test: add progress bar to read operation

test.py

@@ -1,10 +1,25 @@
 import gds
 import sys
 
+import math
+import progress.bar
+
+global bar
+
+def callback(parser):
+    global bar
+
+    bar.max = parser.total
+    bar.index = parser.current
+    bar.update()
+
 for arg in sys.argv[1:]:
     f = open(arg, "rb")
     try:
-        lib = gds.parse_file(f)
+        bar = progress.bar.IncrementalBar("parsing file")
+        lib = gds.parse_file(f, progress_func=callback)
+        print()
+
         print("file version: {}".format(lib.version))
         print("last access: {}".format(lib.last_access.isoformat()))
         print("last modification: {}".format(lib.last_mod.isoformat()))
@@ -14,6 +29,9 @@ for arg in sys.argv[1:]:
         print("library name : {}".format(lib.name))
         print("contains a total of {} structure(s)".format(len(lib.structures)))
                 
+        bar = progress.bar.IncrementalBar("linking structure references")
+        lib.link_srefs(callback)
+
     except gds.ParserError as e:
         print("parser error: {}".format(e))
     finally: