[SCM] PostGIS branch master updated. 3.4.0rc1-960-ga6194d212

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Fri Mar 1 10:28:15 PST 2024


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- Log -----------------------------------------------------------------
commit a6194d212aac5336c93b19c0a4924e8a3abc20a8
Author: Sandro Santilli <strk at kbt.io>
Date:   Fri Mar 1 19:27:53 2024 +0100

    Move topology polygonizer code in its own file
    
    References #5684

diff --git a/liblwgeom/Makefile.in b/liblwgeom/Makefile.in
index 2b51a8b20..db2930ae2 100644
--- a/liblwgeom/Makefile.in
+++ b/liblwgeom/Makefile.in
@@ -123,6 +123,7 @@ SA_OBJS = \
 	lwgeom_geos_node.o \
 	lwgeom_geos_split.o \
 	topo/lwgeom_topo.o \
+	topo/lwgeom_topo_polygonizer.o \
 	lwgeom_transform.o \
 	lwgeom_wrapx.o \
 	lwunionfind.o \
diff --git a/liblwgeom/topo/liblwgeom_topo_internal.h b/liblwgeom/topo/liblwgeom_topo_internal.h
index cbd7ade38..04d55175c 100644
--- a/liblwgeom/topo/liblwgeom_topo_internal.h
+++ b/liblwgeom/topo/liblwgeom_topo_internal.h
@@ -31,6 +31,17 @@
 #include "liblwgeom.h"
 #include "liblwgeom_topo.h"
 
+#include <stdio.h>
+#include <inttypes.h> /* for PRId64 */
+#include <math.h>
+
+#ifdef WIN32
+# define LWTFMT_ELEMID "lld"
+#else
+# define LWTFMT_ELEMID PRId64
+#endif
+
+
 /************************************************************************
  *
  * Generic SQL handler
@@ -58,6 +69,14 @@ LWT_ISO_NODE *lwt_be_getNodeWithinDistance2D(LWT_TOPOLOGY *topo,
 
 LWT_ISO_NODE *lwt_be_getNodeById(LWT_TOPOLOGY *topo, const LWT_ELEMID *ids, uint64_t *numelems, int fields);
 
+LWT_ISO_EDGE *lwt_be_getEdgeWithinBox2D(const LWT_TOPOLOGY *topo, const GBOX *box, uint64_t *numelems, int fields, uint64_t limit);
+LWT_ISO_FACE *lwt_be_getFaceWithinBox2D(const LWT_TOPOLOGY *topo, const GBOX *box, uint64_t *numelems, int fields, uint64_t limit);
+
+void _lwt_release_faces(LWT_ISO_FACE *faces, int num_faces);
+void _lwt_release_edges(LWT_ISO_EDGE *edges, int num_edges);
+int lwt_be_updateEdgesById(LWT_TOPOLOGY* topo, const LWT_ISO_EDGE* edges, int numedges, int upd_fields);
+int lwt_be_insertFaces(LWT_TOPOLOGY *topo, LWT_ISO_FACE *face, uint64_t numelems);
+
 int lwt_be_ExistsCoincidentNode(LWT_TOPOLOGY* topo, LWPOINT* pt);
 int lwt_be_insertNodes(LWT_TOPOLOGY *topo, LWT_ISO_NODE *node, uint64_t numelems);
 
diff --git a/liblwgeom/topo/lwgeom_topo.c b/liblwgeom/topo/lwgeom_topo.c
index a8b0a2e50..87f56d39e 100644
--- a/liblwgeom/topo/lwgeom_topo.c
+++ b/liblwgeom/topo/lwgeom_topo.c
@@ -26,23 +26,13 @@
 
 #include "../postgis_config.h"
 
-/*#define POSTGIS_DEBUG_LEVEL 1*/
+#define POSTGIS_DEBUG_LEVEL 1
 #include "lwgeom_log.h"
 
 #include "liblwgeom_internal.h"
 #include "liblwgeom_topo_internal.h"
 #include "lwgeom_geos.h"
 
-#include <stdio.h>
-#include <inttypes.h> /* for PRId64 */
-#include <math.h>
-
-#ifdef WIN32
-# define LWTFMT_ELEMID "lld"
-#else
-# define LWTFMT_ELEMID PRId64
-#endif
-
 /* This is a non-tolerance based 2d equality for points
  * whereas the p2d_same function is tolerance based
  * TODO: move in higher headers ?
@@ -180,13 +170,13 @@ lwt_be_getNodeWithinBox2D(const LWT_TOPOLOGY *topo, const GBOX *box, uint64_t *n
   CBT4(topo, getNodeWithinBox2D, box, numelems, fields, limit);
 }
 
-static LWT_ISO_EDGE *
+LWT_ISO_EDGE *
 lwt_be_getEdgeWithinBox2D(const LWT_TOPOLOGY *topo, const GBOX *box, uint64_t *numelems, int fields, uint64_t limit)
 {
   CBT4(topo, getEdgeWithinBox2D, box, numelems, fields, limit);
 }
 
-static LWT_ISO_FACE *
+LWT_ISO_FACE *
 lwt_be_getFaceWithinBox2D(const LWT_TOPOLOGY *topo, const GBOX *box, uint64_t *numelems, int fields, uint64_t limit)
 {
   CBT4(topo, getFaceWithinBox2D, box, numelems, fields, limit);
@@ -198,7 +188,7 @@ lwt_be_insertNodes(LWT_TOPOLOGY *topo, LWT_ISO_NODE *node, uint64_t numelems)
   CBT2(topo, insertNodes, node, numelems);
 }
 
-static int
+int
 lwt_be_insertFaces(LWT_TOPOLOGY *topo, LWT_ISO_FACE *face, uint64_t numelems)
 {
   CBT2(topo, insertFaces, face, numelems);
@@ -301,7 +291,7 @@ lwt_be_updateFacesById(LWT_TOPOLOGY* topo,
   CBT2(topo, updateFacesById, faces, numfaces);
 }
 
-static int
+int
 lwt_be_updateEdgesById(LWT_TOPOLOGY* topo,
   const LWT_ISO_EDGE* edges, int numedges, int upd_fields
 )
@@ -457,7 +447,7 @@ _lwt_toposnap(LWGEOM *src, LWGEOM *tgt, double tol)
   return tmp;
 }
 
-static void
+void
 _lwt_release_faces(LWT_ISO_FACE *faces, int num_faces)
 {
   int i;
@@ -467,7 +457,7 @@ _lwt_release_faces(LWT_ISO_FACE *faces, int num_faces)
   lwfree(faces);
 }
 
-static void
+void
 _lwt_release_edges(LWT_ISO_EDGE *edges, int num_edges)
 {
   int i;
@@ -6122,917 +6112,6 @@ lwt_AddPolygon(LWT_TOPOLOGY* topo, LWPOLY* poly, double tol, int* nfaces)
   return ids;
 }
 
-/*
- *---- polygonizer
- */
-
-/* An array of pointers to EDGERING structures */
-typedef struct LWT_ISO_EDGE_TABLE_T {
-  LWT_ISO_EDGE *edges;
-  int size;
-} LWT_ISO_EDGE_TABLE;
-
-static int
-compare_iso_edges_by_id(const void *si1, const void *si2)
-{
-	int a = ((LWT_ISO_EDGE *)si1)->edge_id;
-	int b = ((LWT_ISO_EDGE *)si2)->edge_id;
-	if ( a < b )
-		return -1;
-	else if ( a > b )
-		return 1;
-	else
-		return 0;
-}
-
-static LWT_ISO_EDGE *
-_lwt_getIsoEdgeById(LWT_ISO_EDGE_TABLE *tab, LWT_ELEMID id)
-{
-  LWT_ISO_EDGE key;
-  key.edge_id = id;
-
-  void *match = bsearch( &key, tab->edges, tab->size,
-                     sizeof(LWT_ISO_EDGE),
-                     compare_iso_edges_by_id);
-  return match;
-}
-
-typedef struct LWT_EDGERING_ELEM_T {
-  /* externally owned */
-  LWT_ISO_EDGE *edge;
-  /* 0 if false, 1 if true */
-  int left;
-} LWT_EDGERING_ELEM;
-
-/* A ring of edges */
-typedef struct LWT_EDGERING_T {
-  /* Signed edge identifiers
-   * positive ones are walked in their direction, negative ones
-   * in the opposite direction */
-  LWT_EDGERING_ELEM **elems;
-  /* Number of edges in the ring */
-  int size;
-  int capacity;
-  /* Bounding box of the ring */
-  GBOX *env;
-  /* Bounding box of the ring in GEOS format (for STRTree) */
-  GEOSGeometry *genv;
-} LWT_EDGERING;
-
-#define LWT_EDGERING_INIT(a) { \
-  (a)->size = 0; \
-  (a)->capacity = 1; \
-  (a)->elems = lwalloc(sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
-  (a)->env = NULL; \
-  (a)->genv = NULL; \
-}
-
-#define LWT_EDGERING_PUSH(a, r) { \
-  if ( (a)->size + 1 > (a)->capacity ) { \
-    (a)->capacity *= 2; \
-    (a)->elems = lwrealloc((a)->elems, sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
-  } \
-  /* lwdebug(1, "adding elem %d (%p) of edgering %p", (a)->size, (r), (a)); */ \
-  (a)->elems[(a)->size++] = (r); \
-}
-
-#define LWT_EDGERING_CLEAN(a) { \
-  int i; for (i=0; i<(a)->size; ++i) { \
-    if ( (a)->elems[i] ) { \
-      /* lwdebug(1, "freeing elem %d (%p) of edgering %p", i, (a)->elems[i], (a)); */ \
-      lwfree((a)->elems[i]); \
-    } \
-  } \
-  if ( (a)->elems ) { lwfree((a)->elems); (a)->elems = NULL; } \
-  (a)->size = 0; \
-  (a)->capacity = 0; \
-  if ( (a)->env ) { lwfree((a)->env); (a)->env = NULL; } \
-  if ( (a)->genv ) { GEOSGeom_destroy((a)->genv); (a)->genv = NULL; } \
-}
-
-/* An array of pointers to EDGERING structures */
-typedef struct LWT_EDGERING_ARRAY_T {
-  LWT_EDGERING **rings;
-  int size;
-  int capacity;
-  GEOSSTRtree* tree;
-} LWT_EDGERING_ARRAY;
-
-#define LWT_EDGERING_ARRAY_INIT(a) { \
-  (a)->size = 0; \
-  (a)->capacity = 1; \
-  (a)->rings = lwalloc(sizeof(LWT_EDGERING *) * (a)->capacity); \
-  (a)->tree = NULL; \
-}
-
-/* WARNING: use of 'j' is intentional, not to clash with
- * 'i' used in LWT_EDGERING_CLEAN */
-#define LWT_EDGERING_ARRAY_CLEAN(a) { \
-  int j; for (j=0; j<(a)->size; ++j) { \
-    LWT_EDGERING_CLEAN((a)->rings[j]); \
-  } \
-  if ( (a)->capacity ) lwfree((a)->rings); \
-  if ( (a)->tree ) { \
-    GEOSSTRtree_destroy( (a)->tree ); \
-    (a)->tree = NULL; \
-  } \
-}
-
-#define LWT_EDGERING_ARRAY_PUSH(a, r) { \
-  if ( (a)->size + 1 > (a)->capacity ) { \
-    (a)->capacity *= 2; \
-    (a)->rings = lwrealloc((a)->rings, sizeof(LWT_EDGERING *) * (a)->capacity); \
-  } \
-  (a)->rings[(a)->size++] = (r); \
-}
-
-typedef struct LWT_EDGERING_POINT_ITERATOR_T {
-  LWT_EDGERING *ring;
-  LWT_EDGERING_ELEM *curelem;
-  int curelemidx;
-  int curidx;
-} LWT_EDGERING_POINT_ITERATOR;
-
-static int
-_lwt_EdgeRingIterator_next(LWT_EDGERING_POINT_ITERATOR *it, POINT2D *pt)
-{
-  LWT_EDGERING_ELEM *el = it->curelem;
-  POINTARRAY *pa;
-
-  if ( ! el ) return 0; /* finished */
-
-  pa = el->edge->geom->points;
-
-  int tonext = 0;
-  LWDEBUGF(3, "iterator fetching idx %d from pa of %d points", it->curidx, pa->npoints);
-  getPoint2d_p(pa, it->curidx, pt);
-  if ( el->left ) {
-    it->curidx++;
-    if ( it->curidx >= (int) pa->npoints ) tonext = 1;
-  } else {
-    it->curidx--;
-    if ( it->curidx < 0 ) tonext = 1;
-  }
-
-  if ( tonext )
-  {
-    LWDEBUG(3, "iterator moving to next element");
-    it->curelemidx++;
-    if ( it->curelemidx < it->ring->size )
-    {
-      el = it->curelem = it->ring->elems[it->curelemidx];
-      it->curidx = el->left ? 0 : el->edge->geom->points->npoints - 1;
-    }
-    else
-    {
-      it->curelem = NULL;
-    }
-  }
-
-  return 1;
-}
-
-/* Release return with lwfree */
-static LWT_EDGERING_POINT_ITERATOR *
-_lwt_EdgeRingIterator_begin(LWT_EDGERING *er)
-{
-  LWT_EDGERING_POINT_ITERATOR *ret = lwalloc(sizeof(LWT_EDGERING_POINT_ITERATOR));
-  ret->ring = er;
-  if ( er->size ) ret->curelem = er->elems[0];
-  else ret->curelem = NULL;
-  ret->curelemidx = 0;
-  ret->curidx = (ret->curelem == NULL || ret->curelem->left) ? 0 : ret->curelem->edge->geom->points->npoints - 1;
-  return ret;
-}
-
-/* Identifier for a placeholder face that will be
- * used to mark hole rings */
-#define LWT_HOLES_FACE_PLACEHOLDER INT32_MIN
-
-static int
-_lwt_FetchNextUnvisitedEdge(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *etab, int from)
-{
-  while (
-    from < etab->size &&
-    etab->edges[from].face_left != -1 &&
-    etab->edges[from].face_right != -1
-  ) from++;
-  return from < etab->size ? from : -1;
-}
-
-static LWT_ISO_EDGE *
-_lwt_FetchAllEdges(LWT_TOPOLOGY *topo, int *numedges)
-{
-  LWT_ISO_EDGE *edge;
-  int fields = LWT_COL_EDGE_ALL;
-  uint64_t nelems = 1;
-
-  edge = lwt_be_getEdgeWithinBox2D( topo, NULL, &nelems, fields, 0);
-  *numedges = nelems;
-  if (nelems == UINT64_MAX)
-  {
-	  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
-	  return NULL;
-  }
-  return edge;
-}
-
-/* Update the side face of given ring edges
- *
- * Edge identifiers are signed, those with negative identifier
- * need to be updated their right_face, those with positive
- * identifier need to be updated their left_face.
- *
- * @param face identifier of the face bound by the ring
- * @return 0 on success, -1 on error
- */
-static int
-_lwt_UpdateEdgeRingSideFace(LWT_TOPOLOGY *topo, LWT_EDGERING *ring,
-                            LWT_ELEMID face)
-{
-  LWT_ISO_EDGE *forward_edges = NULL;
-  int forward_edges_count = 0;
-  LWT_ISO_EDGE *backward_edges = NULL;
-  int backward_edges_count = 0;
-  int i, ret;
-
-  /* Make a list of forward_edges and backward_edges */
-
-  forward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
-  forward_edges_count = 0;
-  backward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
-  backward_edges_count = 0;
-
-  for ( i=0; i<ring->size; ++i )
-  {
-    LWT_EDGERING_ELEM *elem = ring->elems[i];
-    LWT_ISO_EDGE *edge = elem->edge;
-    LWT_ELEMID id = edge->edge_id;
-    if ( elem->left )
-    {
-      LWDEBUGF(3, "Forward edge %d is %d", forward_edges_count, id);
-      forward_edges[forward_edges_count].edge_id = id;
-      forward_edges[forward_edges_count++].face_left = face;
-      edge->face_left = face;
-    }
-    else
-    {
-      LWDEBUGF(3, "Backward edge %d is %d", forward_edges_count, id);
-      backward_edges[backward_edges_count].edge_id = id;
-      backward_edges[backward_edges_count++].face_right = face;
-      edge->face_right = face;
-    }
-  }
-
-  /* Update forward edges */
-  if ( forward_edges_count )
-  {
-    ret = lwt_be_updateEdgesById(topo, forward_edges,
-                                 forward_edges_count,
-                                 LWT_COL_EDGE_FACE_LEFT);
-    if ( ret == -1 )
-    {
-      lwfree( forward_edges );
-      lwfree( backward_edges );
