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authordgp <dgp@users.sourceforge.net>2015-10-20 19:21:53 (GMT)
committerdgp <dgp@users.sourceforge.net>2015-10-20 19:21:53 (GMT)
commit5ec3b6491d71b85b55f8927e78f033e75c92170f (patch)
tree2d3cad937af686af85330cceb2cf78d5c96aea39
parentf12c713f8e323f0c7872d83c93b2371c7eb42365 (diff)
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Adaptation of re-better-pushpull.patch from Tom Lane @postgres
-rw-r--r--generic/regc_nfa.c155
-rw-r--r--generic/regcomp.c4
2 files changed, 119 insertions, 40 deletions
diff --git a/generic/regc_nfa.c b/generic/regc_nfa.c
index 5582e4e..bbc4dd6 100644
--- a/generic/regc_nfa.c
+++ b/generic/regc_nfa.c
@@ -1518,6 +1518,7 @@ pullback(
struct state *nexts;
struct arc *a;
struct arc *nexta;
+ struct state *intermediates;
int progress;
/*
@@ -1528,15 +1529,27 @@ pullback(
progress = 0;
for (s=nfa->states ; s!=NULL && !NISERR() ; s=nexts) {
nexts = s->next;
+ intermediates = NULL;
for (a=s->outs ; a!=NULL && !NISERR() ; a=nexta) {
nexta = a->outchain;
if (a->type == '^' || a->type == BEHIND) {
- if (pull(nfa, a)) {
+ if (pull(nfa, a, &intermediates)) {
progress = 1;
}
}
assert(nexta == NULL || s->no != FREESTATE);
}
+ /* clear tmp fields of intermediate states created here */
+ while (intermediates != NULL) {
+ struct state *ns = intermediates->tmp;
+
+ intermediates->tmp = NULL;
+ intermediates = ns;
+ }
+ /* if s is now useless, get rid of it */
+ if ((s->nins == 0 || s->nouts == 0) && !s->flag) {
+ dropstate(nfa, s);
+ }
}
if (progress && f != NULL) {
dumpnfa(nfa, f);
@@ -1564,15 +1577,28 @@ pullback(
/*
- pull - pull a back constraint backward past its source state
- * A significant property of this function is that it deletes at most
- * one state -- the constraint's from state -- and only if the constraint
- * was that state's last outarc.
+ *
+ * Returns 1 if successful (which it always is unless the source is the
+ * start state or we have an internal error), 0 if nothing happened.
+ *
+ * A significant property of this function is that it deletes no pre-existing
+ * states, and no outarcs of the constraint's from state other than the given
+ * constraint arc. This makes the loops in pullback() safe, at the cost that
+ * we may leave useless states behind. Therefore, we leave it to pullback()
+ * to delete such states.
+ *
+ * If the from state has multiple back-constraint outarcs, and/or multiple
+ * compatible constraint inarcs, we only need to create one new intermediate
+ * state per combination of predecessor and successor states. *intermediates
+ * points to a list of such intermediate states for this from state (chained
+ * through their tmp fields).
^ static int pull(struct nfa *, struct arc *);
*/
-static int /* 0 couldn't, 1 could */
+static int
pull(
struct nfa *nfa,
- struct arc *con)
+ struct arc *con,
+ struct state **intermediates)
{
struct state *from = con->from;
struct state *to = con->to;
@@ -1590,7 +1616,9 @@ pull(
}
/*
- * First, clone from state if necessary to avoid other outarcs.
+ * First, clone from state if necessary to avoid other outarcs. This may
+ * seem wasteful, but it simplifies the logic, and we'll get rid of the
+ * clone state again at the bottom.
*/
if (from->nouts > 1) {
@@ -1601,6 +1629,9 @@ pull(
copyins(nfa, from, s, 1); /* duplicate inarcs */
cparc(nfa, con, s, to); /* move constraint arc */
freearc(nfa, con);
+ if (NISERR()) {
+ return 0;
+ }
from = s;
con = from->outs;
}
@@ -1610,7 +1641,7 @@ pull(
* Propagate the constraint into the from state's inarcs.
*/
- for (a=from->ins ; a!=NULL ; a=nexta) {
+ for (a=from->ins ; a!=NULL && !NISERR(); a=nexta) {
nexta = a->inchain;
switch (combine(con, a)) {
case INCOMPATIBLE: /* destroy the arc */
@@ -1619,17 +1650,25 @@ pull(
case SATISFIED: /* no action needed */
break;
case COMPATIBLE: /* swap the two arcs, more or less */
- s = newstate(nfa);
- if (NISERR()) {
- return 0;
+ /* need an intermediate state, but might have one already */
+ for (s = *intermediates; s != NULL; s = s->tmp) {
+ assert(s->nins > 0 && s->nouts > 0);
+ if (s->ins->from == a->from && s->outs->to == to) {
+ break;
+ }
}
- cparc(nfa, a, s, to); /* anticipate move */
- cparc(nfa, con, a->from, s);
- if (NISERR()) {
- return 0;
+ if (s == NULL) {
+ s = newstate(nfa);
+ if (NISERR()) {
+ return 0;
+ }
+ s->tmp = *intermediates;
+ *intermediates = s;
}
- freearc(nfa, a);
- break;
+ cparc(nfa, con, a->from, s);
+ cparc(nfa, a, s, to);
+ freearc(nfa, a);
+ break;
default:
assert(NOTREACHED);
break;
@@ -1641,7 +1680,8 @@ pull(
*/
moveins(nfa, from, to);
- dropstate(nfa, from); /* will free the constraint */
+ freearc(nfa, con);
+ /* from state is now useless, but we leave it to pullback() to clean up */
return 1;
}
@@ -1658,6 +1698,7 @@ pushfwd(
struct state *nexts;
struct arc *a;
struct arc *nexta;
+ struct state *intermediates;
int progress;
/*
@@ -1668,14 +1709,25 @@ pushfwd(
progress = 0;
for (s=nfa->states ; s!=NULL && !NISERR() ; s=nexts) {
nexts = s->next;
+ intermediates = NULL;
for (a = s->ins; a != NULL && !NISERR(); a = nexta) {
nexta = a->inchain;
if (a->type == '$' || a->type == AHEAD) {
- if (push(nfa, a)) {
+ if (push(nfa, a, &intermediates)) {
progress = 1;
}
}
- assert(nexta == NULL || s->no != FREESTATE);
+ }
+ /* clear tmp fields of intermediate states created here */
+ while (intermediates != NULL) {
+ struct state *ns = intermediates->tmp;
+
+ intermediates->tmp = NULL;
+ intermediates = ns;
+ }
+ /* if s is now useless, get rid of it */
+ if ((s->nins == 0 || s->nouts == 0) && !s->flag) {
+ dropstate(nfa, s);
}
}
if (progress && f != NULL) {
@@ -1704,15 +1756,28 @@ pushfwd(
/*
- push - push a forward constraint forward past its destination state
- * A significant property of this function is that it deletes at most
- * one state -- the constraint's to state -- and only if the constraint
- * was that state's last inarc.
