forked from schacon/perl
/
regexec.c
7076 lines (6423 loc) · 227 KB
/
regexec.c
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/* regexec.c
*/
/*
* One Ring to rule them all, One Ring to find them
&
* [p.v of _The Lord of the Rings_, opening poem]
* [p.50 of _The Lord of the Rings_, I/iii: "The Shadow of the Past"]
* [p.254 of _The Lord of the Rings_, II/ii: "The Council of Elrond"]
*/
/* This file contains functions for executing a regular expression. See
* also regcomp.c which funnily enough, contains functions for compiling
* a regular expression.
*
* This file is also copied at build time to ext/re/re_exec.c, where
* it's built with -DPERL_EXT_RE_BUILD -DPERL_EXT_RE_DEBUG -DPERL_EXT.
* This causes the main functions to be compiled under new names and with
* debugging support added, which makes "use re 'debug'" work.
*/
/* NOTE: this is derived from Henry Spencer's regexp code, and should not
* confused with the original package (see point 3 below). Thanks, Henry!
*/
/* Additional note: this code is very heavily munged from Henry's version
* in places. In some spots I've traded clarity for efficiency, so don't
* blame Henry for some of the lack of readability.
*/
/* The names of the functions have been changed from regcomp and
* regexec to pregcomp and pregexec in order to avoid conflicts
* with the POSIX routines of the same names.
*/
#ifdef PERL_EXT_RE_BUILD
#include "re_top.h"
#endif
/*
* pregcomp and pregexec -- regsub and regerror are not used in perl
*
* Copyright (c) 1986 by University of Toronto.
* Written by Henry Spencer. Not derived from licensed software.
*
* Permission is granted to anyone to use this software for any
* purpose on any computer system, and to redistribute it freely,
* subject to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of
* this software, no matter how awful, even if they arise
* from defects in it.
*
* 2. The origin of this software must not be misrepresented, either
* by explicit claim or by omission.
*
* 3. Altered versions must be plainly marked as such, and must not
* be misrepresented as being the original software.
*
**** Alterations to Henry's code are...
****
**** Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
**** 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
**** by Larry Wall and others
****
**** You may distribute under the terms of either the GNU General Public
**** License or the Artistic License, as specified in the README file.
*
* Beware that some of this code is subtly aware of the way operator
* precedence is structured in regular expressions. Serious changes in
* regular-expression syntax might require a total rethink.
*/
#include "EXTERN.h"
#define PERL_IN_REGEXEC_C
#include "perl.h"
#ifdef PERL_IN_XSUB_RE
# include "re_comp.h"
#else
# include "regcomp.h"
#endif
#define RF_tainted 1 /* tainted information used? */
#define RF_warned 2 /* warned about big count? */
#define RF_utf8 8 /* Pattern contains multibyte chars? */
#define UTF_PATTERN ((PL_reg_flags & RF_utf8) != 0)
#define RS_init 1 /* eval environment created */
#define RS_set 2 /* replsv value is set */
#ifndef STATIC
#define STATIC static
#endif
/* Valid for non-utf8 strings only: avoids the reginclass call if there are no
* complications: i.e., if everything matchable is straight forward in the
* bitmap */
#define REGINCLASS(prog,p,c) (ANYOF_FLAGS(p) ? reginclass(prog,p,c,0,0) \
: ANYOF_BITMAP_TEST(p,*(c)))
/*
* Forwards.
*/
#define CHR_SVLEN(sv) (utf8_target ? sv_len_utf8(sv) : SvCUR(sv))
#define CHR_DIST(a,b) (PL_reg_match_utf8 ? utf8_distance(a,b) : a - b)
#define HOPc(pos,off) \
(char *)(PL_reg_match_utf8 \
? reghop3((U8*)pos, off, (U8*)(off >= 0 ? PL_regeol : PL_bostr)) \
: (U8*)(pos + off))
#define HOPBACKc(pos, off) \
(char*)(PL_reg_match_utf8\
? reghopmaybe3((U8*)pos, -off, (U8*)PL_bostr) \
: (pos - off >= PL_bostr) \
? (U8*)pos - off \
: NULL)
#define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
#define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
/* these are unrolled below in the CCC_TRY_XXX defined */
#define LOAD_UTF8_CHARCLASS(class,str) STMT_START { \
if (!CAT2(PL_utf8_,class)) { bool ok; ENTER; save_re_context(); ok=CAT2(is_utf8_,class)((const U8*)str); assert(ok); LEAVE; } } STMT_END
