docopt.py

"""Pythonic command-line interface parser that will make you smile.

 * http://docopt.org
 * Repository and issue-tracker: https://github.com/docopt/docopt
 * Licensed under terms of MIT license (see LICENSE-MIT)
 * Copyright (c) 2013 Vladimir Keleshev, vladimir@keleshev.com

"""
import sys
import re


__all__ = ['docopt']
__version__ = '0.6.1'


class DocoptLanguageError(Exception):

    """Error in construction of usage-message by developer."""


class DocoptExit(SystemExit):

    """Exit in case user invoked program with incorrect arguments."""

    usage = ''

    def __init__(self, message=''):
        SystemExit.__init__(self, (message + '\n' + self.usage).strip())


class Pattern(object):

    def __eq__(self, other):
        return repr(self) == repr(other)

    def __hash__(self):
        return hash(repr(self))

    def fix(self):
        self.fix_identities()
        self.fix_repeating_arguments()
        return self

    def fix_identities(self, uniq=None):
        """Make pattern-tree tips point to same object if they are equal."""
        if not hasattr(self, 'children'):
            return self
        uniq = list(set(self.flat())) if uniq is None else uniq
        for i, child in enumerate(self.children):
            if not hasattr(child, 'children'):
                assert child in uniq
                self.children[i] = uniq[uniq.index(child)]
            else:
                child.fix_identities(uniq)

    def fix_repeating_arguments(self):
        """Fix elements that should accumulate/increment values."""
        either = [list(child.children) for child in transform(self).children]
        for case in either:
            for e in [child for child in case if case.count(child) > 1]:
                if type(e) is Argument or type(e) is Option and e.argcount:
                    if e.value is None:
                        e.value = []
                    elif type(e.value) is not list:
                        e.value = e.value.split()
                if type(e) is Command or type(e) is Option and e.argcount == 0:
                    e.value = 0
        return self


def transform(pattern):
    """Expand pattern into an (almost) equivalent one, but with single Either.

    Example: ((-a | -b) (-c | -d)) => (-a -c | -a -d | -b -c | -b -d)
    Quirks: [-a] => (-a), (-a...) => (-a -a)

    """
    result = []
    groups = [[pattern]]
    while groups:
        children = groups.pop(0)
        parents = [Required, Optional, OptionsShortcut, Either, OneOrMore]
        if any(t in map(type, children) for t in parents):
            child = [c for c in children if type(c) in parents][0]
            children.remove(child)
            if type(child) is Either:
                for c in child.children:
                    groups.append([c] + children)
            elif type(child) is OneOrMore:
                groups.append(child.children * 2 + children)
            else:
                groups.append(child.children + children)
        else:
            result.append(children)
    return Either(*[Required(*e) for e in result])


class LeafPattern(Pattern):

    """Leaf/terminal node of a pattern tree."""

    def __init__(self, name, value=None):
        self.name, self.value = name, value

    def __repr__(self):
        return '%s(%r, %r)' % (self.__class__.__name__, self.name, self.value)

    def flat(self, *types):
        return [self] if not types or type(self) in types else []

    def match(self, left, collected=None):
        collected = [] if collected is None else collected
        pos, match = self.single_match(left)
        if match is None:
            return False, left, collected
        left_ = left[:pos] + left[pos + 1:]
        same_name = [a for a in collected if a.name == self.name]
        if type(self.value) in (int, list):
            if type(self.value) is int:
                increment = 1
            else:
                increment = ([match.value] if type(match.value) is str
                             else match.value)
            if not same_name:
                match.value = increment
                return True, left_, collected + [match]
            same_name[0].value += increment
            return True, left_, collected
        return True, left_, collected + [match]


class BranchPattern(Pattern):

    """Branch/inner node of a pattern tree."""

