Add shell completions

gscholar/__main__.py

@@ -5,17 +5,39 @@
 
 import gscholar as gs
 
+try:
+    import shtab
+except ImportError:
+    from . import _shtab as shtab
+
 
 logger = logging.getLogger('gscholar')
 logging.basicConfig(
     format='%(asctime)s %(levelname)s %(name)s %(message)s',
     level=logging.WARNING
 )
 
+# https://github.com/iterative/shtab/blob/5358dda86e8ea98bf801a43a24ad73cd9f820c63/examples/customcomplete.py#L11-L22
+PDF_FILE = {
+    "bash": "_shtab_greeter_compgen_pdf_files",
+    "zsh": "_files -g '*.pdf'",
+    "tcsh": "f:*.pdf"
+}
+PREAMBLE = {
+    "bash": """\
+# $1=COMP_WORDS[1]
+_shtab_greeter_compgen_pdf_files() {
+  compgen -d -- $1  # recurse into subdirs
+  compgen -f -X '!*?.pdf' -- $1
+}
+"""
+}
+
 
 def main():
-    usage = 'Usage: %prog [options] {pdf | "search terms"}'
-    parser = argparse.ArgumentParser(usage)
+    usage = 'Usage: %(prog)s [options] {pdf | "search terms"}'
+    parser = argparse.ArgumentParser('gscholar', usage)
+    shtab.add_argument_to(parser, preamble=PREAMBLE)
     parser.add_argument(
         "-a", "--all", action="store_true",
         help="show all bibtex results"
@@ -41,7 +63,7 @@ def main():
         '--version', action='version', version=gs.__VERSION__)
     parser.add_argument(
         'keyword', metavar='{pdf | "search terms"}',
-        help='pdf | "search terms"')
+        help='pdf | "search terms"').complete = PDF_FILE
     args = parser.parse_args()
     if args.debug is True:
         logger.setLevel(logging.DEBUG)

gscholar/_shtab.py

@@ -0,0 +1,38 @@
+"""Fake shtab."""
+from argparse import Action, ArgumentParser
+
+FILE = None
+DIRECTORY = DIR = None
+
+
+class PrintCompletionAction(Action):
+    """Print completion action."""
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        """Warn when shtab is not installed.
+
+        :param parser:
+        :param namespace:
+        :param values:
+        :param option_string:
+        """
+        print("Please install shtab firstly!")
+        parser.exit(0)
+
+
+def add_argument_to(parser: ArgumentParser, *args, **kwargs):
+    """Add completion argument to parser.
+
+    :param parser:
+    :type parser: ArgumentParser
+    :param args:
+    :param kwargs:
+    """
+    Action.complete = None  # type: ignore
+    parser.add_argument(
+        "--print-completion",
+        choices=["bash", "zsh", "tcsh"],
+        action=PrintCompletionAction,
+        help="print shell completion script",
+    )
+    return parser

setup.py

@@ -26,6 +26,7 @@
     },
     python_requires='>=3.7',
     packages=['gscholar'],
+    extras_require={'completion': ['shtab']},
     entry_points={
         'console_scripts': [
             'gscholar = gscholar.__main__:main'