-      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
-      return -1;
-    }
-    if ( ret != forward_edges_count )
-    {
-      lwfree( forward_edges );
-      lwfree( backward_edges );
-      lwerror("Unexpected error: %d edges updated when expecting %d (forward)",
-              ret, forward_edges_count);
-      return -1;
-    }
-  }
-
-  /* Update backward edges */
-  if ( backward_edges_count )
-  {
-    ret = lwt_be_updateEdgesById(topo, backward_edges,
-                                 backward_edges_count,
-                                 LWT_COL_EDGE_FACE_RIGHT);
-    if ( ret == -1 )
-    {
-      lwfree( forward_edges );
-      lwfree( backward_edges );
-      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
-      return -1;
-    }
-    if ( ret != backward_edges_count )
-    {
-      lwfree( forward_edges );
-      lwfree( backward_edges );
-      lwerror("Unexpected error: %d edges updated when expecting %d (backward)",
-              ret, backward_edges_count);
-      return -1;
-    }
-  }
-
-  lwfree( forward_edges );
-  lwfree( backward_edges );
-
-  return 0;
-}
-
-/*
- * @param side 1 for left side, -1 for right side
- */
-static LWT_EDGERING *
-_lwt_BuildEdgeRing(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *edges,
-                   LWT_ISO_EDGE *edge, int side)
-{
-  LWT_EDGERING *ring;
-  LWT_EDGERING_ELEM *elem;
-  LWT_ISO_EDGE *cur;
-  int curside;
-
-  ring = lwalloc(sizeof(LWT_EDGERING));
-  LWT_EDGERING_INIT(ring);
-
-  cur = edge;
-  curside = side;
-
-  LWDEBUGF(2, "Building rings for edge %d (side %d)", cur->edge_id, side);
-
-  do {
-    LWT_ELEMID next;
-
-    elem = lwalloc(sizeof(LWT_EDGERING_ELEM));
-    elem->edge = cur;
-    elem->left = ( curside == 1 );
-
-    /* Mark edge as "visited" */
-    if ( elem->left ) cur->face_left = LWT_HOLES_FACE_PLACEHOLDER;
-    else cur->face_right = LWT_HOLES_FACE_PLACEHOLDER;
-
-    LWT_EDGERING_PUSH(ring, elem);
-    next = elem->left ? cur->next_left : cur->next_right;
-
-    LWDEBUGF(3, " next edge is %d", next);
-
-    if ( next > 0 ) curside = 1;
-    else { curside = -1; next = -next; }
-    cur = _lwt_getIsoEdgeById(edges, next);
-    if ( ! cur )
-    {
-      lwerror("Could not find edge with id %d", next);
-      break;
-    }
-  } while (cur != edge || curside != side);
-
-  LWDEBUGF(1, "Ring for edge %d has %d elems", edge->edge_id*side, ring->size);
-
-  return ring;
-}
-
-static double
-_lwt_EdgeRingSignedArea(LWT_EDGERING_POINT_ITERATOR *it)
-{
-	POINT2D P1;
-	POINT2D P2;
-	POINT2D P3;
-	double sum = 0.0;
-	double x0, x, y1, y2;
-
-  if ( ! _lwt_EdgeRingIterator_next(it, &P1) ) return 0.0;
-  if ( ! _lwt_EdgeRingIterator_next(it, &P2) ) return 0.0;
-
-  LWDEBUG(2, "_lwt_EdgeRingSignedArea");
-
-  x0 = P1.x;
-  while ( _lwt_EdgeRingIterator_next(it, &P3)  )
-  {
-    x = P2.x - x0;
-    y1 = P3.y;
-    y2 = P1.y;
-    sum += x * (y2-y1);
-
-    /* Move forwards! */
-    P1 = P2;
-    P2 = P3;
-  }
-
-	return sum / 2.0;
-}
-
-
-/* Return 1 for true, 0 for false */
-static int
-_lwt_EdgeRingIsCCW(LWT_EDGERING *ring)
-{
-  double sa;
-
-  LWDEBUGF(2, "_lwt_EdgeRingIsCCW, ring has %d elems", ring->size);
-  LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
-  sa = _lwt_EdgeRingSignedArea(it);
-  LWDEBUGF(2, "_lwt_EdgeRingIsCCW, signed area is %g", sa);
-  lwfree(it);
-  if ( sa >= 0 ) return 0;
-  else return 1;
-}
-
-static int
-_lwt_EdgeRingCrossingCount(const POINT2D *p, LWT_EDGERING_POINT_ITERATOR *it)
-{
-	int cn = 0;    /* the crossing number counter */
-	POINT2D v1, v2;
-#ifndef RELAX
-  POINT2D v0;
-#endif
-
-  if ( ! _lwt_EdgeRingIterator_next(it, &v1) ) return cn;
-  v0 = v1;
-	while ( _lwt_EdgeRingIterator_next(it, &v2) )
-	{
-		double vt;
-
-		/* edge from vertex i to vertex i+1 */
-		if
-		(
-		    /* an upward crossing */
-		    ((v1.y <= p->y) && (v2.y > p->y))
-		    /* a downward crossing */
-		    || ((v1.y > p->y) && (v2.y <= p->y))
-		)
-		{
-
-			vt = (double)(p->y - v1.y) / (v2.y - v1.y);
-
-			/* P->x <intersect */
-			if (p->x < v1.x + vt * (v2.x - v1.x))
-			{
-				/* a valid crossing of y=p->y right of p->x */
-				++cn;
-			}
-		}
-		v1 = v2;
-	}
-
-	LWDEBUGF(3, "_lwt_EdgeRingCrossingCount returning %d", cn);
-
-#ifndef RELAX
-  if ( memcmp(&v1, &v0, sizeof(POINT2D)) )
-  {
-    lwerror("_lwt_EdgeRingCrossingCount: V[n] != V[0] (%g %g != %g %g)",
-      v1.x, v1.y, v0.x, v0.y);
-    return -1;
-  }
-#endif
-
-  return cn;
-}
-
-/* Return 1 for true, 0 for false */
-static int
-_lwt_EdgeRingContainsPoint(LWT_EDGERING *ring, POINT2D *p)
-{
-  int cn = 0;
-
-  LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
-  cn = _lwt_EdgeRingCrossingCount(p, it);
-  lwfree(it);
-	return (cn&1);    /* 0 if even (out), and 1 if odd (in) */
-}
-
-static GBOX *
-_lwt_EdgeRingGetBbox(LWT_EDGERING *ring)
-{
-  int i;
-
-  if ( ! ring->env )
-  {
-    LWDEBUGF(2, "Computing GBOX for ring %p", ring);
-    for (i=0; i<ring->size; ++i)
-    {
-      LWT_EDGERING_ELEM *elem = ring->elems[i];
-      LWLINE *g = elem->edge->geom;
-      const GBOX *newbox = lwgeom_get_bbox(lwline_as_lwgeom(g));
-      if ( ! i ) ring->env = gbox_clone( newbox );
-      else gbox_merge( newbox, ring->env );
-    }
-  }
-
-  return ring->env;
-}
-
-static LWT_ELEMID
-_lwt_EdgeRingGetFace(LWT_EDGERING *ring)
-{
-  LWT_EDGERING_ELEM *el = ring->elems[0];
-  return el->left ? el->edge->face_left : el->edge->face_right;
-}
-
-
-/*
- * Register a face on an edge side
- *
- * Create and register face to shell (CCW) walks,
- * register arbitrary negative face_id to CW rings.
- *
- * Push CCW rings to shells, CW rings to holes.
- *
- * The ownership of the "geom" and "ids" members of the
- * LWT_EDGERING pushed to the given LWT_EDGERING_ARRAYS
- * are transferred to caller.
- *
- * @param side 1 for left side, -1 for right side
- *
- * @param holes an array where holes will be pushed
- *
- * @param shells an array where shells will be pushed
- *
- * @param registered id of registered face. It will be a negative number
- *  for holes or isolated edge strips (still registered in the face
- *  table, but only temporary).
- *
- * @return 0 on success, -1 on error.
- *
- */
-static int
-_lwt_RegisterFaceOnEdgeSide(LWT_TOPOLOGY *topo, LWT_ISO_EDGE *edge,
-                            int side, LWT_ISO_EDGE_TABLE *edges,
-                            LWT_EDGERING_ARRAY *holes,
-                            LWT_EDGERING_ARRAY *shells,
-                            LWT_ELEMID *registered)
-{
-  const LWT_BE_IFACE *iface = topo->be_iface;
-  /* this is arbitrary, could be taken as parameter */
-  static const int placeholder_faceid = LWT_HOLES_FACE_PLACEHOLDER;
-  LWT_EDGERING *ring;
-
-  /* Get edge ring */
-  ring = _lwt_BuildEdgeRing(topo, edges, edge, side);
-
-	LWDEBUG(2, "Ring built, calling EdgeRingIsCCW");
-
-  /* Compute winding (CW or CCW?) */
-  int isccw = _lwt_EdgeRingIsCCW(ring);
-
-  if ( isccw )
-  {
-    /* Create new face */
-    LWT_ISO_FACE newface;
-
-    LWDEBUGF(1, "Ring of edge %d is a shell (shell %d)", edge->edge_id * side, shells->size);
-
-    newface.mbr = _lwt_EdgeRingGetBbox(ring);
-
-    newface.face_id = -1;
-    /* Insert the new face */
-    int ret = lwt_be_insertFaces( topo, &newface, 1 );
-    newface.mbr = NULL;
-    if ( ret == -1 )
-    {
-      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
-      return -1;
-    }
-    if ( ret != 1 )
-    {
-      lwerror("Unexpected error: %d faces inserted when expecting 1", ret);
-      return -1;
-    }
-    /* return new face_id */
-    *registered = newface.face_id;
-    LWT_EDGERING_ARRAY_PUSH(shells, ring);
