locale_database: Use argparse module to parse command line arguments

arparse is the standard way to parse command line arguments in Python.
It provides help and usage information for free and is easier to extend
than a custom argument parser.

Task-number: QTBUG-83488
Pick-to: 6.2
Change-Id: I1e4c9cd914449e083d01932bc871ef10d26f0bc2
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 25 insertions, 29 deletions

diff --git a/util/locale_database/cldr2qlocalexml.py b/util/locale_database/cldr2qlocalexml.py
index 5f67ee708b..6ebf62e95a 100755
--- a/util/locale_database/cldr2qlocalexml.py
+++ b/util/locale_database/cldr2qlocalexml.py
@@ -27,7 +27,7 @@
 ## $QT_END_LICENSE$
 ##
 #############################################################################
-"""Convert CLDR data to qLocaleXML
+"""Convert CLDR data to QLocaleXML
 
 The CLDR data can be downloaded from CLDR_, which has a sub-directory
 for each version; you need the ``core.zip`` file for your version of
@@ -51,53 +51,49 @@ order.
 While updating the locale data, check also for updates to MS-Win's
 time zone names; see cldr2qtimezone.py for details.
 
+All the scripts mentioned support --help to tell you how to use them.
+
 .. _CLDR: ftp://unicode.org/Public/cldr/
 """
 
 import os
 import sys
+import argparse
 
 from cldr import CldrReader
 from qlocalexml import QLocaleXmlWriter
 
-def usage(name, err, message = ''):
-    err.write(f"""Usage: {name} path/to/cldr/common/main [out-file.xml]
-""") # TODO: expand command-line, improve help message
-    if message:
-        err.write(f'\n{message}\n')
 
-def main(args, out, err):
-    # TODO: make calendars a command-line option
-    calendars = ['gregorian', 'persian', 'islamic'] # 'hebrew'
+def main(out, err):
+    all_calendars = ['gregorian', 'persian', 'islamic']  # 'hebrew'
+
+    parser = argparse.ArgumentParser(
+        description='Generate QLocaleXML from CLDR data.',
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument('cldr_path', help='path to the root of the CLDR tree')
+    parser.add_argument('out_file', help='output XML file name',
+                        nargs='?', metavar='out-file.xml')
+    parser.add_argument('--calendars', help='select calendars to emit data for',
+                        nargs='+', metavar='CALENDAR',
+                        choices=all_calendars, default=all_calendars)
 
-    # TODO: make argument parsing more sophisticated
-    name = args.pop(0)
-    if not args:
-        usage(name, err, 'Where is your CLDR data tree ?')
-        return 1
+    args = parser.parse_args()
 
-    root = args.pop(0)
+    root = args.cldr_path
     if not os.path.exists(os.path.join(root, 'common', 'main', 'root.xml')):
-        usage(name, err, 'First argument is the root of the CLDR tree: '
-                         f'found no common/main/root.xml under {root}')
-        return 1
+        parser.error('First argument is the root of the CLDR tree: '
+                     f'found no common/main/root.xml under {root}')
 
-    xml = args.pop(0) if args else None
+    xml = args.out_file
     if not xml or xml == '-':
         emit = out
     elif not xml.endswith('.xml'):
-        usage(name, err, f'Please use a .xml extension on your output file name, not {xml}')
-        return 1
+        parser.error(f'Please use a .xml extension on your output file name, not {xml}')
     else:
         try:
             emit = open(xml, 'w')
         except IOError as e:
-            usage(name, err, f'Failed to open "{xml}" to write output to it\n')
-            return 1
-
-    if args:
-        usage(name, err, 'Too many arguments - excess: ' + ' '.join(args))
-        return 1
+            parser.error(f'Failed to open "{xml}" to write output to it')
 
     # TODO - command line options to tune choice of grumble and whitter:
     reader = CldrReader(root, err.write, err.write)
@@ -106,10 +102,10 @@ def main(args, out, err):
     writer.version(reader.root.cldrVersion)
     writer.enumData()
     writer.likelySubTags(reader.likelySubTags())
-    writer.locales(reader.readLocales(calendars), calendars)
+    writer.locales(reader.readLocales(args.calendars), args.calendars)
 
     writer.close(err.write)
     return 0
 
 if __name__ == '__main__':
-    sys.exit(main(sys.argv, sys.stdout, sys.stderr))
+    sys.exit(main(sys.stdout, sys.stderr))