158 lines
4.3 KiB
Python
158 lines
4.3 KiB
Python
# A generic class to build line-oriented command interpreters
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#
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# Interpreters constructed with this class obey the following conventions:
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#
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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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#
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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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#
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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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#
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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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#
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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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# 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
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import sys
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import linecache
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PROMPT = '(Cmd) '
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IDENTCHARS = string.letters + string.digits + '_'
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class Cmd:
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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_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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def cmdloop(self, intro=None):
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self.preloop()
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if intro != 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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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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self.precmd()
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stop = self.onecmd(line)
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self.postcmd()
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self.postloop()
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def precmd(self):
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pass
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def postcmd(self):
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pass
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def preloop(self):
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pass
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def postloop(self):
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pass
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def onecmd(self, line):
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line = string.strip(line)
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if line == '?':
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line = 'help'
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elif line == '!':
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if hasattr(self, 'do_shell'):
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line = 'shell'
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else:
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self.default(line)
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return
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elif not line:
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self.emptyline()
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return
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self.lastcmd = 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], string.strip(line[i:])
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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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return self.onecmd(self.lastcmd)
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def default(self, line):
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print '*** Unknown syntax:', line
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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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print '*** No help on', `arg`
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return
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func()
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else:
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names = dir(self.__class__)
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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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for name in names:
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if name[:3] == 'do_':
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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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else:
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cmds_undoc.append(cmd)
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print
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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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