-
-    /* update ring edges set new face_id on resp. side to *registered */
-    ret = _lwt_UpdateEdgeRingSideFace(topo, ring, *registered);
-    if ( ret )
-    {
-        lwerror("Errors updating edgering side face: %s",
-                lwt_be_lastErrorMessage(iface));
-        return -1;
-    }
-
-  }
-  else /* cw, so is an hole */
-  {
-    LWDEBUGF(1, "Ring of edge %d is a hole (hole %d)", edge->edge_id * side, holes->size);
-    *registered = placeholder_faceid;
-    LWT_EDGERING_ARRAY_PUSH(holes, ring);
-  }
-
-  return 0;
-}
-
-static void
-_lwt_AccumulateCanditates(void* item, void* userdata)
-{
-  LWT_EDGERING_ARRAY *candidates = userdata;
-  LWT_EDGERING *sring = item;
-  LWT_EDGERING_ARRAY_PUSH(candidates, sring);
-}
-
-static LWT_ELEMID
-_lwt_FindFaceContainingRing(LWT_TOPOLOGY* topo, LWT_EDGERING *ring,
-                            LWT_EDGERING_ARRAY *shells)
-{
-  LWT_ELEMID foundInFace = -1;
-  int i;
-  const GBOX *minenv = NULL;
-  POINT2D pt;
-  const GBOX *testbox;
-  GEOSGeometry *ghole;
-
-  getPoint2d_p( ring->elems[0]->edge->geom->points, 0, &pt );
-
-  testbox = _lwt_EdgeRingGetBbox(ring);
-
-  /* Create a GEOS Point from a vertex of the hole ring */
-  {
-    LWPOINT *point = lwpoint_make2d(topo->srid, pt.x, pt.y);
-    ghole = LWGEOM2GEOS( lwpoint_as_lwgeom(point), 1 );
-    lwpoint_free(point);
-    if ( ! ghole ) {
-      lwerror("Could not convert edge geometry to GEOS: %s", lwgeom_geos_errmsg);
-      return -1;
-    }
-  }
-
-  /* Build STRtree of shell envelopes */
-  if ( ! shells->tree )
-  {
-    static const int STRTREE_NODE_CAPACITY = 10;
-    LWDEBUG(1, "Building STRtree");
-	  shells->tree = GEOSSTRtree_create(STRTREE_NODE_CAPACITY);
-    if (shells->tree == NULL)
-    {
-      lwerror("Could not create GEOS STRTree: %s", lwgeom_geos_errmsg);
-      return -1;
-    }
-    for (i=0; i<shells->size; ++i)
-    {
-      LWT_EDGERING *sring = shells->rings[i];
-      const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
-      LWDEBUGF(2, "GBOX of shell %p for edge %d is %g %g,%g %g",
-        sring, sring->elems[0]->edge->edge_id, shellbox->xmin,
-        shellbox->ymin, shellbox->xmax, shellbox->ymax);
-      POINTARRAY *pa = ptarray_construct(0, 0, 2);
-      POINT4D pt;
-      LWLINE *diag;
-      pt.x = shellbox->xmin;
-      pt.y = shellbox->ymin;
-      ptarray_set_point4d(pa, 0, &pt);
-      pt.x = shellbox->xmax;
-      pt.y = shellbox->ymax;
-      ptarray_set_point4d(pa, 1, &pt);
-      diag = lwline_construct(topo->srid, NULL, pa);
-      /* Record just envelope in ggeom */
-      /* making valid, probably not needed */
-      sring->genv = LWGEOM2GEOS( lwline_as_lwgeom(diag), 1 );
-      lwline_free(diag);
-      GEOSSTRtree_insert(shells->tree, sring->genv, sring);
-    }
-    LWDEBUG(1, "STRtree build completed");
-  }
-
-  LWT_EDGERING_ARRAY candidates;
-  LWT_EDGERING_ARRAY_INIT(&candidates);
-	GEOSSTRtree_query(shells->tree, ghole, &_lwt_AccumulateCanditates, &candidates);
-  LWDEBUGF(1, "Found %d candidate shells containing first point of ring's originating edge %d",
-          candidates.size, ring->elems[0]->edge->edge_id * ( ring->elems[0]->left ? 1 : -1 ) );
-
-  /* TODO: sort candidates by bounding box size */
-
-  for (i=0; i<candidates.size; ++i)
-  {
-    LWT_EDGERING *sring = candidates.rings[i];
-    const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
-    int contains = 0;
-
-    if ( sring->elems[0]->edge->edge_id == ring->elems[0]->edge->edge_id )
-    {
-      LWDEBUGF(1, "Shell %d is on other side of ring",
-               _lwt_EdgeRingGetFace(sring));
-      continue;
-    }
-
-    /* The hole envelope cannot equal the shell envelope */
-    if ( gbox_same(shellbox, testbox) )
-    {
-      LWDEBUGF(1, "Bbox of shell %d equals that of hole ring",
-               _lwt_EdgeRingGetFace(sring));
-      continue;
-    }
-
-    /* Skip if ring box is not in shell box */
-    if ( ! gbox_contains_2d(shellbox, testbox) )
-    {
-      LWDEBUGF(1, "Bbox of shell %d does not contain bbox of ring point",
-               _lwt_EdgeRingGetFace(sring));
-      continue;
-    }
-
-    /* Skip test if a containing shell was already found
-     * and this shell's bbox is not contained in the other */
-    if ( minenv && ! gbox_contains_2d(minenv, shellbox) )
-    {
-      LWDEBUGF(2, "Bbox of shell %d (face %d) not contained by bbox "
-                  "of last shell found to contain the point",
-                  i, _lwt_EdgeRingGetFace(sring));
-      continue;
-    }
-
-    contains = _lwt_EdgeRingContainsPoint(sring, &pt);
-    if ( contains )
-    {
-      /* Continue until all shells are tested, as we want to
-       * use the one with the smallest bounding box */
-      /* IDEA: sort shells by bbox size, stopping on first match */
-      LWDEBUGF(1, "Shell %d contains hole of edge %d",
-               _lwt_EdgeRingGetFace(sring),
-               ring->elems[0]->edge->edge_id);
-      minenv = shellbox;
-      foundInFace = _lwt_EdgeRingGetFace(sring);
-    }
-  }
-  if ( foundInFace == -1 ) foundInFace = 0;
-
-  candidates.size = 0; /* Avoid destroying the actual shell rings */
-  LWT_EDGERING_ARRAY_CLEAN(&candidates);
-
-  GEOSGeom_destroy(ghole);
-
-  return foundInFace;
-}
-
-/*
- * @return -1 on error (and report error),
- *          1 if faces beside the universal one exist
- *          0 otherwise
- */
-static int
-_lwt_CheckFacesExist(LWT_TOPOLOGY *topo)
-{
-  LWT_ISO_FACE *faces;
-  int fields = LWT_COL_FACE_FACE_ID;
-  uint64_t nelems = 1;
-  GBOX qbox;
-
-  qbox.xmin = qbox.ymin = -DBL_MAX;
-  qbox.xmax = qbox.ymax = DBL_MAX;
-  faces = lwt_be_getFaceWithinBox2D( topo, &qbox, &nelems, fields, 1);
-  if (nelems == UINT64_MAX)
-  {
-	  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
-	  return -1;
-  }
-  if ( faces ) _lwt_release_faces(faces, nelems);
-  return nelems;
-}
-
-int
-lwt_Polygonize(LWT_TOPOLOGY* topo)
-{
-  /*
-     Fetch all edges
-     Sort edges by edge_id
-     Mark all edges' left and right face as -1
-     Iteratively:
-       Fetch next edge with left or right face == -1
-       For each side with face == -1:
-         Find ring on its side
-         If ring is CCW:
-            create a new face, assign to the ring edges' appropriate side
-         If ring is CW (face needs to be same of external):
-            assign a negative face_id the ring edges' appropriate side
-     Now for each edge with a negative face_id on the side:
-       Find containing face (mbr cache and all)
-       Update with id of containing face
-   */
-
-  const LWT_BE_IFACE *iface = topo->be_iface;
-  LWT_ISO_EDGE *edge;
-  int numfaces = -1;
-  LWT_ISO_EDGE_TABLE edgetable;
-  LWT_EDGERING_ARRAY holes, shells;
-  int i;
-  int err = 0;
-
-  LWT_EDGERING_ARRAY_INIT(&holes);
-  LWT_EDGERING_ARRAY_INIT(&shells);
-
-  initGEOS(lwnotice, lwgeom_geos_error);
-
-  /*
-   Check if Topology already contains some Face
-   (ignoring the Universal Face)
-  */
-  numfaces = _lwt_CheckFacesExist(topo);
-  if ( numfaces != 0 ) {
-    if ( numfaces > 0 ) {
-      /* Faces exist */
-      lwerror("Polygonize: face table is not empty.");
-    }
-    /* Backend error, message should have been printed already */
-    return -1;
-  }
-
-
-  edgetable.edges = _lwt_FetchAllEdges(topo, &(edgetable.size));
-  if ( ! edgetable.edges ) {
-    if (edgetable.size == 0) {
-      /* not an error: no Edges */
-      return 0;
-    }
-    /* error should have been printed already */
-    return -1;
-  }
-
-  /* Sort edges by ID (to allow btree searches) */