+ *
+ * Returns 1 if successful (which it always is unless the destination is the
+ * post state or we have an internal error), 0 if nothing happened.
+ *
+ * A significant property of this function is that it deletes no pre-existing
+ * states, and no inarcs of the constraint's to state other than the given
+ * constraint arc. This makes the loops in pushfwd() safe, at the cost that
+ * we may leave useless states behind. Therefore, we leave it to pushfwd()
+ * to delete such states.
+ *
+ * If the to state has multiple forward-constraint inarcs, and/or multiple
+ * compatible constraint outarcs, we only need to create one new intermediate
+ * state per combination of predecessor and successor states. *intermediates
+ * points to a list of such intermediate states for this to state (chained
+ * through their tmp fields).
^ static int push(struct nfa *, struct arc *);
*/
-static int /* 0 couldn't, 1 could */
+static int
push(
struct nfa *nfa,
- struct arc *con)
+ struct arc *con,
+ struct state **intermediates)
{
struct state *from = con->from;
struct state *to = con->to;
@@ -1730,7 +1795,9 @@ push(
}
/*
- * First, clone to state if necessary to avoid other inarcs.
+ * First, clone to state if necessary to avoid other inarcs. This may
+ * seem wasteful, but it simplifies the logic, and we'll get rid of the
+ * clone state again at the bottom.
*/
if (to->nins > 1) {
@@ -1739,8 +1806,11 @@ push(
return 0;
}
copyouts(nfa, to, s, 1); /* duplicate outarcs */
- cparc(nfa, con, from, s); /* move constraint */
+ cparc(nfa, con, from, s); /* move constraint arc */
freearc(nfa, con);
+ if (NISERR()) {
+ return 0;
+ }
to = s;
con = to->ins;
}
@@ -1750,7 +1820,7 @@ push(
* Propagate the constraint into the to state's outarcs.
*/
- for (a = to->outs; a != NULL; a = nexta) {
+ for (a = to->outs; a != NULL && !NISERR(); a = nexta) {
nexta = a->outchain;
switch (combine(con, a)) {
case INCOMPATIBLE: /* destroy the arc */
@@ -1759,17 +1829,25 @@ push(
case SATISFIED: /* no action needed */
break;
case COMPATIBLE: /* swap the two arcs, more or less */
- s = newstate(nfa);
- if (NISERR()) {
- return 0;
+ /* need an intermediate state, but might have one already */
+ for (s = *intermediates; s != NULL; s = s->tmp) {
+ assert(s->nins > 0 && s->nouts > 0);
+ if (s->ins->from == from && s->outs->to == a->to) {
+ break;
+ }
}
- cparc(nfa, con, s, a->to); /* anticipate move */
- cparc(nfa, a, from, s);
- if (NISERR()) {
- return 0;
+ if (s == NULL) {
+ s = newstate(nfa);
+ if (NISERR()) {
+ return 0;
+ }
+ s->tmp = *intermediates;
+ *intermediates = s;
}
- freearc(nfa, a);
- break;
+ cparc(nfa, con, s, a->to);
+ cparc(nfa, a, from, s);
+ freearc(nfa, a);
+ break;
default:
assert(NOTREACHED);
break;
@@ -1781,7 +1859,8 @@ push(
*/
moveouts(nfa, to, from);
- dropstate(nfa, to); /* will free the constraint */
+ freearc(nfa, con);
+ /* to state is now useless, but we leave it to pushfwd() to clean up */
return 1;
}
diff --git a/generic/regcomp.c b/generic/regcomp.c
index 985cb93..6b40100 100644
--- a/generic/regcomp.c
+++ b/generic/regcomp.c
@@ -144,9 +144,9 @@ static void cleartraverse(struct nfa *, struct state *);
static void specialcolors(struct nfa *);
static long optimize(struct nfa *, FILE *);
static void pullback(struct nfa *, FILE *);
-static int pull(struct nfa *, struct arc *);
+static int pull(struct nfa *, struct arc *, struct state **);
static void pushfwd(struct nfa *, FILE *);
-static int push(struct nfa *, struct arc *);
+static int push(struct nfa *, struct arc *, struct state **);
#define INCOMPATIBLE 1 /* destroys arc */
#define SATISFIED 2 /* constraint satisfied */
#define COMPATIBLE 3 /* compatible but not satisfied yet */