Catch exception when trying to write /proc/.../ip_forward in the config file.

[software/pymin.git] / pymin / dispatcher.py

diff --git a/pymin/dispatcher.py b/pymin/dispatcher.py
index 39b4b75cf6522f64e78b2d097422a2bfc69285e1..0d28cb337bf1686d53f46446cdef03ec2272c2bc 100644 (file)
--- a/pymin/dispatcher.py
+++ b/pymin/dispatcher.py
@@ -7,7 +7,11 @@ It's based on Zope or Cherrypy dispatching (but implemented from the scratch)
 and translates commands to functions/objects/methods.
 """
 
 and translates commands to functions/objects/methods.
 """
 

-__ALL__ = ('Error', 'HandlerError', 'CommandNotFoundError', 'Handler',
+import re
+import inspect
+import logging ; log = logging.getLogger('pymin.dispatcher')
+
+__all__ = ('Error', 'HandlerError', 'CommandNotFoundError', 'Handler',

             'Dispatcher', 'handler', 'is_handler', 'get_help')
 
 class Error(RuntimeError):
             'Dispatcher', 'handler', 'is_handler', 'get_help')
 
 class Error(RuntimeError):


@@ -52,6 +56,51 @@ class CommandError(Error):
     def __unicode__(self):
         return u'Error in command "%s".' % u' '.join(self.command)
 
     def __unicode__(self):
         return u'Error in command "%s".' % u' '.join(self.command)
 

+class WrongArgumentsError(CommandError):
+    r"""WrongArgumentsError(handler, error) -> WrongArgumentsError instance.
+
+    This exception is raised when an empty command string is received.
+    """
+
+    def __init__(self, handler, error):
+        r"Initialize the object, see class documentation for more info."
+        self.handler = handler
+        self.error = error
+
+    args_re = re.compile(r'\w+\(\) takes (.+) (\d+) \w+ \((\d+) given\)')
+
+    extra_kw_re = re.compile(r'\w+\(\) got an unexpected keyword argument (.+)')
+
+    dup_kw_re = re.compile(r'\w+\(\) got multiple values for keyword argument '
+                            r"'(.+)'")
+
+    def format(self):
+        r"format() -> unicode - Format a TypeError to adapt it to a command."
+        m = self.args_re.match(unicode(self.error))
+        if m:
+            (quant, n_ok, n_bad)  = m.groups()
+            n_ok = int(n_ok)
+            n_bad = int(n_bad)
+            n_ok -= 1
+            n_bad -= 1
+            pl = ''
+            if n_ok != 1:
+                pl = 's'
+            return u'takes %s %s argument%s, %s given' \
+                        % (quant, n_ok, pl, n_bad)
+        m = self.extra_kw_re.match(unicode(self.error))
+        if m:
+            (kw,)  = m.groups()
+            return u'got an unexpected keyword argument %s' % kw
+        m = self.dup_kw_re.match(unicode(self.error))
+        if m:
+            (kw,)  = m.groups()
+            return u'got multiple values for argument %s' % kw
+        return u'got wrong arguments'
+
+    def __unicode__(self):
+        return u'Command "%s" %s.' % (self.handler.__name__, self.format())
+

 class CommandNotSpecifiedError(CommandError):
     r"""CommandNotSpecifiedError() -> CommandNotSpecifiedError instance.
 
 class CommandNotSpecifiedError(CommandError):
     r"""CommandNotSpecifiedError() -> CommandNotSpecifiedError instance.
 


@@ -146,13 +195,52 @@ def handler(help):
 
     help - Help string for the handler.
     """
 
     help - Help string for the handler.
     """