-  qsort(edgetable.edges, edgetable.size, sizeof(LWT_ISO_EDGE), compare_iso_edges_by_id);
-
-  /* Mark all edges as unvisited */
-  for (i=0; i<edgetable.size; ++i)
-    edgetable.edges[i].face_left = edgetable.edges[i].face_right = -1;
-
-  i = 0;
-  while (1)
-  {
-    i = _lwt_FetchNextUnvisitedEdge(topo, &edgetable, i);
-    if ( i < 0 ) break; /* end of unvisited */
-    edge = &(edgetable.edges[i]);
-
-    LWT_ELEMID newface = -1;
-
-    LWDEBUGF(1, "Next face-missing edge has id:%d, face_left:%d, face_right:%d",
-               edge->edge_id, edge->face_left, edge->face_right);
-    if ( edge->face_left == -1 )
-    {
-      err = _lwt_RegisterFaceOnEdgeSide(topo, edge, 1, &edgetable,
-                                        &holes, &shells, &newface);
-      if ( err ) break;
-      LWDEBUGF(1, "New face on the left of edge %d is %d",
-                 edge->edge_id, newface);
-      edge->face_left = newface;
-    }
-    if ( edge->face_right == -1 )
-    {
-      err = _lwt_RegisterFaceOnEdgeSide(topo, edge, -1, &edgetable,
-                                        &holes, &shells, &newface);
-      if ( err ) break;
-      LWDEBUGF(1, "New face on the right of edge %d is %d",
-                 edge->edge_id, newface);
-      edge->face_right = newface;
-    }
-  }
-
-  if ( err )
-  {
-      _lwt_release_edges(edgetable.edges, edgetable.size);
-      LWT_EDGERING_ARRAY_CLEAN( &holes );
-      LWT_EDGERING_ARRAY_CLEAN( &shells );
-      lwerror("Errors fetching or registering face-missing edges: %s",
-              lwt_be_lastErrorMessage(iface));
-      return -1;
-  }
-
-  LWDEBUGF(1, "Found %d holes and %d shells", holes.size, shells.size);
-
-  /* TODO: sort holes by pt.x, sort shells by bbox.xmin */
-
-  /* Assign shells to holes */
-  for (i=0; i<holes.size; ++i)
-  {
-    LWT_ELEMID containing_face;
-    LWT_EDGERING *ring = holes.rings[i];
-
-    containing_face = _lwt_FindFaceContainingRing(topo, ring, &shells);
-    LWDEBUGF(1, "Ring %d contained by face %" LWTFMT_ELEMID, i, containing_face);
-    if ( containing_face == -1 )
-    {
-      _lwt_release_edges(edgetable.edges, edgetable.size);
-      LWT_EDGERING_ARRAY_CLEAN( &holes );
-      LWT_EDGERING_ARRAY_CLEAN( &shells );
-      lwerror("Errors finding face containing ring: %s",
-              lwt_be_lastErrorMessage(iface));
-      return -1;
-    }
-    int ret = _lwt_UpdateEdgeRingSideFace(topo, holes.rings[i], containing_face);
-    if ( ret )
-    {
-      _lwt_release_edges(edgetable.edges, edgetable.size);
-      LWT_EDGERING_ARRAY_CLEAN( &holes );
-      LWT_EDGERING_ARRAY_CLEAN( &shells );
-      lwerror("Errors updating edgering side face: %s",
-              lwt_be_lastErrorMessage(iface));
-      return -1;
-    }
-  }
-
-  LWDEBUG(1, "All holes assigned, cleaning up");
-
-  _lwt_release_edges(edgetable.edges, edgetable.size);
-
-  /* delete all shell and hole EDGERINGS */
-  LWT_EDGERING_ARRAY_CLEAN( &holes );
-  LWT_EDGERING_ARRAY_CLEAN( &shells );
-
-  return 0;
-}
-
 LWT_ELEMID
 lwt_GetFaceContainingPoint(LWT_TOPOLOGY* topo, const LWPOINT* pt)
 {
diff --git a/liblwgeom/topo/lwgeom_topo_polygonizer.c b/liblwgeom/topo/lwgeom_topo_polygonizer.c
new file mode 100644
index 000000000..320310d72
--- /dev/null
+++ b/liblwgeom/topo/lwgeom_topo_polygonizer.c
@@ -0,0 +1,946 @@
+/**********************************************************************
+ *
+ * PostGIS - Spatial Types for PostgreSQL
+ * http://postgis.net
+ *
+ * PostGIS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * PostGIS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ **********************************************************************
+ *
+ * Copyright (C) 2015-2024 Sandro Santilli <strk at kbt.io>
+ *
+ **********************************************************************
+ *
+ *  Topology Polygonizer
+ *
+ **********************************************************************/
+
+#include "../postgis_config.h"
+
+#define POSTGIS_DEBUG_LEVEL 1
+#include "lwgeom_log.h"
+
+#include "liblwgeom_internal.h"
+#include "liblwgeom_topo_internal.h"
+
+#include "lwgeom_geos.h"
+
+/* An array of pointers to EDGERING structures */
+typedef struct LWT_ISO_EDGE_TABLE_T {
+  LWT_ISO_EDGE *edges;
+  int size;
+} LWT_ISO_EDGE_TABLE;
+
+static int
+compare_iso_edges_by_id(const void *si1, const void *si2)
+{
+	int a = ((LWT_ISO_EDGE *)si1)->edge_id;
+	int b = ((LWT_ISO_EDGE *)si2)->edge_id;
+	if ( a < b )
+		return -1;
+	else if ( a > b )
+		return 1;
+	else
+		return 0;
+}
+
+static LWT_ISO_EDGE *
+_lwt_getIsoEdgeById(LWT_ISO_EDGE_TABLE *tab, LWT_ELEMID id)
+{
+  LWT_ISO_EDGE key;
+  key.edge_id = id;
+
+  void *match = bsearch( &key, tab->edges, tab->size,
+                     sizeof(LWT_ISO_EDGE),
+                     compare_iso_edges_by_id);
+  return match;
+}
+
+typedef struct LWT_EDGERING_ELEM_T {
+  /* externally owned */
+  LWT_ISO_EDGE *edge;
+  /* 0 if false, 1 if true */
+  int left;
+} LWT_EDGERING_ELEM;
+
+/* A ring of edges */
+typedef struct LWT_EDGERING_T {
+  /* Signed edge identifiers
+   * positive ones are walked in their direction, negative ones
+   * in the opposite direction */
+  LWT_EDGERING_ELEM **elems;
+  /* Number of edges in the ring */
+  int size;
+  int capacity;
+  /* Bounding box of the ring */
+  GBOX *env;
+  /* Bounding box of the ring in GEOS format (for STRTree) */
+  GEOSGeometry *genv;
+} LWT_EDGERING;
+
+#define LWT_EDGERING_INIT(a) { \
+  (a)->size = 0; \
+  (a)->capacity = 1; \
+  (a)->elems = lwalloc(sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
+  (a)->env = NULL; \
+  (a)->genv = NULL; \
+}
+
+#define LWT_EDGERING_PUSH(a, r) { \
+  if ( (a)->size + 1 > (a)->capacity ) { \
+    (a)->capacity *= 2; \
+    (a)->elems = lwrealloc((a)->elems, sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
+  } \
+  /* lwdebug(1, "adding elem %d (%p) of edgering %p", (a)->size, (r), (a)); */ \
+  (a)->elems[(a)->size++] = (r); \
+}
+
+#define LWT_EDGERING_CLEAN(a) { \
+  int i; for (i=0; i<(a)->size; ++i) { \
+    if ( (a)->elems[i] ) { \
+      /* lwdebug(1, "freeing elem %d (%p) of edgering %p", i, (a)->elems[i], (a)); */ \
+      lwfree((a)->elems[i]); \
+    } \
+  } \
+  if ( (a)->elems ) { lwfree((a)->elems); (a)->elems = NULL; } \
+  (a)->size = 0; \
+  (a)->capacity = 0; \
+  if ( (a)->env ) { lwfree((a)->env); (a)->env = NULL; } \
+  if ( (a)->genv ) { GEOSGeom_destroy((a)->genv); (a)->genv = NULL; } \
+}
+
+/* An array of pointers to EDGERING structures */
+typedef struct LWT_EDGERING_ARRAY_T {
+  LWT_EDGERING **rings;
+  int size;
+  int capacity;
+  GEOSSTRtree* tree;
+} LWT_EDGERING_ARRAY;
+
+#define LWT_EDGERING_ARRAY_INIT(a) { \
+  (a)->size = 0; \
+  (a)->capacity = 1; \
+  (a)->rings = lwalloc(sizeof(LWT_EDGERING *) * (a)->capacity); \
+  (a)->tree = NULL; \
+}
+
+/* WARNING: use of 'j' is intentional, not to clash with
+ * 'i' used in LWT_EDGERING_CLEAN */
+#define LWT_EDGERING_ARRAY_CLEAN(a) { \
+  int j; for (j=0; j<(a)->size; ++j) { \
+    LWT_EDGERING_CLEAN((a)->rings[j]); \
+  } \
+  if ( (a)->capacity ) lwfree((a)->rings); \
+  if ( (a)->tree ) { \
+    GEOSSTRtree_destroy( (a)->tree ); \
+    (a)->tree = NULL; \
+  } \
+}
+
+#define LWT_EDGERING_ARRAY_PUSH(a, r) { \
+  if ( (a)->size + 1 > (a)->capacity ) { \
+    (a)->capacity *= 2; \
+    (a)->rings = lwrealloc((a)->rings, sizeof(LWT_EDGERING *) * (a)->capacity); \
+  } \
+  (a)->rings[(a)->size++] = (r); \
+}
+
+typedef struct LWT_EDGERING_POINT_ITERATOR_T {
+  LWT_EDGERING *ring;
+  LWT_EDGERING_ELEM *curelem;
+  int curelemidx;
+  int curidx;
+} LWT_EDGERING_POINT_ITERATOR;
+
+static int