/* Doesn't do an assert to verify that is correct */
#define LOAD_UTF8_CHARCLASS_NO_CHECK(class) STMT_START { \
if (!CAT2(PL_utf8_,class)) { bool throw_away; ENTER; save_re_context(); throw_away = CAT2(is_utf8_,class)((const U8*)" "); LEAVE; } } STMT_END
#define LOAD_UTF8_CHARCLASS_ALNUM() LOAD_UTF8_CHARCLASS(alnum,"a")
#define LOAD_UTF8_CHARCLASS_DIGIT() LOAD_UTF8_CHARCLASS(digit,"0")
#define LOAD_UTF8_CHARCLASS_SPACE() LOAD_UTF8_CHARCLASS(space," ")
#define LOAD_UTF8_CHARCLASS_GCB() /* Grapheme cluster boundaries */ \
LOAD_UTF8_CHARCLASS(X_begin, " "); \
LOAD_UTF8_CHARCLASS(X_non_hangul, "A"); \
/* These are utf8 constants, and not utf-ebcdic constants, so the \
* assert should likely and hopefully fail on an EBCDIC machine */ \
LOAD_UTF8_CHARCLASS(X_extend, "\xcc\x80"); /* U+0300 */ \
\
/* No asserts are done for these, in case called on an early \
* Unicode version in which they map to nothing */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_prepend);/* U+0E40 "\xe0\xb9\x80" */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_L); /* U+1100 "\xe1\x84\x80" */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV); /* U+AC00 "\xea\xb0\x80" */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_LVT); /* U+AC01 "\xea\xb0\x81" */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV_LVT_V);/* U+AC01 "\xea\xb0\x81" */\
LOAD_UTF8_CHARCLASS_NO_CHECK(X_T); /* U+11A8 "\xe1\x86\xa8" */ \
LOAD_UTF8_CHARCLASS_NO_CHECK(X_V) /* U+1160 "\xe1\x85\xa0" */
/*
We dont use PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS as the direct test
so that it is possible to override the option here without having to
rebuild the entire core. as we are required to do if we change regcomp.h
which is where PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS is defined.
*/
#if PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS
#define BROKEN_UNICODE_CHARCLASS_MAPPINGS
#endif
#ifdef BROKEN_UNICODE_CHARCLASS_MAPPINGS
#define LOAD_UTF8_CHARCLASS_PERL_WORD() LOAD_UTF8_CHARCLASS_ALNUM()
#define LOAD_UTF8_CHARCLASS_PERL_SPACE() LOAD_UTF8_CHARCLASS_SPACE()
#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS_DIGIT()
#define RE_utf8_perl_word PL_utf8_alnum
#define RE_utf8_perl_space PL_utf8_space
#define RE_utf8_posix_digit PL_utf8_digit
#define perl_word alnum
#define perl_space space
#define posix_digit digit
#else
#define LOAD_UTF8_CHARCLASS_PERL_WORD() LOAD_UTF8_CHARCLASS(perl_word,"a")
#define LOAD_UTF8_CHARCLASS_PERL_SPACE() LOAD_UTF8_CHARCLASS(perl_space," ")
#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS(posix_digit,"0")
#define RE_utf8_perl_word PL_utf8_perl_word
#define RE_utf8_perl_space PL_utf8_perl_space
#define RE_utf8_posix_digit PL_utf8_posix_digit
#endif
#define PLACEHOLDER /* Something for the preprocessor to grab onto */
/* The actual code for CCC_TRY, which uses several variables from the routine
* it's callable from. It is designed to be the bulk of a case statement.
* FUNC is the macro or function to call on non-utf8 targets that indicate if
* nextchr matches the class.
* UTF8_TEST is the whole test string to use for utf8 targets
* LOAD is what to use to test, and if not present to load in the swash for the
* class
* POS_OR_NEG is either empty or ! to complement the results of FUNC or
* UTF8_TEST test.
* The logic is: Fail if we're at the end-of-string; otherwise if the target is
* utf8 and a variant, load the swash if necessary and test using the utf8
* test. Advance to the next character if test is ok, otherwise fail; If not
* utf8 or an invariant under utf8, use the non-utf8 test, and fail if it
* fails, or advance to the next character */
#define _CCC_TRY_CODE(POS_OR_NEG, FUNC, UTF8_TEST, CLASS, STR) \
if (locinput >= PL_regeol) { \
sayNO; \
} \
if (utf8_target && UTF8_IS_CONTINUED(nextchr)) { \
LOAD_UTF8_CHARCLASS(CLASS, STR); \
if (POS_OR_NEG (UTF8_TEST)) { \
sayNO; \
} \
locinput += PL_utf8skip[nextchr]; \
nextchr = UCHARAT(locinput); \
break; \
} \
if (POS_OR_NEG (FUNC(nextchr))) { \
sayNO; \
} \
nextchr = UCHARAT(++locinput); \
break;
/* Handle the non-locale cases for a character class and its complement. It
* calls _CCC_TRY_CODE with a ! to complement the test for the character class.
