lit: add join_path

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/lib/standard/file.nit b/lib/standard/file.nit
index b7e3a15..de73438 100644 (file)
--- a/lib/standard/file.nit
+++ b/lib/standard/file.nit
@@ -258,6 +258,29 @@ redef class String
                return a2.join("/")
        end
 
+       # Correctly join two path using the directory separator.
+       #
+       # Using a standard "{self}/{path}" does not work when `self' is the empty string.
+       # This method ensure that the join is valid.
+       #
+       #     "hello".join_path("world") # -> "hello/world"
+       #     "hel/lo".join_path("wor/ld") # -> "hel/lo/wor/ld"
+       #     "".join_path("world") # -> "world"
+       #     "/hello".join_path("/world") # -> "/world"
+       #
+       # Note: you may want to use `simplify_path' on the result
+       #
+       # Note: I you want to join a great number of path, you can write
+       #
+       #     [p1, p2, p3, p4].join("/")
+       fun join_path(path: String): String
+       do
+               if path.is_empty then return self
+               if self.is_empty then return path
+               if path[0] == '/' then return path
+               return "{self}/{path}"
+       end
+
        # Create a directory (and all intermediate directories if needed)
        fun mkdir
        do