no Next opcode should set the flag only. + + # This is not used yet + RENUM off 1 1 Group with independently numbered parens. + + # This is not really a node, but an optimized away piece of a "long" node. + # To simplify debugging output, we mark it as if it were a node + OPTIMIZED off Placeholder for dump. + +=head2 Run-time output + +First of all, when doing a match, one may get no run-time output even +if debugging is enabled. this means that the RE engine was never +entered, all of the job was done by the optimizer. + +If RE engine was entered, the output may look like this: + + Matching `[bc]d(ef*g)+h[ij]k$' against `abcdefg__gh__' + Setting an EVAL scope, savestack=3 + 2 | 1: ANYOF + 3 | 11: EXACT + 4 | 13: CURLYX {1,32767} + 4 | 26: WHILEM + 0 out of 1..32767 cc=effff31c + 4 | 15: OPEN1 + 4 | 17: EXACT + 5 | 19: STAR + EXACT can match 1 times out of 32767... + Setting an EVAL scope, savestack=3 + 6 | 22: EXACT + 7 <__gh__> | 24: CLOSE1 + 7 <__gh__> | 26: WHILEM + 1 out of 1..32767 cc=effff31c + Setting an EVAL scope, savestack=12 + 7 <__gh__> | 15: OPEN1 + 7 <__gh__> | 17: EXACT + restoring \1 to 4(4)..7 + failed, try continuation... + 7 <__gh__> | 27: NOTHING + 7 <__gh__> | 28: EXACT + failed... + failed... + +The most significant information in the output is about the particular I +of the compiled RE which is currently being tested against the target string. +The format of these lines is + +C< >I > > |I: I + +The I info is indented with respect to the backtracking level. +Other incidental information appears interspersed within. + =cut diff --git a/regcomp.c b/regcomp.c index f9e2539..420d2fb 100644 --- a/regcomp.c +++ b/regcomp.c @@ -2246,7 +2246,7 @@ dumpuntil(regnode *start, regnode *node, regnode *last, SV* sv, I32 l) if (OP(node) == OPTIMIZED) goto after_print; regprop(sv, node); - PerlIO_printf(Perl_debug_log, "%4d%*s%s", node - start, + PerlIO_printf(Perl_debug_log, "%4d:%*s%s", node - start, 2*l + 1, "", SvPVX(sv)); if (next == NULL) /* Next ptr. */ PerlIO_printf(Perl_debug_log, "(0)"); @@ -2364,7 +2364,7 @@ regprop(SV *sv, regnode *o) #ifdef DEBUGGING register char *p = 0; - sv_setpv(sv, ":"); + sv_setpvn(sv, "", 0); switch (OP(o)) { case BOL: p = "BOL"; diff --git a/regexec.c b/regexec.c index deb61aa..0634539 100644 --- a/regexec.c +++ b/regexec.c @@ -774,14 +774,14 @@ regmatch(regnode *prog) ? (5 + taill) - pref_len : regeol - locinput); regprop(prop, scan); PerlIO_printf(Perl_debug_log, - "%4i <%s%.*s%s%s%s%.*s%s>%*s|%*s%2d%s\n", + "%4i <%s%.*s%s%s%s%.*s%s>%*s|%3d:%*s%s\n", locinput - bostr, colors[2], pref_len, locinput - pref_len, colors[3], (docolor ? "" : "> <"), colors[0], l, locinput, colors[1], 15 - l - pref_len + 1, "", - regindent*2, "", scan - regprogram, + scan - regprogram, regindent*2, "", SvPVX(prop)); } );