updated for version 7.3.1037

Problem:    Look-behind matching is very slow on long lines.
Solution:   Add a byte limit to how far back an attempt is made.

src/regexp.c

@@ -701,6 +701,7 @@ static void	regmbc __ARGS((int c));
 # define CASEMBC(x)
 #endif
 static void	reginsert __ARGS((int, char_u *));
+static void	reginsert_nr __ARGS((int op, long val, char_u *opnd));
 static void	reginsert_limits __ARGS((int, long, long, char_u *));
 static char_u	*re_put_long __ARGS((char_u *pr, long_u val));
 static int	read_limits __ARGS((long *, long *));
@@ -1781,7 +1782,9 @@ regpiece(flagp)
 	case Magic('@'):
 	    {
 		int	lop = END;
+		int	nr;
 
+		nr = getdecchrs();
 		switch (no_Magic(getchr()))
 		{
 		    case '=': lop = MATCH; break;		  /* \@= */
@@ -1803,6 +1806,13 @@ regpiece(flagp)
 		    *flagp |= HASLOOKBH;
 		}
 		regtail(ret, regnode(END)); /* operand ends */
+		if (lop == BEHIND || lop == NOBEHIND)
+		{
+		    if (nr < 0)
+			nr = 0; /* no limit is same as zero limit */
+		    reginsert_nr(lop, nr, ret);
+		}
+		else
 		    reginsert(lop, ret);
 		break;
 	    }
@@ -2778,6 +2788,38 @@ reginsert(op, opnd)
     *place = NUL;
 }
 
+/*
+ * Insert an operator in front of already-emitted operand.
+ * Add a number to the operator.
+ */
+    static void
+reginsert_nr(op, val, opnd)
+    int		op;
+    long	val;
+    char_u	*opnd;
+{
+    char_u	*src;
+    char_u	*dst;
+    char_u	*place;
+
+    if (regcode == JUST_CALC_SIZE)
+    {
+	regsize += 7;
+	return;
+    }
+    src = regcode;
+    regcode += 7;
+    dst = regcode;
+    while (src > opnd)
+	*--dst = *--src;
+
+    place = opnd;		/* Op node, where operand used to be. */
+    *place++ = op;
+    *place++ = NUL;
+    *place++ = NUL;
+    place = re_put_long(place, (long_u)val);
+}
+
 /*
  * Insert an operator in front of already-emitted operand.
  * The operator has the given limit values as operands.  Also set next pointer.
@@ -3182,7 +3224,7 @@ gethexchrs(maxinputlen)
 }
 
 /*
- * get and return the value of the decimal string immediately after the
+ * Get and return the value of the decimal string immediately after the
  * current position. Return -1 for invalid.  Consumes all digits.
  */
     static int
@@ -3200,6 +3242,7 @@ getdecchrs()
 	nr *= 10;
 	nr += c - '0';
 	++regparse;
+	curchr = -1; /* no longer valid */
     }
 
     if (i == 0)
@@ -5432,7 +5475,7 @@ regmatch(scan)
 		/* save the position after the found match for next */
 		reg_save(&(((regbehind_T *)rp) - 1)->save_after, &backpos);
 
-		/* start looking for a match with operand at the current
+		/* Start looking for a match with operand at the current
 		 * position.  Go back one character until we find the
 		 * result, hitting the start of the line or the previous
 		 * line (for multi-line matching).
@@ -5444,7 +5487,7 @@ regmatch(scan)
 		rp->rs_state = RS_BEHIND2;
 
 		reg_restore(&rp->rs_un.regsave, &backpos);
-		scan = OPERAND(rp->rs_scan);
+		scan = OPERAND(rp->rs_scan) + 4;
 	    }
 	    break;
 
@@ -5472,9 +5515,12 @@ regmatch(scan)
 	    }
 	    else
 	    {
+		long limit;
+
 		/* No match or a match that doesn't end where we want it: Go
 		 * back one character.  May go to previous line once. */
 		no = OK;
+		limit = OPERAND_MIN(rp->rs_scan);
 		if (REG_MULTI)
 		{
 		    if (rp->rs_un.regsave.rs_u.pos.col == 0)
@@ -5493,6 +5539,7 @@ regmatch(scan)
 			}
 		    }
 		    else
+		    {
 #ifdef FEAT_MBYTE
 			if (has_mbyte)
 			    rp->rs_un.regsave.rs_u.pos.col -=
@@ -5501,19 +5548,32 @@ regmatch(scan)
 			else
 #endif
 			    --rp->rs_un.regsave.rs_u.pos.col;
+			if (limit > 0
+				&& ((rp->rs_un.regsave.rs_u.pos.lnum
+						    < behind_pos.rs_u.pos.lnum
+					? (colnr_T)STRLEN(regline)
+					: behind_pos.rs_u.pos.col)
+				    - rp->rs_un.regsave.rs_u.pos.col > limit))
+			    no = FAIL;
+		    }
 		}
 		else
 		{
 		    if (rp->rs_un.regsave.rs_u.ptr == regline)
 			no = FAIL;
 		    else
-			--rp->rs_un.regsave.rs_u.ptr;
+		    {
+			mb_ptr_back(regline, rp->rs_un.regsave.rs_u.ptr);
+			if (limit > 0 && (long)(behind_pos.rs_u.ptr
+				     - rp->rs_un.regsave.rs_u.ptr) > limit)
+			    no = FAIL;
+		    }
 		}
 		if (no == OK)
 		{
 		    /* Advanced, prepare for finding match again. */
 		    reg_restore(&rp->rs_un.regsave, &backpos);
-		    scan = OPERAND(rp->rs_scan);
+		    scan = OPERAND(rp->rs_scan) + 4;
 		    if (status == RA_MATCH)
 		    {
 			/* We did match, so subexpr may have been changed,
@@ -7773,7 +7833,7 @@ static int regexp_engine = 0;
 #ifdef DEBUG
 static char_u regname[][30] = {
 		    "AUTOMATIC Regexp Engine",
-		    "BACKTACKING Regexp Engine",
+		    "BACKTRACKING Regexp Engine",
 		    "NFA Regexp Engine"
 			    };
 #endif

