glapi: gl_table.py: replace getopt with argparse.

This results in slightly less code, but code that is much more readable.
It has the advantage of putting everything together in one place, all of
the code is self documenting, help messages are auto-generated, choices
are automatically enforced, and the syntax is much less C like, taking
advantage of python features and idioms.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Acked-by: Matt Turner <mattst88@gmail.com>

src/mapi/glapi/gen/gl_table.py

@@ -26,8 +26,7 @@
 # Authors:
 #    Ian Romanick <idr@us.ibm.com>
 
-import sys
-import getopt
+import argparse
 
 import gl_XML
 import license
@@ -203,45 +202,42 @@ class PrintRemapTable(gl_XML.gl_print_base):
         return
 
 
-def show_usage():
-    print "Usage: %s [-f input_file_name] [-m mode] [-c ver]" % sys.argv[0]
-    print "    -m mode   Mode can be 'table' or 'remap_table'."
-    print "    -c ver    Version can be 'es1' or 'es2'."
-    sys.exit(1)
+def _parser():
+    """Parse arguments and return a namespace."""
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-f', '--filename',
+                        type=gl_XML.parse_GL_API,
+                        default='gl_API.xml',
+                        metavar="input_file_name",
+                        dest='api',
+                        help="Path to an XML description of OpenGL API.")
+    parser.add_argument('-m', '--mode',
+                        choices=['table', 'remap_table'],
+                        default='table',
+                        metavar="mode",
+                        help="Generate either a table or a remap_table")
+    parser.add_argument('-c', '--es-version',
+                        choices=[None, 'es1', 'es2'],
+                        default=None,
+                        metavar="ver",
+                        dest='es',
+                        help="filter functions for es")
+    return parser.parse_args()
 
 
 def main():
     """Main function."""
-    file_name = "gl_API.xml"
+    args = _parser()
 
-    try:
-        args, _ = getopt.getopt(sys.argv[1:], "f:m:c:")
-    except Exception:
-        show_usage()
+    if args.mode == "table":
+        printer = PrintGlTable(args.es)
+    elif args.mode == "remap_table":
+        printer = PrintRemapTable(args.es)
 
-    mode = "table"
-    es = None
-    for (arg, val) in args:
-        if arg == "-f":
-            file_name = val
-        elif arg == "-m":
-            mode = val
-        elif arg == "-c":
-            es = val
+    if args.es is not None:
+        args.api.filter_functions_by_api(args.es)
 
-    if mode == "table":
-        printer = PrintGlTable(es)
-    elif mode == "remap_table":
-        printer = PrintRemapTable(es)
-    else:
-        show_usage()
-
-    api = gl_XML.parse_GL_API(file_name)
-
-    if es is not None:
-        api.filter_functions_by_api(es)
-
-    printer.Print(api)
+    printer.Print(args.api)
 
 
 if __name__ == '__main__':