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regexec.c
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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
/* At least one required character in the target string is expressible only in
* UTF-8. */
static const char* const non_utf8_target_but_utf8_required
= "Can't match, because target string needs to be in UTF-8\n";
#define NON_UTF8_TARGET_BUT_UTF8_REQUIRED(target) STMT_START { \
DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%s", non_utf8_target_but_utf8_required));\
goto target; \
} STMT_END
/*
* 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
#include "inline_invlist.c"
#include "unicode_constants.h"
#define HAS_NONLATIN1_FOLD_CLOSURE(i) _HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(i)
#ifndef STATIC
#define STATIC static
#endif
/* Valid for non-utf8 strings: 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) \
: ANYOF_BITMAP_TEST(p,*(c)))
/*
* Forwards.
*/
#define CHR_SVLEN(sv) (utf8_target ? sv_len_utf8(sv) : SvCUR(sv))
#define CHR_DIST(a,b) (reginfo->is_utf8_target ? utf8_distance(a,b) : a - b)
#define HOPc(pos,off) \
(char *)(reginfo->is_utf8_target \
? reghop3((U8*)pos, off, \
(U8*)(off >= 0 ? reginfo->strend : reginfo->strbeg)) \
: (U8*)(pos + off))
#define HOPBACKc(pos, off) \
(char*)(reginfo->is_utf8_target \
? reghopmaybe3((U8*)pos, -off, (U8*)(reginfo->strbeg)) \
: (pos - off >= reginfo->strbeg) \
? (U8*)pos - off \
: NULL)
#define HOP3(pos,off,lim) (reginfo->is_utf8_target ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
#define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
#define NEXTCHR_EOS -10 /* nextchr has fallen off the end */
#define NEXTCHR_IS_EOS (nextchr < 0)
#define SET_nextchr \
nextchr = ((locinput < reginfo->strend) ? UCHARAT(locinput) : NEXTCHR_EOS)
#define SET_locinput(p) \
locinput = (p); \
SET_nextchr
#define LOAD_UTF8_CHARCLASS(swash_ptr, property_name) STMT_START { \
if (!swash_ptr) { \
U8 flags = _CORE_SWASH_INIT_ACCEPT_INVLIST; \
swash_ptr = _core_swash_init("utf8", property_name, &PL_sv_undef, \
1, 0, NULL, &flags); \
assert(swash_ptr); \
} \
} STMT_END
/* If in debug mode, we test that a known character properly matches */
#ifdef DEBUGGING
# define LOAD_UTF8_CHARCLASS_DEBUG_TEST(swash_ptr, \
property_name, \
utf8_char_in_property) \
LOAD_UTF8_CHARCLASS(swash_ptr, property_name); \
assert(swash_fetch(swash_ptr, (U8 *) utf8_char_in_property, TRUE));
#else
# define LOAD_UTF8_CHARCLASS_DEBUG_TEST(swash_ptr, \
property_name, \
utf8_char_in_property) \
LOAD_UTF8_CHARCLASS(swash_ptr, property_name)
#endif
#define LOAD_UTF8_CHARCLASS_ALNUM() LOAD_UTF8_CHARCLASS_DEBUG_TEST( \
PL_utf8_swash_ptrs[_CC_WORDCHAR], \
swash_property_names[_CC_WORDCHAR], \
GREEK_SMALL_LETTER_IOTA_UTF8)
#define LOAD_UTF8_CHARCLASS_GCB() /* Grapheme cluster boundaries */ \
STMT_START { \
LOAD_UTF8_CHARCLASS_DEBUG_TEST(PL_utf8_X_regular_begin, \
"_X_regular_begin", \
GREEK_SMALL_LETTER_IOTA_UTF8); \
LOAD_UTF8_CHARCLASS_DEBUG_TEST(PL_utf8_X_extend, \
"_X_extend", \
COMBINING_GRAVE_ACCENT_UTF8); \
} STMT_END
#define PLACEHOLDER /* Something for the preprocessor to grab onto */
/* 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)==EXACTFU_SS || OP(rn)==EXACTFU_TRICKYFOLD || OP(rn)==EXACTFA || 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 || OP(rn)==EXACTFU_SS || OP(rn)==EXACTFU_TRICKYFOLD || OP(rn) == EXACTFA)
#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
/* These constants are for finding GCB=LV and GCB=LVT in the CLUMP regnode.
* These are for the pre-composed Hangul syllables, which are all in a
* contiguous block and arranged there in such a way so as to facilitate
* alorithmic determination of their characteristics. As such, they don't need
* a swash, but can be determined by simple arithmetic. Almost all are
* GCB=LVT, but every 28th one is a GCB=LV */
#define SBASE 0xAC00 /* Start of block */
#define SCount 11172 /* Length of block */
#define TCount 28
#define SLAB_FIRST(s) (&(s)->states[0])
#define SLAB_LAST(s) (&(s)->states[PERL_REGMATCH_SLAB_SLOTS-1])
static void S_setup_eval_state(pTHX_ regmatch_info *const reginfo);
static void S_cleanup_regmatch_info_aux(pTHX_ void *arg);
static regmatch_state * S_push_slab(pTHX);
#define REGCP_PAREN_ELEMS 3
#define REGCP_OTHER_ELEMS 3
#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_ const regexp *rex, I32 parenfloor, U32 maxopenparen)
{
dVAR;
const int retval = PL_savestack_ix;
const int paren_elems_to_push =
(maxopenparen - parenfloor) * REGCP_PAREN_ELEMS;
const UV total_elems = paren_elems_to_push + REGCP_OTHER_ELEMS;
const UV elems_shifted = total_elems << SAVE_TIGHT_SHIFT;
I32 p;
GET_RE_DEBUG_FLAGS_DECL;
PERL_ARGS_ASSERT_REGCPPUSH;
if (paren_elems_to_push < 0)
Perl_croak(aTHX_ "panic: paren_elems_to_push, %i < 0",
paren_elems_to_push);
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)maxopenparen,
(long)parenfloor);
SSGROW(total_elems + REGCP_FRAME_ELEMS);
DEBUG_BUFFERS_r(
if ((int)maxopenparen > (int)parenfloor)
PerlIO_printf(Perl_debug_log,
"rex=0x%"UVxf" offs=0x%"UVxf": saving capture indices:\n",
PTR2UV(rex),
PTR2UV(rex->offs)
);
);
for (p = parenfloor+1; p <= (I32)maxopenparen; p++) {
/* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
SSPUSHINT(rex->offs[p].end);
SSPUSHINT(rex->offs[p].start);
SSPUSHINT(rex->offs[p].start_tmp);
DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
" \\%"UVuf": %"IVdf"(%"IVdf")..%"IVdf"\n",
(UV)p,
(IV)rex->offs[p].start,
(IV)rex->offs[p].start_tmp,
(IV)rex->offs[p].end
));
}
/* REGCP_OTHER_ELEMS are pushed in any case, parentheses or no. */
SSPUSHINT(maxopenparen);
SSPUSHINT(rex->lastparen);
SSPUSHINT(rex->lastcloseparen);
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)
#define UNWIND_PAREN(lp, lcp) \
for (n = rex->lastparen; n > lp; n--) \
rex->offs[n].end = -1; \
rex->lastparen = n; \
rex->lastcloseparen = lcp;
STATIC void
S_regcppop(pTHX_ regexp *rex, U32 *maxopenparen_p)
{
dVAR;
UV i;
U32 paren;
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. */
rex->lastcloseparen = SSPOPINT;
rex->lastparen = SSPOPINT;
*maxopenparen_p = SSPOPINT;
i -= REGCP_OTHER_ELEMS;
/* Now restore the parentheses context. */
DEBUG_BUFFERS_r(
if (i || rex->lastparen + 1 <= rex->nparens)
PerlIO_printf(Perl_debug_log,
"rex=0x%"UVxf" offs=0x%"UVxf": restoring capture indices to:\n",
PTR2UV(rex),
PTR2UV(rex->offs)
);
);
paren = *maxopenparen_p;
for ( ; i > 0; i -= REGCP_PAREN_ELEMS) {
I32 tmps;
rex->offs[paren].start_tmp = SSPOPINT;
rex->offs[paren].start = SSPOPINT;
tmps = SSPOPINT;
if (paren <= rex->lastparen)
rex->offs[paren].end = tmps;
DEBUG_BUFFERS_r( PerlIO_printf(Perl_debug_log,
" \\%"UVuf": %"IVdf"(%"IVdf")..%"IVdf"%s\n",
(UV)paren,
(IV)rex->offs[paren].start,
(IV)rex->offs[paren].start_tmp,
(IV)rex->offs[paren].end,
(paren > rex->lastparen ? "(skipped)" : ""));
);
paren--;
}
#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 = rex->lastparen + 1; i <= rex->nparens; i++) {
if (i > *maxopenparen_p)
rex->offs[i].start = -1;
rex->offs[i].end = -1;
DEBUG_BUFFERS_r( PerlIO_printf(Perl_debug_log,
" \\%"UVuf": %s ..-1 undeffing\n",
(UV)i,
(i > *maxopenparen_p) ? "-1" : " "
));
}
#endif
}
/* restore the parens and associated vars at savestack position ix,
* but without popping the stack */
STATIC void
S_regcp_restore(pTHX_ regexp *rex, I32 ix, U32 *maxopenparen_p)
{
I32 tmpix = PL_savestack_ix;
PL_savestack_ix = ix;
regcppop(rex, maxopenparen_p);
PL_savestack_ix = tmpix;
}
#define regcpblow(cp) LEAVE_SCOPE(cp) /* Ignores regcppush()ed data. */
STATIC bool
S_isFOO_lc(pTHX_ const U8 classnum, const U8 character)
{
/* Returns a boolean as to whether or not 'character' is a member of the
* Posix character class given by 'classnum' that should be equivalent to a
* value in the typedef '_char_class_number'.
*
* Ideally this could be replaced by a just an array of function pointers
* to the C library functions that implement the macros this calls.
* However, to compile, the precise function signatures are required, and
* these may vary from platform to to platform. To avoid having to figure
* out what those all are on each platform, I (khw) am using this method,
* which adds an extra layer of function call overhead (unless the C
* optimizer strips it away). But we don't particularly care about
* performance with locales anyway. */
switch ((_char_class_number) classnum) {
case _CC_ENUM_ALPHANUMERIC: return isALPHANUMERIC_LC(character);
case _CC_ENUM_ALPHA: return isALPHA_LC(character);
case _CC_ENUM_ASCII: return isASCII_LC(character);
case _CC_ENUM_BLANK: return isBLANK_LC(character);
case _CC_ENUM_CASED: return isLOWER_LC(character)
|| isUPPER_LC(character);
case _CC_ENUM_CNTRL: return isCNTRL_LC(character);
case _CC_ENUM_DIGIT: return isDIGIT_LC(character);
case _CC_ENUM_GRAPH: return isGRAPH_LC(character);
case _CC_ENUM_LOWER: return isLOWER_LC(character);
case _CC_ENUM_PRINT: return isPRINT_LC(character);
case _CC_ENUM_PSXSPC: return isPSXSPC_LC(character);
case _CC_ENUM_PUNCT: return isPUNCT_LC(character);
case _CC_ENUM_SPACE: return isSPACE_LC(character);
case _CC_ENUM_UPPER: return isUPPER_LC(character);
case _CC_ENUM_WORDCHAR: return isWORDCHAR_LC(character);
case _CC_ENUM_XDIGIT: return isXDIGIT_LC(character);
default: /* VERTSPACE should never occur in locales */
Perl_croak(aTHX_ "panic: isFOO_lc() has an unexpected character class '%d'", classnum);
}
assert(0); /* NOTREACHED */
return FALSE;
}
STATIC bool
S_isFOO_utf8_lc(pTHX_ const U8 classnum, const U8* character)
{
/* Returns a boolean as to whether or not the (well-formed) UTF-8-encoded
* 'character' is a member of the Posix character class given by 'classnum'
* that should be equivalent to a value in the typedef
* '_char_class_number'.
