updated for version 7.3.1151

Problem:    New regexp engine: Slow when a look-behind match is followed by a
            zero-width match.
Solution:   Postpone the look-behind match more often.

diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 18bcad09807a2b53f4be4f12a90d995bfa35fc78..5c6e986f4f82fae32aa2e4c66462dc1591b53da3 100644 (file)
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -2794,6 +2794,7 @@ nfa_max_width(startstate, depth)
     /* unrecognized */
     return -1;
 }
+
 /*
  * Convert a postfix form into its equivalent NFA.
  * Return the NFA start state on success, NULL otherwise.
@@ -3433,6 +3434,7 @@ static void copy_sub __ARGS((regsub_T *to, regsub_T *from));
 static void copy_sub_off __ARGS((regsub_T *to, regsub_T *from));
 static int sub_equal __ARGS((regsub_T *sub1, regsub_T *sub2));
 static int has_state_with_pos __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs));
+static int match_follows __ARGS((nfa_state_T *startstate, int depth));
 static int state_in_list __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs));
 static void addstate __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs, int off));
 static void addstate_here __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs, nfa_pim_T *pim, int *ip));
@@ -3625,6 +3627,88 @@ has_state_with_pos(l, state, subs)
     return FALSE;
 }
 
+/*
+ * Return TRUE if "state" leads to a NFA_MATCH without advancing the input.
+ */
+    static int
+match_follows(startstate, depth)
+    nfa_state_T *startstate;
+    int                depth;
+{
+    nfa_state_T            *state = startstate;
+
+    /* avoid too much recursion */
+    if (depth > 10)
+       return FALSE;
+
+    for (;;)
+    {
+       switch (state->c)
+       {
+           case NFA_MATCH:
+               return TRUE;
+
+           case NFA_SPLIT:
+               return match_follows(state->out, depth + 1)
+                                    || match_follows(state->out1, depth + 1);
+
+           case NFA_START_INVISIBLE:
+           case NFA_START_INVISIBLE_BEFORE:
+           case NFA_START_INVISIBLE_NEG:
+           case NFA_START_INVISIBLE_BEFORE_NEG:
+           case NFA_COMPOSING:
+               /* skip ahead to next state */
+               state = state->out1->out;
+               break;
+
+           case NFA_ANY:
+           case NFA_IDENT:
+           case NFA_SIDENT:
+           case NFA_KWORD:
+           case NFA_SKWORD:
+           case NFA_FNAME:
+           case NFA_SFNAME:
+           case NFA_PRINT:
+           case NFA_SPRINT:
+           case NFA_WHITE:
+           case NFA_NWHITE:
+           case NFA_DIGIT:
+           case NFA_NDIGIT:
+           case NFA_HEX:
+           case NFA_NHEX:
+           case NFA_OCTAL:
+           case NFA_NOCTAL:
+           case NFA_WORD:
+           case NFA_NWORD:
+           case NFA_HEAD:
+           case NFA_NHEAD:
+           case NFA_ALPHA:
+           case NFA_NALPHA:
+           case NFA_LOWER:
+           case NFA_NLOWER:
+           case NFA_UPPER:
+           case NFA_NUPPER:
+           case NFA_START_COLL:
+           case NFA_START_NEG_COLL:
+           case NFA_NEWL:
+               /* state will advance input */
+               return FALSE;
+
+           default:
+               if (state->c > 0)
+                   /* state will advance input */
+                   return FALSE;
+
+               /* Others: zero-width or possibly zero-width, might still find
+                * a match at the same position, keep looking. */
+               break;
+       }
+       state = state->out;
+    }
+    return FALSE;
+}
+
+
 /*
  * Return TRUE if "state" is already in list "l".
  */
@@ -5714,9 +5798,11 @@ nfa_regmatch(prog, start, submatch, m)
 
            if (add_state != NULL)
            {
-               if (t->pim != NULL)
+               /* Handle the postponed invisible match before advancing to
+                * the next character and for a zero-width match if the match
+                * might end without advancing. */
+               if (t->pim != NULL && (!add_here || match_follows(add_state, 0)))
                {
-                   /* postponed invisible match */
                    if (t->pim->result == NFA_PIM_TODO)
                    {
 #ifdef ENABLE_LOG
@@ -5773,7 +5859,7 @@ nfa_regmatch(prog, start, submatch, m)
                }
 
                if (add_here)
-                   addstate_here(thislist, add_state, &t->subs, NULL, &listidx);
+                   addstate_here(thislist, add_state, &t->subs, t->pim, &listidx);
                else
                {
                    addstate(nextlist, add_state, &t->subs, add_off);

diff --git a/src/version.c b/src/version.c
index 05b23ad3a3a61637f647cc62cdef11159e2ebf55..a442ecb96662a20c46fa02db2d1eb1dbf6d09990 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -728,6 +728,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1151,
 /**/
     1150,
 /**/