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regexec.c
11566 lines (10161 loc) · 445 KB
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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
/*
* 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 "invlist_inline.h"
#include "unicode_constants.h"
static const char b_utf8_locale_required[] =
"Use of \\b{} or \\B{} for non-UTF-8 locale is wrong."
" Assuming a UTF-8 locale";
#define CHECK_AND_WARN_NON_UTF8_CTYPE_LOCALE_IN_BOUND \
STMT_START { \
if (! IN_UTF8_CTYPE_LOCALE) { \
Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE), \
b_utf8_locale_required); \
} \
} STMT_END
static const char sets_utf8_locale_required[] =
"Use of (?[ ]) for non-UTF-8 locale is wrong. Assuming a UTF-8 locale";
#define CHECK_AND_WARN_NON_UTF8_CTYPE_LOCALE_IN_SETS(n) \
STMT_START { \
if (! IN_UTF8_CTYPE_LOCALE && ANYOFL_UTF8_LOCALE_REQD(FLAGS(n))) { \
Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE), \
sets_utf8_locale_required); \
} \
} STMT_END
#ifdef DEBUGGING
/* At least one required character in the target string is expressible only in
* UTF-8. */
static const char non_utf8_target_but_utf8_required[]
= "Can't match, because target string needs to be in UTF-8\n";
#endif
#define NON_UTF8_TARGET_BUT_UTF8_REQUIRED(target) STMT_START { \
DEBUG_EXECUTE_r(Perl_re_printf( aTHX_ "%s", non_utf8_target_but_utf8_required));\
goto target; \
} STMT_END
#ifndef STATIC
#define STATIC static
#endif
/*
* Forwards.
*/
#define CHR_SVLEN(sv) (utf8_target ? sv_len_utf8(sv) : SvCUR(sv))
#define HOPc(pos,off) \
(char *)(reginfo->is_utf8_target \
? reghop3((U8*)pos, off, \
(U8*)(off >= 0 ? reginfo->strend : reginfo->strbeg)) \
: (U8*)(pos + off))
/* like HOPMAYBE3 but backwards. lim must be +ve. Returns NULL on overshoot */
#define HOPBACK3(pos, off, lim) \
(reginfo->is_utf8_target \
? reghopmaybe3((U8*)pos, (SSize_t)0-off, (U8*)(lim)) \
: (pos - off >= lim) \
? (U8*)pos - off \
: NULL)
#define HOPBACKc(pos, off) ((char*)HOPBACK3(pos, off, reginfo->strbeg))
#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))
/* lim must be +ve. Returns NULL on overshoot */
#define HOPMAYBE3(pos,off,lim) \
(reginfo->is_utf8_target \
? reghopmaybe3((U8*)pos, off, (U8*)(lim)) \
: ((U8*)pos + off <= lim) \
? (U8*)pos + off \
: NULL)
/* like HOP3, but limits the result to <= lim even for the non-utf8 case.
* off must be >=0; args should be vars rather than expressions */
#define HOP3lim(pos,off,lim) (reginfo->is_utf8_target \
? reghop3((U8*)(pos), off, (U8*)(lim)) \
: (U8*)((pos + off) > lim ? lim : (pos + off)))
#define HOP3clim(pos,off,lim) ((char*)HOP3lim(pos,off,lim))
#define HOP4(pos,off,llim, rlim) (reginfo->is_utf8_target \
? reghop4((U8*)(pos), off, (U8*)(llim), (U8*)(rlim)) \
: (U8*)(pos + off))
#define HOP4c(pos,off,llim, rlim) ((char*)HOP4(pos,off,llim, rlim))
#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 && \
!EVAL_CLOSE_PAREN_IS(cur_eval,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 )
/*
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
#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 _pDEPTH)
{
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;
DECLARE_AND_GET_RE_DEBUG_FLAGS;
PERL_ARGS_ASSERT_REGCPPUSH;
if (paren_elems_to_push < 0)
Perl_croak(aTHX_ "panic: paren_elems_to_push, %i < 0, maxopenparen: %i parenfloor: %i REGCP_PAREN_ELEMS: %u",