*
* This just calls isFOO_lc on the code point for the character if it is in
* the range 0-255. Outside that range, all characters avoid Unicode
* rules, ignoring any locale. So use the Unicode function if this class
* requires a swash, and use the Unicode macro otherwise. */
PERL_ARGS_ASSERT_ISFOO_UTF8_LC;
if (UTF8_IS_INVARIANT(*character)) {
return isFOO_lc(classnum, *character);
}
else if (UTF8_IS_DOWNGRADEABLE_START(*character)) {
return isFOO_lc(classnum,
TWO_BYTE_UTF8_TO_UNI(*character, *(character + 1)));
}
if (classnum < _FIRST_NON_SWASH_CC) {
/* Initialize the swash unless done already */
if (! PL_utf8_swash_ptrs[classnum]) {
U8 flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;
PL_utf8_swash_ptrs[classnum] = _core_swash_init("utf8",
swash_property_names[classnum], &PL_sv_undef, 1, 0, NULL, &flags);
}
return cBOOL(swash_fetch(PL_utf8_swash_ptrs[classnum], (U8 *)
character,
TRUE /* is UTF */ ));
}
switch ((_char_class_number) classnum) {
case _CC_ENUM_SPACE:
case _CC_ENUM_PSXSPC: return is_XPERLSPACE_high(character);
case _CC_ENUM_BLANK: return is_HORIZWS_high(character);
case _CC_ENUM_XDIGIT: return is_XDIGIT_high(character);
case _CC_ENUM_VERTSPACE: return is_VERTWS_high(character);
default: return 0; /* Things like CNTRL are always
below 256 */
}
assert(0); /* NOTREACHED */
return FALSE;
}
/*
* pregexec and friends
*/
#ifndef PERL_IN_XSUB_RE
/*
- pregexec - match a regexp against a string
*/
I32
Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char *strend,
char *strbeg, I32 minend, SV *screamer, U32 nosave)
/* stringarg: the point in the string at which to begin matching */
/* strend: pointer to null at end of string */
/* strbeg: real beginning of string */
/* minend: end of match must be >= minend bytes after stringarg. */
/* screamer: SV being matched: only used for utf8 flag, pos() etc; string
* itself is accessed via the pointers above */
/* 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).
*/
/* If SCREAM, then SvPVX_const(sv) should be compatible with strpos and strend.
Otherwise, only SvCUR(sv) is used to get strbeg. */
/* 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 fewer 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. */
/* args:
* rx: the regex to match against
* sv: the SV being matched: only used for utf8 flag; the string
* itself is accessed via the pointers below. Note that on
* something like an overloaded SV, SvPOK(sv) may be false
* and the string pointers may point to something unrelated to
* the SV itself.
* strbeg: real beginning of string
* strpos: the point in the string at which to begin matching
* strend: pointer to the byte following the last char of the string
* flags currently unused; set to 0
* data: currently unused; set to NULL
*/
char *
Perl_re_intuit_start(pTHX_
REGEXP * const rx,
SV *sv,
const char * const strbeg,
char *strpos,
char *strend,
const U32 flags,
re_scream_pos_data *data)
{
dVAR;
struct regexp *const prog = ReANY(rx);
I32 start_shift = 0;
/* Should be nonnegative! */
I32 end_shift = 0;
char *s;
SV *check;
char *t;
const bool utf8_target = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
I32 ml_anch;
char *other_last = NULL; /* other substr checked before this */
char *check_at = NULL; /* check substr found at this pos */
char *checked_upto = NULL; /* how far into the string we have already checked using find_byclass*/
const I32 multiline = prog->extflags & RXf_PMf_MULTILINE;
RXi_GET_DECL(prog,progi);
regmatch_info reginfo_buf; /* create some info to pass to find_byclass */
regmatch_info *const reginfo = ®info_buf;
#ifdef DEBUGGING
const char * const i_strpos = strpos;
#endif
GET_RE_DEBUG_FLAGS_DECL;
PERL_ARGS_ASSERT_RE_INTUIT_START;
PERL_UNUSED_ARG(flags);
PERL_UNUSED_ARG(data);
/* 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;
}
reginfo->is_utf8_target = cBOOL(utf8_target);
reginfo->info_aux = NULL;
reginfo->strbeg = strbeg;
reginfo->strend = strend;
reginfo->is_utf8_pat = cBOOL(RX_UTF8(rx));
reginfo->intuit = 1;
/* not actually used within intuit, but zero for safety anyway */
reginfo->poscache_maxiter = 0;
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) {
if (! to_byte_substr(prog)) {
NON_UTF8_TARGET_BUT_UTF8_REQUIRED(fail);
}
}
check = prog->check_substr;
}
if ((prog->extflags & RXf_ANCH) /* Match at beg-of-str or after \n */
&& !(prog->extflags & RXf_ANCH_GPOS)) /* \G isn't a BOS or \n */
{
ml_anch = !( (prog->extflags & RXf_ANCH_SINGLE)
|| ( (prog->extflags & RXf_ANCH_BOL)
&& !multiline ) ); /* Check after \n? */
if (!ml_anch) {
if ( !(prog->intflags & PREGf_IMPLICIT) /* not a real BOL */
&& (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)
&& ! multiline) /* /m can cause \n's to match that aren't
accounted for in the string max length.
See [perl #115242] */
{
/* 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;
U8* start_point;
U8* end_point;
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 (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') {