Miscellaneous cleanup of regular-expression compiler.

Revert our previous addition of "all" flags to copyins() and copyouts();
they're no longer needed, and were never anything but an unsightly hack.

Improve a couple of infelicities in the REG_DEBUG code for dumping
the NFA data structure, including adding code to count the total
number of states and arcs.

Add a couple of missed error checks.

Add some more documentation in the README file, and some regression tests
illustrating cases that exceeded the state-count limit and/or took
unreasonable amounts of time before this set of patches.

Back-patch to all supported branches.

2 files changed, 23 insertions, 43 deletions

diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c
index fe8a4a12d17..6f04321cd35 100644
--- a/src/backend/regex/regc_nfa.c
+++ b/src/backend/regex/regc_nfa.c
@@ -823,14 +823,11 @@ moveins(struct nfa * nfa,
 
 /*
  * copyins - copy in arcs of a state to another state
- *
- * Either all arcs, or only non-empty ones as determined by all value.
  */
 static void
 copyins(struct nfa * nfa,
 		struct state * oldState,
-		struct state * newState,
-		int all)
+		struct state * newState)
 {
 	assert(oldState != newState);
 
@@ -840,8 +837,7 @@ copyins(struct nfa * nfa,
 		struct arc *a;
 
 		for (a = oldState->ins; a != NULL; a = a->inchain)
-			if (all || a->type != EMPTY)
-				cparc(nfa, a, a->from, newState);
+			cparc(nfa, a, a->from, newState);
 	}
 	else
 	{
@@ -873,12 +869,6 @@ copyins(struct nfa * nfa,
 		{
 			struct arc *a = oa;
 
-			if (!all && a->type == EMPTY)
-			{
-				oa = oa->inchain;
-				continue;
-			}
-
 			switch (sortins_cmp(&oa, &na))
 			{
 				case -1:
@@ -904,12 +894,6 @@ copyins(struct nfa * nfa,
 			/* newState does not have anything matching oa */
 			struct arc *a = oa;
 
-			if (!all && a->type == EMPTY)
-			{
-				oa = oa->inchain;
-				continue;
-			}
-
 			oa = oa->inchain;
 			createarc(nfa, a->type, a->co, a->from, newState);
 		}
@@ -1107,14 +1091,11 @@ moveouts(struct nfa * nfa,
 
 /*
  * copyouts - copy out arcs of a state to another state
- *
- * Either all arcs, or only non-empty ones as determined by all value.
  */
 static void
 copyouts(struct nfa * nfa,
 		 struct state * oldState,
-		 struct state * newState,
-		 int all)
+		 struct state * newState)
 {
 	assert(oldState != newState);
 
@@ -1124,8 +1105,7 @@ copyouts(struct nfa * nfa,
 		struct arc *a;
 
 		for (a = oldState->outs; a != NULL; a = a->outchain)
-			if (all || a->type != EMPTY)
-				cparc(nfa, a, newState, a->to);
+			cparc(nfa, a, newState, a->to);
 	}
 	else
 	{
@@ -1157,12 +1137,6 @@ copyouts(struct nfa * nfa,
 		{
 			struct arc *a = oa;
 
-			if (!all && a->type == EMPTY)
-			{
-				oa = oa->outchain;
-				continue;
-			}
-
 			switch (sortouts_cmp(&oa, &na))
 			{
 				case -1:
@@ -1188,12 +1162,6 @@ copyouts(struct nfa * nfa,
 			/* newState does not have anything matching oa */
 			struct arc *a = oa;
 
-			if (!all && a->type == EMPTY)
-			{
-				oa = oa->outchain;
-				continue;
-			}
-
 			oa = oa->outchain;
 			createarc(nfa, a->type, a->co, newState, a->to);
 		}
@@ -1452,6 +1420,10 @@ optimize(struct nfa * nfa,
 		fprintf(f, "\nfinal cleanup:\n");
 #endif
 	cleanup(nfa);				/* final tidying */
+#ifdef REG_DEBUG
+	if (verbose)
+		dumpnfa(nfa, f);
+#endif
 	return analyze(nfa);		/* and analysis */
 }
 