-    def wrapper(f):
-        if not help:
-            raise TypeError("'help' should not be empty")
-        f._dispatcher_handler = True
-        f.handler_help = help
-        return f
-    return wrapper
+    if not help:
+        raise TypeError("'help' should not be empty")
+    def make_wrapper(f):
+        log.debug('handler(): Decorating %s()', f.__name__)
+        # Here comes the tricky part:
+        # We need to make our wrapped function to accept any number of
+        # positional and keyword arguments, but checking for the correct
+        # arguments and raising an exception in case the arguments doesn't
+        # match.
+        # So we create a dummy function, with the same signature as the
+        # wrapped one, so we can check later (at "dispatch-time") if the
+        # real function call will be successful. If the dummy function don't
+        # raise a TypeError, the arguments are just fine.
+        env = dict()
+        argspec = inspect.getargspec(f)
+        signature = inspect.formatargspec(*argspec)
+        # The dummy function
+        exec "def f%s: pass" % signature in env
+        signature_check = env['f']
+        # The wrapper to check the signature at "dispatch-time"
+        def wrapper(*args, **kwargs):
+            # First we check if the arguments passed are OK.
+            try:
+                signature_check(*args, **kwargs)
+            except TypeError, e:
+                # If not, we raise an appropriate error.
+                raise WrongArgumentsError(f, e)
+            # If they are fine, we call the real function
+            return f(*args, **kwargs)
+        # Some flag to mark our handlers for simple checks
+        wrapper._dispatcher_handler = True
+        # The help string we asked for in the first place =)
+        wrapper.handler_help = help
+        # We store the original signature for better help generation
+        wrapper.handler_argspec = argspec
+        # And some makeup, to make our wrapper look like the original function
+        wrapper.__name__ = f.__name__
+        wrapper.__dict__.update(f.__dict__)
+        # We add a hint in the documentation
+        wrapper.__doc__ = "Pymin handler with signature: %s%s" \
+                            % (wrapper.__name__, signature)
+        if f.__doc__ is not None:
+            wrapper.__doc__ += "\n\n" + f.__doc__
+        wrapper.__module__ = f.__module__
+        return wrapper
+    return make_wrapper

 
 def is_handler(handler):
     r"is_handler(handler) -> bool :: Tell if a object is a handler."
 
 def is_handler(handler):
     r"is_handler(handler) -> bool :: Tell if a object is a handler."


@@ -186,17 +274,31 @@ class Handler:
             d = dict()
             for a in dir(self):
                 h = getattr(self, a)
             d = dict()
             for a in dir(self):
                 h = getattr(self, a)

+                if a == 'parent': continue # Skip parents in SubHandlers

                 if is_handler(h) or isinstance(h, Handler):
                     d[a] = h.handler_help
             return d
         # A command was specified
                 if is_handler(h) or isinstance(h, Handler):
                     d[a] = h.handler_help
             return d
         # A command was specified

+        if command == 'parent': # Skip parents in SubHandlers
+            raise HelpNotFoundError(command)

         if not hasattr(self, command.encode('utf-8')):
             raise HelpNotFoundError(command)
         handler = getattr(self, command.encode('utf-8'))
         if not hasattr(self, command.encode('utf-8')):
             raise HelpNotFoundError(command)
         handler = getattr(self, command.encode('utf-8'))

-        if not is_handler(handler) and not hasattr(handler):
+        if not is_handler(handler) and not hasattr(handler, 'handler_help'):

             raise HelpNotFoundError(command)
         return handler.handler_help
 
             raise HelpNotFoundError(command)
         return handler.handler_help
 

+    def handle_timer(self):
+        r"""handle_timer() -> None :: Do periodic tasks.
+
+        By default we do nothing but calling handle_timer() on subhandlers.
+        """
+        for a in dir(self):
+            if a == 'parent': continue # Skip parents in SubHandlers
+            h = getattr(self, a)
+            if isinstance(h, Handler):
+                h.handle_timer()
+

 def parse_command(command):
     r"""parse_command(command) -> (args, kwargs) :: Parse a command.
 
 def parse_command(command):
     r"""parse_command(command) -> (args, kwargs) :: Parse a command.
 


@@ -223,6 +325,8 @@ def parse_command(command):
     arguments is preserved and if there are multiple keyword arguments with
     the same key, the last value is the winner (all other values are lost).
 
     arguments is preserved and if there are multiple keyword arguments with
     the same key, the last value is the winner (all other values are lost).
 

