X-Git-Url: https://git.llucax.com/software/pymin.git/blobdiff_plain/3b99e97a104a8207085b241f20b1e98e58afb9fc..f607bd2a0afe9d30f7d033c90b6602d3b42e02a7:/dispatcher.py?ds=sidebyside

diff --git a/dispatcher.py b/dispatcher.py
index 78ae246..b10303f 100644
--- a/dispatcher.py
+++ b/dispatcher.py
@@ -1,89 +1,408 @@
 # vim: set et sts=4 sw=4 encoding=utf-8 :
 
-class BadRouteError(Exception):
+r"""Command dispatcher.
 
-	def __init__(self,cmd):
-		self.cmd = cmd
+This module provides a convenient and extensible command dispatching mechanism.
+It's based on Zope or Cherrypy dispatching (but implemented from the scratch)
+and translates commands to functions/objects/methods.
+"""
 
-	def __str__(self):
-		return repr(cmd)
+__ALL__ = ('Error', 'HandlerError', 'CommandNotFoundError', 'Handler',
+            'Dispatcher', 'handler', 'is_handler', 'get_help')
 
-class CommandNotFoundError(Exception):
+class Error(RuntimeError):
+    r"""Error(command) -> Error instance :: Base dispatching exceptions class.
 
-	def __init__(self,cmd):
-		self.cmd = cmd
+    All exceptions raised by the Dispatcher inherits from this one, so you can
+    easily catch any dispatching exception.
 
-	def __str__(self):
-		return repr(cmd)
+    command - is the command that raised the exception, expressed as a list of
+              paths (or subcommands).
+    """
+    pass
 
-class Dispatcher:
+class HandlerError(Error):
+    r"""HandlerError(command) -> HandlerError instance :: Base handlers error.
+
+    All exceptions raised by the handlers should inherit from this one, so
+    dispatching errors could be separated from real programming errors (bugs).
+    """
+    pass
+
+class CommandError(Error):
+    r"""CommandError(command) -> CommandError instance :: Base command error.
+
+    This exception is raised when there's a problem with the command itself.
+    It's the base class for all command (as a string) related error.
+    """
+
+    def __init__(self, command):
+        r"""Initialize the object.
+
+        See class documentation for more info.
+        """
+        self.command = command
+
+    def __str__(self):
+        return 'Command error: "%s"' % self.command
+
+class CommandNotFoundError(CommandError):
+    r"""CommandNotFoundError(command) -> CommandNotFoundError instance.
+
+    This exception is raised when the command received can't be dispatched
+    because there is no handlers to process it.
+    """
+
+    def __str__(self):
+        return 'Command not found: "%s"' % ' '.join(
+                                                repr(c) for c in self.command)
+
+class ParseError(CommandError):
+    r"""ParseError(command[, desc]) -> ParseError instance
+
+    This exception is raised when there is an error parsing a command.
+
+    command - Command that can't be parsed.
+
+    desc - Description of the error.
+    """
+
+    def __init__(self, command, desc="can't parse"):
+        r"""Initialize the object.
+
+        See class documentation for more info.
+        """
+        self.command = command
+        self.desc = desc
+
+    def __str__(self):
+        return 'Syntax error, %s: %s' % (self.desc, self.command)
+
+def handler(help):
+    r"""handler(help) -> function wrapper :: Mark a callable as a handler.
+
+    This is a decorator to mark a callable object as a dispatcher handler.
 
-	def __init__(self, routes=dict()):
-		self.routes = routes
+    help - Help string for the handler.
+    """
+    def wrapper(f):
+        if not help:
+            raise TypeError("'help' should not be empty")
+        f._dispatcher_help = help
+        return f
+    return wrapper
 
-	def dispatch(self, route):
-		route = route.split() # TODO considerar comillas
-		try:
-			handler = self.routes[route[0]]
-			route = route[1:]
-			while not callable(handler):
-				handler = getattr(handler, route[0])
-				route = route[1:]
-			handler(*route)
+def is_handler(handler):
+    r"is_handler(handler) -> bool :: Tell if a object is a handler."
+    return callable(handler) and hasattr(handler, '_dispatcher_help')
 
-		except KeyError:
-			raise CommandNotFoundError(route[0])
-		except AttributeError:
-			raise BadRouteError(route[0])
-		except IndexError:
-			pass
+def get_help(handler):
+    r"get_help(handler) -> unicode :: Get a handler's help string."
+    if not is_handler(handler):
+        raise TypeError("'%s' should be a handler" % handler.__name__)
+    return handler._dispatcher_help
 
+class Handler:
+    r"""Handler() -> Handler instance :: Base class for all dispatcher handlers.
 
-def test_func(*args):
-  	print 'func:', args
+    All dispatcher handlers should inherit from this class to have some extra
+    commands, like help.
+    """
 
+    @handler(u'List available commands.')
+    def commands(self):
+        r"""commands() -> generator :: List the available commands."""
+        return (a for a in dir(self) if is_handler(getattr(self, a)))
 
-class TestClassSubHandler:
+    @handler(u'Show available commands with their help.')
+    def help(self, command=None):
+        r"""help([command]) -> unicode/dict :: Show help on available commands.
 
-	def subcmd(self, *args):
-		print 'class.subclass.subcmd:', args
+        If command is specified, it returns the help of that particular command.
+        If not, it returns a dictionary which keys are the available commands
+        and values are the help strings.
+        """
+        if command is None:
+            return dict((a, get_help(getattr(self, a)))
+                        for a in dir(self) if is_handler(getattr(self, a)))
+        if not hasattr(self, command):
+            raise CommandNotFoundError(command)
+        handler = getattr(self, command)
+        if not is_handler(handler):
+            raise CommandNotFoundError(command)
+        return get_help(handler)
 
+def parse_command(command):
+    r"""parse_command(command) -> (args, kwargs) :: Parse a command.
 
-class TestClass:
+    This function parses a command and split it into a list of parameters. It
+    has a similar to bash commandline parser. Spaces are the basic token
+    separator but you can group several tokens into one by using (single or
+    double) quotes. You can escape the quotes with a backslash (\' and \"),
+    express a backslash literal using a double backslash (\\), use special
+    meaning escaped sequences (like \a, \n, \r, \b, \v) and use unescaped
+    single quotes inside a double quoted token or vice-versa.
 
-	def cmd1(self, *args):
-		print 'class.cmd1:', args
+    Additionally it accepts keyword arguments. When an (not-escaped) equal
+    sign (=) is found, the argument is considered a keyword, and the next
+    argument it's interpreted as its value.
 
-	def cmd2(self, *args):
-		print 'class.cmd2:', args
+    This function returns a tuple containing a list and a dictionary. The
+    first has the positional arguments, the second, the keyword arguments.
 
