Initial approach to the pyscript revamp.

Doesn't handle all argparse argument options yet (nargs, append, flag, probably more)
For #368

1 files changed, 107 insertions, 0 deletions

diff --git a/cmd2/pyscript_bridge.py b/cmd2/pyscript_bridge.py
new file mode 100644
index 00000000..88e12bfb
--- /dev/null
+++ b/cmd2/pyscript_bridge.py
@@ -0,0 +1,107 @@
+"""Bridges calls made inside of pyscript with the Cmd2 host app while maintaining a reasonable
+degree of isolation between the two"""
+
+import argparse
+
+class ArgparseFunctor:
+    def __init__(self, cmd2_app, item, parser):
+        self._cmd2_app = cmd2_app
+        self._item = item
+        self._parser = parser
+
+        self._args = {}
+        self.__current_subcommand_parser = parser
+
+    def __getattr__(self, item):
+        # look for sub-command
+        for action in self.__current_subcommand_parser._actions:
+            if not action.option_strings and isinstance(action, argparse._SubParsersAction):
+                if item in action.choices:
+                    # item matches the a sub-command, save our position in argparse,
+                    # save the sub-command, return self to allow next level of traversal
+                    self.__current_subcommand_parser = action.choices[item]
+                    self._args[action.dest] = item
+                    return self
+        return super().__getatttr__(item)
+
+    def __call__(self, *args, **kwargs):
+        next_pos_index = 0
+
+        has_subcommand = False
+        consumed_kw = []
+        for action in self.__current_subcommand_parser._actions:
+            # is this a flag option?
+            if action.option_strings:
+                if action.dest in kwargs:
+                    self._args[action.dest] = kwargs[action.dest]
+                    consumed_kw.append(action.dest)
+            else:
+                if not isinstance(action, argparse._SubParsersAction):
+                    if next_pos_index < len(args):
+                        self._args[action.dest] = args[next_pos_index]
+                        next_pos_index += 1
+                else:
+                    has_subcommand = True
+
+        for kw in kwargs:
+            if kw not in consumed_kw:
+                raise TypeError('{}() got an unexpected keyword argument \'{}\''.format(
+                    self.__current_subcommand_parser.prog, kw))
+
+        if has_subcommand:
+            return self
+        else:
+            return self._run()
+
+    def _run(self):
+        # look up command function
+        func = getattr(self._cmd2_app, 'do_' + self._item)
+
+        # reconstruct the cmd2 command from the python call
+        cmd_str = ['']
+
+        def traverse_parser(parser):
+            for action in parser._actions:
+                # was something provided for the argument
+                if action.dest in self._args:
+                    # was the argument a flag?
+                    # TODO: Handle 'narg' and 'append' options
+                    if action.option_strings:
+                        cmd_str[0] += '"{}" "{}" '.format(action.option_strings[0], self._args[action.dest])
+                    else:
+                        cmd_str[0] += '"{}" '.format(self._args[action.dest])
+
+                        if isinstance(action, argparse._SubParsersAction):
+                            traverse_parser(action.choices[self._args[action.dest]])
+        traverse_parser(self._parser)
+
+        func(cmd_str[0])
+        return self._cmd2_app._last_result
+
+
+class PyscriptBridge(object):
+    def __init__(self, cmd2_app):
+        self._cmd2_app = cmd2_app
+        self._last_result = None
+
+    def __getattr__(self, item: str):
+        commands = self._cmd2_app.get_all_commands()
+        if item in commands:
+            func = getattr(self._cmd2_app, 'do_' + item)
+
+            try:
+                parser = getattr(func, 'argparser')
+            except AttributeError:
+                def wrap_func(args=''):
+                    func(args)
+                    return self._cmd2_app._last_result
+                return wrap_func
+            else:
+                return ArgparseFunctor(self._cmd2_app, item, parser)
+
+        return super().__getattr__(item)
+
+    def __call__(self, args):
+        self._cmd2_app.onecmd_plus_hooks(args + '\n')
+        self._last_result = self._cmd2_app._last_result
+        return self._cmd2_app._last_result