(int)paren_elems_to_push, (int)maxopenparen,
(int)parenfloor, (unsigned)REGCP_PAREN_ELEMS);
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)
Perl_re_exec_indentf( aTHX_
"rex=0x%" UVxf " offs=0x%" UVxf ": saving capture indices:\n",
depth,
PTR2UV(rex),
PTR2UV(rex->offs)
);
);
for (p = parenfloor+1; p <= (I32)maxopenparen; p++) {
/* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
SSPUSHIV(rex->offs[p].end);
SSPUSHIV(rex->offs[p].start);
SSPUSHINT(rex->offs[p].start_tmp);
DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_
" \\%" UVuf ": %" IVdf "(%" IVdf ")..%" IVdf "\n",
depth,
(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( \
Perl_re_exec_indentf( aTHX_ \
"Setting an EVAL scope, savestack=%" IVdf ",\n", \
depth, (IV)PL_savestack_ix \
) \
); \
cp = PL_savestack_ix
#define REGCP_UNWIND(cp) \
DEBUG_STATE_r( \
if (cp != PL_savestack_ix) \
Perl_re_exec_indentf( aTHX_ \
"Clearing an EVAL scope, savestack=%" \
IVdf "..%" IVdf "\n", \
depth, (IV)(cp), (IV)PL_savestack_ix \
) \
); \
regcpblow(cp)
/* set the start and end positions of capture ix */
#define CLOSE_CAPTURE(ix, s, e) \
rex->offs[ix].start = s; \
rex->offs[ix].end = e; \
if (ix > rex->lastparen) \
rex->lastparen = ix; \
rex->lastcloseparen = ix; \
DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_ \
"CLOSE: rex=0x%" UVxf " offs=0x%" UVxf ": \\%" UVuf ": set %" IVdf "..%" IVdf " max: %" UVuf "\n", \
depth, \
PTR2UV(rex), \
PTR2UV(rex->offs), \
(UV)ix, \
(IV)rex->offs[ix].start, \
(IV)rex->offs[ix].end, \
(UV)rex->lastparen \
))
#define UNWIND_PAREN(lp, lcp) \
DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_ \
"UNWIND_PAREN: rex=0x%" UVxf " offs=0x%" UVxf ": invalidate (%" UVuf "..%" UVuf "] set lcp: %" UVuf "\n", \
depth, \
PTR2UV(rex), \
PTR2UV(rex->offs), \
(UV)(lp), \
(UV)(rex->lastparen), \
(UV)(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 _pDEPTH)
{
UV i;
U32 paren;
DECLARE_AND_GET_RE_DEBUG_FLAGS;
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)
Perl_re_exec_indentf( aTHX_
"rex=0x%" UVxf " offs=0x%" UVxf ": restoring capture indices to:\n",
depth,
PTR2UV(rex),
PTR2UV(rex->offs)
);
);
paren = *maxopenparen_p;
for ( ; i > 0; i -= REGCP_PAREN_ELEMS) {
SSize_t tmps;
rex->offs[paren].start_tmp = SSPOPINT;
rex->offs[paren].start = SSPOPIV;
tmps = SSPOPIV;
if (paren <= rex->lastparen)
rex->offs[paren].end = tmps;
DEBUG_BUFFERS_r( Perl_re_exec_indentf( aTHX_
" \\%" UVuf ": %" IVdf "(%" IVdf ")..%" IVdf "%s\n",
depth,
(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( Perl_re_exec_indentf( aTHX_
" \\%" UVuf ": %s ..-1 undeffing\n",
depth,
(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 _pDEPTH)
{
I32 tmpix = PL_savestack_ix;
PERL_ARGS_ASSERT_REGCP_RESTORE;
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 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_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);
}
NOT_REACHED; /* NOTREACHED */
return FALSE;
}
PERL_STATIC_INLINE I32
S_foldEQ_latin1_s2_folded(const char *s1, const char *s2, I32 len)
{
/* Compare non-UTF-8 using Unicode (Latin1) semantics. s2 must already be
* folded. Works on all folds representable without UTF-8, except for
* LATIN_SMALL_LETTER_SHARP_S, and does not check for this. Nor does it
* check that the strings each have at least 'len' characters.