@@ -1568,7 +1540,7 @@ pull(struct nfa * nfa,
 		s = newstate(nfa);
 		if (NISERR())
 			return 0;
-		copyins(nfa, from, s, 1);		/* duplicate inarcs */
+		copyins(nfa, from, s);	/* duplicate inarcs */
 		cparc(nfa, con, s, to); /* move constraint arc */
 		freearc(nfa, con);
 		if (NISERR())
@@ -1735,7 +1707,7 @@ push(struct nfa * nfa,
 		s = newstate(nfa);
 		if (NISERR())
 			return 0;
-		copyouts(nfa, to, s, 1);	/* duplicate outarcs */
+		copyouts(nfa, to, s);	/* duplicate outarcs */
 		cparc(nfa, con, from, s);		/* move constraint arc */
 		freearc(nfa, con);
 		if (NISERR())
@@ -2952,6 +2924,8 @@ dumpnfa(struct nfa * nfa,
 {
 #ifdef REG_DEBUG
 	struct state *s;
+	int			nstates = 0;
+	int			narcs = 0;
 
 	fprintf(f, "pre %d, post %d", nfa->pre->no, nfa->post->no);
 	if (nfa->bos[0] != COLORLESS)
@@ -2964,7 +2938,12 @@ dumpnfa(struct nfa * nfa,
 		fprintf(f, ", eol [%ld]", (long) nfa->eos[1]);
 	fprintf(f, "\n");
 	for (s = nfa->states; s != NULL; s = s->next)
+	{
 		dumpstate(s, f);
+		nstates++;
+		narcs += s->nouts;
+	}
+	fprintf(f, "total of %d states, %d arcs\n", nstates, narcs);
 	if (nfa->parent == NULL)
 		dumpcolors(nfa->cm, f);
 	fflush(f);
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 9e04a4f298a..f4eebf84d7b 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -136,10 +136,10 @@ static int	sortins_cmp(const void *, const void *);
 static void sortouts(struct nfa *, struct state *);
 static int	sortouts_cmp(const void *, const void *);
 static void moveins(struct nfa *, struct state *, struct state *);
-static void copyins(struct nfa *, struct state *, struct state *, int);
+static void copyins(struct nfa *, struct state *, struct state *);
 static void mergeins(struct nfa *, struct state *, struct arc **, int);
 static void moveouts(struct nfa *, struct state *, struct state *);
-static void copyouts(struct nfa *, struct state *, struct state *, int);
+static void copyouts(struct nfa *, struct state *, struct state *);
 static void cloneouts(struct nfa *, struct state *, struct state *, struct state *, int);
 static void delsub(struct nfa *, struct state *, struct state *);
 static void deltraverse(struct nfa *, struct state *, struct state *);
@@ -181,7 +181,6 @@ static void dumpnfa(struct nfa *, FILE *);
 #ifdef REG_DEBUG
 static void dumpstate(struct state *, FILE *);
 static void dumparcs(struct state *, FILE *);
-static int	dumprarcs(struct arc *, struct state *, FILE *, int);
 static void dumparc(struct arc *, struct state *, FILE *);
 static void dumpcnfa(struct cnfa *, FILE *);
 static void dumpcstate(int, struct cnfa *, FILE *);
@@ -613,7 +612,9 @@ makesearch(struct vars * v,
 	for (s = slist; s != NULL; s = s2)
 	{
 		s2 = newstate(nfa);
-		copyouts(nfa, s, s2, 1);
+		NOERR();
+		copyouts(nfa, s, s2);
+		NOERR();
 		for (a = s->ins; a != NULL; a = b)
 		{
 			b = a->inchain;
@@ -1997,7 +1998,7 @@ dump(regex_t *re,
 	dumpcolors(&g->cmap, f);
 	if (!NULLCNFA(g->search))
 	{
-		printf("\nsearch:\n");
+		fprintf(f, "\nsearch:\n");
 		dumpcnfa(&g->search, f);
 	}
 	for (i = 1; i < g->nlacons; i++)