From 2f3c2195f89ceab5f6ab51f4d50fe978f8bbfa9d Mon Sep 17 00:00:00 2001
From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Wed, 26 Nov 2008 19:04:15 +0000
Subject: [PATCH] ST_IsValidReason(geometry) returns text reason for validity
 failure. Requires GEOS >= 3.1. GBT#51

git-svn-id: http://svn.osgeo.org/postgis/trunk@3341 b70326c6-7e19-0410-871a-916f4a2858ee
---
 lwgeom/lwgeom_geos.c      | 39 +++++++++++++++++++++++++++++++++++++++
 lwgeom/lwpostgis.sql.in.c | 11 ++++++++++-
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/lwgeom/lwgeom_geos.c b/lwgeom/lwgeom_geos.c
index bc75710f9..60ff0d6e5 100644
--- a/lwgeom/lwgeom_geos.c
+++ b/lwgeom/lwgeom_geos.c
@@ -37,6 +37,7 @@ Datum containsproperly(PG_FUNCTION_ARGS);
 Datum covers(PG_FUNCTION_ARGS);
 Datum overlaps(PG_FUNCTION_ARGS);
 Datum isvalid(PG_FUNCTION_ARGS);
+Datum isvalidreason(PG_FUNCTION_ARGS);
 Datum buffer(PG_FUNCTION_ARGS);
 Datum intersection(PG_FUNCTION_ARGS);
 Datum convexhull(PG_FUNCTION_ARGS);
@@ -1080,6 +1081,44 @@ Datum isvalid(PG_FUNCTION_ARGS)
 }
 
 
+PG_FUNCTION_INFO_V1(isvalidreason);
+Datum isvalidreason(PG_FUNCTION_ARGS)
+{
+	PG_LWGEOM *geom = NULL;
+	char *reason_str = NULL;
+	int len = 0;
+	char *result = NULL;
+	GEOSGeom g1 = NULL;
+
+	geom = (PG_LWGEOM *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+
+	initGEOS(lwnotice, lwnotice);
+
+	g1 = POSTGIS2GEOS(geom);
+	if ( ! g1 )
+	{
+		PG_RETURN_NULL();
+	}
+
+	reason_str = GEOSisValidReason(g1);
+	GEOSGeom_destroy(g1);
+	
+	if (reason_str == NULL)
+	{
+		elog(ERROR,"GEOS isvalidreason() threw an error!");
+		PG_RETURN_NULL(); /* never get here */
+	}
+	len = strlen(reason_str);
+	result = palloc(VARHDRSZ + len);
+	SET_VARSIZE(result, VARHDRSZ + len);
+	memcpy(VARDATA(result), reason_str, len);
+	free(reason_str);
+
+	PG_FREE_IF_COPY(geom, 0);
+	PG_RETURN_POINTER(result);
+	
+}
+
 /*
  * overlaps(PG_LWGEOM g1,PG_LWGEOM g2)
  * returns  if GEOS::g1->overlaps(g2) returns true
diff --git a/lwgeom/lwpostgis.sql.in.c b/lwgeom/lwpostgis.sql.in.c
index 9f4d942f4..7cc0ac61e 100644
--- a/lwgeom/lwpostgis.sql.in.c
+++ b/lwgeom/lwpostgis.sql.in.c
@@ -2352,7 +2352,7 @@ LANGUAGE 'SQL' _IMMUTABLE;
 -----------------------------------------------------------------------
 -- This function will:
 --
---	o try to fix the schema of records with an invalid one
+--	o try to fix the schema of records with an integer one
 --		(for PG>=73)
 --
 --	o link records to system tables through attrelid and varattnum
@@ -3939,6 +3939,15 @@ CREATEFUNCTION ST_SimplifyPreserveTopology(geometry, float8)
     LANGUAGE 'C' _IMMUTABLE_STRICT; -- WITH (isstrict,iscachable);
 #endif
 
+#if POSTGIS_GEOS_VERSION >= 31
+-- Requires GEOS >= 3.1.0
+-- Availability: 1.4.0
+CREATEFUNCTION ST_IsValidReason(geometry)
+    RETURNS text
+    AS 'MODULE_PATHNAME', 'isvalidreason'
+    LANGUAGE 'C' _IMMUTABLE_STRICT; -- WITH (isstrict,iscachable);
+#endif
+
 -- Deprecation in 1.2.3
 CREATEFUNCTION difference(geometry,geometry)
 	RETURNS geometry
-- 
2.49.0