    def __init__(self, *children):
        self.children = list(children)

    def __repr__(self):
        return '%s(%s)' % (self.__class__.__name__,
                           ', '.join(repr(a) for a in self.children))

    def flat(self, *types):
        if type(self) in types:
            return [self]
        return sum([child.flat(*types) for child in self.children], [])


class Argument(LeafPattern):

    def single_match(self, left):
        for n, pattern in enumerate(left):
            if type(pattern) is Argument:
                return n, Argument(self.name, pattern.value)
        return None, None

    @classmethod
    def parse(class_, source):
        name = re.findall('(<\S*?>)', source)[0]
        value = re.findall('\[default: (.*)\]', source, flags=re.I)
        return class_(name, value[0] if value else None)


class Command(Argument):

    def __init__(self, name, value=False):
        self.name, self.value = name, value

    def single_match(self, left):
        for n, pattern in enumerate(left):
            if type(pattern) is Argument:
                if pattern.value == self.name:
                    return n, Command(self.name, True)
                else:
                    break
        return None, None


class Option(LeafPattern):

    def __init__(self, short=None, long=None, argcount=0, value=False):
        assert argcount in (0, 1)
        self.short, self.long, self.argcount = short, long, argcount
        self.value = None if value is False and argcount else value

    @classmethod
    def parse(class_, option_description):
        short, long, argcount, value = None, None, 0, False
        options, _, description = option_description.strip().partition('  ')
        options = options.replace(',', ' ').replace('=', ' ')
        for s in options.split():
            if s.startswith('--'):
                long = s
            elif s.startswith('-'):
                short = s
            else:
                argcount = 1
        if argcount:
            matched = re.findall('\[default: (.*)\]', description, flags=re.I)
            value = matched[0] if matched else None
        return class_(short, long, argcount, value)

    def single_match(self, left):
        for n, pattern in enumerate(left):
            if self.name == pattern.name:
                return n, pattern
        return None, None

    @property
    def name(self):
        return self.long or self.short

    def __repr__(self):
        return 'Option(%r, %r, %r, %r)' % (self.short, self.long,
                                           self.argcount, self.value)


class Required(BranchPattern):

    def match(self, left, collected=None):
        collected = [] if collected is None else collected
        l = left
        c = collected
        for pattern in self.children:
            matched, l, c = pattern.match(l, c)
            if not matched:
                return False, left, collected
        return True, l, c


class Optional(BranchPattern):

    def match(self, left, collected=None):
        collected = [] if collected is None else collected
        for pattern in self.children:
            m, left, collected = pattern.match(left, collected)
        return True, left, collected


class OptionsShortcut(Optional):

    """Marker/placeholder for [options] shortcut."""


class OneOrMore(BranchPattern):

    def match(self, left, collected=None):
        assert len(self.children) == 1
        collected = [] if collected is None else collected
        l = left
        c = collected
        l_ = None
        matched = True
        times = 0
        while matched:
            # could it be that something didn't match but changed l or c?
            matched, l, c = self.children[0].match(l, c)
            times += 1 if matched else 0
            if l_ == l:
                break
            l_ = l
        if times >= 1:
            return True, l, c
        return False, left, collected


class Either(BranchPattern):

    def match(self, left, collected=None):
        collected = [] if collected is None else collected
        outcomes = []
        for pattern in self.children:
            matched, _, _ = outcome = pattern.match(left, collected)
            if matched:
                outcomes.append(outcome)
        if outcomes:
            return min(outcomes, key=lambda outcome: len(outcome[1]))
        return False, left, collected


class Tokens(list):

    def __init__(self, source, error=DocoptExit):
        self += source.split() if hasattr(source, 'split') else source
        self.error = error

    @staticmethod
    def from_pattern(source):
        source = re.sub(r'([\[\]\(\)\|]|\.\.\.)', r' \1 ', source)
        source = [s for s in re.split('\s+|(\S*<.*?>)', source) if s]
        return Tokens(source, error=DocoptLanguageError)

    def move(self):
        return self.pop(0) if len(self) else None

    def current(self):
        return self[0] if len(self) else None


def parse_long(tokens, options):
    """long ::= '--' chars [ ( ' ' | '=' ) chars ] ;"""
    long, eq, value = tokens.move().partition('=')
    assert long.startswith('--')
    value = None if eq == value == '' else value
    similar = [o for o in options if o.long == long]
    if tokens.error is DocoptExit and similar == []:  # if no exact match
        similar = [o for o in options if o.long and o.long.startswith(long)]
    if len(similar) > 1:  # might be simply specified ambiguously 2+ times?
        raise tokens.error('%s is not a unique prefix: %s?' %
                           (long, ', '.join(o.long for o in similar)))
    elif len(similar) < 1:
        argcount = 1 if eq == '=' else 0
        o = Option(None, long, argcount)
        options.append(o)
        if tokens.error is DocoptExit:
            o = Option(None, long, argcount, value if argcount else True)
    else:
        o = Option(similar[0].short, similar[0].long,
                   similar[0].argcount, similar[0].value)
        if o.argcount == 0:
            if value is not None:
                raise tokens.error('%s must not have an argument' % o.long)
        else:
            if value is None:
                if tokens.current() in [None, '--']:
                    raise tokens.error('%s requires argument' % o.long)
                value = tokens.move()
        if tokens.error is DocoptExit:
            o.value = value if value is not None else True
    return [o]


def parse_shorts(tokens, options):
    """shorts ::= '-' ( chars )* [ [ ' ' ] chars ] ;"""
    token = tokens.move()
    assert token.startswith('-') and not token.startswith('--')
    left = token.lstrip('-')
    parsed = []
    while left != '':
        short, left = '-' + left[0], left[1:]
        similar = [o for o in options if o.short == short]
        if len(similar) > 1:
            raise tokens.error('%s is specified ambiguously %d times' %
                               (short, len(similar)))
        elif len(similar) < 1:
            o = Option(short, None, 0)
            options.append(o)
            if tokens.error is DocoptExit:
                o = Option(short, None, 0, True)
        else:  # why copying is necessary here?
            o = Option(short, similar[0].long,
                       similar[0].argcount, similar[0].value)
            value = None
            if o.argcount != 0:
                if left == '':
                    if tokens.current() in [None, '--']:
                        raise tokens.error('%s requires argument' % short)
                    value = tokens.move()
                else:
                    value = left
                    left = ''
            if tokens.error is DocoptExit:
                o.value = value if value is not None else True
        parsed.append(o)
    return parsed


def parse_pattern(source, options):
    tokens = Tokens.from_pattern(source)
    result = parse_expr(tokens, options)
    if tokens.current() is not None:
        raise tokens.error('unexpected ending: %r' % ' '.join(tokens))
    return Required(*result)


def parse_expr(tokens, options):
    """expr ::= seq ( '|' seq )* ;"""
    seq = parse_seq(tokens, options)
    if tokens.current() != '|':
        return seq
    result = [Required(*seq)] if len(seq) > 1 else seq
    while tokens.current() == '|':
        tokens.move()
        seq = parse_seq(tokens, options)
        result += [Required(*seq)] if len(seq) > 1 else seq
    return [Either(*result)] if len(result) > 1 else result


def parse_seq(tokens, options):
    """seq ::= ( atom [ '...' ] )* ;"""
    result = []
    while tokens.current() not in [None, ']', ')', '|']:
        atom = parse_atom(tokens, options)
        if tokens.current() == '...':
            atom = [OneOrMore(*atom)]
            tokens.move()
        result += atom
    return result