-	subclass = TestClassSubHandler()
+    There is no restriction about the order, a keyword argument can be
+    followed by a positional argument and vice-versa. All type of arguments
+    are grouped in the list/dict returned. The order of the positional
+    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).
+
+    Examples:
+
+    >>> parse_command('hello world')
+    ([u'hello', u'world'], {})
+    >>> parse_command('hello planet=earth')
+    ([u'hello'], {u'planet': u'earth'})
+    >>> parse_command('hello planet="third rock from the sun"')
+    ([u'hello'], {u'planet': u'third rock from the sun'})
+    >>> parse_command(u'  planet="third rock from the sun" hello ')
+    ([u'hello'], {u'planet': u'third rock from the sun'})
+    >>> parse_command(u'  planet="third rock from the sun" "hi, hello"'
+            '"how are you" ')
+    ([u'hi, hello', u'how are you'], {u'planet': u'third rock from the sun'})
+    >>> parse_command(u'one two three "fourth number"=four')
+    ([u'one', u'two', u'three'], {u'fourth number': u'four'})
+    >>> parse_command(u'one two three "fourth number=four"')
+    ([u'one', u'two', u'three', u'fourth number=four'], {})
+    >>> parse_command(u'one two three fourth\=four')
+    ([u'one', u'two', u'three', u'fourth=four'], {})
+    >>> parse_command(u'one two three fourth=four=five')
+    ([u'one', u'two', u'three'], {u'fourth': u'four=five'})
+    >>> parse_command(ur'nice\nlong\n\ttext')
+    ([u'nice\nlong\n\ttext'], {})
+    >>> parse_command('=hello')
+    ([u'=hello'], {})
+
+    This examples are syntax errors:
+    Missing quote: "hello world
+    Missing value: hello=
+    """
+    SEP, TOKEN, DQUOTE, SQUOTE, EQUAL = u' ', None, u'"', u"'", u'=' # states
+    separators = (u' ', u'\t', u'\v', u'\n') # token separators
+    escaped_chars = (u'a', u'n', u'r', u'b', u'v', u't') # escaped sequences
+    seq = []
+    dic = {}
+    buff = u''
+    escape = False
+    keyword = None
+    state = SEP
+    for n, c in enumerate(command):
+        # Escaped character
+        if escape:
+            for e in escaped_chars:
+                if c == e:
+                    buff += eval(u'"\\' + e + u'"')
+                    break
+            else:
+                buff += c
+            escape = False
+            continue
+        # Escaped sequence start
+        if c == u'\\':
+            escape = True
+            continue
+        # Looking for spaces
+        if state == SEP:
+            if c in separators:
+                continue
+            if buff and n != 2: # First item, not a escape sequence
+                if c == EQUAL: # Keyword found
+                    keyword = buff
+                    buff = u''
+                    continue
+                if keyword is not None: # Value found
+                    dic[str(keyword)] = buff
+                    keyword = None
+                else: # Normal parameter found
+                    seq.append(buff)
+                buff = u''
+            state = TOKEN
+        # Getting a token
+        if state == TOKEN:
+            if c == DQUOTE:
+                state = DQUOTE
+                continue
+            if c == SQUOTE:
+                state = SQUOTE
+                continue
+            # Check if a keyword is added
+            if c == EQUAL and keyword is None and buff:
+                keyword = buff
+                buff = u''
+                state = SEP
+                continue
+            if c in separators:
+                state = SEP
+                continue
+            buff += c
+            continue
+        # Inside a double quote
+        if state == DQUOTE:
+            if c == DQUOTE:
+                state = TOKEN
+                continue
+            buff += c
+            continue
+        # Inside a single quote
+        if state == SQUOTE:
+            if c == SQUOTE:
+                state = TOKEN
+                continue
+            buff += c
+            continue
+        assert 0, u'Unexpected state'
+    if state == DQUOTE or state == SQUOTE:
+        raise ParseError(command, u'missing closing quote (%s)' % state)
+    if not buff and keyword is not None:
+        raise ParseError(command,
+                        u'keyword argument (%s) without value' % keyword)
+    if buff:
+        if keyword is not None:
+            dic[str(keyword)] = buff
+        else:
+            seq.append(buff)
+    return (seq, dic)
+
+class Dispatcher:
+    r"""Dispatcher([routes]) -> Dispatcher instance :: Command dispatcher
+
+    This class provides a modular and extensible dispatching mechanism. You
+    can specify root 'routes' (as a dict where the key is the string of the
+    root command and the value is a callable object to handle that command,
+    or a subcommand if the callable is an instance and the command can be
+    sub-routed).
+
+    The command can have arguments, separated by (any number of) spaces.
+
+    The dispatcher tries to route the command as deeply as it can, passing
+    the other "path" components as arguments to the callable. To route the
+    command it inspects the callable attributes to find a suitable callable
+    attribute to handle the command in a more specific way, and so on.
+
+    Example:
+    >>> d = Dispatcher(dict(handler=some_handler))
+    >>> d.dispatch('handler attribute method arg1 arg2 "third argument"')
+
+    If 'some_handler' is an object with an 'attribute' that is another
+    object which has a method named 'method', then
+    some_handler.attribute.method('arg1', 'arg2') will be called. If
+    some_handler is a function, then some_handler('attribute', 'method',
+    'arg1', 'arg2') will be called. The handler "tree" can be as complex
+    and deep as you want.
+
+    If some command can't be dispatched (because there is no root handler or
+    there is no matching callable attribute), a CommandNotFoundError is raised.
+    """
+
+    def __init__(self, routes=dict()):
+        r"""Initialize the Dispatcher object.
+
+        See Dispatcher class documentation for more info.
+        """
+        self.routes = routes
+
+    def dispatch(self, route):
+        r"""dispatch(route) -> None :: Dispatch a command string.
+
+        This method searches for a suitable callable object in the routes
+        "tree" and call it, or raises a CommandNotFoundError if the command
+        can't be dispatched.
+        """
+        command = list()
+        (route, kwargs) = parse_command(route)
+        if not route:
+            raise CommandNotFoundError(command)
+        command.append(route[0])
+        handler = self.routes.get(route[0], None)
+        if handler is None:
+            raise CommandNotFoundError(command)
+        route = route[1:]
+        while not is_handler(handler):
+            if len(route) is 0:
+                raise CommandNotFoundError(command)
+            command.append(route[0])
+            if not hasattr(handler, route[0]):
+                raise CommandNotFoundError(command)
+            handler = getattr(handler, route[0])
+            route = route[1:]
+        return handler(*route, **kwargs)
 