src/regexp_nfa.c

@@ -1331,6 +1331,16 @@ nfa_regpiece()
 		case '=':
 		    EMIT(NFA_PREV_ATOM_NO_WIDTH);
 		    break;
+		case '0':
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9':
 		case '!':
 		case '<':
 		case '>':
@@ -3817,7 +3827,9 @@ nfa_regmatch(start, submatch, m)
 	 * because recursive calls should only start in the first position.
 	 * Also don't start a match past the first line. */
 	if (nfa_match == FALSE && start->c == NFA_MOPEN + 0
-						 && reglnum == 0 && clen != 0)
+		&& reglnum == 0 && clen != 0
+		&& (ireg_maxcol == 0
+			      || (colnr_T)(reginput - regline) < ireg_maxcol))
 	{
 #ifdef ENABLE_LOG
 	    fprintf(log_fd, "(---) STARTSTATE\n");

src/testdir/test64.in

@@ -336,6 +336,14 @@ STARTTEST
 :"call add(tl, [2, '\(\i\+\) \1', 'xgoo goox', 'goo goo', 'goo'])
 :call add(tl, [2, '\(a\)\(b\)\(c\)\(dd\)\(e\)\(f\)\(g\)\(h\)\(i\)\1\2\3\4\5\6\7\8\9', 'xabcddefghiabcddefghix', 'abcddefghiabcddefghi', 'a', 'b', 'c', 'dd', 'e', 'f', 'g', 'h', 'i'])
 :"
+:"""" Look-behind with limit
+:call add(tl, [0, '<\@<=span.', 'xxspanxx<spanyyy', 'spany'])
+:call add(tl, [0, '<\@1<=span.', 'xxspanxx<spanyyy', 'spany'])
+:call add(tl, [0, '<\@2<=span.', 'xxspanxx<spanyyy', 'spany'])
+:call add(tl, [0, '\(<<\)\@<=span.', 'xxspanxxxx<spanxx<<spanyyy', 'spany', '<<'])
+:call add(tl, [0, '\(<<\)\@1<=span.', 'xxspanxxxx<spanxx<<spanyyy'])
+:call add(tl, [0, '\(<<\)\@2<=span.', 'xxspanxxxx<spanxx<<spanyyy', 'spany', '<<'])
+:"
 :"""" Run the tests
 :"
 :"
@@ -406,6 +414,12 @@ Gop:"
 y$Gop:"
 :"
 :"
+:" Check a pattern with a look beind crossing a line boundary
+/^Behind:
+/\(<\_[xy]\+\)\@3<=start
+:.yank
+Gop:"
+:"
 :/\%#=1^Results/,$wq! test.out
 ENDTEST
 
@@ -423,4 +437,12 @@ ghi
 xjk
 lmn
 
+Behind:
+asdfasd<yyy
+xxstart1
+asdfasd<yy
+xxxxstart2
+asdfasd<yy
+xxxstart3
+
 Results of test64:

src/testdir/test64.ok

@@ -719,6 +719,18 @@ OK 2 - \(\i\+\) \1
 OK 0 - \(a\)\(b\)\(c\)\(dd\)\(e\)\(f\)\(g\)\(h\)\(i\)\1\2\3\4\5\6\7\8\9
 OK 1 - \(a\)\(b\)\(c\)\(dd\)\(e\)\(f\)\(g\)\(h\)\(i\)\1\2\3\4\5\6\7\8\9
 OK 2 - \(a\)\(b\)\(c\)\(dd\)\(e\)\(f\)\(g\)\(h\)\(i\)\1\2\3\4\5\6\7\8\9
+OK 0 - <\@<=span.
+OK 1 - <\@<=span.
+OK 0 - <\@1<=span.
+OK 1 - <\@1<=span.
+OK 0 - <\@2<=span.
+OK 1 - <\@2<=span.
+OK 0 - \(<<\)\@<=span.
+OK 1 - \(<<\)\@<=span.
+OK 0 - \(<<\)\@1<=span.
+OK 1 - \(<<\)\@1<=span.
+OK 0 - \(<<\)\@2<=span.
+OK 1 - \(<<\)\@2<=span.
 192.168.0.1
 192.168.0.1
 192.168.0.1
@@ -726,3 +738,5 @@ OK 2 - \(a\)\(b\)\(c\)\(dd\)\(e\)\(f\)\(g\)\(h\)\(i\)\1\2\3\4\5\6\7\8\9
 <T="5">Ta 5</Title>
 <T="7">Ac 7</Title>
 ghi
+
+xxxstart3

src/version.c

@@ -728,6 +728,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1037,
 /**/
     1036,
 /**/