lwt_RemIsoEdge()

int lwt_RemIsoEdge	(	LWT_TOPOLOGY *	topo,
		LWT_ELEMID	edge
	)

Remove an isolated edge.

For ST_RemIsoEdge

Parameters

topo	the topology to operate on
edge	the identifier of the edge to be moved

Returns

0 on success, -1 on error (liblwgeom error handler will be invoked with error message)

Definition at line 3779 of file lwgeom_topo.c.

References LWT_TOPOLOGY_T::be_iface, LWT_ISO_NODE::containing_face, LWT_ISO_EDGE::edge_id, LWT_ISO_EDGE::end_node, LWT_ISO_EDGE::face_left, lwerror(), lwfree(), lwt_be_deleteEdges(), lwt_be_getEdgeById(), lwt_be_getEdgeByNode(), lwt_be_lastErrorMessage(), lwt_be_updateNodesById(), LWT_COL_EDGE_EDGE_ID, LWT_COL_EDGE_END_NODE, LWT_COL_EDGE_FACE_LEFT, LWT_COL_EDGE_FACE_RIGHT, LWT_COL_EDGE_START_NODE, LWT_COL_NODE_CONTAINING_FACE, LWTFMT_ELEMID, LWT_ISO_NODE::node_id, and LWT_ISO_EDGE::start_node.

{
  LWT_ISO_EDGE deledge;
  LWT_ISO_EDGE *edge;
  LWT_ELEMID nid[2];
  LWT_ISO_NODE upd_node[2];
  LWT_ELEMID containing_face;
  int n = 1;
  int i;

  edge = lwt_be_getEdgeById( topo, &id, &n, LWT_COL_EDGE_START_NODE|
                                            LWT_COL_EDGE_END_NODE |
                                            LWT_COL_EDGE_FACE_LEFT |
                                            LWT_COL_EDGE_FACE_RIGHT );
  if ( ! edge )
  {
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  if ( ! n )
  {
    lwerror("SQL/MM Spatial exception - non-existent edge");
    return -1;
  }
  if ( n > 1 )
  {
    lwfree(edge);
    lwerror("Corrupted topology: more than a single edge have id %"
            LWTFMT_ELEMID, id);
    return -1;
  }

  if ( edge[0].face_left != edge[0].face_right )
  {
    lwfree(edge);
    lwerror("SQL/MM Spatial exception - not isolated edge");
    return -1;
  }
  containing_face = edge[0].face_left;

  nid[0] = edge[0].start_node;
  nid[1] = edge[0].end_node;
  lwfree(edge);

  n = 2;
  edge = lwt_be_getEdgeByNode( topo, nid, &n, LWT_COL_EDGE_EDGE_ID );
  if ( n == -1 )
  {
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  for ( i=0; i<n; ++i )
  {
    if ( edge[i].edge_id == id ) continue;
    lwfree(edge);
    lwerror("SQL/MM Spatial exception - not isolated edge");
    return -1;
  }
  if ( edge ) lwfree(edge);

  deledge.edge_id = id;
  n = lwt_be_deleteEdges( topo, &deledge, LWT_COL_EDGE_EDGE_ID );
  if ( n == -1 )
  {
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  if ( n != 1 )
  {
    lwerror("Unexpected error: %d edges deleted when expecting 1", n);
    return -1;
  }

  upd_node[0].node_id = nid[0];
  upd_node[0].containing_face = containing_face;
  n = 1;
  if ( nid[1] != nid[0] ) {
    upd_node[1].node_id = nid[1];
    upd_node[1].containing_face = containing_face;
    ++n;
  }
  n = lwt_be_updateNodesById(topo, upd_node, n,
                               LWT_COL_NODE_CONTAINING_FACE);
  if ( n == -1 )
  {
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }

  /* TODO: notify to caller about edge being removed ?
   * See https://trac.osgeo.org/postgis/ticket/3248
   */

  return 0; /* success */
}

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