Patch #416224: add readline completion to cmd.Cmd.

Lib/cmd.py

@@ -15,10 +15,20 @@ Interpreters constructed with this class obey the following conventions:
    commands, miscellaneous help topics, and undocumented commands.
 6. The command '?' is a synonym for `help'.  The command '!' is a synonym
    for `shell', if a do_shell method exists.
+7. If completion is enabled, completing commands will be done automatically,
+   and completing of commands args is done by calling complete_foo() with
+   arguments text, line, begidx, endidx.  text is string we are matching
+   against, all returned matches must begin with it.  line is the current
+   input line (lstripped), begidx and endidx are the beginning and end
+   indexes of the text being matched, which could be used to provide 
+   different completion depending upon which position the argument is in.
 
 The `default' method may be overridden to intercept commands for which there
 is no do_ method.
 
+The `completedefault' method may be overridden to intercept completions for
+commands that have no complete_ method. 
+
 The data member `self.ruler' sets the character used to draw separator lines
 in the help messages.  If empty, no ruler line is drawn.  It defaults to "=".
 
@@ -56,7 +66,14 @@ class Cmd:
     nohelp = "*** No help on %s"
     use_rawinput = 1
 
-    def __init__(self): pass
+    def __init__(self, completekey='tab'): 
+        if completekey:
+            try:
+                import readline
+                readline.set_completer(self.complete)
+                readline.parse_and_bind(completekey+": complete")
+            except ImportError:
+                pass
 
     def cmdloop(self, intro=None):
         self.preloop()
@@ -99,21 +116,29 @@ class Cmd:
     def postloop(self):
         pass
 
-    def onecmd(self, line):
+    def parseline(self, line):
         line = line.strip()
         if not line:
-            return self.emptyline()
+            return None, None, line
         elif line[0] == '?':
             line = 'help ' + line[1:]
         elif line[0] == '!':
             if hasattr(self, 'do_shell'):
                 line = 'shell ' + line[1:]
             else:
-                return self.default(line)
-        self.lastcmd = line
+                return None, None, line
         i, n = 0, len(line)
         while i < n and line[i] in self.identchars: i = i+1
         cmd, arg = line[:i], line[i:].strip()
+        return cmd, arg, line
+    
+    def onecmd(self, line):
+        cmd, arg, line = self.parseline(line)
+        if not line:
+            return self.emptyline()
+        if cmd is None:
+            return self.default(line)
+        self.lastcmd = line
         if cmd == '':
             return self.default(line)
         else:
@@ -130,6 +155,59 @@ class Cmd:
     def default(self, line):
         print '*** Unknown syntax:', line
 
+    def completedefault(self, *ignored):
+        return []
+
+    def completenames(self, text, *ignored):
+        dotext = 'do_'+text
+        return [a[3:] for a in self.get_names() if a.startswith(dotext)]
+
+    def complete(self, text, state):
+        """Return the next possible completion for 'text'.
+
+        If a command has not been entered, then complete against command list.
+        Otherwise try to call complete_<command> to get list of completions.
+        """
+        if state == 0:
+            import readline
+            origline = readline.get_line_buffer()
+            line = origline.lstrip()
+            stripped = len(origline) - len(line)
+            begidx = readline.get_begidx() - stripped
+            endidx = readline.get_endidx() - stripped
+            if begidx>0:
+                cmd, args, foo = self.parseline(line)
+                if cmd == '':
+                    compfunc = self.completedefault
+                else:
+                    try:
+                        compfunc = getattr(self, 'complete_' + cmd)
+                    except AttributeError:
+                        compfunc = self.completedefault
+            else:
+                compfunc = self.completenames
+            self.completion_matches = compfunc(text, line, begidx, endidx)
+        try:
+            return self.completion_matches[state]
+        except IndexError:
+            return None
+    
+    def get_names(self):
+        # Inheritance says we have to look in class and
+        # base classes; order is not important.
+        names = []
+        classes = [self.__class__]
+        while classes:
+            aclass = classes[0]
+            if aclass.__bases__:
+                classes = classes + list(aclass.__bases__)
+            names = names + dir(aclass)
+            del classes[0]
+        return names
+
+    def complete_help(self, *args):
+        return self.completenames(*args)
+
     def do_help(self, arg):
         if arg:
             # XXX check arg syntax
@@ -147,16 +225,7 @@ class Cmd:
                 return
             func()
         else:
-            # Inheritance says we have to look in class and
-            # base classes; order is not important.
-            names = []
-            classes = [self.__class__]
-            while classes:
-                aclass = classes[0]
-                if aclass.__bases__:
-                    classes = classes + list(aclass.__bases__)
-                names = names + dir(aclass)
-                del classes[0]
+            names = self.get_names()
             cmds_doc = []
             cmds_undoc = []
             help = {}