1"""A generic class to build line-oriented command interpreters. 2 3Interpreters constructed with this class obey the following conventions: 4 51. End of file on input is processed as the command 'EOF'. 62. A command is parsed out of each line by collecting the prefix composed 7 of characters in the identchars member. 83. 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. 104. Typing an empty line repeats the last command. (Actually, it calls the 11 method `emptyline', which may be overridden in a subclass.) 125. 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. 166. The command '?' is a synonym for `help'. The command '!' is a synonym 17 for `shell', if a do_shell method exists. 187. 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 26The `default' method may be overridden to intercept commands for which there 27is no do_ method. 28 29The `completedefault' method may be overridden to intercept completions for 30commands that have no complete_ method. 31 32The data member `self.ruler' sets the character used to draw separator lines 33in the help messages. If empty, no ruler line is drawn. It defaults to "=". 34 35If the value of `self.intro' is nonempty when the cmdloop method is called, 36it is printed out on interpreter startup. This value may be overridden 37via an optional argument to the cmdloop() method. 38 39The data members `self.doc_header', `self.misc_header', and 40`self.undoc_header' set the headers used for the help function's 41listings of documented functions, miscellaneous topics, and undocumented 42functions respectively. 43""" 44 45import inspect, string, sys 46 47__all__ = ["Cmd"] 48 49PROMPT = '(Cmd) ' 50IDENTCHARS = string.ascii_letters + string.digits + '_' 51 52class Cmd: 53 """A simple framework for writing line-oriented command interpreters. 54 55 These are often useful for test harnesses, administrative tools, and 56 prototypes that will later be wrapped in a more sophisticated interface. 57 58 A Cmd instance or subclass instance is a line-oriented interpreter 59 framework. There is no good reason to instantiate Cmd itself; rather, 60 it's useful as a superclass of an interpreter class you define yourself 61 in order to inherit Cmd's methods and encapsulate action methods. 62 63 """ 64 prompt = PROMPT 65 identchars = IDENTCHARS 66 ruler = '=' 67 lastcmd = '' 68 intro = None 69 doc_leader = "" 70 doc_header = "Documented commands (type help <topic>):" 71 misc_header = "Miscellaneous help topics:" 72 undoc_header = "Undocumented commands:" 73 nohelp = "*** No help on %s" 74 use_rawinput = 1 75 76 def __init__(self, completekey='tab', stdin=None, stdout=None): 77 """Instantiate a line-oriented interpreter framework. 78 79 The optional argument 'completekey' is the readline name of a 80 completion key; it defaults to the Tab key. If completekey is 81 not None and the readline module is available, command completion 82 is done automatically. The optional arguments stdin and stdout 83 specify alternate input and output file objects; if not specified, 84 sys.stdin and sys.stdout are used. 85 86 """ 87 if stdin is not None: 88 self.stdin = stdin 89 else: 90 self.stdin = sys.stdin 91 if stdout is not None: 92 self.stdout = stdout 93 else: 94 self.stdout = sys.stdout 95 self.cmdqueue = [] 96 self.completekey = completekey 97 98 def cmdloop(self, intro=None): 99 """Repeatedly issue a prompt, accept input, parse an initial prefix 100 off the received input, and dispatch to action methods, passing them 101 the remainder of the line as argument. 102 103 """ 104 105 self.preloop() 106 if self.use_rawinput and self.completekey: 107 try: 108 import readline 109 self.old_completer = readline.get_completer() 110 readline.set_completer(self.complete) 111 if readline.backend == "editline": 112 if self.completekey == 'tab': 113 # libedit uses "^I" instead of "tab" 114 command_string = "bind ^I rl_complete" 115 else: 116 command_string = f"bind {self.completekey} rl_complete" 117 else: 118 command_string = f"{self.completekey}: complete" 119 readline.parse_and_bind(command_string) 120 except ImportError: 121 pass 122 try: 123 if intro is not None: 124 self.intro = intro 125 if self.intro: 126 self.stdout.write(str(self.intro)+"\n") 127 stop = None 128 while not stop: 129 if self.cmdqueue: 130 line = self.cmdqueue.pop(0) 131 else: 132 if self.use_rawinput: 133 try: 134 line = input(self.prompt) 135 except EOFError: 136 line = 'EOF' 137 else: 138 self.stdout.write(self.prompt) 139 self.stdout.flush() 140 line = self.stdin.readline() 141 if not len(line): 142 line = 'EOF' 143 else: 144 line = line.rstrip('\r\n') 145 line = self.precmd(line) 146 stop = self.onecmd(line) 147 stop = self.postcmd(stop, line) 148 self.postloop() 149 finally: 150 if self.use_rawinput and self.completekey: 151 try: 152 import readline 153 readline.set_completer(self.old_completer) 154 except ImportError: 155 pass 156 157 158 def precmd(self, line): 159 """Hook method executed just before the command line is 160 interpreted, but after the input prompt is generated and issued. 161 162 """ 163 return line 164 165 def postcmd(self, stop, line): 166 """Hook method executed just after a command dispatch is finished.""" 167 return stop 168 169 def preloop(self): 170 """Hook method executed once when the cmdloop() method is called.""" 171 pass 172 173 def postloop(self): 174 """Hook method executed once when the cmdloop() method is about to 175 return. 176 177 """ 178 pass 179 180 def parseline(self, line): 181 """Parse the line into a command name and a string containing 182 the arguments. Returns a tuple containing (command, args, line). 183 'command' and 'args' may be None if the line couldn't be parsed. 184 """ 185 line = line.strip() 186 if not line: 187 return None, None, line 188 elif line[0] == '?': 189 line = 'help ' + line[1:] 190 elif line[0] == '!': 191 if hasattr(self, 'do_shell'): 192 line = 'shell ' + line[1:] 193 else: 194 return None, None, line 195 i, n = 0, len(line) 196 while i < n and line[i] in self.identchars: i = i+1 197 cmd, arg = line[:i], line[i:].strip() 198 return cmd, arg, line 199 200 def onecmd(self, line): 201 """Interpret the argument as though it had been typed in response 202 to the prompt. 203 204 This may be overridden, but should not normally need to be; 205 see the precmd() and postcmd() methods for useful execution hooks. 206 The return value is a flag indicating whether interpretation of 207 commands by the interpreter should stop. 208 209 """ 210 cmd, arg, line = self.parseline(line) 211 if not line: 212 return self.emptyline() 213 if cmd is None: 214 return self.default(line) 215 self.lastcmd = line 216 if line == 'EOF' : 217 self.lastcmd = '' 218 if cmd == '': 219 return self.default(line) 220 else: 221 func = getattr(self, 'do_' + cmd, None) 222 if func is None: 223 return self.default(line) 224 return func(arg) 225 226 def emptyline(self): 227 """Called when an empty line is entered in response to the prompt. 228 229 If this method is not overridden, it repeats the last nonempty 230 command entered. 231 232 """ 233 if self.lastcmd: 234 return self.onecmd(self.lastcmd) 235 236 def default(self, line): 237 """Called on an input line when the command prefix is not recognized. 238 239 If this method is not overridden, it prints an error message and 240 returns. 241 242 """ 243 self.stdout.write('*** Unknown syntax: %s\n'%line) 244 245 def completedefault(self, *ignored): 246 """Method called to complete an input line when no command-specific 247 complete_*() method is available. 248 249 By default, it returns an empty list. 250 251 """ 252 return [] 253 254 def completenames(self, text, *ignored): 255 dotext = 'do_'+text 256 return [a[3:] for a in self.get_names() if a.startswith(dotext)] 257 258 def complete(self, text, state): 259 """Return the next possible completion for 'text'. 260 261 If a command has not been entered, then complete against command list. 262 Otherwise try to call complete_<command> to get list of completions. 