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      1 """A generic class to build line-oriented command interpreters.
      2 
      3 Interpreters constructed with this class obey the following conventions:
      4 
      5 1. End of file on input is processed as the command 'EOF'.
      6 2. A command is parsed out of each line by collecting the prefix composed
      7    of characters in the identchars member.
      8 3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method
      9    is passed a single argument consisting of the remainder of the line.
     10 4. Typing an empty line repeats the last command.  (Actually, it calls the
     11    method `emptyline', which may be overridden in a subclass.)
     12 5. There is a predefined `help' method.  Given an argument `topic', it
     13    calls the command `help_topic'.  With no arguments, it lists all topics
     14    with defined help_ functions, broken into up to three topics; documented
     15    commands, miscellaneous help topics, and undocumented commands.
     16 6. The command '?' is a synonym for `help'.  The command '!' is a synonym
     17    for `shell', if a do_shell method exists.
     18 7. If completion is enabled, completing commands will be done automatically,
     19    and completing of commands args is done by calling complete_foo() with
     20    arguments text, line, begidx, endidx.  text is string we are matching
     21    against, all returned matches must begin with it.  line is the current
     22    input line (lstripped), begidx and endidx are the beginning and end
     23    indexes of the text being matched, which could be used to provide
     24    different completion depending upon which position the argument is in.
     25 
     26 The `default' method may be overridden to intercept commands for which there
     27 is no do_ method.
     28 
     29 The `completedefault' method may be overridden to intercept completions for
     30 commands that have no complete_ method.
     31 
     32 The data member `self.ruler' sets the character used to draw separator lines
     33 in the help messages.  If empty, no ruler line is drawn.  It defaults to "=".
     34 
     35 If the value of `self.intro' is nonempty when the cmdloop method is called,
     36 it is printed out on interpreter startup.  This value may be overridden
     37 via an optional argument to the cmdloop() method.
     38 
     39 The data members `self.doc_header', `self.misc_header', and
     40 `self.undoc_header' set the headers used for the help function's
     41 listings of documented functions, miscellaneous topics, and undocumented
     42 functions respectively.
     43 
     44 These interpreters use raw_input; thus, if the readline module is loaded,
     45 they automatically support Emacs-like command history and editing features.
     46 """
     47 
     48 import string
     49 
     50 __all__ = ["Cmd"]
     51 
     52 PROMPT = '(Cmd) '
     53 IDENTCHARS = string.ascii_letters + string.digits + '_'
     54 
     55 class Cmd:
     56     """A simple framework for writing line-oriented command interpreters.
     57 
     58     These are often useful for test harnesses, administrative tools, and
     59     prototypes that will later be wrapped in a more sophisticated interface.
     60 
     61     A Cmd instance or subclass instance is a line-oriented interpreter
     62     framework.  There is no good reason to instantiate Cmd itself; rather,
     63     it's useful as a superclass of an interpreter class you define yourself
     64     in order to inherit Cmd's methods and encapsulate action methods.
     65 
     66     """
     67     prompt = PROMPT
     68     identchars = IDENTCHARS
     69     ruler = '='
     70     lastcmd = ''
     71     intro = None
     72     doc_leader = ""
     73     doc_header = "Documented commands (type help <topic>):"
     74     misc_header = "Miscellaneous help topics:"
     75     undoc_header = "Undocumented commands:"
     76     nohelp = "*** No help on %s"
     77     use_rawinput = 1
     78 
     79     def __init__(self, completekey='tab', stdin=None, stdout=None):
     80         """Instantiate a line-oriented interpreter framework.
     81 
     82         The optional argument 'completekey' is the readline name of a
     83         completion key; it defaults to the Tab key. If completekey is
     84         not None and the readline module is available, command completion
     85         is done automatically. The optional arguments stdin and stdout
     86         specify alternate input and output file objects; if not specified,
     87         sys.stdin and sys.stdout are used.
     88 
     89         """
     90         import sys
     91         if stdin is not None:
     92             self.stdin = stdin
     93         else:
     94             self.stdin = sys.stdin
     95         if stdout is not None:
     96             self.stdout = stdout
     97         else:
     98             self.stdout = sys.stdout
     99         self.cmdqueue = []
    100         self.completekey = completekey
    101 
    102     def cmdloop(self, intro=None):
    103         """Repeatedly issue a prompt, accept input, parse an initial prefix
    104         off the received input, and dispatch to action methods, passing them
    105         the remainder of the line as argument.
