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330 lines
12 KiB
330 lines
12 KiB
"""A generic class to build line-oriented command interpreters. |
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Interpreters constructed with this class obey the following conventions: |
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1. End of file on input is processed as the command 'EOF'. |
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2. A command is parsed out of each line by collecting the prefix composed |
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of characters in the identchars member. |
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3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method |
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is passed a single argument consisting of the remainder of the line. |
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4. Typing an empty line repeats the last command. (Actually, it calls the |
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method `emptyline', which may be overridden in a subclass.) |
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5. There is a predefined `help' method. Given an argument `topic', it |
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calls the command `help_topic'. With no arguments, it lists all topics |
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with defined help_ functions, broken into up to three topics; documented |
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commands, miscellaneous help topics, and undocumented commands. |
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6. The command '?' is a synonym for `help'. The command '!' is a synonym |
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for `shell', if a do_shell method exists. |
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7. If completion is enabled, completing commands will be done automatically, |
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and completing of commands args is done by calling complete_foo() with |
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arguments text, line, begidx, endidx. text is string we are matching |
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against, all returned matches must begin with it. line is the current |
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input line (lstripped), begidx and endidx are the beginning and end |
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indexes of the text being matched, which could be used to provide |
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different completion depending upon which position the argument is in. |
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The `default' method may be overridden to intercept commands for which there |
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is no do_ method. |
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The `completedefault' method may be overridden to intercept completions for |
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commands that have no complete_ method. |
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The data member `self.ruler' sets the character used to draw separator lines |
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in the help messages. If empty, no ruler line is drawn. It defaults to "=". |
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If the value of `self.intro' is nonempty when the cmdloop method is called, |
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it is printed out on interpreter startup. This value may be overridden |
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via an optional argument to the cmdloop() method. |
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The data members `self.doc_header', `self.misc_header', and |
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`self.undoc_header' set the headers used for the help function's |
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listings of documented functions, miscellaneous topics, and undocumented |
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functions respectively. |
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These interpreters use raw_input; thus, if the readline module is loaded, |
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they automatically support Emacs-like command history and editing features. |
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""" |
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import string, sys |
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__all__ = ["Cmd"] |
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PROMPT = '(Cmd) ' |
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IDENTCHARS = string.ascii_letters + string.digits + '_' |
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class Cmd: |
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"""A simple framework for writing line-oriented command interpreters. |
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These are often useful for test harnesses, administrative tools, and |
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prototypes that will later be wrapped in a more sophisticated interface. |
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A Cmd instance or subclass instance is a line-oriented interpreter |
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framework. There is no good reason to instantiate Cmd itself; rather, |
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it's useful as a superclass of an interpreter class you define yourself |
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in order to inherit Cmd's methods and encapsulate action methods. |
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""" |
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prompt = PROMPT |
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identchars = IDENTCHARS |
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ruler = '=' |
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lastcmd = '' |
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cmdqueue = [] |
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intro = None |
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doc_leader = "" |
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doc_header = "Documented commands (type help <topic>):" |
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misc_header = "Miscellaneous help topics:" |
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undoc_header = "Undocumented commands:" |
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nohelp = "*** No help on %s" |
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use_rawinput = 1 |
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def __init__(self, completekey='tab'): |
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"""Instantiate a line-oriented interpreter framework. |
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The optional argument is the readline name of a completion key; |
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it defaults to the Tab key. If completekey is not None and the |
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readline module is available, command completion is done |
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automatically. |
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""" |
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if completekey: |
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try: |
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import readline |
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readline.set_completer(self.complete) |
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readline.parse_and_bind(completekey+": complete") |
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except ImportError: |
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pass |
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def cmdloop(self, intro=None): |
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"""Repeatedly issue a prompt, accept input, parse an initial prefix |
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off the received input, and dispatch to action methods, passing them |
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the remainder of the line as argument. |
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""" |
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self.preloop() |
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if intro is not None: |
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self.intro = intro |
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if self.intro: |
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print self.intro |
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stop = None |
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while not stop: |
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if self.cmdqueue: |
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line = self.cmdqueue[0] |
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del self.cmdqueue[0] |
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else: |
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if self.use_rawinput: |
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try: |
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line = raw_input(self.prompt) |
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except EOFError: |
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line = 'EOF' |
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else: |
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sys.stdout.write(self.prompt) |
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sys.stdout.flush() |
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line = sys.stdin.readline() |
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if not len(line): |
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line = 'EOF' |
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else: |
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line = line[:-1] # chop \n |
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line = self.precmd(line) |
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stop = self.onecmd(line) |
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stop = self.postcmd(stop, line) |
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self.postloop() |
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def precmd(self, line): |
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"""Hook method executed just before the command line is |
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interpreted, but after the input prompt is generated and issued. |
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""" |
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return line |
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def postcmd(self, stop, line): |
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"""Hook method executed just after a command dispatch is finished.""" |
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return stop |
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def preloop(self): |
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"""Hook method executed once when the cmdloop() method is called.""" |
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pass |
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def postloop(self): |
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"""Hook method executed once when the cmdloop() method is about to |
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return. |
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""" |
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pass |
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def parseline(self, line): |
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line = line.strip() |
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if not line: |
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return None, None, line |
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elif line[0] == '?': |
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line = 'help ' + line[1:] |
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elif line[0] == '!': |
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if hasattr(self, 'do_shell'): |
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line = 'shell ' + line[1:] |
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else: |
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return None, None, line |
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i, n = 0, len(line) |
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while i < n and line[i] in self.identchars: i = i+1 |
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cmd, arg = line[:i], line[i:].strip() |
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return cmd, arg, line |
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def onecmd(self, line): |
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"""Interpret the argument as though it had been typed in response |
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to the prompt. |
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This may be overridden, but should not normally need to be; |
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see the precmd() and postcmd() methods for useful execution hooks. |
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The return value is a flag indicating whether interpretation of |
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commands by the interpreter should stop. |
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""" |
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cmd, arg, line = self.parseline(line) |
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if not line: |
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return self.emptyline() |
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if cmd is None: |
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return self.default(line) |
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self.lastcmd = line |
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if cmd == '': |
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return self.default(line) |
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else: |
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try: |
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func = getattr(self, 'do_' + cmd) |
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except AttributeError: |
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return self.default(line) |
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return func(arg) |
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def emptyline(self): |
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"""Called when an empty line is entered in response to the prompt. |
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If this method is not overridden, it repeats the last nonempty |
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command entered. |
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""" |
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if self.lastcmd: |
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return self.onecmd(self.lastcmd) |
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def default(self, line): |
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"""Called on an input line when the command prefix is not recognized. |
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If this method is not overridden, it prints an error message and |
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returns. |
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""" |
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print '*** Unknown syntax:', line |
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def completedefault(self, *ignored): |
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"""Method called to complete an input line when no command-specific |
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complete_*() method is available. |
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By default, it returns an empty list. |
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""" |
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return [] |
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def completenames(self, text, *ignored): |
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dotext = 'do_'+text |
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return [a[3:] for a in self.get_names() if a.startswith(dotext)] |
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def complete(self, text, state): |
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"""Return the next possible completion for 'text'. |
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If a command has not been entered, then complete against command list. |
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Otherwise try to call complete_<command> to get list of completions. |
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""" |
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if state == 0: |
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import readline |
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origline = readline.get_line_buffer() |
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line = origline.lstrip() |
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stripped = len(origline) - len(line) |
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begidx = readline.get_begidx() - stripped |
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endidx = readline.get_endidx() - stripped |
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if begidx>0: |
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cmd, args, foo = self.parseline(line) |
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if cmd == '': |
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compfunc = self.completedefault |
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else: |
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try: |
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compfunc = getattr(self, 'complete_' + cmd) |
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except AttributeError: |
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compfunc = self.completedefault |
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else: |
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compfunc = self.completenames |
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self.completion_matches = compfunc(text, line, begidx, endidx) |
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try: |
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return self.completion_matches[state] |
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except IndexError: |
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return None |
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def get_names(self): |
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# Inheritance says we have to look in class and |
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# base classes; order is not important. |
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names = [] |
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classes = [self.__class__] |
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while classes: |
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aclass = classes[0] |
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if aclass.__bases__: |
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classes = classes + list(aclass.__bases__) |
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names = names + dir(aclass) |
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del classes[0] |
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return names |
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def complete_help(self, *args): |
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return self.completenames(*args) |
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def do_help(self, arg): |
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if arg: |
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# XXX check arg syntax |
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try: |
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func = getattr(self, 'help_' + arg) |
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except: |
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try: |
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doc=getattr(self, 'do_' + arg).__doc__ |
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if doc: |
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print doc |
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return |
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except: |
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pass |
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print self.nohelp % (arg,) |
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return |
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func() |
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else: |
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names = self.get_names() |
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cmds_doc = [] |
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cmds_undoc = [] |
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help = {} |
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for name in names: |
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if name[:5] == 'help_': |
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help[name[5:]]=1 |
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names.sort() |
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# There can be duplicates if routines overridden |
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prevname = '' |
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for name in names: |
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if name[:3] == 'do_': |
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if name == prevname: |
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continue |
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prevname = name |
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cmd=name[3:] |
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if help.has_key(cmd): |
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cmds_doc.append(cmd) |
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del help[cmd] |
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elif getattr(self, name).__doc__: |
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cmds_doc.append(cmd) |
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else: |
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cmds_undoc.append(cmd) |
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print self.doc_leader |
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self.print_topics(self.doc_header, cmds_doc, 15,80) |
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self.print_topics(self.misc_header, help.keys(),15,80) |
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self.print_topics(self.undoc_header, cmds_undoc, 15,80) |
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def print_topics(self, header, cmds, cmdlen, maxcol): |
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if cmds: |
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print header |
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if self.ruler: |
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print self.ruler * len(header) |
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(cmds_per_line,junk)=divmod(maxcol,cmdlen) |
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col=cmds_per_line |
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for cmd in cmds: |
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if col==0: print |
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print (("%-"+`cmdlen`+"s") % cmd), |
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col = (col+1) % cmds_per_line |
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print "\n"
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