Generate zsh completion script automatically

Modified from <https://github.com/ytdl-org/youtube-dl/tree/master/devscripts>

1. `scripts/zsh_completion.py`
2. `sudo mv _* /usr/share/zsh/site-functions`
3. `compinit`

ptpython/__init__.py

@@ -1,3 +1,4 @@
 from .repl import embed
+from .entry_points.run_ptpython import create_parser
 
 __all__ = ["embed"]

ptpython/entry_points/run_ptpython.py

@@ -77,9 +77,11 @@ def create_parser() -> _Parser:
         help="Run on a dark background (use light colors for text).",
     ),
     parser.add_argument(
-        "--config-file", type=str, help="Location of configuration file."
+        "--config-file", type=str, metavar="file", help="Location of configuration file."
+    )
+    parser.add_argument(
+        "--history-file", type=str, metavar="file", help="Location of history file."
     )
-    parser.add_argument("--history-file", type=str, help="Location of history file.")
     parser.add_argument(
         "-V",
         "--version",

scripts/zsh_completion.in

@@ -0,0 +1,6 @@
+#compdef -P ptpython[0-9.]# ptipython[0-9.]#
+# https://github.com/zsh-users/zsh/blob/master/Etc/completion-style-guide
+
+_arguments -s -S \
+  {{flags}} \
+  '*:file:_files'