    106 
    107         """
    108 
    109         self.preloop()
    110         if self.use_rawinput and self.completekey:
    111             try:
    112                 import readline
    113                 self.old_completer = readline.get_completer()
    114                 readline.set_completer(self.complete)
    115                 readline.parse_and_bind(self.completekey+": complete")
    116             except ImportError:
    117                 pass
    118         try:
    119             if intro is not None:
    120                 self.intro = intro
    121             if self.intro:
    122                 self.stdout.write(str(self.intro)+"\n")
    123             stop = None
    124             while not stop:
    125                 if self.cmdqueue:
    126                     line = self.cmdqueue.pop(0)
    127                 else:
    128                     if self.use_rawinput:
    129                         try:
    130                             line = raw_input(self.prompt)
    131                         except EOFError:
    132                             line = 'EOF'
    133                     else:
    134                         self.stdout.write(self.prompt)
    135                         self.stdout.flush()
    136                         line = self.stdin.readline()
    137                         if not len(line):
    138                             line = 'EOF'
    139                         else:
    140                             line = line.rstrip('\r\n')
    141                 line = self.precmd(line)
    142                 stop = self.onecmd(line)
    143                 stop = self.postcmd(stop, line)
    144             self.postloop()
    145         finally:
    146             if self.use_rawinput and self.completekey:
    147                 try:
    148                     import readline
    149                     readline.set_completer(self.old_completer)
    150                 except ImportError:
    151                     pass
    152 
    153 
    154     def precmd(self, line):
    155         """Hook method executed just before the command line is
    156         interpreted, but after the input prompt is generated and issued.
    157 
    158         """
    159         return line
    160 
    161     def postcmd(self, stop, line):
    162         """Hook method executed just after a command dispatch is finished."""
    163         return stop
    164 
    165     def preloop(self):
    166         """Hook method executed once when the cmdloop() method is called."""
    167         pass
    168 
    169     def postloop(self):
    170         """Hook method executed once when the cmdloop() method is about to
    171         return.
    172 
    173         """
    174         pass
    175 
    176     def parseline(self, line):
    177         """Parse the line into a command name and a string containing
    178         the arguments.  Returns a tuple containing (command, args, line).
    179         'command' and 'args' may be None if the line couldn't be parsed.
    180         """
    181         line = line.strip()
    182         if not line:
    183             return None, None, line
    184         elif line[0] == '?':
    185             line = 'help ' + line[1:]
    186         elif line[0] == '!':
    187             if hasattr(self, 'do_shell'):
    188                 line = 'shell ' + line[1:]
    189             else:
    190                 return None, None, line
    191         i, n = 0, len(line)
    192         while i < n and line[i] in self.identchars: i = i+1
    193         cmd, arg = line[:i], line[i:].strip()
    194         return cmd, arg, line
    195 
    196     def onecmd(self, line):
    197         """Interpret the argument as though it had been typed in response
    198         to the prompt.
    199 
    200         This may be overridden, but should not normally need to be;
    201         see the precmd() and postcmd() methods for useful execution hooks.
    202         The return value is a flag indicating whether interpretation of
    203         commands by the interpreter should stop.
    204 
    205         """
    206         cmd, arg, line = self.parseline(line)
    207         if not line:
    208             return self.emptyline()
    209         if cmd is None:
    210             return self.default(line)
    211         self.lastcmd = line
    212         if cmd == '':
    213             return self.default(line)
    214         else:
    215             try:
    216                 func = getattr(self, 'do_' + cmd)
    217             except AttributeError:
    218                 return self.default(line)
    219             return func(arg)
    220 
    221     def emptyline(self):
    222         """Called when an empty line is entered in response to the prompt.
    223 
    224         If this method is not overridden, it repeats the last nonempty
    225         command entered.
    226 
    227         """
    228         if self.lastcmd:
    229             return self.onecmd(self.lastcmd)
    230 
    231     def default(self, line):
    232         """Called on an input line when the command prefix is not recognized.
    233 
    234         If this method is not overridden, it prints an error message and
    235         returns.
    236 
    237         """
    238         self.stdout.write('*** Unknown syntax: %s\n'%line)
    239 
    240     def completedefault(self, *ignored):
    241         """Method called to complete an input line when no command-specific
    242         complete_*() method is available.
    243 
    244         By default, it returns an empty list.
    245 
    246         """
    247         return []
    248 
    249     def completenames(self, text, *ignored):
    250         dotext = 'do_'+text
    251         return [a[3:] for a in self.get_names() if a.startswith(dotext)]
    252 
    253     def complete(self, text, state):
    254         """Return the next possible completion for 'text'.
