PostGIS  2.5.0dev-r@@SVN_REVISION@@
LWGEOM * lwgeom_node ( const LWGEOM lwgeom_in)

Definition at line 130 of file lwgeom_geos_node.c.

References LWGEOM::flags, FLAGS_GET_M, FLAGS_GET_Z, LWCOLLECTION::geoms, GEOS2LWGEOM(), lwcollection_clone_deep(), lwcollection_construct_empty(), lwcollection_free(), lwcollection_reserve(), lwerror(), LWGEOM2GEOS(), lwgeom_dimension(), lwgeom_extract_unique_endpoints(), lwgeom_free(), lwgeom_geos_errmsg, lwgeom_geos_error(), lwgeom_is_collection(), lwgeom_ngeoms(), lwgeom_subgeom(), lwline_split_by_point_to(), MULTILINETYPE, LWCOLLECTION::ngeoms, s, and LWGEOM::srid.

Referenced by _lwt_AddLine(), ST_Node(), and test_lwgeom_node().

131 {
132  GEOSGeometry *g1, *gn, *gm;
133  LWGEOM *ep, *lines;
134  LWCOLLECTION *col, *tc;
135  int pn, ln, np, nl;
136 
137  if ( lwgeom_dimension(lwgeom_in) != 1 ) {
138  lwerror("Noding geometries of dimension != 1 is unsupported");
139  return NULL;
140  }
141 
143  g1 = LWGEOM2GEOS(lwgeom_in, 1);
144  if ( ! g1 ) {
145  lwerror("LWGEOM2GEOS: %s", lwgeom_geos_errmsg);
146  return NULL;
147  }
148 
149  ep = lwgeom_extract_unique_endpoints(lwgeom_in);
150  if ( ! ep ) {
151  GEOSGeom_destroy(g1);
152  lwerror("Error extracting unique endpoints from input");
153  return NULL;
154  }
155 
156  gn = GEOSNode(g1);
157  GEOSGeom_destroy(g1);
158  if ( ! gn ) {
159  lwgeom_free(ep);
160  lwerror("GEOSNode: %s", lwgeom_geos_errmsg);
161  return NULL;
162  }
163 
164  gm = GEOSLineMerge(gn);
165  GEOSGeom_destroy(gn);
166  if ( ! gm ) {
167  lwgeom_free(ep);
168  lwerror("GEOSLineMerge: %s", lwgeom_geos_errmsg);
169  return NULL;
170  }
171 
172  lines = GEOS2LWGEOM(gm, FLAGS_GET_Z(lwgeom_in->flags));
173  GEOSGeom_destroy(gm);
174  if ( ! lines ) {
175  lwgeom_free(ep);
176  lwerror("Error during GEOS2LWGEOM");
177  return NULL;
178  }
179 
180  /*
181  * Reintroduce endpoints from input, using split-line-by-point.
182  * Note that by now we can be sure that each point splits at
183  * most _one_ segment as any point shared by multiple segments
184  * would already be a node. Also we can be sure that any of
185  * the segments endpoints won't split any other segment.
186  * We can use the above 2 assertions to early exit the loop.
187  */
188 
190  FLAGS_GET_Z(lwgeom_in->flags),
191  FLAGS_GET_M(lwgeom_in->flags));
192 
193  np = lwgeom_ngeoms(ep);
194  for (pn=0; pn<np; ++pn) { /* for each point */
195 
196  const LWPOINT* p = (LWPOINT*)lwgeom_subgeom(ep, pn);
197 
198  nl = lwgeom_ngeoms(lines);
199  for (ln=0; ln<nl; ++ln) { /* for each line */
200 
201  const LWLINE* l = (LWLINE*)lwgeom_subgeom(lines, ln);
202 
203  int s = lwline_split_by_point_to(l, p, (LWMLINE*)col);
204 
205  if ( ! s ) continue; /* not on this line */
206 
207  if ( s == 1 ) {
208  /* found on this line, but not splitting it */
209  break;
210  }
211 
212  /* splits this line */
213 
214  /* replace this line with the two splits */
215  if ( lwgeom_is_collection(lines) ) {
216  tc = (LWCOLLECTION*)lines;
217  lwcollection_reserve(tc, nl + 1);
218  while (nl > ln+1) {
219  tc->geoms[nl] = tc->geoms[nl-1];
220  --nl;
221  }
222  lwgeom_free(tc->geoms[ln]);
223  tc->geoms[ln] = col->geoms[0];
224  tc->geoms[ln+1] = col->geoms[1];
225  tc->ngeoms++;
226  } else {
227  lwgeom_free(lines);
228  /* transfer ownership rather than cloning */
229  lines = (LWGEOM*)lwcollection_clone_deep(col);
230  assert(col->ngeoms == 2);
231  lwgeom_free(col->geoms[0]);
232  lwgeom_free(col->geoms[1]);
233  }
234 
235  /* reset the vector */
236  assert(col->ngeoms == 2);
237  col->ngeoms = 0;
238 
239  break;
240  }
241 
242  }
243 
244  lwgeom_free(ep);
245  lwcollection_free(col);
246 
247  lines->srid = lwgeom_in->srid;
248  return (LWGEOM*)lines;
249 }
int lwgeom_is_collection(const LWGEOM *lwgeom)
Determine whether a LWGEOM can contain sub-geometries or not.
Definition: lwgeom.c:1078
static LWGEOM * lwgeom_extract_unique_endpoints(const LWGEOM *lwg)
uint8_t flags
Definition: liblwgeom.h:396
void lwgeom_free(LWGEOM *geom)
Definition: lwgeom.c:1137
static int lwgeom_ngeoms(const LWGEOM *n)
char lwgeom_geos_errmsg[LWGEOM_GEOS_ERRMSG_MAXSIZE]
uint32_t ngeoms
Definition: liblwgeom.h:506
int32_t srid
Definition: liblwgeom.h:398
void lwgeom_geos_error(const char *fmt,...)
static const LWGEOM * lwgeom_subgeom(const LWGEOM *g, int n)
LWGEOM ** geoms
Definition: liblwgeom.h:508
char * s
Definition: cu_in_wkt.c:23
#define FLAGS_GET_Z(flags)
Macros for manipulating the 'flags' byte.
Definition: liblwgeom.h:139
GEOSGeometry * LWGEOM2GEOS(const LWGEOM *lwgeom, int autofix)
LWCOLLECTION * lwcollection_clone_deep(const LWCOLLECTION *lwgeom)
Deep clone LWCOLLECTION object.
Definition: lwcollection.c:149
int lwgeom_dimension(const LWGEOM *geom)
For an LWGEOM, returns 0 for points, 1 for lines, 2 for polygons, 3 for volume, and the max dimension...
Definition: lwgeom.c:1280
#define FLAGS_GET_M(flags)
Definition: liblwgeom.h:140
LWGEOM * GEOS2LWGEOM(const GEOSGeometry *geom, char want3d)
void lwcollection_free(LWCOLLECTION *col)
Definition: lwcollection.c:342
void lwcollection_reserve(LWCOLLECTION *col, uint32_t ngeoms)
Ensure the collection can hold at least up to ngeoms geometries.
Definition: lwcollection.c:174
#define MULTILINETYPE
Definition: liblwgeom.h:88
LWCOLLECTION * lwcollection_construct_empty(uint8_t type, int srid, char hasz, char hasm)
Definition: lwcollection.c:94
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
int lwline_split_by_point_to(const LWLINE *ln, const LWPOINT *pt, LWMLINE *to)
Split a line by a point and push components to the provided multiline.

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