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"""A generic class to build line-oriented command interpreters.
Interpreters constructed with this class obey the following conventions:
1. End of file on input is processed as the command 'EOF'.
2. A command is parsed out of each line by collecting the prefix composed
of characters in the identchars member.
3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method
is passed a single argument consisting of the remainder of the line.
4. Typing an empty line repeats the last command. (Actually, it calls the
method `emptyline', which may be overridden in a subclass.)
5. There is a predefined `help' method. Given an argument `topic', it
calls the command `help_topic'. With no arguments, it lists all topics
with defined help_ functions, broken into up to three topics; documented
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.
The `default' method may be overridden to intercept commands for which there
is no do_ 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 "=".
If the value of `self.intro' is nonempty when the cmdloop method is called,
it is printed out on interpreter startup. This value may be overridden
via an optional argument to the cmdloop() method.
The data members `self.doc_header', `self.misc_header', and
`self.undoc_header' set the headers used for the help function's
listings of documented functions, miscellaneous topics, and undocumented
functions respectively.
These interpreters use raw_input; thus, if the readline module is loaded,
they automatically support Emacs-like command history and editing features.
"""
import string
__all__ = ["Cmd"]
PROMPT = '(Cmd) '
IDENTCHARS = string.letters + string.digits + '_'
class Cmd:
prompt = PROMPT
identchars = IDENTCHARS
ruler = '='
lastcmd = ''
cmdqueue = []
intro = None
doc_leader = ""
doc_header = "Documented commands (type help <topic>):"
misc_header = "Miscellaneous help topics:"
undoc_header = "Undocumented commands:"
nohelp = "*** No help on %s"
def __init__(self): pass
def cmdloop(self, intro=None):
self.preloop()
if intro is not None:
self.intro = intro
if self.intro:
print self.intro
stop = None
while not stop:
if self.cmdqueue:
line = self.cmdqueue[0]
del self.cmdqueue[0]
else:
try:
line = raw_input(self.prompt)
except EOFError:
line = 'EOF'
line = self.precmd(line)
stop = self.onecmd(line)
stop = self.postcmd(stop, line)
self.postloop()
def precmd(self, line):
return line
def postcmd(self, stop, line):
return stop
def preloop(self):
pass
def postloop(self):
pass
def onecmd(self, line):
line = line.strip()
if not line:
return self.emptyline()
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
i, n = 0, len(line)
while i < n and line[i] in self.identchars: i = i+1
cmd, arg = line[:i], line[i:].strip()
if cmd == '':
return self.default(line)
else:
try:
func = getattr(self, 'do_' + cmd)
except AttributeError:
return self.default(line)
return func(arg)
def emptyline(self):
if self.lastcmd:
return self.onecmd(self.lastcmd)
def default(self, line):
print '*** Unknown syntax:', line
def do_help(self, arg):
if arg:
# XXX check arg syntax
try:
func = getattr(self, 'help_' + arg)
except:
try:
doc=getattr(self, 'do_' + arg).__doc__
if doc:
print doc
return
except:
pass
print self.nohelp % (arg,)
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]
cmds_doc = []
cmds_undoc = []
help = {}
for name in names:
if name[:5] == 'help_':
help[name[5:]]=1
names.sort()
# There can be duplicates if routines overridden
prevname = ''
for name in names:
if name[:3] == 'do_':
if name == prevname:
continue
prevname = name
cmd=name[3:]
if help.has_key(cmd):
cmds_doc.append(cmd)
del help[cmd]
elif getattr(self, name).__doc__:
cmds_doc.append(cmd)
else:
cmds_undoc.append(cmd)
print self.doc_leader
self.print_topics(self.doc_header, cmds_doc, 15,80)
self.print_topics(self.misc_header, help.keys(),15,80)
self.print_topics(self.undoc_header, cmds_undoc, 15,80)
def print_topics(self, header, cmds, cmdlen, maxcol):
if cmds:
print header
if self.ruler:
print self.ruler * len(header)
(cmds_per_line,junk)=divmod(maxcol,cmdlen)
col=cmds_per_line
for cmd in cmds:
if col==0: print
print (("%-"+`cmdlen`+"s") % cmd),
col = (col+1) % cmds_per_line
print "\n"
|