* This is because that code fails when the test succeeds, so we want to have
* the test fail so that the code succeeds. The swash is stored in a
* predictable PL_ place */
#define _CCC_TRY_NONLOCALE(NAME, NNAME, FUNC, \
CLASS, STR) \
case NAME: \
_CCC_TRY_CODE( !, FUNC, \
cBOOL(swash_fetch(CAT2(PL_utf8_,CLASS), \
(U8*)locinput, TRUE)), \
CLASS, STR) \
case NNAME: \
_CCC_TRY_CODE( PLACEHOLDER , FUNC, \
cBOOL(swash_fetch(CAT2(PL_utf8_,CLASS), \
(U8*)locinput, TRUE)), \
CLASS, STR) \
/* Generate the case statements for both locale and non-locale character
* classes in regmatch for classes that don't have special unicode semantics.
* Locales don't use an immediate swash, but an intermediary special locale
* function that is called on the pointer to the current place in the input
* string. That function will resolve to needing the same swash. One might
* think that because we don't know what the locale will match, we shouldn't
* check with the swash loading function that it loaded properly; ie, that we
* should use LOAD_UTF8_CHARCLASS_NO_CHECK for those, but what is passed to the
* regular LOAD_UTF8_CHARCLASS is in non-locale terms, and so locale is
* irrelevant here */
#define CCC_TRY(NAME, NNAME, FUNC, \
NAMEL, NNAMEL, LCFUNC, LCFUNC_utf8, \
NAMEA, NNAMEA, FUNCA, \
CLASS, STR) \
case NAMEL: \
PL_reg_flags |= RF_tainted; \
_CCC_TRY_CODE( !, LCFUNC, LCFUNC_utf8((U8*)locinput), CLASS, STR) \
case NNAMEL: \
PL_reg_flags |= RF_tainted; \
_CCC_TRY_CODE( PLACEHOLDER, LCFUNC, LCFUNC_utf8((U8*)locinput), \
CLASS, STR) \
case NAMEA: \
if (locinput >= PL_regeol || ! FUNCA(nextchr)) { \
sayNO; \
} \
/* Matched a utf8-invariant, so don't have to worry about utf8 */ \
nextchr = UCHARAT(++locinput); \
break; \
case NNAMEA: \
if (locinput >= PL_regeol || FUNCA(nextchr)) { \
sayNO; \
} \
if (utf8_target) { \
locinput += PL_utf8skip[nextchr]; \
nextchr = UCHARAT(locinput); \
} \
else { \
nextchr = UCHARAT(++locinput); \
} \
break; \
/* Generate the non-locale cases */ \
_CCC_TRY_NONLOCALE(NAME, NNAME, FUNC, CLASS, STR)
/* This is like CCC_TRY, but has an extra set of parameters for generating case
* statements to handle separate Unicode semantics nodes */
#define CCC_TRY_U(NAME, NNAME, FUNC, \
NAMEL, NNAMEL, LCFUNC, LCFUNC_utf8, \
NAMEU, NNAMEU, FUNCU, \
NAMEA, NNAMEA, FUNCA, \
CLASS, STR) \
CCC_TRY(NAME, NNAME, FUNC, \
NAMEL, NNAMEL, LCFUNC, LCFUNC_utf8, \
NAMEA, NNAMEA, FUNCA, \
CLASS, STR) \
_CCC_TRY_NONLOCALE(NAMEU, NNAMEU, FUNCU, CLASS, STR)
/* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
/* for use after a quantifier and before an EXACT-like node -- japhy */
/* it would be nice to rework regcomp.sym to generate this stuff. sigh
*
* NOTE that *nothing* that affects backtracking should be in here, specifically
* VERBS must NOT be included. JUMPABLE is used to determine if we can ignore a
* node that is in between two EXACT like nodes when ascertaining what the required
* "follow" character is. This should probably be moved to regex compile time
* although it may be done at run time beause of the REF possibility - more
* investigation required. -- demerphq
*/
#define JUMPABLE(rn) ( \
OP(rn) == OPEN || \
(OP(rn) == CLOSE && (!cur_eval || cur_eval->u.eval.close_paren != ARG(rn))) || \
OP(rn) == EVAL || \
OP(rn) == SUSPEND || OP(rn) == IFMATCH || \
OP(rn) == PLUS || OP(rn) == MINMOD || \
OP(rn) == KEEPS || \
(PL_regkind[OP(rn)] == CURLY && ARG1(rn) > 0) \
)
#define IS_EXACT(rn) (PL_regkind[OP(rn)] == EXACT)
#define HAS_TEXT(rn) ( IS_EXACT(rn) || PL_regkind[OP(rn)] == REF )
#if 0
/* Currently these are only used when PL_regkind[OP(rn)] == EXACT so
we don't need this definition. */
#define IS_TEXT(rn) ( OP(rn)==EXACT || OP(rn)==REF || OP(rn)==NREF )
#define IS_TEXTF(rn) ( (OP(rn)==EXACTFU || OP(rn)==EXACTF) || OP(rn)==REFF || OP(rn)==NREFF )
#define IS_TEXTFL(rn) ( OP(rn)==EXACTFL || OP(rn)==REFFL || OP(rn)==NREFFL )
#else
/* ... so we use this as its faster. */
#define IS_TEXT(rn) ( OP(rn)==EXACT )
#define IS_TEXTFU(rn) ( OP(rn)==EXACTFU )
#define IS_TEXTF(rn) ( OP(rn)==EXACTF )
#define IS_TEXTFL(rn) ( OP(rn)==EXACTFL )
#endif
/*
Search for mandatory following text node; for lookahead, the text must
follow but for lookbehind (rn->flags != 0) we skip to the next step.
