text: /**********************************************************************
   *
   * 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 2015 Daniel Baston <dbaston@gmail.com>
   * Modifications Copyright (c) 2017 - Present Pivotal Software, Inc. All Rights Reserved.
   *
   **********************************************************************/
  
  
  #ifndef _LWUNIONFIND
  #define _LWUNIONFIND 1
  
  #include "liblwgeom.h"
  
  typedef struct
  {
  	uint32_t* clusters;
  	uint32_t* cluster_sizes;
  	uint32_t num_clusters;
  	uint32_t N;
  } UNIONFIND;
  
  /* Allocate a UNIONFIND structure of capacity N */
  UNIONFIND* UF_create(uint32_t N);
  
  /* Release memory associated with UNIONFIND structure */
  void UF_destroy(UNIONFIND* uf);
  
  /* Identify the cluster id associated with specified component id */
  uint32_t UF_find(UNIONFIND* uf, uint32_t i);
  
  /* Get the size of the cluster associated with the specified component id */
  uint32_t UF_size(UNIONFIND* uf, uint32_t i);
  
  /* Merge the clusters that contain the two specified component ids */
  void UF_union(UNIONFIND* uf, uint32_t i, uint32_t j);
  
  /* Return an array of component ids, where components that are in the
   * same cluster are contiguous in the array */
  uint32_t* UF_ordered_by_cluster(UNIONFIND* uf);
  
  /* Replace the cluster ids in a UNIONFIND with sequential ids starting at one.
   * If is_in_cluster array is provided, it will be used to skip any indexes
   * that are not in a cluster.
   * */
  uint32_t* UF_get_collapsed_cluster_ids(UNIONFIND* uf, const char* is_in_cluster);
  
  #endif
  