+_lwt_EdgeRingIterator_next(LWT_EDGERING_POINT_ITERATOR *it, POINT2D *pt)
+{
+  LWT_EDGERING_ELEM *el = it->curelem;
+  POINTARRAY *pa;
+
+  if ( ! el ) return 0; /* finished */
+
+  pa = el->edge->geom->points;
+
+  int tonext = 0;
+  LWDEBUGF(3, "iterator fetching idx %d from pa of %d points", it->curidx, pa->npoints);
+  getPoint2d_p(pa, it->curidx, pt);
+  if ( el->left ) {
+    it->curidx++;
+    if ( it->curidx >= (int) pa->npoints ) tonext = 1;
+  } else {
+    it->curidx--;
+    if ( it->curidx < 0 ) tonext = 1;
+  }
+
+  if ( tonext )
+  {
+    LWDEBUG(3, "iterator moving to next element");
+    it->curelemidx++;
+    if ( it->curelemidx < it->ring->size )
+    {
+      el = it->curelem = it->ring->elems[it->curelemidx];
+      it->curidx = el->left ? 0 : el->edge->geom->points->npoints - 1;
+    }
+    else
+    {
+      it->curelem = NULL;
+    }
+  }
+
+  return 1;
+}
+
+/* Release return with lwfree */
+static LWT_EDGERING_POINT_ITERATOR *
+_lwt_EdgeRingIterator_begin(LWT_EDGERING *er)
+{
+  LWT_EDGERING_POINT_ITERATOR *ret = lwalloc(sizeof(LWT_EDGERING_POINT_ITERATOR));
+  ret->ring = er;
+  if ( er->size ) ret->curelem = er->elems[0];
+  else ret->curelem = NULL;
+  ret->curelemidx = 0;
+  ret->curidx = (ret->curelem == NULL || ret->curelem->left) ? 0 : ret->curelem->edge->geom->points->npoints - 1;
+  return ret;
+}
+
+/* Identifier for a placeholder face that will be
+ * used to mark hole rings */
+#define LWT_HOLES_FACE_PLACEHOLDER INT32_MIN
+
+static int
+_lwt_FetchNextUnvisitedEdge(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *etab, int from)
+{
+  while (
+    from < etab->size &&
+    etab->edges[from].face_left != -1 &&
+    etab->edges[from].face_right != -1
+  ) from++;
+  return from < etab->size ? from : -1;
+}
+
+static LWT_ISO_EDGE *
+_lwt_FetchAllEdges(LWT_TOPOLOGY *topo, int *numedges)
+{
+  LWT_ISO_EDGE *edge;
+  int fields = LWT_COL_EDGE_ALL;
+  uint64_t nelems = 1;
+
+  edge = lwt_be_getEdgeWithinBox2D( topo, NULL, &nelems, fields, 0);
+  *numedges = nelems;
+  if (nelems == UINT64_MAX)
+  {
+	  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
+	  return NULL;
+  }
+  return edge;
+}
+
+/* Update the side face of given ring edges
+ *
+ * Edge identifiers are signed, those with negative identifier
+ * need to be updated their right_face, those with positive
+ * identifier need to be updated their left_face.
+ *
+ * @param face identifier of the face bound by the ring
+ * @return 0 on success, -1 on error
+ */
+static int
+_lwt_UpdateEdgeRingSideFace(LWT_TOPOLOGY *topo, LWT_EDGERING *ring,
+                            LWT_ELEMID face)
+{
+  LWT_ISO_EDGE *forward_edges = NULL;
+  int forward_edges_count = 0;
+  LWT_ISO_EDGE *backward_edges = NULL;
+  int backward_edges_count = 0;
+  int i, ret;
+
+  /* Make a list of forward_edges and backward_edges */
+
+  forward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
+  forward_edges_count = 0;
+  backward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
+  backward_edges_count = 0;
+
+  for ( i=0; i<ring->size; ++i )
+  {
+    LWT_EDGERING_ELEM *elem = ring->elems[i];
+    LWT_ISO_EDGE *edge = elem->edge;
+    LWT_ELEMID id = edge->edge_id;
+    if ( elem->left )
+    {
+      LWDEBUGF(3, "Forward edge %d is %d", forward_edges_count, id);
+      forward_edges[forward_edges_count].edge_id = id;
+      forward_edges[forward_edges_count++].face_left = face;
+      edge->face_left = face;
+    }
+    else
+    {
+      LWDEBUGF(3, "Backward edge %d is %d", forward_edges_count, id);
+      backward_edges[backward_edges_count].edge_id = id;
+      backward_edges[backward_edges_count++].face_right = face;
+      edge->face_right = face;
+    }
+  }
+
+  /* Update forward edges */
+  if ( forward_edges_count )
+  {
+    ret = lwt_be_updateEdgesById(topo, forward_edges,
+                                 forward_edges_count,
+                                 LWT_COL_EDGE_FACE_LEFT);
+    if ( ret == -1 )
+    {
+      lwfree( forward_edges );
+      lwfree( backward_edges );
+      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
+      return -1;
+    }
+    if ( ret != forward_edges_count )
+    {
+      lwfree( forward_edges );
+      lwfree( backward_edges );
+      lwerror("Unexpected error: %d edges updated when expecting %d (forward)",
+              ret, forward_edges_count);
+      return -1;
+    }
+  }
+
+  /* Update backward edges */
+  if ( backward_edges_count )
+  {
+    ret = lwt_be_updateEdgesById(topo, backward_edges,
+                                 backward_edges_count,
+                                 LWT_COL_EDGE_FACE_RIGHT);
+    if ( ret == -1 )
+    {
+      lwfree( forward_edges );
+      lwfree( backward_edges );
+      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
+      return -1;
+    }
+    if ( ret != backward_edges_count )
+    {
+      lwfree( forward_edges );
+      lwfree( backward_edges );
+      lwerror("Unexpected error: %d edges updated when expecting %d (backward)",
+              ret, backward_edges_count);
+      return -1;
+    }
+  }
+
+  lwfree( forward_edges );
+  lwfree( backward_edges );
+
+  return 0;
+}
+
+/*
+ * @param side 1 for left side, -1 for right side
+ */
+static LWT_EDGERING *
+_lwt_BuildEdgeRing(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *edges,
+                   LWT_ISO_EDGE *edge, int side)
+{
+  LWT_EDGERING *ring;
+  LWT_EDGERING_ELEM *elem;
+  LWT_ISO_EDGE *cur;
+  int curside;
+
+  ring = lwalloc(sizeof(LWT_EDGERING));
+  LWT_EDGERING_INIT(ring);
+
+  cur = edge;
+  curside = side;
+
+  LWDEBUGF(2, "Building rings for edge %d (side %d)", cur->edge_id, side);
+
+  do {
+    LWT_ELEMID next;
+
+    elem = lwalloc(sizeof(LWT_EDGERING_ELEM));
+    elem->edge = cur;
+    elem->left = ( curside == 1 );
+
+    /* Mark edge as "visited" */
+    if ( elem->left ) cur->face_left = LWT_HOLES_FACE_PLACEHOLDER;
+    else cur->face_right = LWT_HOLES_FACE_PLACEHOLDER;
+
+    LWT_EDGERING_PUSH(ring, elem);
+    next = elem->left ? cur->next_left : cur->next_right;
+
+    LWDEBUGF(3, " next edge is %d", next);
+
+    if ( next > 0 ) curside = 1;
+    else { curside = -1; next = -next; }
+    cur = _lwt_getIsoEdgeById(edges, next);
+    if ( ! cur )
+    {
+      lwerror("Could not find edge with id %d", next);
+      break;
+    }
+  } while (cur != edge || curside != side);
+
+  LWDEBUGF(1, "Ring for edge %d has %d elems", edge->edge_id*side, ring->size);
+
+  return ring;
+}
+
+static double
+_lwt_EdgeRingSignedArea(LWT_EDGERING_POINT_ITERATOR *it)
+{
+	POINT2D P1;
+	POINT2D P2;
+	POINT2D P3;
+	double sum = 0.0;
+	double x0, x, y1, y2;
+
+  if ( ! _lwt_EdgeRingIterator_next(it, &P1) ) return 0.0;
+  if ( ! _lwt_EdgeRingIterator_next(it, &P2) ) return 0.0;
+
+  LWDEBUG(2, "_lwt_EdgeRingSignedArea");
+
+  x0 = P1.x;
+  while ( _lwt_EdgeRingIterator_next(it, &P3)  )
+  {
+    x = P2.x - x0;
+    y1 = P3.y;
+    y2 = P1.y;
+    sum += x * (y2-y1);
+
+    /* Move forwards! */
+    P1 = P2;
+    P2 = P3;
+  }
+
+	return sum / 2.0;
+}
+
+
+/* Return 1 for true, 0 for false */
+static int
+_lwt_EdgeRingIsCCW(LWT_EDGERING *ring)
+{
+  double sa;
+
+  LWDEBUGF(2, "_lwt_EdgeRingIsCCW, ring has %d elems", ring->size);
+  LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
+  sa = _lwt_EdgeRingSignedArea(it);
+  LWDEBUGF(2, "_lwt_EdgeRingIsCCW, signed area is %g", sa);
+  lwfree(it);
+  if ( sa >= 0 ) return 0;
+  else return 1;
+}
+
+static int
+_lwt_EdgeRingCrossingCount(const POINT2D *p, LWT_EDGERING_POINT_ITERATOR *it)
+{
+	int cn = 0;    /* the crossing number counter */