*/
#define FIND_NEXT_IMPT(rn) STMT_START { \
while (JUMPABLE(rn)) { \
const OPCODE type = OP(rn); \
if (type == SUSPEND || PL_regkind[type] == CURLY) \
rn = NEXTOPER(NEXTOPER(rn)); \
else if (type == PLUS) \
rn = NEXTOPER(rn); \
else if (type == IFMATCH) \
rn = (rn->flags == 0) ? NEXTOPER(NEXTOPER(rn)) : rn + ARG(rn); \
else rn += NEXT_OFF(rn); \
} \
} STMT_END
static void restore_pos(pTHX_ void *arg);
#define REGCP_PAREN_ELEMS 4
#define REGCP_OTHER_ELEMS 5
#define REGCP_FRAME_ELEMS 1
/* REGCP_FRAME_ELEMS are not part of the REGCP_OTHER_ELEMS and
* are needed for the regexp context stack bookkeeping. */
STATIC CHECKPOINT
S_regcppush(pTHX_ I32 parenfloor)
{
dVAR;
const int retval = PL_savestack_ix;
const int paren_elems_to_push = (PL_regsize - parenfloor) * REGCP_PAREN_ELEMS;
const UV total_elems = paren_elems_to_push + REGCP_OTHER_ELEMS;
const UV elems_shifted = total_elems << SAVE_TIGHT_SHIFT;
int p;
GET_RE_DEBUG_FLAGS_DECL;
if (paren_elems_to_push < 0)
Perl_croak(aTHX_ "panic: paren_elems_to_push < 0");
if ((elems_shifted >> SAVE_TIGHT_SHIFT) != total_elems)
Perl_croak(aTHX_ "panic: paren_elems_to_push offset %"UVuf
" out of range (%lu-%ld)",
total_elems, (unsigned long)PL_regsize, (long)parenfloor);
SSGROW(total_elems + REGCP_FRAME_ELEMS);
for (p = PL_regsize; p > parenfloor; p--) {
/* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
SSPUSHINT(PL_regoffs[p].end);
SSPUSHINT(PL_regoffs[p].start);
SSPUSHPTR(PL_reg_start_tmp[p]);
SSPUSHINT(p);
DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
" saving \\%"UVuf" %"IVdf"(%"IVdf")..%"IVdf"\n",
(UV)p, (IV)PL_regoffs[p].start,
(IV)(PL_reg_start_tmp[p] - PL_bostr),
(IV)PL_regoffs[p].end
));
}
/* REGCP_OTHER_ELEMS are pushed in any case, parentheses or no. */
SSPUSHPTR(PL_regoffs);
SSPUSHINT(PL_regsize);
SSPUSHINT(*PL_reglastparen);
SSPUSHINT(*PL_reglastcloseparen);
SSPUSHPTR(PL_reginput);
SSPUSHUV(SAVEt_REGCONTEXT | elems_shifted); /* Magic cookie. */
return retval;
}
/* These are needed since we do not localize EVAL nodes: */
#define REGCP_SET(cp) \
DEBUG_STATE_r( \
PerlIO_printf(Perl_debug_log, \
" Setting an EVAL scope, savestack=%"IVdf"\n", \
(IV)PL_savestack_ix)); \
cp = PL_savestack_ix
#define REGCP_UNWIND(cp) \
DEBUG_STATE_r( \
if (cp != PL_savestack_ix) \
PerlIO_printf(Perl_debug_log, \
" Clearing an EVAL scope, savestack=%"IVdf"..%"IVdf"\n", \
(IV)(cp), (IV)PL_savestack_ix)); \
regcpblow(cp)
STATIC char *
S_regcppop(pTHX_ const regexp *rex)
{
dVAR;
UV i;
char *input;
GET_RE_DEBUG_FLAGS_DECL;
PERL_ARGS_ASSERT_REGCPPOP;
/* Pop REGCP_OTHER_ELEMS before the parentheses loop starts. */
i = SSPOPUV;
assert((i & SAVE_MASK) == SAVEt_REGCONTEXT); /* Check that the magic cookie is there. */
i >>= SAVE_TIGHT_SHIFT; /* Parentheses elements to pop. */
input = (char *) SSPOPPTR;
*PL_reglastcloseparen = SSPOPINT;
*PL_reglastparen = SSPOPINT;
PL_regsize = SSPOPINT;
PL_regoffs=(regexp_paren_pair *) SSPOPPTR;
i -= REGCP_OTHER_ELEMS;
/* Now restore the parentheses context. */
for ( ; i > 0; i -= REGCP_PAREN_ELEMS) {
I32 tmps;
U32 paren = (U32)SSPOPINT;
PL_reg_start_tmp[paren] = (char *) SSPOPPTR;
PL_regoffs[paren].start = SSPOPINT;
tmps = SSPOPINT;
if (paren <= *PL_reglastparen)
PL_regoffs[paren].end = tmps;
DEBUG_BUFFERS_r(
PerlIO_printf(Perl_debug_log,
" restoring \\%"UVuf" to %"IVdf"(%"IVdf")..%"IVdf"%s\n",
(UV)paren, (IV)PL_regoffs[paren].start,
(IV)(PL_reg_start_tmp[paren] - PL_bostr),
(IV)PL_regoffs[paren].end,
(paren > *PL_reglastparen ? "(no)" : ""));
);
}
DEBUG_BUFFERS_r(
if (*PL_reglastparen + 1 <= rex->nparens) {
PerlIO_printf(Perl_debug_log,
" restoring \\%"IVdf"..\\%"IVdf" to undef\n",
(IV)(*PL_reglastparen + 1), (IV)rex->nparens);
}
);
#if 1
/* It would seem that the similar code in regtry()
* already takes care of this, and in fact it is in
* a better location to since this code can #if 0-ed out
* but the code in regtry() is needed or otherwise tests
* requiring null fields (pat.t#187 and split.t#{13,14}
* (as of patchlevel 7877) will fail. Then again,
* this code seems to be necessary or otherwise
* this erroneously leaves $1 defined: "1" =~ /^(?:(\d)x)?\d$/
* --jhi updated by dapm */
for (i = *PL_reglastparen + 1; i <= rex->nparens; i++) {
if (i > PL_regsize)
PL_regoffs[i].start = -1;
PL_regoffs[i].end = -1;
}
#endif
return input;
}
#define regcpblow(cp) LEAVE_SCOPE(cp) /* Ignores regcppush()ed data. */
/*
* pregexec and friends
*/
#ifndef PERL_IN_XSUB_RE
/*
- pregexec - match a regexp against a string
*/
I32
Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, register char *strend,
char *strbeg, I32 minend, SV *screamer, U32 nosave)
/* strend: pointer to null at end of string */
/* strbeg: real beginning of string */
/* minend: end of match must be >=minend after stringarg. */
/* nosave: For optimizations. */
{
PERL_ARGS_ASSERT_PREGEXEC;
return
regexec_flags(prog, stringarg, strend, strbeg, minend, screamer, NULL,
nosave ? 0 : REXEC_COPY_STR);
}
#endif
/*
* Need to implement the following flags for reg_anch:
*
* USE_INTUIT_NOML - Useful to call re_intuit_start() first
* USE_INTUIT_ML
* INTUIT_AUTORITATIVE_NOML - Can trust a positive answer
* INTUIT_AUTORITATIVE_ML
* INTUIT_ONCE_NOML - Intuit can match in one location only.
* INTUIT_ONCE_ML
*
* Another flag for this function: SECOND_TIME (so that float substrs
* with giant delta may be not rechecked).
*/
/* Assumptions: if ANCH_GPOS, then strpos is anchored. XXXX Check GPOS logic */
/* If SCREAM, then SvPVX_const(sv) should be compatible with strpos and strend.
Otherwise, only SvCUR(sv) is used to get strbeg. */
/* XXXX We assume that strpos is strbeg unless sv. */
/* XXXX Some places assume that there is a fixed substring.
An update may be needed if optimizer marks as "INTUITable"
RExen without fixed substrings. Similarly, it is assumed that
lengths of all the strings are no more than minlen, thus they
cannot come from lookahead.
(Or minlen should take into account lookahead.)
NOTE: Some of this comment is not correct. minlen does now take account
of lookahead/behind. Further research is required. -- demerphq
*/
/* A failure to find a constant substring means that there is no need to make
an expensive call to REx engine, thus we celebrate a failure. Similarly,
finding a substring too deep into the string means that less calls to
regtry() should be needed.
REx compiler's optimizer found 4 possible hints:
a) Anchored substring;
b) Fixed substring;
c) Whether we are anchored (beginning-of-line or \G);
d) First node (of those at offset 0) which may distinguish positions;
We use a)b)d) and multiline-part of c), and try to find a position in the
string which does not contradict any of them.
*/
/* Most of decisions we do here should have been done at compile time.
The nodes of the REx which we used for the search should have been
deleted from the finite automaton. */
char *
Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
char *strend, const U32 flags, re_scream_pos_data *data)
{
dVAR;
struct regexp *const prog = (struct regexp *)SvANY(rx);
register I32 start_shift = 0;
/* Should be nonnegative! */
register I32 end_shift = 0;
register char *s;
register SV *check;
char *strbeg;
char *t;
const bool utf8_target = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
I32 ml_anch;
register char *other_last = NULL; /* other substr checked before this */
char *check_at = NULL; /* check substr found at this pos */
const I32 multiline = prog->extflags & RXf_PMf_MULTILINE;
RXi_GET_DECL(prog,progi);
#ifdef DEBUGGING
const char * const i_strpos = strpos;
#endif
GET_RE_DEBUG_FLAGS_DECL;
PERL_ARGS_ASSERT_RE_INTUIT_START;
RX_MATCH_UTF8_set(rx,utf8_target);
if (RX_UTF8(rx)) {
PL_reg_flags |= RF_utf8;
}
DEBUG_EXECUTE_r(
debug_start_match(rx, utf8_target, strpos, strend,
sv ? "Guessing start of match in sv for"
: "Guessing start of match in string for");
);
/* CHR_DIST() would be more correct here but it makes things slow. */
if (prog->minlen > strend - strpos) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
"String too short... [re_intuit_start]\n"));
goto fail;
}
strbeg = (sv && SvPOK(sv)) ? strend - SvCUR(sv) : strpos;
PL_regeol = strend;
if (utf8_target) {
if (!prog->check_utf8 && prog->check_substr)
to_utf8_substr(prog);
check = prog->check_utf8;
} else {
if (!prog->check_substr && prog->check_utf8)
to_byte_substr(prog);
check = prog->check_substr;
}
if (check == &PL_sv_undef) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
"Non-utf8 string cannot match utf8 check string\n"));
goto fail;
}
if (prog->extflags & RXf_ANCH) { /* Match at beg-of-str or after \n */
ml_anch = !( (prog->extflags & RXf_ANCH_SINGLE)
|| ( (prog->extflags & RXf_ANCH_BOL)
&& !multiline ) ); /* Check after \n? */
if (!ml_anch) {
if ( !(prog->extflags & RXf_ANCH_GPOS) /* Checked by the caller */
&& !(prog->intflags & PREGf_IMPLICIT) /* not a real BOL */
/* SvCUR is not set on references: SvRV and SvPVX_const overlap */
&& sv && !SvROK(sv)
&& (strpos != strbeg)) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not at start...\n"));
goto fail;
}
if (prog->check_offset_min == prog->check_offset_max &&
!(prog->extflags & RXf_CANY_SEEN)) {
/* Substring at constant offset from beg-of-str... */
I32 slen;
s = HOP3c(strpos, prog->check_offset_min, strend);
if (SvTAIL(check)) {
slen = SvCUR(check); /* >= 1 */
if ( strend - s > slen || strend - s < slen - 1
|| (strend - s == slen && strend[-1] != '\n')) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String too long...\n"));
goto fail_finish;
}
/* Now should match s[0..slen-2] */
slen--;
if (slen && (*SvPVX_const(check) != *s
|| (slen > 1
&& memNE(SvPVX_const(check), s, slen)))) {
report_neq:
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String not equal...\n"));
goto fail_finish;
}
}
else if (*SvPVX_const(check) != *s
|| ((slen = SvCUR(check)) > 1
&& memNE(SvPVX_const(check), s, slen)))
goto report_neq;
check_at = s;
goto success_at_start;
}
}
/* Match is anchored, but substr is not anchored wrt beg-of-str. */
s = strpos;
start_shift = prog->check_offset_min; /* okay to underestimate on CC */
end_shift = prog->check_end_shift;
if (!ml_anch) {
const I32 end = prog->check_offset_max + CHR_SVLEN(check)
- (SvTAIL(check) != 0);
const I32 eshift = CHR_DIST((U8*)strend, (U8*)s) - end;
if (end_shift < eshift)
end_shift = eshift;
}
}
else { /* Can match at random position */
ml_anch = 0;
s = strpos;
start_shift = prog->check_offset_min; /* okay to underestimate on CC */
end_shift = prog->check_end_shift;
/* end shift should be non negative here */
}
#ifdef QDEBUGGING /* 7/99: reports of failure (with the older version) */
if (end_shift < 0)
Perl_croak(aTHX_ "panic: end_shift: %"IVdf" pattern:\n%s\n ",
(IV)end_shift, RX_PRECOMP(prog));
#endif
restart:
/* Find a possible match in the region s..strend by looking for
the "check" substring in the region corrected by start/end_shift. */
{
I32 srch_start_shift = start_shift;
I32 srch_end_shift = end_shift;
if (srch_start_shift < 0 && strbeg - s > srch_start_shift) {
srch_end_shift -= ((strbeg - s) - srch_start_shift);
srch_start_shift = strbeg - s;
}
DEBUG_OPTIMISE_MORE_r({
PerlIO_printf(Perl_debug_log, "Check offset min: %"IVdf" Start shift: %"IVdf" End shift %"IVdf" Real End Shift: %"IVdf"\n",
(IV)prog->check_offset_min,
(IV)srch_start_shift,
(IV)srch_end_shift,
(IV)prog->check_end_shift);
});
if (flags & REXEC_SCREAM) {
I32 p = -1; /* Internal iterator of scream. */
I32 * const pp = data ? data->scream_pos : &p;
if (PL_screamfirst[BmRARE(check)] >= 0
|| ( BmRARE(check) == '\n'
&& (BmPREVIOUS(check) == SvCUR(check) - 1)
&& SvTAIL(check) ))
s = screaminstr(sv, check,
srch_start_shift + (s - strbeg), srch_end_shift, pp, 0);
else
goto fail_finish;
/* we may be pointing at the wrong string */
if (s && RXp_MATCH_COPIED(prog))
s = strbeg + (s - SvPVX_const(sv));
if (data)
*data->scream_olds = s;
}
else {
U8* start_point;
U8* end_point;
if (prog->extflags & RXf_CANY_SEEN) {
start_point= (U8*)(s + srch_start_shift);
end_point= (U8*)(strend - srch_end_shift);
} else {
start_point= HOP3(s, srch_start_shift, srch_start_shift < 0 ? strbeg : strend);
end_point= HOP3(strend, -srch_end_shift, strbeg);
}
DEBUG_OPTIMISE_MORE_r({
PerlIO_printf(Perl_debug_log, "fbm_instr len=%d str=<%.*s>\n",
(int)(end_point - start_point),
(int)(end_point - start_point) > 20 ? 20 : (int)(end_point - start_point),
start_point);
});
s = fbm_instr( start_point, end_point,
check, multiline ? FBMrf_MULTILINE : 0);
}
}
/* Update the count-of-usability, remove useless subpatterns,
unshift s. */
DEBUG_EXECUTE_r({
RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
SvPVX_const(check), RE_SV_DUMPLEN(check), 30);
PerlIO_printf(Perl_debug_log, "%s %s substr %s%s%s",
(s ? "Found" : "Did not find"),
(check == (utf8_target ? prog->anchored_utf8 : prog->anchored_substr)
? "anchored" : "floating"),
quoted,
RE_SV_TAIL(check),
(s ? " at offset " : "...\n") );
});
if (!s)
goto fail_finish;
/* Finish the diagnostic message */
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%ld...\n", (long)(s - i_strpos)) );
/* XXX dmq: first branch is for positive lookbehind...
Our check string is offset from the beginning of the pattern.
So we need to do any stclass tests offset forward from that
point. I think. :-(
*/
check_at=s;
/* Got a candidate. Check MBOL anchoring, and the *other* substr.
Start with the other substr.
XXXX no SCREAM optimization yet - and a very coarse implementation
XXXX /ttx+/ results in anchored="ttx", floating="x". floating will
*always* match. Probably should be marked during compile...
Probably it is right to do no SCREAM here...
*/
if (utf8_target ? (prog->float_utf8 && prog->anchored_utf8)
: (prog->float_substr && prog->anchored_substr))
{
/* Take into account the "other" substring. */
/* XXXX May be hopelessly wrong for UTF... */
if (!other_last)
other_last = strpos;
if (check == (utf8_target ? prog->float_utf8 : prog->float_substr)) {
do_other_anchored:
{
char * const last = HOP3c(s, -start_shift, strbeg);
char *last1, *last2;
char * const saved_s = s;
SV* must;
t = s - prog->check_offset_max;
if (s - strpos > prog->check_offset_max /* signed-corrected t > strpos */
&& (!utf8_target
|| ((t = (char*)reghopmaybe3((U8*)s, -(prog->check_offset_max), (U8*)strpos))
&& t > strpos)))
NOOP;
else
t = strpos;
t = HOP3c(t, prog->anchored_offset, strend);
if (t < other_last) /* These positions already checked */
t = other_last;
last2 = last1 = HOP3c(strend, -prog->minlen, strbeg);
if (last < last1)
last1 = last;
/* XXXX It is not documented what units *_offsets are in.
We assume bytes, but this is clearly wrong.
Meaning this code needs to be carefully reviewed for errors.
dmq.
