cpython/Lib/cmd.py

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# A generic class to build line-oriented command interpreters
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#
# 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.
#
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import string
import sys
import linecache
PROMPT = '(Cmd) '
IDENTCHARS = string.letters + string.digits + '_'
class Cmd:
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prompt = PROMPT
identchars = IDENTCHARS
ruler = '='
lastcmd = ''
intro = None
doc_header = "Documented commands (type help <topic>):"
misc_header = "Miscellaneous help topics:"
undoc_header = "Undocumented commands:"
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def cmdloop(self, intro=None):
self.preloop()
if intro != None:
self.intro = intro
if self.intro:
print self.intro
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stop = None
while not stop:
try:
line = raw_input(self.prompt)
except EOFError:
line = 'EOF'
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self.precmd()
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stop = self.onecmd(line)
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self.postcmd()
self.postloop()
def precmd(self):
pass
def postcmd(self):
pass
def preloop(self):
pass
def postloop(self):
pass
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def onecmd(self, line):
line = string.strip(line)
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if line == '?':
line = 'help'
elif line == '!':
if hasattr(self, 'do_shell'):
line = 'shell'
else:
self.default(line)
return
elif not line:
self.emptyline()
return
self.lastcmd = line
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i, n = 0, len(line)
while i < n and line[i] in self.identchars: i = i+1
cmd, arg = line[:i], string.strip(line[i:])
if cmd == '':
return self.default(line)
else:
try:
func = getattr(self, 'do_' + cmd)
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except AttributeError:
return self.default(line)
return func(arg)
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def emptyline(self):
return self.onecmd(self.lastcmd)
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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)
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except:
print '*** No help on', `arg`
return
func()
else:
names = dir(self.__class__)
cmds_doc = []
cmds_undoc = []
help = {}
for name in names:
if name[:5] == 'help_':
help[name[5:]]=1
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for name in names:
if name[:3] == 'do_':
cmd=name[3:]
if help.has_key(cmd):
cmds_doc.append(cmd)
del help[cmd]
else:
cmds_undoc.append(cmd)
print
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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;
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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"