(conditionally) use lwgeom::st_astext; #800

DESCRIPTION

@@ -64,7 +64,7 @@ Suggests:
     dplyr (>= 0.7-0),
     ggplot2,
     knitr,
-    lwgeom (>= 0.1-2),
+    lwgeom (>= 0.1-5),
     maps,
     maptools,
     mapview,

R/wkt.R

@@ -83,7 +83,10 @@ st_as_text = function(x, ...) UseMethod("st_as_text")
 #' st_as_text(st_point(1:2))
 #' st_as_text(st_sfc(st_point(c(-90,40)), crs = 4326), EWKT = TRUE)
 st_as_text.sfg = function(x, ...) {
-	switch(class(x)[2],
+	if (Sys.getenv("LWGEOM_WKT") == "true" && requireNamespace("lwgeom", quietly = TRUE) && utils::packageVersion("lwgeom") >= "0.1-5")
+		lwgeom::st_astext(x, ...)
+	else 
+	  switch(class(x)[2],
 		POINT = prnt.POINT(x, ...),
 		MULTIPOINT =        prnt.MULTIPOINT(x, ...),
 		LINESTRING =        prnt.LINESTRING(x, ...),
@@ -108,12 +111,16 @@ st_as_text.sfg = function(x, ...) {
 #' @param EWKT logical; if TRUE, print SRID=xxx; before the WKT string if \code{epsg} is available
 #' @export
 st_as_text.sfc = function(x, ..., EWKT = FALSE) {
-	if (EWKT) {
-		epsg = attr(x, "crs")$epsg
-		if (!is.na(epsg) && epsg != 0)
-			x = lapply(x, function(sfg) structure(sfg, epsg = epsg))
+	if (Sys.getenv("LWGEOM_WKT") == "true" && requireNamespace("lwgeom", quietly = TRUE) && utils::packageVersion("lwgeom") >= "0.1-5")
+		lwgeom::st_astext(x, ..., EWKT = EWKT)
+	else {
+		if (EWKT) {
+			epsg = attr(x, "crs")$epsg
+			if (!is.na(epsg) && epsg != 0)
+				x = lapply(x, function(sfg) structure(sfg, epsg = epsg))
+		}
+		vapply(x, st_as_text, "", ..., EWKT = EWKT)
 	}
-	vapply(x, st_as_text, "", ..., EWKT = EWKT)
 }
 
 #' @name st_as_sfc