*/
/* On end-of-str: see comment below. */
must = utf8_target ? prog->anchored_utf8 : prog->anchored_substr;
if (must == &PL_sv_undef) {
s = (char*)NULL;
DEBUG_r(must = prog->anchored_utf8); /* for debug */
}
else
s = fbm_instr(
(unsigned char*)t,
HOP3(HOP3(last1, prog->anchored_offset, strend)
+ SvCUR(must), -(SvTAIL(must)!=0), strbeg),
must,
multiline ? FBMrf_MULTILINE : 0
);
DEBUG_EXECUTE_r({
RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
PerlIO_printf(Perl_debug_log, "%s anchored substr %s%s",
(s ? "Found" : "Contradicts"),
quoted, RE_SV_TAIL(must));
});
if (!s) {
if (last1 >= last2) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
", giving up...\n"));
goto fail_finish;
}
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
", trying floating at offset %ld...\n",
(long)(HOP3c(saved_s, 1, strend) - i_strpos)));
other_last = HOP3c(last1, prog->anchored_offset+1, strend);
s = HOP3c(last, 1, strend);
goto restart;
}
else {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
(long)(s - i_strpos)));
t = HOP3c(s, -prog->anchored_offset, strbeg);
other_last = HOP3c(s, 1, strend);
s = saved_s;
if (t == strpos)
goto try_at_start;
goto try_at_offset;
}
}
}
else { /* Take into account the floating substring. */
char *last, *last1;
char * const saved_s = s;
SV* must;
t = HOP3c(s, -start_shift, strbeg);
last1 = last =
HOP3c(strend, -prog->minlen + prog->float_min_offset, strbeg);
if (CHR_DIST((U8*)last, (U8*)t) > prog->float_max_offset)
last = HOP3c(t, prog->float_max_offset, strend);
s = HOP3c(t, prog->float_min_offset, strend);
if (s < other_last)
s = other_last;
/* XXXX It is not documented what units *_offsets are in. Assume bytes. */
must = utf8_target ? prog->float_utf8 : prog->float_substr;
/* fbm_instr() takes into account exact value of end-of-str
if the check is SvTAIL(ed). Since false positives are OK,
and end-of-str is not later than strend we are OK. */
if (must == &PL_sv_undef) {
s = (char*)NULL;
DEBUG_r(must = prog->float_utf8); /* for debug message */
}
else
s = fbm_instr((unsigned char*)s,
(unsigned char*)last + SvCUR(must)
- (SvTAIL(must)!=0),
must, multiline ? FBMrf_MULTILINE : 0);
DEBUG_EXECUTE_r({
RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
PerlIO_printf(Perl_debug_log, "%s floating substr %s%s",
(s ? "Found" : "Contradicts"),
quoted, RE_SV_TAIL(must));
});
if (!s) {
if (last1 == last) {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
", giving up...\n"));
goto fail_finish;
}
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
", trying anchored starting at offset %ld...\n",
(long)(saved_s + 1 - i_strpos)));
other_last = last;
s = HOP3c(t, 1, strend);
goto restart;
}
else {
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
(long)(s - i_strpos)));
other_last = s; /* Fix this later. --Hugo */
s = saved_s;
if (t == strpos)
goto try_at_start;
goto try_at_offset;
}
}
}
t= (char*)HOP3( s, -prog->check_offset_max, (prog->check_offset_max<0) ? strend : strpos);
DEBUG_OPTIMISE_MORE_r(
PerlIO_printf(Perl_debug_log,
"Check offset min:%"IVdf" max:%"IVdf" S:%"IVdf" t:%"IVdf" D:%"IVdf" end:%"IVdf"\n",
(IV)prog->check_offset_min,
(IV)prog->check_offset_max,
(IV)(s-strpos),
(IV)(t-strpos),
(IV)(t-s),
(IV)(strend-strpos)
)
);
if (s - strpos > prog->check_offset_max /* signed-corrected t > strpos */
&& (!utf8_target
|| ((t = (char*)reghopmaybe3((U8*)s, -prog->check_offset_max, (U8*) ((prog->check_offset_max<0) ? strend : strpos)))
&& t > strpos)))
{
/* Fixed substring is found far enough so that the match
cannot start at strpos. */
try_at_offset:
if (ml_anch && t[-1] != '\n') {
/* Eventually fbm_*() should handle this, but often
anchored_offset is not 0, so this check will not be wasted. */
/* XXXX In the code below we prefer to look for "^" even in
presence of anchored substrings. And we search even
beyond the found float position. These pessimizations
are historical artefacts only. */
find_anchor:
while (t < strend - prog->minlen) {
if (*t == '\n') {
if (t < check_at - prog->check_offset_min) {
if (utf8_target ? prog->anchored_utf8 : prog->anchored_substr) {
/* Since we moved from the found position,
we definitely contradict the found anchored
substr. Due to the above check we do not
contradict "check" substr.
Thus we can arrive here only if check substr
is float. Redo checking for "other"=="fixed".
*/
strpos = t + 1;
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld, rescanning for anchored from offset %ld...\n",
PL_colors[0], PL_colors[1], (long)(strpos - i_strpos), (long)(strpos - i_strpos + prog->anchored_offset)));
goto do_other_anchored;
}
/* We don't contradict the found floating substring. */
/* XXXX Why not check for STCLASS? */
s = t + 1;
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld...\n",
PL_colors[0], PL_colors[1], (long)(s - i_strpos)));
goto set_useful;
}
/* Position contradicts check-string */
/* XXXX probably better to look for check-string
than for "\n", so one should lower the limit for t? */
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m, restarting lookup for check-string at offset %ld...\n",
PL_colors[0], PL_colors[1], (long)(t + 1 - i_strpos)));
other_last = strpos = s = t + 1;
goto restart;
}
t++;
}
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Did not find /%s^%s/m...\n",