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