scripts/zsh_completion.py

@@ -0,0 +1,236 @@
+#!/usr/bin/env python
+"""Generate zsh completion script.
+
+Usage
+-----
+.. code-block:: zsh
+    scripts/zsh_completion.py
+    sudo mv _[^_]* /usr/share/zsh/site-functions  # don't mv __pycache__
+    rm -f ~/.zcompdump  # optional
+    compinit  # regenerate ~/.zcompdump
+
+Debug
+-----
+.. code-block:: zsh
+    scripts/zsh_completion.py MODULE_NAME -  # will output to stdout
+
+Refer
+-----
+- https://github.com/ytdl-org/youtube-dl/blob/master/devscripts/zsh-completion.py
+- https://github.com/zsh-users/zsh/blob/master/Etc/completion-style-guide
+
+Examples
+--------
+.. code-block::
+    '(- *)'{-h,--help}'[show this help message and exit]'
+    |<-1->||<---2--->||<---------------3--------------->|
+
+.. code-block:: console
+    % foo --<TAB>
+    option
+    --help      show this help message and exit
+    % foo --help <TAB>
+    no more arguments
+
+.. code-block::
+    --color'[When to show color. Default: auto. Support: auto, always, never]:when:(auto always never)'
+    |<-2->||<------------------------------3------------------------------->||<4>||<--------5-------->|
+
+.. code-block:: console
+    % foo --color <TAB>
+    when
+    always
+    auto
+    never
+
+.. code-block::
+    --color'[When to show color. Default: auto. Support: auto, always, never]:when:((auto\:"only when output is stdout" always\:always never\:never))'
+    |<-2->||<------------------------------3------------------------------->||<4>||<--------------------------------5------------------------------->|
+
+.. code-block:: console
+    % foo --color <TAB>
+    when
+    always   always
+    auto     only when output is stdout
+    never    never
+
+.. code-block::
+    --config='[Config file. Default: ~/.config/foo/foo.toml]:config file:_files -g toml'
+    |<--2-->||<---------------------3--------------------->||<---4---->||<-----5------>|
+
+.. code-block:: console
+    % foo --config <TAB>
+    config file
+    a.toml  b/
+    ...
+
+.. code-block::
+    {1,2}'::_command_names -e'
+    |<2->|4|<-------5------->|
+
+.. code-block:: console
+    % foo hel<TAB>
+    _command_names -e
+    hello     friendly greeting program
+    help2man  generate a simple manual page
+    ...
+    % foo hello hello <TAB>
+    no more arguments
+
+.. code-block::
+    '*: :_command_names -e'
+    2|4||<-------5------->|
+
+.. code-block:: console
+    % foo hel<TAB>
+    external command
+    hello     friendly greeting program
+    help2man  generate a simple manual page
+    ...
+    % foo hello hello hel<TAB>
+    external command
+    hello     friendly greeting program
+    help2man  generate a simple manual page
+    ...
+
++----+------------+----------+------+
+| id | variable   | requierd | expr |
++====+============+==========+======+
+| 1  | prefix     | F        | (.*) |
+| 2  | optionstr  | T        | .*   |
+| 3  | helpstr    | F        | [.*] |
+| 4  | metavar    | F        | :.*  |
+| 5  | completion | F        | :.*  |
++----+------------+----------+------+
+"""
+from argparse import (
+    FileType,
+    SUPPRESS,
+    _HelpAction,
+    _SubParsersAction,
+    _VersionAction,
+)
+import os
+from os.path import dirname as dirn
+import sys
+from typing import Final, Tuple
+
+from setuptools import find_packages
+
+rootpath = dirn(dirn(os.path.abspath(__file__)))
+path = os.path.join(rootpath, "src")
+packages = find_packages(path)
+if packages == []:
+    path = rootpath
+    packages = find_packages(path)
+sys.path.insert(0, path)
+PACKAGES: Final = packages
+PACKAGE: Final = PACKAGES[0] if sys.argv[1:2] == [] else sys.argv[1]
+parser = __import__(PACKAGE).create_parser()
+actions = parser._actions
+BINNAME: Final = PACKAGE.replace("_", "-")
+BINNAMES: Final = [BINNAME]
+ZSH_COMPLETION_FILE: Final = (
+    "_" + BINNAME if sys.argv[2:3] == [] else sys.argv[2]
+)
+ZSH_COMPLETION_TEMPLATE: Final = os.path.join(
+    dirn(os.path.abspath(__file__)), "zsh_completion.in"
+)
+SUPPRESS_HELP = SUPPRESS
+SUPPRESS_USAGE = SUPPRESS
+
+flags = []
+position = 1
+for action in actions:
+    if action.__class__ in [_HelpAction, _VersionAction]:
+        prefix = "'(- *)'"
+    elif isinstance(action, _SubParsersAction):  # TODO
+        raise NotImplementedError
+    elif action.option_strings == []:
+        prefix = "'(-)"
+    else:
+        prefix = ""
+
+    if len(action.option_strings) > 1:  # {} cannot be quoted
+        optionstr = "{" + ",".join(action.option_strings) + "}'"
+    elif len(action.option_strings) == 1:
+        optionstr = action.option_strings[0] + "'"
+    else:  # action.option_strings == [], positional argument
+        if action.nargs in ["*", "+"]:
+            optionstr = "1"  # change in template file
+        else:
+            if isinstance(action.nargs, int) and action.nargs > 1:
+                old_position = position
+                position += action.nargs
+                optionstr = ",".join(map(str, range(old_position, position)))
+                optionstr = "{" + optionstr + "}'"
+            else:  # action.nargs in [1, None, "?"]:
+                optionstr = str(position) + "'"
+                position += 1
+
+    if (
+        action.help
+        and action.help != SUPPRESS_HELP
+        and action.option_strings != []
+    ):
+        helpstr = action.help.replace("]", "\\]").replace("'", "'\\''")
+        helpstr = "[" + helpstr + "]"
+    else:
+        helpstr = ""
+
+    if isinstance(action.metavar, str):
+        metavar = action.metavar
+    elif isinstance(action.metavar, Tuple):
+        metavar = " ".join(map(str, action.metavar))
+        # need some changes in template file
+    else:  # action.metavar is None
+        if action.nargs == 0:
+            metavar = ""
+        elif action.option_strings == []:
+            metavar = action.dest
+        elif isinstance(action.type, FileType):
+            metavar = "file"
+        elif action.type:
+            metavar = action.type.__name__
+        else:
+            metavar = action.default.__class__.__name__
+    if metavar != "":
+        # use lowcase conventionally
+        metavar = metavar.lower().replace(":", "\\:")
+
+    if action.choices:
+        completion = "(" + " ".join(map(str, action.choices)) + ")"
+    elif metavar == "file":
+        completion = "_files"
+    elif metavar == "args":
+        completion = "_files -g *.py"
+    elif metavar == "dir":
+        completion = "_dirs"
+    elif metavar == "url":
+        completion = "_urls"
+    elif metavar == "command":
+        completion = "_command_names -e"
+    else:
+        completion = ""
+
+    if metavar != "":
+        metavar = ":" + metavar
+    if completion != "":
+        completion = ":" + completion
+
+    flag = "{0}{1}{2}{3}{4}'".format(
+        prefix, optionstr, helpstr, metavar, completion
+    )
+    flags += [flag]
+
+with open(ZSH_COMPLETION_TEMPLATE) as f:
+    template = f.read()
+
+template = template.replace("{{flags}}", " \\\n  ".join(flags))
+
+with (
+    open(ZSH_COMPLETION_FILE, "w")
+    if ZSH_COMPLETION_FILE != "-"
+    else sys.stdout
+) as f:
+    f.write(template)