Mercurial > hg
view mercurial/fancyopts.py @ 39559:07b58266bce3
wireprotov2: implement commands as a generator of objects
Previously, wire protocol version 2 inherited version 1's model of
having separate types to represent the results of different wire
protocol commands.
As I implemented more powerful commands in future commits, I found
I was using a common pattern of returning a special type to hold a
generator. This meant the command function required a closure to
do most of the work. That made logic flow more difficult to follow.
I also noticed that many commands were effectively a sequence of
objects to be CBOR encoded.
I think it makes sense to define version 2 commands as generators.
This way, commands can simply emit the data structures they wish to
send to the client. This eliminates the need for a closure in
command functions and removes encoding from the bodies of commands.
As part of this commit, the handling of response objects has been
moved into the serverreactor class. This puts the reactor in the
driver's seat with regards to CBOR encoding and error handling.
Having error handling in the function that emits frames is
particularly important because exceptions in that function can lead
to things getting in a bad state: I'm fairly certain that uncaught
exceptions in the frame generator were causing deadlocks.
I also introduced a dedicated error type for explicit error reporting
in command handlers. This will be used in subsequent commits.
There's still a bit of work to be done here, especially around
formalizing the error handling "protocol." I've added yet another
TODO to track this so we don't forget.
Test output changed because we're using generators and no longer know
we are at the end of the data until we hit the end of the generator.
This means we can't emit the end-of-stream flag until we've exhausted
the generator. Hence the introduction of 0-sized end-of-stream frames.
Differential Revision: https://phab.mercurial-scm.org/D4472
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 05 Sep 2018 09:06:40 -0700 |
parents | 39e5e346eba7 |
children | 2372284d9457 |
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# fancyopts.py - better command line parsing # # Copyright 2005-2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import abc import functools from .i18n import _ from . import ( error, pycompat, ) # Set of flags to not apply boolean negation logic on nevernegate = { # avoid --no-noninteractive 'noninteractive', # These two flags are special because they cause hg to do one # thing and then exit, and so aren't suitable for use in things # like aliases anyway. 'help', 'version', } def _earlyoptarg(arg, shortlist, namelist): """Check if the given arg is a valid unabbreviated option Returns (flag_str, has_embedded_value?, embedded_value, takes_value?) >>> def opt(arg): ... return _earlyoptarg(arg, b'R:q', [b'cwd=', b'debugger']) long form: >>> opt(b'--cwd') ('--cwd', False, '', True) >>> opt(b'--cwd=') ('--cwd', True, '', True) >>> opt(b'--cwd=foo') ('--cwd', True, 'foo', True) >>> opt(b'--debugger') ('--debugger', False, '', False) >>> opt(b'--debugger=') # invalid but parsable ('--debugger', True, '', False) short form: >>> opt(b'-R') ('-R', False, '', True) >>> opt(b'-Rfoo') ('-R', True, 'foo', True) >>> opt(b'-q') ('-q', False, '', False) >>> opt(b'-qfoo') # invalid but parsable ('-q', True, 'foo', False) unknown or invalid: >>> opt(b'--unknown') ('', False, '', False) >>> opt(b'-u') ('', False, '', False) >>> opt(b'-ufoo') ('', False, '', False) >>> opt(b'--') ('', False, '', False) >>> opt(b'-') ('', False, '', False) >>> opt(b'-:') ('', False, '', False) >>> opt(b'-:foo') ('', False, '', False) """ if arg.startswith('--'): flag, eq, val = arg.partition('=') if flag[2:] in namelist: return flag, bool(eq), val, False