*
* There is almost an identical API function where s2 need not be folded:
* Perl_foldEQ_latin1() */
const U8 *a = (const U8 *)s1;
const U8 *b = (const U8 *)s2;
PERL_ARGS_ASSERT_FOLDEQ_LATIN1_S2_FOLDED;
assert(len >= 0);
while (len--) {
assert(! isUPPER_L1(*b));
if (toLOWER_L1(*a) != *b) {
return 0;
}
a++, b++;
}
return 1;
}
STATIC bool
S_isFOO_utf8_lc(pTHX_ const U8 classnum, const U8* character, const U8* e)
{
/* 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 use Unicode
* rules, ignoring any locale. So use the Unicode function if this class
* requires an inversion list, 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,
EIGHT_BIT_UTF8_TO_NATIVE(*character, *(character + 1)));
}
_CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(character, e);
switch ((_char_class_number) classnum) {
case _CC_ENUM_SPACE: 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 _invlist_contains_cp(PL_XPosix_ptrs[classnum],
utf8_to_uvchr_buf(character, e, NULL));
}
return FALSE; /* Things like CNTRL are always below 256 */
}
STATIC U8 *
S_find_span_end(U8 * s, const U8 * send, const U8 span_byte)
{
/* Returns the position of the first byte in the sequence between 's' and
* 'send-1' inclusive that isn't 'span_byte'; returns 'send' if none found.
* */
PERL_ARGS_ASSERT_FIND_SPAN_END;
assert(send >= s);
if ((STRLEN) (send - s) >= PERL_WORDSIZE
+ PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
- (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
{
PERL_UINTMAX_T span_word;
/* Process per-byte until reach word boundary. XXX This loop could be
* eliminated if we knew that this platform had fast unaligned reads */
while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
if (*s != span_byte) {
return s;
}
s++;
}
/* Create a word filled with the bytes we are spanning */
span_word = PERL_COUNT_MULTIPLIER * span_byte;
/* Process per-word as long as we have at least a full word left */
do {
/* Keep going if the whole word is composed of 'span_byte's */
if ((* (PERL_UINTMAX_T *) s) == span_word) {
s += PERL_WORDSIZE;
continue;
}
/* Here, at least one byte in the word isn't 'span_byte'. */
#ifdef EBCDIC
break;
#else
/* This xor leaves 1 bits only in those non-matching bytes */
span_word ^= * (PERL_UINTMAX_T *) s;
/* Make sure the upper bit of each non-matching byte is set. This
* makes each such byte look like an ASCII platform variant byte */
span_word |= span_word << 1;
span_word |= span_word << 2;
span_word |= span_word << 4;
/* That reduces the problem to what this function solves */
return s + variant_byte_number(span_word);
#endif
} while (s + PERL_WORDSIZE <= send);
}
/* Process the straggler bytes beyond the final word boundary */
while (s < send) {
if (*s != span_byte) {
return s;
}
s++;
}
return s;
}
STATIC U8 *
S_find_next_masked(U8 * s, const U8 * send, const U8 byte, const U8 mask)
{
/* Returns the position of the first byte in the sequence between 's'
* and 'send-1' inclusive that when ANDed with 'mask' yields 'byte';
* returns 'send' if none found. It uses word-level operations instead of
* byte to speed up the process */
PERL_ARGS_ASSERT_FIND_NEXT_MASKED;
assert(send >= s);
assert((byte & mask) == byte);
#ifndef EBCDIC
if ((STRLEN) (send - s) >= PERL_WORDSIZE
+ PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
- (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
{
PERL_UINTMAX_T word, mask_word;
while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
if (((*s) & mask) == byte) {
return s;
}
s++;
}
word = PERL_COUNT_MULTIPLIER * byte;
mask_word = PERL_COUNT_MULTIPLIER * mask;
do {
PERL_UINTMAX_T masked = (* (PERL_UINTMAX_T *) s) & mask_word;
/* If 'masked' contains bytes with the bit pattern of 'byte' within
* it, xoring with 'word' will leave each of the 8 bits in such
* bytes be 0, and no byte containing any other bit pattern will be
* 0. */
masked ^= word;
/* This causes the most significant bit to be set to 1 for any
* bytes in the word that aren't completely 0 */
masked |= masked << 1;
masked |= masked << 2;
masked |= masked << 4;
/* The msbits are the same as what marks a byte as variant, so we
* can use this mask. If all msbits are 1, the word doesn't
* contain 'byte' */
if ((masked & PERL_VARIANTS_WORD_MASK) == PERL_VARIANTS_WORD_MASK) {
s += PERL_WORDSIZE;
continue;
}
/* Here, the msbit of bytes in the word that aren't 'byte' are 1,
* and any that are, are 0. Complement and re-AND to swap that */
masked = ~ masked;
masked &= PERL_VARIANTS_WORD_MASK;
/* This reduces the problem to that solved by this function */
s += variant_byte_number(masked);
return s;
} while (s + PERL_WORDSIZE <= send);
}
#endif
while (s < send) {
if (((*s) & mask) == byte) {
return s;
}
s++;
}
return s;
}
STATIC U8 *
S_find_span_end_mask(U8 * s, const U8 * send, const U8 span_byte, const U8 mask)
{
/* Returns the position of the first byte in the sequence between 's' and
* 'send-1' inclusive that when ANDed with 'mask' isn't 'span_byte'.