263 """ 264 if state == 0: 265 import readline 266 origline = readline.get_line_buffer() 267 line = origline.lstrip() 268 stripped = len(origline) - len(line) 269 begidx = readline.get_begidx() - stripped 270 endidx = readline.get_endidx() - stripped 271 if begidx>0: 272 cmd, args, foo = self.parseline(line) 273 if cmd == '': 274 compfunc = self.completedefault 275 else: 276 try: 277 compfunc = getattr(self, 'complete_' + cmd) 278 except AttributeError: 279 compfunc = self.completedefault 280 else: 281 compfunc = self.completenames 282 self.completion_matches = compfunc(text, line, begidx, endidx) 283 try: 284 return self.completion_matches[state] 285 except IndexError: 286 return None 287 288 def get_names(self): 289 # This method used to pull in base class attributes 290 # at a time dir() didn't do it yet. 291 return dir(self.__class__) 292 293 def complete_help(self, *args): 294 commands = set(self.completenames(*args)) 295 topics = set(a[5:] for a in self.get_names() 296 if a.startswith('help_' + args[0])) 297 return list(commands | topics) 298 299 def do_help(self, arg): 300 'List available commands with "help" or detailed help with "help cmd".' 301 if arg: 302 # XXX check arg syntax 303 try: 304 func = getattr(self, 'help_' + arg) 305 except AttributeError: 306 try: 307 doc=getattr(self, 'do_' + arg).__doc__ 308 doc = inspect.cleandoc(doc) 309 if doc: 310 self.stdout.write("%s\n"%str(doc)) 311 return 312 except AttributeError: 313 pass 314 self.stdout.write("%s\n"%str(self.nohelp % (arg,))) 315 return 316 func() 317 else: 318 names = self.get_names() 319 cmds_doc = [] 320 cmds_undoc = [] 321 topics = set() 322 for name in names: 323 if name[:5] == 'help_': 324 topics.add(name[5:]) 325 names.sort() 326 # There can be duplicates if routines overridden 327 prevname = '' 328 for name in names: 329 if name[:3] == 'do_': 330 if name == prevname: 331 continue 332 prevname = name 333 cmd=name[3:] 334 if cmd in topics: 335 cmds_doc.append(cmd) 336 topics.remove(cmd) 337 elif getattr(self, name).__doc__: 338 cmds_doc.append(cmd) 339 else: 340 cmds_undoc.append(cmd) 341 self.stdout.write("%s\n"%str(self.doc_leader)) 342 self.print_topics(self.doc_header, cmds_doc, 15,80) 343 self.print_topics(self.misc_header, sorted(topics),15,80) 344 self.print_topics(self.undoc_header, cmds_undoc, 15,80) 345 346 def print_topics(self, header, cmds, cmdlen, maxcol): 347 if cmds: 348 self.stdout.write("%s\n"%str(header)) 349 if self.ruler: 350 self.stdout.write("%s\n"%str(self.ruler * len(header))) 351 self.columnize(cmds, maxcol-1) 352 self.stdout.write("\n") 353 354 def columnize(self, list, displaywidth=80): 355 """Display a list of strings as a compact set of columns. 356 357 Each column is only as wide as necessary. 358 Columns are separated by two spaces (one was not legible enough). 359 """ 360 if not list: 361 self.stdout.write("<empty>\n") 362 return 363 364 nonstrings = [i for i in range(len(list)) 365 if not isinstance(list[i], str)] 366 if nonstrings: 367 raise TypeError("list[i] not a string for i in %s" 368 % ", ".join(map(str, nonstrings))) 369 size = len(list) 370 if size == 1: 371 self.stdout.write('%s\n'%str(list[0])) 372 return 373 # Try every row count from 1 upwards 374 for nrows in range(1, len(list)): 375 ncols = (size+nrows-1) // nrows 376 colwidths = [] 377 totwidth = -2 378 for col in range(ncols): 379 colwidth = 0 380 for row in range(nrows): 381 i = row + nrows*col 382 if i >= size: 383 break 384 x = list[i] 385 colwidth = max(colwidth, len(x)) 386 colwidths.append(colwidth) 387 totwidth += colwidth + 2 388 if totwidth > displaywidth: 389 break 390 if totwidth <= displaywidth: 391 break 392 else: 393 nrows = len(list) 394 ncols = 1 395 colwidths = [0] 396 for row in range(nrows): 397 texts = [] 398 for col in range(ncols): 399 i = row + nrows*col 400 if i >= size: 401 x = "" 402 else: 403 x = list[i] 404 texts.append(x) 405 while texts and not texts[-1]: 406 del texts[-1] 407 for col in range(len(texts)): 408 texts[col] = texts[col].ljust(colwidths[col]) 409 self.stdout.write("%s\n"%str(" ".join(texts))) 410