if flag[2:] + '=' in namelist: return flag, bool(eq), val, True elif arg.startswith('-') and arg != '-' and not arg.startswith('-:'): flag, val = arg[:2], arg[2:] i = shortlist.find(flag[1:]) if i >= 0: return flag, bool(val), val, shortlist.startswith(':', i + 1) return '', False, '', False def earlygetopt(args, shortlist, namelist, gnu=False, keepsep=False): """Parse options like getopt, but ignores unknown options and abbreviated forms If gnu=False, this stops processing options as soon as a non/unknown-option argument is encountered. Otherwise, option and non-option arguments may be intermixed, and unknown-option arguments are taken as non-option. If keepsep=True, '--' won't be removed from the list of arguments left. This is useful for stripping early options from a full command arguments. >>> def get(args, gnu=False, keepsep=False): ... return earlygetopt(args, b'R:q', [b'cwd=', b'debugger'], ... gnu=gnu, keepsep=keepsep) default parsing rules for early options: >>> get([b'x', b'--cwd', b'foo', b'-Rbar', b'-q', b'y'], gnu=True) ([('--cwd', 'foo'), ('-R', 'bar'), ('-q', '')], ['x', 'y']) >>> get([b'x', b'--cwd=foo', b'y', b'-R', b'bar', b'--debugger'], gnu=True) ([('--cwd', 'foo'), ('-R', 'bar'), ('--debugger', '')], ['x', 'y']) >>> get([b'--unknown', b'--cwd=foo', b'--', '--debugger'], gnu=True) ([('--cwd', 'foo')], ['--unknown', '--debugger']) restricted parsing rules (early options must come first): >>> get([b'--cwd', b'foo', b'-Rbar', b'x', b'-q', b'y'], gnu=False) ([('--cwd', 'foo'), ('-R', 'bar')], ['x', '-q', 'y']) >>> get([b'--cwd=foo', b'x', b'y', b'-R', b'bar', b'--debugger'], gnu=False) ([('--cwd', 'foo')], ['x', 'y', '-R', 'bar', '--debugger']) >>> get([b'--unknown', b'--cwd=foo', b'--', '--debugger'], gnu=False) ([], ['--unknown', '--cwd=foo', '--', '--debugger']) stripping early options (without loosing '--'): >>> get([b'x', b'-Rbar', b'--', '--debugger'], gnu=True, keepsep=True)[1] ['x', '--', '--debugger'] last argument: >>> get([b'--cwd']) ([], ['--cwd']) >>> get([b'--cwd=foo']) ([('--cwd', 'foo')], []) >>> get([b'-R']) ([], ['-R']) >>> get([b'-Rbar']) ([('-R', 'bar')], []) >>> get([b'-q']) ([('-q', '')], []) >>> get([b'-q', b'--']) ([('-q', '')], []) '--' may be a value: >>> get([b'-R', b'--', b'x']) ([('-R', '--')], ['x']) >>> get([b'--cwd', b'--', b'x']) ([('--cwd', '--')], ['x']) value passed to bool options: >>> get([b'--debugger=foo', b'x']) ([], ['--debugger=foo', 'x']) >>> get([b'-qfoo', b'x']) ([], ['-qfoo', 'x']) short option isn't separated with '=': >>> get([b'-R=bar']) ([('-R', '=bar')], []) ':' may be in shortlist, but shouldn't be taken as an option letter: >>> get([b'-:', b'y']) ([], ['-:', 'y']) '-' is a valid non-option argument: >>> get([b'-', b'y']) ([], ['-', 'y']) """ parsedopts = [] parsedargs = [] pos = 0 while pos < len(args): arg = args[pos] if arg == '--': pos += not keepsep break flag, hasval, val, takeval = _earlyoptarg(arg, shortlist, namelist) if not hasval and takeval and pos + 1 >= len(args): # missing last argument break if not flag or hasval and not takeval: # non-option argument or -b/--bool=INVALID_VALUE if gnu: parsedargs.append(arg) pos += 1 else: break elif hasval == takeval: # -b/--bool or -s/--str=VALUE parsedopts.append((flag, val)) pos += 1 else: # -s/--str VALUE parsedopts.append((flag, args[pos + 1])) pos += 2 parsedargs.extend(args[pos:]) return parsedopts, parsedargs class customopt(object): """Manage defaults and mutations for any type of opt.""" __metaclass__ = abc.ABCMeta def __init__(self, defaultvalue): self._defaultvalue = defaultvalue def _isboolopt(self): return False def getdefaultvalue(self): """Returns the default value for this opt. Subclasses should override this to return a new value if the value type is mutable.""" return self._defaultvalue @abc.abstractmethod def newstate(self, oldstate, newparam, abort): """Adds newparam to oldstate and returns the new state. On failure, abort can be called with a string error message.""" class _simpleopt(customopt): def _isboolopt(self): return isinstance(self._defaultvalue, (bool, type(None))) def newstate(self, oldstate, newparam, abort): return newparam class _callableopt(customopt): def __init__(self, callablefn): self.callablefn = callablefn super(_callableopt, self).