Improved by Eric Raymond.

This commit is contained in:
Guido van Rossum 1998-06-29 17:58:55 +00:00
parent 716b78474c
commit 80884075f0
1 changed files with 84 additions and 17 deletions

View File

@ -1,4 +1,39 @@
# 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
import sys
@ -8,27 +43,58 @@ PROMPT = '(Cmd) '
IDENTCHARS = string.letters + string.digits + '_'
class Cmd:
prompt = PROMPT
identchars = IDENTCHARS
ruler = '='
lastcmd = ''
intro = None
doc_header = "Documented commands (type help <topic>):"
misc_header = "Miscellaneous help topics:"
undoc_header = "Undocumented commands:"
def __init__(self):
self.prompt = PROMPT
self.identchars = IDENTCHARS
self.lastcmd = ''
def cmdloop(self):
def cmdloop(self, intro=None):
self.preloop()
if intro != None:
self.intro = intro
if self.intro:
print self.intro
stop = None
while not stop:
try:
line = raw_input(self.prompt)
except EOFError:
line = 'EOF'
self.precmd()
stop = self.onecmd(line)
self.postcmd()
self.postloop()
def precmd(self):
pass
def postcmd(self):
pass
def preloop(self):
pass
def postloop(self):
pass
def onecmd(self, line):
line = string.strip(line)
if not line:
line = self.lastcmd
else:
self.lastcmd = line
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
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:])
@ -41,6 +107,9 @@ class Cmd:
return self.default(line)
return func(arg)
def emptyline(self):
return self.onecmd(self.lastcmd)
def default(self, line):
print '*** Unknown syntax:', line
@ -70,17 +139,15 @@ class Cmd:
else:
cmds_undoc.append(cmd)
print
self.print_topics("Documented commands (type help " \
"<topic>):",cmds_doc, 15, 80)
self.print_topics("Miscellaneous help topics:",
help.keys(), 15, 80)
self.print_topics("Undocumented commands:",
cmds_undoc, 15, 80)
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;
print "="*len(header)
if self.ruler:
print self.ruler * len(header)
(cmds_per_line,junk)=divmod(maxcol,cmdlen)
col=cmds_per_line
for cmd in cmds: