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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 line == 'EOF' :
    213             self.lastcmd = ''
    214         if cmd == '':
    215             return self.default(line)
    216         else:
    217             try:
    218                 func = getattr(self, 'do_' + cmd)
    219             except AttributeError:
    220                 return self.default(line)
    221             return func(arg)
    222 
    223     def emptyline(self):
    224         """Called when an empty line is entered in response to the prompt.
    225 
    226         If this method is not overridden, it repeats the last nonempty
    227         command entered.
    228 
    229         """
    230         if self.lastcmd:
    231             return self.onecmd(self.lastcmd)
    232 
    233     def default(self, line):
    234         """Called on an input line when the command prefix is not recognized.
    235 
    236         If this method is not overridden, it prints an error message and
    237         returns.
    238 
    239         """
    240         self.stdout.write('*** Unknown syntax: %s\n'%line)
    241 
    242     def completedefault(self, *ignored):
    243         """Method called to complete an input line when no command-specific
    244         complete_*() method is available.
    245 
    246         By default, it returns an empty list.
    247 
    248         """
    249         return []
    250 
    251     def completenames(self, text, *ignored):
    252         dotext = 'do_'+text
    253         return [a[3:] for a in self.get_names() if a.startswith(dotext)]
    254 
    255     def complete(self, text, state):
    256         """Return the next possible completion for 'text'.
    257 
    258         If a command has not been entered, then complete against command list.
    259         Otherwise try to call complete_<command> to get list of completions.
    260         """
    261         if state == 0:
    262             import readline
    263             origline = readline.get_line_buffer()
    264             line = origline.lstrip()
    265             stripped = len(origline) - len(line)
    266             begidx = readline.get_begidx() - stripped
    267             endidx = readline.get_endidx() - stripped
    268             if begidx>0:
    269                 cmd, args, foo = self.parseline(line)
    270                 if cmd == '':
    271                     compfunc = self.completedefault
    272                 else:
    273                     try:
    274                         compfunc = getattr(self, 'complete_' + cmd)
    275                     except AttributeError:
    276                         compfunc = self.completedefault
    277             else:
    278                 compfunc = self.completenames
    279             self.completion_matches = compfunc(text, line, begidx, endidx)
    280         try:
    281             return self.completion_matches[state]
    282         except IndexError:
    283             return None
    284 
    285     def get_names(self):
    286         # This method used to pull in base class attributes
    287         # at a time dir() didn't do it yet.
    288         return dir(self.__class__)
    289 
    290     def complete_help(self, *args):
    291         commands = set(self.completenames(*args))
    292         topics = set(a[5:] for a in self.get_names()
    293                      if a.startswith('help_' + args[0]))
    294         return list(commands | topics)
    295 
    296     def do_help(self, arg):
    297         'List available commands with "help" or detailed help with "help cmd".'
    298         if arg:
    299             # XXX check arg syntax
    300             try:
    301                 func = getattr(self, 'help_' + arg)
    302             except AttributeError:
    303                 try:
    304                     doc=getattr(self, 'do_' + arg).__doc__
    305                     if doc:
    306                         self.stdout.write("%s\n"%str(doc))
    307                         return
    308                 except AttributeError:
    309                     pass
    310                 self.stdout.write("%s\n"%str(self.nohelp % (arg,)))
    311                 return
    312             func()
    313         else:
    314             names = self.get_names()
    315             cmds_doc = []
    316             cmds_undoc = []
    317             help = {}
    318             for name in names:
    319                 if name[:5] == 'help_':
    320                     help[name[5:]]=1
    321             names.sort()
    322             # There can be duplicates if routines overridden
    323             prevname = ''
    324             for name in names:
    325                 if name[:3] == 'do_':
    326                     if name == prevname:
    327                         continue
    328                     prevname = name
    329                     cmd=name[3:]
    330                     if cmd in help:
    331                         cmds_doc.append(cmd)
    332                         del help[cmd]
    333                     elif getattr(self, name).__doc__:
    334                         cmds_doc.append(cmd)
    335                     else:
    336                         cmds_undoc.append(cmd)
    337             self.stdout.write("%s\n"%str(self.doc_leader))
    338             self.print_topics(self.doc_header,   cmds_doc,   15,80)
    339             self.print_topics(self.misc_header,  help.keys(),15,80)
    340             self.print_topics(self.undoc_header, cmds_undoc, 15,80)
    341 
    342     def print_topics(self, header, cmds, cmdlen, maxcol):
    343         if cmds:
    344             self.stdout.write("%s\n"%str(header))
    345             if self.ruler:
    346                 self.stdout.write("%s\n"%str(self.ruler * len(header)))
    347             self.columnize(cmds, maxcol-1)
    348             self.stdout.write("\n")
    349 
    350     def columnize(self, list, displaywidth=80):
    351         """Display a list of strings as a compact set of columns.
    352 
    353         Each column is only as wide as necessary.
    354         Columns are separated by two spaces (one was not legible enough).
    355         """
    356         if not list:
    357             self.stdout.write("<empty>\n")
    358             return
    359         nonstrings = [i for i in range(len(list))
    360                         if not isinstance(list[i], str)]
    361         if nonstrings:
    362             raise TypeError, ("list[i] not a string for i in %s" %
    363                               ", ".join(map(str, nonstrings)))
    364         size = len(list)
    365         if size == 1:
    366             self.stdout.write('%s\n'%str(list[0]))
    367             return
    368         # Try every row count from 1 upwards
    369         for nrows in range(1, len(list)):
    370             ncols = (size+nrows-1) // nrows
    371             colwidths = []
    372             totwidth = -2
    373             for col in range(ncols):
    374                 colwidth = 0
    375                 for row in range(nrows):
    376                     i = row + nrows*col
    377                     if i >= size:
    378                         break
    379                     x = list[i]
    380                     colwidth = max(colwidth, len(x))
    381                 colwidths.append(colwidth)
    382                 totwidth += colwidth + 2
    383                 if totwidth > displaywidth:
    384                     break
    385             if totwidth <= displaywidth:
    386                 break
    387         else:
    388             nrows = len(list)
    389             ncols = 1
    390             colwidths = [0]
    391         for row in range(nrows):
    392             texts = []
    393             for col in range(ncols):
    394                 i = row + nrows*col
    395                 if i >= size:
    396                     x = ""
    397                 else:
    398                     x = list[i]
    399                 texts.append(x)
    400             while texts and not texts[-1]:
    401                 del texts[-1]
    402             for col in range(len(texts)):
    403                 texts[col] = texts[col].ljust(colwidths[col])
    404             self.stdout.write("%s\n"%str("  ".join(texts)))
    405