__init__(None) def newstate(self, oldstate, newparam, abort): return self.callablefn(newparam) class _listopt(customopt): def getdefaultvalue(self): return self._defaultvalue[:] def newstate(self, oldstate, newparam, abort): oldstate.append(newparam) return oldstate class _intopt(customopt): def newstate(self, oldstate, newparam, abort): try: return int(newparam) except ValueError: abort(_('expected int')) def _defaultopt(default): """Returns a default opt implementation, given a default value.""" if isinstance(default, customopt): return default elif callable(default): return _callableopt(default) elif isinstance(default, list): return _listopt(default[:]) elif type(default) is type(1): return _intopt(default) else: return _simpleopt(default) def fancyopts(args, options, state, gnu=False, early=False, optaliases=None): """ read args, parse options, and store options in state each option is a tuple of: short option or '' long option default value description option value label(optional) option types include: boolean or none - option sets variable in state to true string - parameter string is stored in state list - parameter string is added to a list integer - parameter strings is stored as int function - call function with parameter customopt - subclass of 'customopt' optaliases is a mapping from a canonical option name to a list of additional long options. This exists for preserving backward compatibility of early options. If we want to use it extensively, please consider moving the functionality to the options table (e.g separate long options by '|'.) non-option args are returned """ if optaliases is None: optaliases = {} namelist = [] shortlist = '' argmap = {} defmap = {} negations = {} alllong = set(o[1] for o in options) for option in options: if len(option) == 5: short, name, default, comment, dummy = option else: short, name, default, comment = option # convert opts to getopt format onames = [name] onames.extend(optaliases.get(name, [])) name = name.replace('-', '_') argmap['-' + short] = name for n in onames: argmap['--' + n] = name defmap[name] = _defaultopt(default) # copy defaults to state state[name] = defmap[name].getdefaultvalue() # does it take a parameter? if not defmap[name]._isboolopt(): if short: short += ':' onames = [n + '=' for n in onames] elif name not in nevernegate: for n in onames: if n.startswith('no-'): insert = n[3:] else: insert = 'no-' + n # backout (as a practical example) has both --commit and # --no-commit options, so we don't want to allow the # negations of those flags. if insert not in alllong: assert ('--' + n) not in negations negations['--' + insert] = '--' + n namelist.append(insert) if short: shortlist += short if name: namelist.extend(onames) # parse arguments if early: parse = functools.partial(earlygetopt, gnu=gnu) elif gnu: parse = pycompat.gnugetoptb else: parse = pycompat.getoptb opts, args = parse(args, shortlist, namelist) # transfer result to state for opt, val in opts: boolval = True negation = negations.get(opt, False) if negation: opt = negation boolval = False name = argmap[opt] obj = defmap[name] if obj._isboolopt(): state[name] = boolval else: def abort(s): raise error.Abort(_('invalid value %r for option %s, %s') % (pycompat.maybebytestr(val), opt, s)) state[name] = defmap[name].newstate(state[name], val, abort) # return unparsed args return args