* 'span_byte' should have been ANDed with 'mask' in the call of this
* function. Returns 'send' if none found. Works like find_span_end(),
* except for the AND */
PERL_ARGS_ASSERT_FIND_SPAN_END_MASK;
assert(send >= s);
assert((span_byte & mask) == span_byte);
if ((STRLEN) (send - s) >= PERL_WORDSIZE
+ PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
- (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
{
PERL_UINTMAX_T span_word, mask_word;
while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
if (((*s) & mask) != span_byte) {
return s;
}
s++;
}
span_word = PERL_COUNT_MULTIPLIER * span_byte;
mask_word = PERL_COUNT_MULTIPLIER * mask;
do {
PERL_UINTMAX_T masked = (* (PERL_UINTMAX_T *) s) & mask_word;
if (masked == span_word) {
s += PERL_WORDSIZE;
continue;
}
#ifdef EBCDIC
break;
#else
masked ^= span_word;
masked |= masked << 1;
masked |= masked << 2;
masked |= masked << 4;
return s + variant_byte_number(masked);
#endif
} while (s + PERL_WORDSIZE <= send);
}
while (s < send) {
if (((*s) & mask) != span_byte) {
return s;
}
s++;
}
return s;
}
/*
* 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, SSize_t 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
/* re_intuit_start():
*
* Based on some optimiser hints, try to find the earliest position in the
* string where the regex could match.
*
* 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
*
* The basic idea of re_intuit_start() is to use some known information
* about the pattern, namely:
*
* a) the longest known anchored substring (i.e. one that's at a
* constant offset from the beginning of the pattern; but not
* necessarily at a fixed offset from the beginning of the
* string);
* b) the longest floating substring (i.e. one that's not at a constant
* offset from the beginning of the pattern);
* c) Whether the pattern is anchored to the string; either
* an absolute anchor: /^../, or anchored to \n: /^.../m,
* or anchored to pos(): /\G/;
* d) A start class: a real or synthetic character class which
* represents which characters are legal at the start of the pattern;
*
* to either quickly reject the match, or to find the earliest position
* within the string at which the pattern might match, thus avoiding
* running the full NFA engine at those earlier locations, only to
* eventually fail and retry further along.
*
* Returns NULL if the pattern can't match, or returns the address within
* the string which is the earliest place the match could occur.
*
* The longest of the anchored and floating substrings is called 'check'
* and is checked first. The other is called 'other' and is checked
* second. The 'other' substring may not be present. For example,
*
* /(abc|xyz)ABC\d{0,3}DEFG/
*
* will have
*
* check substr (float) = "DEFG", offset 6..9 chars
* other substr (anchored) = "ABC", offset 3..3 chars
* stclass = [ax]
*
* Be aware that during the course of this function, sometimes 'anchored'
* refers to a substring being anchored relative to the start of the
* pattern, and sometimes to the pattern itself being anchored relative to
* the string. For example:
*
* /\dabc/: "abc" is anchored to the pattern;
* /^\dabc/: "abc" is anchored to the pattern and the string;
* /\d+abc/: "abc" is anchored to neither the pattern nor the string;
* /^\d+abc/: "abc" is anchored to neither the pattern nor the string,
* but the pattern is anchored to the string.
*/
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)
{
struct regexp *const prog = ReANY(rx);
SSize_t start_shift = prog->check_offset_min;
/* Should be nonnegative! */
SSize_t end_shift = 0;
/* current lowest pos in string where the regex can start matching */
char *rx_origin = strpos;
SV *check;
const bool utf8_target = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
U8 other_ix = 1 - prog->substrs->check_ix;
bool ml_anch = 0;
char *other_last = strpos;/* latest pos 'other' substr already checked to */
char *check_at = NULL; /* check substr found at this pos */
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;
DECLARE_AND_GET_RE_DEBUG_FLAGS;
PERL_ARGS_ASSERT_RE_INTUIT_START;
PERL_UNUSED_ARG(flags);
PERL_UNUSED_ARG(data);
DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
"Intuit: trying to determine minimum start position...\n"));
/* for now, assume that all substr offsets are positive. If at some point
* in the future someone wants to do clever things with lookbehind and
* -ve offsets, they'll need to fix up any code in this function
* which uses these offsets. See the thread beginning
* <20140113145929.GF27210@iabyn.com>
*/
assert(prog->substrs->data[0].min_offset >= 0);
assert(prog->substrs->data[0].max_offset >= 0);
assert(prog->substrs->data[1].min_offset >= 0);
assert(prog->substrs->data[1].max_offset >= 0);
assert(prog->substrs->data[2].min_offset >= 0);
assert(prog->substrs->data[2].max_offset >= 0);
/* for now, assume that if both present, that the floating substring
* doesn't start before the anchored substring.
* If you break this assumption (e.g. doing better optimisations
* with lookahead/behind), then you'll need to audit the code in this
* function carefully first
*/
assert(
! ( (prog->anchored_utf8 || prog->anchored_substr)
&& (prog->float_utf8 || prog->float_substr))
|| (prog->float_min_offset >= prog->anchored_offset));
/* byte rather than char calculation for efficiency. It fails
* to quickly reject some cases that can't match, but will reject
* them later after doing full char arithmetic */
if (prog->minlen > strend - strpos) {
DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
" String too short...\n"));
goto fail;
}
RXp_MATCH_UTF8_set(prog, utf8_target);
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->anchored_utf8 && prog->anchored_substr)
|| (!prog->float_utf8 && prog->float_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;
}
/* dump the various substring data */
DEBUG_OPTIMISE_MORE_r({
int i;
for (i=0; i<=2; i++) {
SV *sv = (utf8_target ? prog->substrs->data[i].utf8_substr
: prog->substrs->data[i].substr);
if (!sv)
continue;
Perl_re_printf( aTHX_
" substrs[%d]: min=%" IVdf " max=%" IVdf " end shift=%" IVdf
" useful=%" IVdf " utf8=%d [%s]\n",
i,
(IV)prog->substrs->data[i].min_offset,
(IV)prog->substrs->data[i].max_offset,
(IV)prog->substrs->data[i].end_shift,
BmUSEFUL(sv),
utf8_target ? 1 : 0,
SvPEEK(sv));
}
});
if (prog->intflags & PREGf_ANCH) { /* Match at \G, beg-of-str or after \n */
/* ml_anch: check after \n?
*
* A note about PREGf_IMPLICIT: on an un-anchored pattern beginning
* with /.*.../, these flags will have been added by the
* compiler:
* /.*abc/, /.*abc/m: PREGf_IMPLICIT | PREGf_ANCH_MBOL
* /.*abc/s: PREGf_IMPLICIT | PREGf_ANCH_SBOL
*/
ml_anch = (prog->intflags & PREGf_ANCH_MBOL)
&& !(prog->intflags & PREGf_IMPLICIT);
if (!ml_anch && !(prog->intflags & PREGf_IMPLICIT)) {
/* we are only allowed to match at BOS or \G */
/* trivially reject if there's a BOS anchor and we're not at BOS.
*
* Note that we don't try to do a similar quick reject for
* \G, since generally the caller will have calculated strpos
* based on pos() and gofs, so the string is already correctly
* anchored by definition; and handling the exceptions would
* be too fiddly (e.g. REXEC_IGNOREPOS).
*/
if ( strpos != strbeg
&& (prog->intflags & PREGf_ANCH_SBOL))
{
DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
" Not at start...\n"));
goto fail;
}
/* in the presence of an anchor, the anchored (relative to the
* start of the regex) substr must also be anchored relative
* to strpos. So quickly reject if substr isn't found there.
* This works for \G too, because the caller will already have
* subtracted gofs from pos, and gofs is the offset from the
* \G to the start of the regex. For example, in /.abc\Gdef/,
* where substr="abcdef", pos()=3, gofs=4, offset_min=1:
* caller will have set strpos=pos()-4; we look for the substr
* at position pos()-4+1, which lines up with the "a" */