+    The command should be a unicode string.
+

     Examples:
 
     >>> parse_command('hello world')
     Examples:
 
     >>> parse_command('hello world')


@@ -250,6 +354,12 @@ def parse_command(command):
     ([u'=hello'], {})
     >>> parse_command(r'\thello')
     ([u'\thello'], {})
     ([u'=hello'], {})
     >>> parse_command(r'\thello')
     ([u'\thello'], {})

+    >>> parse_command(r'hello \n')
+    ([u'hello', u'\n'], {})
+    >>> parse_command(r'hello \nmundo')
+    ([u'hello', u'\nmundo'], {})
+    >>> parse_command(r'test \N')
+    ([u'test', None], {})

     >>> parse_command(r'\N')
     ([None], {})
     >>> parse_command(r'none=\N')
     >>> parse_command(r'\N')
     ([None], {})
     >>> parse_command(r'none=\N')


@@ -274,9 +384,23 @@ def parse_command(command):
     escape = False
     keyword = None
     state = SEP
     escape = False
     keyword = None
     state = SEP

+    def register_token(buff, keyword, seq, dic):
+        if buff == r'\N':
+            buff = None
+        if keyword is not None:
+            dic[keyword.encode('utf-8')] = buff
+            keyword = None
+        else:
+            seq.append(buff)
+        buff = u''
+        return (buff, keyword)

     for n, c in enumerate(command):
         # Escaped character
         if escape:
     for n, c in enumerate(command):
         # Escaped character
         if escape:

+            # Not yet registered the token
+            if state == SEP and buff:
+                (buff, keyword) = register_token(buff, keyword, seq, dic)
+                state = TOKEN

             for e in escaped_chars:
                 if c == e:
                     buff += eval(u'"\\' + e + u'"')
             for e in escaped_chars:
                 if c == e:
                     buff += eval(u'"\\' + e + u'"')


@@ -301,14 +425,7 @@ def parse_command(command):
                     keyword = buff
                     buff = u''
                     continue
                     keyword = buff
                     buff = u''
                     continue

-                if buff == r'\N':
-                    buff = None
-                if keyword is not None: # Value found
-                    dic[str(keyword)] = buff
-                    keyword = None
-                else: # Normal parameter found
-                    seq.append(buff)
-                buff = u''
+                (buff, keyword) = register_token(buff, keyword, seq, dic)

             state = TOKEN
         # Getting a token
         if state == TOKEN:
             state = TOKEN
         # Getting a token
         if state == TOKEN:


@@ -350,12 +467,7 @@ def parse_command(command):
         raise ParseError(command,
                         u'keyword argument (%s) without value' % keyword)
     if buff:
         raise ParseError(command,
                         u'keyword argument (%s) without value' % keyword)
     if buff:

-        if buff == r'\N':
-            buff = None
-        if keyword is not None:
-            dic[str(keyword)] = buff
-        else:
-            seq.append(buff)
+        register_token(buff, keyword, seq, dic)

     return (seq, dic)
 
 class Dispatcher:
     return (seq, dic)
 
 class Dispatcher:


@@ -391,6 +503,7 @@ class Dispatcher:
 
         See Dispatcher class documentation for more info.
         """
 
         See Dispatcher class documentation for more info.
         """

+        log.debug(u'Dispatcher(%r)', root)

         self.root = root
 
     def dispatch(self, route):
         self.root = root
 
     def dispatch(self, route):


@@ -402,28 +515,51 @@ class Dispatcher:
 
         route - *unicode* string with the command route.
         """
 
         route - *unicode* string with the command route.
         """

+        log.debug('Dispatcher.dispatch(%r)', route)

         command = list()
         (route, kwargs) = parse_command(route)
         command = list()
         (route, kwargs) = parse_command(route)

+        log.debug(u'Dispatcher.dispatch: route=%r, kwargs=%r', route, kwargs)

         if not route:
         if not route:

+            log.debug(u'Dispatcher.dispatch: command not specified')

             raise CommandNotSpecifiedError()
         handler = self.root
         while not is_handler(handler):
             raise CommandNotSpecifiedError()
         handler = self.root
         while not is_handler(handler):

+            log.debug(u'Dispatcher.dispatch: handler=%r, route=%r',
+                        handler, route)

             if len(route) is 0:
                 if isinstance(handler, Handler):
             if len(route) is 0:
                 if isinstance(handler, Handler):

+                    log.debug(u'Dispatcher.dispatch: command is a handler')

                     raise CommandIsAHandlerError(command)
                     raise CommandIsAHandlerError(command)

+                log.debug(u'Dispatcher.dispatch: command not found')

                 raise CommandNotFoundError(command)
             command.append(route[0])
                 raise CommandNotFoundError(command)
             command.append(route[0])

+            log.debug(u'Dispatcher.dispatch: command=%r', command)
+            if route[0] == 'parent':
+                log.debug(u'Dispatcher.dispatch: is parent => not found')
+                raise CommandNotFoundError(command)

             if not hasattr(handler, route[0].encode('utf-8')):
                 if isinstance(handler, Handler) and len(command) > 1:
             if not hasattr(handler, route[0].encode('utf-8')):
                 if isinstance(handler, Handler) and len(command) > 1:

+                    log.debug(u'Dispatcher.dispatch: command not in handler')

                     raise CommandNotInHandlerError(command)
                     raise CommandNotInHandlerError(command)

+                log.debug(u'Dispatcher.dispatch: command not found')

                 raise CommandNotFoundError(command)
             handler = getattr(handler, route[0].encode('utf-8'))
             route = route[1:]
                 raise CommandNotFoundError(command)
             handler = getattr(handler, route[0].encode('utf-8'))
             route = route[1:]

-        return handler(*route, **kwargs)
+        log.debug(u'Dispatcher.dispatch: %r is a handler, calling it with '
+                    u'route=%r, kwargs=%r', handler, route, kwargs)
+        r = handler(*route, **kwargs)
+        log.debug(u'Dispatcher.dispatch: handler returned %s', r)
+        return r

 
 
 if __name__ == '__main__':
 
 
 
 if __name__ == '__main__':
 

+    logging.basicConfig(
+        level   = logging.DEBUG,
+        format  = '%(asctime)s %(levelname)-8s %(message)s',
+        datefmt = '%H:%M:%S',
+    )
+

     @handler(u"test: Print all the arguments, return nothing")
     def test_func(*args):
         print 'func:', args
     @handler(u"test: Print all the arguments, return nothing")
     def test_func(*args):
         print 'func:', args


@@ -438,8 +574,8 @@ if __name__ == '__main__':
         def cmd1(self, *args):
             print 'class.cmd1:', args
         @handler(u"cmd2: Print all the arguments, return nothing")
         def cmd1(self, *args):
             print 'class.cmd1:', args
         @handler(u"cmd2: Print all the arguments, return nothing")

-        def cmd2(self, *args):
-            print 'class.cmd2:', args
+        def cmd2(self, arg1, arg2):
+            print 'class.cmd2:', arg1, arg2

         subclass = TestClassSubHandler()
 
     class RootHandler(Handler):
         subclass = TestClassSubHandler()
 
     class RootHandler(Handler):


@@ -448,29 +584,74 @@ if __name__ == '__main__':
 
     d = Dispatcher(RootHandler())
 
 
     d = Dispatcher(RootHandler())
 

-    d.dispatch(r'''func arg1 arg2 arg3 "fourth 'argument' with \", a\ttab and\n\\n"''')
-    print 'inst commands:', tuple(d.dispatch('inst commands'))
-    print 'inst help:', d.dispatch('inst help')
-    d.dispatch('inst cmd1 arg1 arg2 arg3 arg4')
-    d.dispatch('inst cmd2 arg1 arg2')
-    print 'inst subclass help:', d.dispatch('inst subclass help')
-    d.dispatch('inst subclass subcmd arg1 arg2 arg3 arg4 arg5')
+    r = d.dispatch(r'''func arg1 arg2 arg3 "fourth 'argument' with \", a\ttab and\n\\n"''')
+    assert r is None
+    r = list(d.dispatch('inst commands'))
+    r.sort()
+    assert r == ['cmd1', 'cmd2', 'commands', 'help']
+    print 'inst commands:', r
+    r = d.dispatch('inst help')
+    assert r == {
+                'commands': u'List available commands',
+                'subclass': u'Undocumented handler',
+                'cmd1': u'cmd1: Print all the arguments, return nothing',
+                'cmd2': u'cmd2: Print all the arguments, return nothing',
+                'help': u'Show available commands with their help'
+    }
+    print 'inst help:', r
+    r = d.dispatch('inst cmd1 arg1 arg2 arg3 arg4')
+    assert r is None
+    r = d.dispatch('inst cmd2 arg1 arg2')
+    assert r is None
+    r = d.dispatch('inst subclass help')
+    assert r == {
+                'subcmd': u'subcmd: Print all the arguments, return nothing',
+                'commands': u'List available commands',
+                'help': u'Show available commands with their help'
+    }
+    print 'inst subclass help:', r
+    r = d.dispatch('inst subclass subcmd arg1 arg2 arg3 arg4 arg5')
+    assert r is None

     try:
         d.dispatch('')
     try:
         d.dispatch('')

