Add subcommand for printing comment area

jplephem/__main__.py

@@ -1,3 +1,4 @@
-from sys import argv, exit
+import sys
 from .commandline import main
-exit(main(argv[1:]) or 0)
+sys.stdout.write(main(sys.argv[1:]))
+sys.exit(0)

jplephem/commandline.py

@@ -14,6 +14,13 @@ def main(args):
     )
     subparsers = parser.add_subparsers()
 
+    p = subparsers.add_parser(
+        'comment',
+        help="Print a file's comment blocks",
+    )
+    p.set_defaults(func=comment)
+    p.add_argument('path', help='Path to a SPICE file')
+
     p = subparsers.add_parser(
         'daf',
         help="List a file's raw segment descriptors",
@@ -44,9 +51,15 @@ def main(args):
         sys.exit(2)
 
     lines = list(func(args))
-    lines.append('')
+    if lines and not lines[-1].endswith('\n'):
+        lines.append('')
     return '\n'.join(lines)
 
+def comment(args):
+    with open(args.path, 'rb') as f:
+        d = DAF(f)
+        yield d.comments()
+
 def daf_segments(args):
     with open(args.path, 'rb') as f:
         d = DAF(f)

jplephem/test.py

@@ -377,6 +377,11 @@ class NAIF_DAF_Tests(TestCase):
 class CommandLineTests(TestCase):
     maxDiff = 9999
 
+    def test_comment_command(self):
+        output = commandline.main(['comment', 'de405.bsp'])
+        self.assertEqual(output[:30], '; de405.bsp LOG FILE\n;\n; Creat')
+        self.assertEqual(output[-30:], "rom Standish's DE405 memo <<<\n")
+
     def test_daf_command(self):
         self.assertEqual(commandline.main(['daf', 'de405.bsp']), """\
  1 DE-405 -1577879958.8160586 1577880064.1839132 1 0 1 2 1409 202316