 
 if __name__ == '__main__':
 
+    @handler(u"test: Print all the arguments, return nothing.")
+    def test_func(*args):
+        print 'func:', args
+
+    class TestClassSubHandler(Handler):
+        @handler(u"subcmd: Print all the arguments, return nothing.")
+        def subcmd(self, *args):
+            print 'class.subclass.subcmd:', args
+
+    class TestClass(Handler):
+        @handler(u"cmd1: 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
+        subclass = TestClassSubHandler()
+
+    test_class = TestClass()
+
     d = Dispatcher(dict(
             func=test_func,
-            inst=TestClass(),
+            inst=test_class,
     ))
 
-    d.dispatch('func arg1 arg2 arg3')
+    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')
+    try:
+        d.dispatch('')
+    except CommandNotFoundError, e:
+        print 'Not found:', e
+    try:
+        d.dispatch('sucutrule piquete culete')
+    except CommandNotFoundError, e:
+        print 'Not found:', e
+    try:
+        d.dispatch('inst cmd3 arg1 arg2 arg3')
+    except CommandNotFoundError, e:
+        print 'Not found:', e
 
-# Ideas / TODO:
-#
-# * Soportar comillas para argumentos con espacios y otros caracteres, onda:
-#   'misc set motd "Hola!\nEste es el servidor de garombia"'
-#
-# * Soportar keyword arguments, onda que:
-#   'dns set pepe=10.10.10.1 juan=10.10.10.2'
-#   se mapee a algo como: dns.set(pepe='10.10.10.1', juan='10.10.10.2')
-#
-# Estas cosas quedan sujetas a necesitada y a definición del protocolo.
-# Para mí lo ideal es que el protocolo de red sea igual que la consola del
-# usuario, porque después de todo no va a ser más que eso, mandar comanditos.
-#
-# Por otro lado, el cliente de consola, por que no es el cliente web pero
-# accedido via ssh usando un navegador de texto como w3m???
+    # Parser tests
+    print parse_command('hello world')
+    print parse_command('hello planet=earth')
+    print parse_command('hello planet="third rock from the sun"')
+    print parse_command(u'  planet="third rock from the sun" hello ')
+    print parse_command(u'  planet="third rock from the sun" "hi, hello"'
+                                                            '"how are you" ')
+    print parse_command(u'one two three "fourth number"=four')
+    print parse_command(u'one two three "fourth number=four"')
+    print parse_command(u'one two three fourth\=four')
+    print parse_command(u'one two three fourth=four=five')
+    print parse_command(ur'nice\nlong\n\ttext')
+    print parse_command('=hello')
+    try:
+        parse_command('hello=')
+    except ParseError, e:
+        print e
+    try:
+        parse_command('"hello')
+    except ParseError, e:
+        print e