+        assert False, 'It should raised a CommandNotSpecifiedError'

     except CommandNotSpecifiedError, e:
         print 'Not found:', e
     try:
         d.dispatch('sucutrule piquete culete')
     except CommandNotSpecifiedError, e:
         print 'Not found:', e
     try:
         d.dispatch('sucutrule piquete culete')

+        assert False, 'It should raised a CommandNotFoundError'

     except CommandNotFoundError, e:
         print 'Not found:', e
     try:
         d.dispatch('inst cmd3 arg1 arg2 arg3')
     except CommandNotFoundError, e:
         print 'Not found:', e
     try:
         d.dispatch('inst cmd3 arg1 arg2 arg3')

+        assert False, 'It should raised a CommandNotInHandlerError'

     except CommandNotInHandlerError, e:
         print 'Not found:', e
     try:
         d.dispatch('inst')
     except CommandNotInHandlerError, e:
         print 'Not found:', e
     try:
         d.dispatch('inst')

+        assert False, 'It should raised a CommandIsAHandlerError'

     except CommandIsAHandlerError, e:
         print 'Not found:', e
     except CommandIsAHandlerError, e:
         print 'Not found:', e

+    try:
+        d.dispatch('inst cmd2 "just one arg"')
+        assert False, 'It should raised a WrongArgumentsError'
+    except WrongArgumentsError, e:
+        print 'Bad arguments:', e
+    try:
+        d.dispatch('inst cmd2 arg1 arg2 "an extra argument"')
+        assert False, 'It should raised a WrongArgumentsError'
+    except WrongArgumentsError, e:
+        print 'Bad arguments:', e
+    try:
+        d.dispatch('inst cmd2 arg1 arg2 arg3="unexpected keyword arg"')
+        assert False, 'It should raised a WrongArgumentsError'
+    except WrongArgumentsError, e:
+        print 'Bad arguments:', e
+    try:
+        d.dispatch('inst cmd2 arg1 arg2 arg2="duplicated keyword arg"')
+        assert False, 'It should raised a WrongArgumentsError'
+    except WrongArgumentsError, e:
+        print 'Bad arguments:', e

     print
     print
 
     print
     print
 


@@ -501,6 +682,12 @@ if __name__ == '__main__':
     assert p == ([u'=hello'], {}), p
     p = parse_command(r'\thello')
     assert p == ([u'\thello'], {}), p
     assert p == ([u'=hello'], {}), p
     p = parse_command(r'\thello')
     assert p == ([u'\thello'], {}), p

+    p = parse_command(r'hello \n')
+    assert p == ([u'hello', u'\n'], {}), p
+    p = parse_command(r'hello \nmundo')
+    assert p == ([u'hello', u'\nmundo'], {}), p
+    p = parse_command(r'test \N')
+    assert p == ([u'test', None], {}), p

     p = parse_command(r'\N')
     assert p == ([None], {}), p
     p = parse_command(r'none=\N')
     p = parse_command(r'\N')
     assert p == ([None], {}), p
     p = parse_command(r'none=\N')


@@ -513,14 +700,12 @@ if __name__ == '__main__':
     assert p == ([u'\\None'], {}), p
     try:
         p = parse_command('hello=')
     assert p == ([u'\\None'], {}), p
     try:
         p = parse_command('hello=')

+        assert False, p + ' should raised a ParseError'

     except ParseError, e:
         pass
     except ParseError, e:
         pass

-    else:
-        assert False, p + ' should raised a ParseError'

     try:
         p = parse_command('"hello')
     try:
         p = parse_command('"hello')

+        assert False, p + ' should raised a ParseError'

     except ParseError, e:
         pass
     except ParseError, e:
         pass

-    else:
-        assert False, p + ' should raised a ParseError'