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svn+ssh://pythondev@svn.python.org/python/branches/py3k ........ r83380 | r.david.murray | 2010-07-31 23:31:09 -0400 (Sat, 31 Jul 2010) | 17 lines #8620: Cmd no longer truncates last character if stdin ends without newline Cmd used to blindly chop off the last character of every input line. If the input reached EOF and there was no final new line, it would truncate the last character of the last command. This fix instead strips trailing \r\n from the input lines. While this is a small behavior change, it should not break any working code, since feeding a '\r\n' terminated file to Cmd would previously leave the \r's on the lines, resulting in failed command execution. I wrote the unit test in preparation for a PyOhio TeachMe session run by Catherine Devlin, and we can thank Catherine and the PyOhio session attendees for the fix. I've added Catherine to the Acks file for organizing and leading the TeachMe session, out of which we will hopefully get some new contributors. ........
404 lines
14 KiB
Python
404 lines
14 KiB
Python
"""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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"""
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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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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', stdin=None, stdout=None):
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"""Instantiate a line-oriented interpreter framework.
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The optional argument 'completekey' is the readline name of a
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completion key; it defaults to the Tab key. If completekey is
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not None and the readline module is available, command completion
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is done automatically. The optional arguments stdin and stdout
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specify alternate input and output file objects; if not specified,
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sys.stdin and sys.stdout are used.
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"""
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import sys
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if stdin is not None:
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self.stdin = stdin
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else:
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self.stdin = sys.stdin
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if stdout is not None:
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self.stdout = stdout
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else:
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self.stdout = sys.stdout
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self.cmdqueue = []
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self.completekey = completekey
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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 self.use_rawinput and self.completekey:
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try:
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import readline
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self.old_completer = readline.get_completer()
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readline.set_completer(self.complete)
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readline.parse_and_bind(self.completekey+": complete")
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except ImportError:
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pass
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try:
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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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self.stdout.write(str(self.intro)+"\n")
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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.pop(0)
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else:
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if self.use_rawinput:
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try:
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line = input(self.prompt)
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except EOFError:
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line = 'EOF'
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else:
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self.stdout.write(self.prompt)
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self.stdout.flush()
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line = self.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.rstrip('\r\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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finally:
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if self.use_rawinput and self.completekey:
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try:
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import readline
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readline.set_completer(self.old_completer)
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except ImportError:
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pass
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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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"""Parse the line into a command name and a string containing
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the arguments. Returns a tuple containing (command, args, line).
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'command' and 'args' may be None if the line couldn't be parsed.
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"""
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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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self.stdout.write('*** Unknown syntax: %s\n'%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.pop(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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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 AttributeError:
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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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self.stdout.write("%s\n"%str(doc))
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return
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except AttributeError:
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pass
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self.stdout.write("%s\n"%str(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 cmd in help:
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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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self.stdout.write("%s\n"%str(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, list(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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self.stdout.write("%s\n"%str(header))
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if self.ruler:
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self.stdout.write("%s\n"%str(self.ruler * len(header)))
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self.columnize(cmds, maxcol-1)
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self.stdout.write("\n")
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def columnize(self, list, displaywidth=80):
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"""Display a list of strings as a compact set of columns.
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Each column is only as wide as necessary.
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Columns are separated by two spaces (one was not legible enough).
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"""
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if not list:
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self.stdout.write("<empty>\n")
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return
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nonstrings = [i for i in range(len(list))
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if not isinstance(list[i], str)]
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if nonstrings:
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raise TypeError("list[i] not a string for i in %s"
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% ", ".join(map(str, nonstrings)))
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size = len(list)
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if size == 1:
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self.stdout.write('%s\n'%str(list[0]))
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return
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# Try every row count from 1 upwards
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for nrows in range(1, len(list)):
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ncols = (size+nrows-1) // nrows
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colwidths = []
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totwidth = -2
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for col in range(ncols):
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colwidth = 0
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for row in range(nrows):
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i = row + nrows*col
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if i >= size:
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break
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x = list[i]
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colwidth = max(colwidth, len(x))
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colwidths.append(colwidth)
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totwidth += colwidth + 2
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if totwidth > displaywidth:
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break
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if totwidth <= displaywidth:
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break
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else:
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nrows = len(list)
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ncols = 1
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colwidths = [0]
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for row in range(nrows):
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texts = []
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for col in range(ncols):
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i = row + nrows*col
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if i >= size:
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x = ""
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else:
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x = list[i]
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texts.append(x)
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while texts and not texts[-1]:
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del texts[-1]
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for col in range(len(texts)):
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texts[col] = texts[col].ljust(colwidths[col])
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self.stdout.write("%s\n"%str(" ".join(texts)))
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