    255 
    256         If a command has not been entered, then complete against command list.
    257         Otherwise try to call complete_<command> to get list of completions.
    258         """
    259         if state == 0:
    260             import readline
    261             origline = readline.get_line_buffer()
    262             line = origline.lstrip()
    263             stripped = len(origline) - len(line)
    264             begidx = readline.get_begidx() - stripped
    265             endidx = readline.get_endidx() - stripped
    266             if begidx>0:
    267                 cmd, args, foo = self.parseline(line)
    268                 if cmd == '':
    269                     compfunc = self.completedefault
    270                 else:
    271                     try:
    272                         compfunc = getattr(self, 'complete_' + cmd)
    273                     except AttributeError:
    274                         compfunc = self.completedefault
    275             else:
    276                 compfunc = self.completenames
    277             self.completion_matches = compfunc(text, line, begidx, endidx)
    278         try:
    279             return self.completion_matches[state]
    280         except IndexError:
    281             return None
    282 
    283     def get_names(self):
    284         # This method used to pull in base class attributes
    285         # at a time dir() didn't do it yet.
    286         return dir(self.__class__)
    287 
    288     def complete_help(self, *args):
    289         commands = set(self.completenames(*args))
    290         topics = set(a[5:] for a in self.get_names()
    291                      if a.startswith('help_' + args[0]))
    292         return list(commands | topics)
    293 
    294     def do_help(self, arg):
    295         if arg:
    296             # XXX check arg syntax
    297             try:
    298                 func = getattr(self, 'help_' + arg)
    299             except AttributeError:
    300                 try:
    301                     doc=getattr(self, 'do_' + arg).__doc__
    302                     if doc:
    303                         self.stdout.write("%s\n"%str(doc))
    304                         return
    305                 except AttributeError:
    306                     pass
    307                 self.stdout.write("%s\n"%str(self.nohelp % (arg,)))
    308                 return
    309             func()
    310         else:
    311             names = self.get_names()
    312             cmds_doc = []
    313             cmds_undoc = []
    314             help = {}
    315             for name in names:
    316                 if name[:5] == 'help_':
    317                     help[name[5:]]=1
    318             names.sort()
    319             # There can be duplicates if routines overridden
    320             prevname = ''
    321             for name in names:
    322                 if name[:3] == 'do_':
    323                     if name == prevname:
    324                         continue
    325                     prevname = name
    326                     cmd=name[3:]
    327                     if cmd in help:
    328                         cmds_doc.append(cmd)
    329                         del help[cmd]
    330                     elif getattr(self, name).__doc__:
    331                         cmds_doc.append(cmd)
    332                     else:
    333                         cmds_undoc.append(cmd)
    334             self.stdout.write("%s\n"%str(self.doc_leader))
    335             self.print_topics(self.doc_header,   cmds_doc,   15,80)
    336             self.print_topics(self.misc_header,  help.keys(),15,80)
    337             self.print_topics(self.undoc_header, cmds_undoc, 15,80)
    338 
    339     def print_topics(self, header, cmds, cmdlen, maxcol):
    340         if cmds:
    341             self.stdout.write("%s\n"%str(header))
    342             if self.ruler:
    343                 self.stdout.write("%s\n"%str(self.ruler * len(header)))
    344             self.columnize(cmds, maxcol-1)
    345             self.stdout.write("\n")
    346 
    347     def columnize(self, list, displaywidth=80):
    348         """Display a list of strings as a compact set of columns.
    349 
    350         Each column is only as wide as necessary.
    351         Columns are separated by two spaces (one was not legible enough).
    352         """
    353         if not list:
    354             self.stdout.write("<empty>\n")
    355             return
    356         nonstrings = [i for i in range(len(list))
    357                         if not isinstance(list[i], str)]
    358         if nonstrings:
    359             raise TypeError, ("list[i] not a string for i in %s" %
    360                               ", ".join(map(str, nonstrings)))
    361         size = len(list)
    362         if size == 1:
    363             self.stdout.write('%s\n'%str(list[0]))
    364             return
    365         # Try every row count from 1 upwards
    366         for nrows in range(1, len(list)):
    367             ncols = (size+nrows-1) // nrows
    368             colwidths = []
    369             totwidth = -2
    370             for col in range(ncols):
    371                 colwidth = 0
    372                 for row in range(nrows):
    373                     i = row + nrows*col
    374                     if i >= size:
    375                         break
    376                     x = list[i]
    377                     colwidth = max(colwidth, len(x))
    378                 colwidths.append(colwidth)
    379                 totwidth += colwidth + 2
    380                 if totwidth > displaywidth:
    381                     break
    382             if totwidth <= displaywidth:
    383                 break
    384         else:
    385             nrows = len(list)
    386             ncols = 1
    387             colwidths = [0]
    388         for row in range(nrows):
    389             texts = []
    390             for col in range(ncols):
    391                 i = row + nrows*col
    392                 if i >= size:
    393                     x = ""
    394                 else:
    395                     x = list[i]
    396                 texts.append(x)
    397             while texts and not texts[-1]:
    398                 del texts[-1]
    399             for col in range(len(texts)):
    400                 texts[col] = texts[col].ljust(colwidths[col])
    401             self.stdout.write("%s\n"%str("  ".join(texts)))
    402