+	POINT2D v1, v2;
+#ifndef RELAX
+  POINT2D v0;
+#endif
+
+  if ( ! _lwt_EdgeRingIterator_next(it, &v1) ) return cn;
+  v0 = v1;
+	while ( _lwt_EdgeRingIterator_next(it, &v2) )
+	{
+		double vt;
+
+		/* edge from vertex i to vertex i+1 */
+		if
+		(
+		    /* an upward crossing */
+		    ((v1.y <= p->y) && (v2.y > p->y))
+		    /* a downward crossing */
+		    || ((v1.y > p->y) && (v2.y <= p->y))
+		)
+		{
+
+			vt = (double)(p->y - v1.y) / (v2.y - v1.y);
+
+			/* P->x <intersect */
+			if (p->x < v1.x + vt * (v2.x - v1.x))
+			{
+				/* a valid crossing of y=p->y right of p->x */
+				++cn;
+			}
+		}
+		v1 = v2;
+	}
+
+	LWDEBUGF(3, "_lwt_EdgeRingCrossingCount returning %d", cn);
+
+#ifndef RELAX
+  if ( memcmp(&v1, &v0, sizeof(POINT2D)) )
+  {
+    lwerror("_lwt_EdgeRingCrossingCount: V[n] != V[0] (%g %g != %g %g)",
+      v1.x, v1.y, v0.x, v0.y);
+    return -1;
+  }
+#endif
+
+  return cn;
+}
+
+/* Return 1 for true, 0 for false */
+static int
+_lwt_EdgeRingContainsPoint(LWT_EDGERING *ring, POINT2D *p)
+{
+  int cn = 0;
+
+  LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
+  cn = _lwt_EdgeRingCrossingCount(p, it);
+  lwfree(it);
+	return (cn&1);    /* 0 if even (out), and 1 if odd (in) */
+}
+
+static GBOX *
+_lwt_EdgeRingGetBbox(LWT_EDGERING *ring)
+{
+  int i;
+
+  if ( ! ring->env )
+  {
+    LWDEBUGF(2, "Computing GBOX for ring %p", ring);
+    for (i=0; i<ring->size; ++i)
+    {
+      LWT_EDGERING_ELEM *elem = ring->elems[i];
+      LWLINE *g = elem->edge->geom;
+      const GBOX *newbox = lwgeom_get_bbox(lwline_as_lwgeom(g));
+      if ( ! i ) ring->env = gbox_clone( newbox );
+      else gbox_merge( newbox, ring->env );
+    }
+  }
+
+  return ring->env;
+}
+
+static LWT_ELEMID
+_lwt_EdgeRingGetFace(LWT_EDGERING *ring)
+{
+  LWT_EDGERING_ELEM *el = ring->elems[0];
+  return el->left ? el->edge->face_left : el->edge->face_right;
+}
+
+
+/*
+ * Register a face on an edge side
+ *
+ * Create and register face to shell (CCW) walks,
+ * register arbitrary negative face_id to CW rings.
+ *
+ * Push CCW rings to shells, CW rings to holes.
+ *
+ * The ownership of the "geom" and "ids" members of the
+ * LWT_EDGERING pushed to the given LWT_EDGERING_ARRAYS
+ * are transferred to caller.
+ *
+ * @param side 1 for left side, -1 for right side
+ *
+ * @param holes an array where holes will be pushed
+ *
+ * @param shells an array where shells will be pushed
+ *
+ * @param registered id of registered face. It will be a negative number
+ *  for holes or isolated edge strips (still registered in the face
+ *  table, but only temporary).
+ *
+ * @return 0 on success, -1 on error.
+ *
+ */
+static int
+_lwt_RegisterFaceOnEdgeSide(LWT_TOPOLOGY *topo, LWT_ISO_EDGE *edge,
+                            int side, LWT_ISO_EDGE_TABLE *edges,
+                            LWT_EDGERING_ARRAY *holes,
+                            LWT_EDGERING_ARRAY *shells,
+                            LWT_ELEMID *registered)
+{
+  const LWT_BE_IFACE *iface = topo->be_iface;
+  /* this is arbitrary, could be taken as parameter */
+  static const int placeholder_faceid = LWT_HOLES_FACE_PLACEHOLDER;
+  LWT_EDGERING *ring;
+
+  /* Get edge ring */
+  ring = _lwt_BuildEdgeRing(topo, edges, edge, side);
+
+	LWDEBUG(2, "Ring built, calling EdgeRingIsCCW");
+
+  /* Compute winding (CW or CCW?) */
+  int isccw = _lwt_EdgeRingIsCCW(ring);
+
+  if ( isccw )
+  {
+    /* Create new face */
+    LWT_ISO_FACE newface;
+
+    LWDEBUGF(1, "Ring of edge %d is a shell (shell %d)", edge->edge_id * side, shells->size);
+
+    newface.mbr = _lwt_EdgeRingGetBbox(ring);
+
+    newface.face_id = -1;
+    /* Insert the new face */
+    int ret = lwt_be_insertFaces( topo, &newface, 1 );
+    newface.mbr = NULL;
+    if ( ret == -1 )
+    {
+      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
+      return -1;
+    }
+    if ( ret != 1 )
+    {
+      lwerror("Unexpected error: %d faces inserted when expecting 1", ret);
+      return -1;
+    }
+    /* return new face_id */
+    *registered = newface.face_id;
+    LWT_EDGERING_ARRAY_PUSH(shells, ring);
+
+    /* update ring edges set new face_id on resp. side to *registered */
+    ret = _lwt_UpdateEdgeRingSideFace(topo, ring, *registered);
+    if ( ret )
+    {
+        lwerror("Errors updating edgering side face: %s",
+                lwt_be_lastErrorMessage(iface));
+        return -1;
+    }
+
+  }
+  else /* cw, so is an hole */
+  {
+    LWDEBUGF(1, "Ring of edge %d is a hole (hole %d)", edge->edge_id * side, holes->size);
+    *registered = placeholder_faceid;
+    LWT_EDGERING_ARRAY_PUSH(holes, ring);
+  }
+
+  return 0;
+}
+
+static void
+_lwt_AccumulateCanditates(void* item, void* userdata)
+{
+  LWT_EDGERING_ARRAY *candidates = userdata;
+  LWT_EDGERING *sring = item;
+  LWT_EDGERING_ARRAY_PUSH(candidates, sring);
+}
+
+static LWT_ELEMID
+_lwt_FindFaceContainingRing(LWT_TOPOLOGY* topo, LWT_EDGERING *ring,
+                            LWT_EDGERING_ARRAY *shells)
+{
+  LWT_ELEMID foundInFace = -1;
+  int i;
+  const GBOX *minenv = NULL;
+  POINT2D pt;
+  const GBOX *testbox;
+  GEOSGeometry *ghole;
+
+  getPoint2d_p( ring->elems[0]->edge->geom->points, 0, &pt );
+
+  testbox = _lwt_EdgeRingGetBbox(ring);
+
+  /* Create a GEOS Point from a vertex of the hole ring */
+  {
+    LWPOINT *point = lwpoint_make2d(topo->srid, pt.x, pt.y);
+    ghole = LWGEOM2GEOS( lwpoint_as_lwgeom(point), 1 );
+    lwpoint_free(point);
+    if ( ! ghole ) {
+      lwerror("Could not convert edge geometry to GEOS: %s", lwgeom_geos_errmsg);
+      return -1;
+    }
+  }
+
+  /* Build STRtree of shell envelopes */
+  if ( ! shells->tree )
+  {
+    static const int STRTREE_NODE_CAPACITY = 10;
+    LWDEBUG(1, "Building STRtree");
+	  shells->tree = GEOSSTRtree_create(STRTREE_NODE_CAPACITY);
+    if (shells->tree == NULL)
+    {
+      lwerror("Could not create GEOS STRTree: %s", lwgeom_geos_errmsg);
+      return -1;
+    }
+    for (i=0; i<shells->size; ++i)
+    {
+      LWT_EDGERING *sring = shells->rings[i];
+      const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
+      LWDEBUGF(2, "GBOX of shell %p for edge %d is %g %g,%g %g",
+        sring, sring->elems[0]->edge->edge_id, shellbox->xmin,
+        shellbox->ymin, shellbox->xmax, shellbox->ymax);
+      POINTARRAY *pa = ptarray_construct(0, 0, 2);
+      POINT4D pt;
+      LWLINE *diag;
+      pt.x = shellbox->xmin;
+      pt.y = shellbox->ymin;
+      ptarray_set_point4d(pa, 0, &pt);
+      pt.x = shellbox->xmax;
+      pt.y = shellbox->ymax;
+      ptarray_set_point4d(pa, 1, &pt);
+      diag = lwline_construct(topo->srid, NULL, pa);
+      /* Record just envelope in ggeom */
+      /* making valid, probably not needed */
+      sring->genv = LWGEOM2GEOS( lwline_as_lwgeom(diag), 1 );
+      lwline_free(diag);
+      GEOSSTRtree_insert(shells->tree, sring->genv, sring);
+    }
+    LWDEBUG(1, "STRtree build completed");
+  }
+
+  LWT_EDGERING_ARRAY candidates;
+  LWT_EDGERING_ARRAY_INIT(&candidates);
+	GEOSSTRtree_query(shells->tree, ghole, &_lwt_AccumulateCanditates, &candidates);
+  LWDEBUGF(1, "Found %d candidate shells containing first point of ring's originating edge %d",
+          candidates.size, ring->elems[0]->edge->edge_id * ( ring->elems[0]->left ? 1 : -1 ) );
+
+  /* TODO: sort candidates by bounding box size */
+
+  for (i=0; i<candidates.size; ++i)
+  {
+    LWT_EDGERING *sring = candidates.rings[i];
+    const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
+    int contains = 0;
+
+    if ( sring->elems[0]->edge->edge_id == ring->elems[0]->edge->edge_id )
+    {
+      LWDEBUGF(1, "Shell %d is on other side of ring",
+               _lwt_EdgeRingGetFace(sring));
+      continue;
+    }
+
+    /* The hole envelope cannot equal the shell envelope */
+    if ( gbox_same(shellbox, testbox) )
+    {
+      LWDEBUGF(1, "Bbox of shell %d equals that of hole ring",
+               _lwt_EdgeRingGetFace(sring));
+      continue;
+    }
+
+    /* Skip if ring box is not in shell box */
+    if ( ! gbox_contains_2d(shellbox, testbox) )
+    {
+      LWDEBUGF(1, "Bbox of shell %d does not contain bbox of ring point",
+               _lwt_EdgeRingGetFace(sring));
+      continue;
+    }
+
+    /* Skip test if a containing shell was already found
+     * and this shell's bbox is not contained in the other */
+    if ( minenv && ! gbox_contains_2d(minenv, shellbox) )
+    {
+      LWDEBUGF(2, "Bbox of shell %d (face %d) not contained by bbox "
+                  "of last shell found to contain the point",
+                  i, _lwt_EdgeRingGetFace(sring));
+      continue;
+    }
+
+    contains = _lwt_EdgeRingContainsPoint(sring, &pt);
+    if ( contains )
+    {
+      /* Continue until all shells are tested, as we want to
+       * use the one with the smallest bounding box */
+      /* IDEA: sort shells by bbox size, stopping on first match */
+      LWDEBUGF(1, "Shell %d contains hole of edge %d",
+               _lwt_EdgeRingGetFace(sring),
+               ring->elems[0]->edge->edge_id);
+      minenv = shellbox;
+      foundInFace = _lwt_EdgeRingGetFace(sring);
+    }
+  }
+  if ( foundInFace == -1 ) foundInFace = 0;
+
+  candidates.size = 0; /* Avoid destroying the actual shell rings */
+  LWT_EDGERING_ARRAY_CLEAN(&candidates);
+
+  GEOSGeom_destroy(ghole);
+
+  return foundInFace;
+}
+
+/*
+ * @return -1 on error (and report error),
+ *          1 if faces beside the universal one exist
+ *          0 otherwise
+ */
+static int
+_lwt_CheckFacesExist(LWT_TOPOLOGY *topo)
+{
+  LWT_ISO_FACE *faces;
+  int fields = LWT_COL_FACE_FACE_ID;
+  uint64_t nelems = 1;
+  GBOX qbox;
+
+  qbox.xmin = qbox.ymin = -DBL_MAX;
+  qbox.xmax = qbox.ymax = DBL_MAX;
+  faces = lwt_be_getFaceWithinBox2D( topo, &qbox, &nelems, fields, 1);
+  if (nelems == UINT64_MAX)
+  {
+	  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
+	  return -1;
+  }
+  if ( faces ) _lwt_release_faces(faces, nelems);
+  return nelems;
+}
+
+int
+lwt_Polygonize(LWT_TOPOLOGY* topo)
+{
+  /*
+     Fetch all edges
+     Sort edges by edge_id
+     Mark all edges' left and right face as -1
+     Iteratively:
+       Fetch next edge with left or right face == -1
+       For each side with face == -1:
+         Find ring on its side
+         If ring is CCW:
+            create a new face, assign to the ring edges' appropriate side
+         If ring is CW (face needs to be same of external):
+            assign a negative face_id the ring edges' appropriate side
+     Now for each edge with a negative face_id on the side:
+       Find containing face (mbr cache and all)
+       Update with id of containing face
+   */
+
+  const LWT_BE_IFACE *iface = topo->be_iface;
+  LWT_ISO_EDGE *edge;
+  int numfaces = -1;
+  LWT_ISO_EDGE_TABLE edgetable;
+  LWT_EDGERING_ARRAY holes, shells;
+  int i;
+  int err = 0;
+
+  LWT_EDGERING_ARRAY_INIT(&holes);
+  LWT_EDGERING_ARRAY_INIT(&shells);
+
+  initGEOS(lwnotice, lwgeom_geos_error);
+
+  /*
+   Check if Topology already contains some Face
+   (ignoring the Universal Face)
+  */
+  numfaces = _lwt_CheckFacesExist(topo);
+  if ( numfaces != 0 ) {
+    if ( numfaces > 0 ) {
+      /* Faces exist */
+      lwerror("Polygonize: face table is not empty.");
+    }
+    /* Backend error, message should have been printed already */
+    return -1;
+  }
+
+
+  edgetable.edges = _lwt_FetchAllEdges(topo, &(edgetable.size));
+  if ( ! edgetable.edges ) {
+    if (edgetable.size == 0) {
+      /* not an error: no Edges */
+      return 0;
+    }
+    /* error should have been printed already */
+    return -1;
+  }
+
+  /* Sort edges by ID (to allow btree searches) */
+  qsort(edgetable.edges, edgetable.size, sizeof(LWT_ISO_EDGE), compare_iso_edges_by_id);
+
+  /* Mark all edges as unvisited */
+  for (i=0; i<edgetable.size; ++i)
+    edgetable.edges[i].face_left = edgetable.edges[i].face_right = -1;
+
+  i = 0;
+  while (1)
+  {
+    i = _lwt_FetchNextUnvisitedEdge(topo, &edgetable, i);
+    if ( i < 0 ) break; /* end of unvisited */
+    edge = &(edgetable.edges[i]);
+
+    LWT_ELEMID newface = -1;
+
+    LWDEBUGF(1, "Next face-missing edge has id:%d, face_left:%d, face_right:%d",
+               edge->edge_id, edge->face_left, edge->face_right);
+    if ( edge->face_left == -1 )
+    {
+      err = _lwt_RegisterFaceOnEdgeSide(topo, edge, 1, &edgetable,
+                                        &holes, &shells, &newface);
+      if ( err ) break;
+      LWDEBUGF(1, "New face on the left of edge %d is %d",
+                 edge->edge_id, newface);
+      edge->face_left = newface;
+    }
+    if ( edge->face_right == -1 )
+    {
+      err = _lwt_RegisterFaceOnEdgeSide(topo, edge, -1, &edgetable,
+                                        &holes, &shells, &newface);
+      if ( err ) break;
+      LWDEBUGF(1, "New face on the right of edge %d is %d",
+                 edge->edge_id, newface);
+      edge->face_right = newface;
+    }
+  }
+
+  if ( err )
+  {
+      _lwt_release_edges(edgetable.edges, edgetable.size);
+      LWT_EDGERING_ARRAY_CLEAN( &holes );
+      LWT_EDGERING_ARRAY_CLEAN( &shells );
+      lwerror("Errors fetching or registering face-missing edges: %s",
+              lwt_be_lastErrorMessage(iface));
+      return -1;
+  }
+
+  LWDEBUGF(1, "Found %d holes and %d shells", holes.size, shells.size);
+
+  /* TODO: sort holes by pt.x, sort shells by bbox.xmin */
+
+  /* Assign shells to holes */
+  for (i=0; i<holes.size; ++i)
+  {
+    LWT_ELEMID containing_face;
+    LWT_EDGERING *ring = holes.rings[i];
+
+    containing_face = _lwt_FindFaceContainingRing(topo, ring, &shells);
+    LWDEBUGF(1, "Ring %d contained by face %" LWTFMT_ELEMID, i, containing_face);
+    if ( containing_face == -1 )
+    {
+      _lwt_release_edges(edgetable.edges, edgetable.size);
+      LWT_EDGERING_ARRAY_CLEAN( &holes );
+      LWT_EDGERING_ARRAY_CLEAN( &shells );
+      lwerror("Errors finding face containing ring: %s",
+              lwt_be_lastErrorMessage(iface));
+      return -1;
+    }
+    int ret = _lwt_UpdateEdgeRingSideFace(topo, holes.rings[i], containing_face);
+    if ( ret )
+    {
+      _lwt_release_edges(edgetable.edges, edgetable.size);
+      LWT_EDGERING_ARRAY_CLEAN( &holes );
+      LWT_EDGERING_ARRAY_CLEAN( &shells );
+      lwerror("Errors updating edgering side face: %s",
+              lwt_be_lastErrorMessage(iface));
+      return -1;
+    }
+  }
+
+  LWDEBUG(1, "All holes assigned, cleaning up");
+
+  _lwt_release_edges(edgetable.edges, edgetable.size);
+
+  /* delete all shell and hole EDGERINGS */
+  LWT_EDGERING_ARRAY_CLEAN( &holes );
+  LWT_EDGERING_ARRAY_CLEAN( &shells );
+
+  return 0;
+}
+
+

-----------------------------------------------------------------------

Summary of changes:
 liblwgeom/Makefile.in                    |   1 +
 liblwgeom/topo/liblwgeom_topo_internal.h |  19 +
 liblwgeom/topo/lwgeom_topo.c             | 935 +-----------------------------
 liblwgeom/topo/lwgeom_topo_polygonizer.c | 946 +++++++++++++++++++++++++++++++
 4 files changed, 973 insertions(+), 928 deletions(-)
 create mode 100644 liblwgeom/topo/lwgeom_topo_polygonizer.c


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