def parse_atom(tokens, options):
    """atom ::= '(' expr ')' | '[' expr ']' | 'options'
             | long | shorts | argument | command ;
    """
    token = tokens.current()
    result = []
    if token in '([':
        tokens.move()
        matching, pattern = {'(': [')', Required], '[': [']', Optional]}[token]
        result = pattern(*parse_expr(tokens, options))
        if tokens.move() != matching:
            raise tokens.error("unmatched '%s'" % token)
        return [result]
    elif token == 'options':
        tokens.move()
        return [OptionsShortcut()]
    elif token.startswith('--') and token != '--':
        return parse_long(tokens, options)
    elif token.startswith('-') and token not in ('-', '--'):
        return parse_shorts(tokens, options)
    elif token.startswith('<') and token.endswith('>') or token.isupper():
        return [Argument(tokens.move())]
    else:
        return [Command(tokens.move())]


def parse_argv(tokens, options, options_first=False):
    """Parse command-line argument vector.

    If options_first:
        argv ::= [ long | shorts ]* [ argument ]* [ '--' [ argument ]* ] ;
    else:
        argv ::= [ long | shorts | argument ]* [ '--' [ argument ]* ] ;

    """
    parsed = []
    while tokens.current() is not None:
        if tokens.current() == '--':
            return parsed + [Argument(None, v) for v in tokens]
        elif tokens.current().startswith('--'):
            parsed += parse_long(tokens, options)
        elif tokens.current().startswith('-') and tokens.current() != '-':
            parsed += parse_shorts(tokens, options)
        elif options_first:
            return parsed + [Argument(None, v) for v in tokens]
        else:
            parsed.append(Argument(None, tokens.move()))
    return parsed


def parse_defaults(doc):
    defaults = []
    for s in parse_section('options:', doc):
        # FIXME corner case "bla: options: --foo"
        _, _, s = s.partition(':')  # get rid of "options:"
        split = re.split('\n *(-\S+?)', '\n' + s)[1:]
        split = [s1 + s2 for s1, s2 in zip(split[::2], split[1::2])]
        options = [Option.parse(s) for s in split if s.startswith('-')]
        defaults += options
    return defaults


def parse_section(name, source):
    pattern = re.compile('^([^\n]*' + name + '[^\n]*\n?(?:[ \t].*?(?:\n|$))*)',
                         re.IGNORECASE | re.MULTILINE)
    return [s.strip() for s in pattern.findall(source)]


def formal_usage(section):
    _, _, section = section.partition(':')  # drop "usage:"
    pu = section.split()
    return '( ' + ' '.join(') | (' if s == pu[0] else s for s in pu[1:]) + ' )'


def extras(help, version, options, doc):
    if help and any((o.name in ('-h', '--help')) and o.value for o in options):
        print(doc.strip("\n"))
        sys.exit()
    if version and any(o.name == '--version' and o.value for o in options):
        print(version)
        sys.exit()


class Dict(dict):
    def __repr__(self):
        return '{%s}' % ',\n '.join('%r: %r' % i for i in sorted(self.items()))


def docopt(doc, argv=None, help=True, version=None, options_first=False):
    """Parse `argv` based on command-line interface described in `doc`.

    `docopt` creates your command-line interface based on its
    description that you pass as `doc`. Such description can contain
    --options, <positional-argument>, commands, which could be
    [optional], (required), (mutually | exclusive) or repeated...

    Parameters
    ----------
    doc : str
        Description of your command-line interface.
    argv : list of str, optional
        Argument vector to be parsed. sys.argv[1:] is used if not
        provided.
    help : bool (default: True)
        Set to False to disable automatic help on -h or --help
        options.
    version : any object
        If passed, the object will be printed if --version is in
        `argv`.
    options_first : bool (default: False)
        Set to True to require options precede positional arguments,
        i.e. to forbid options and positional arguments intermix.

    Returns
    -------
    args : dict
        A dictionary, where keys are names of command-line elements
        such as e.g. "--verbose" and "<path>", and values are the
        parsed values of those elements.

    Example
    -------
    >>> from docopt import docopt
    >>> doc = '''
    ... Usage:
    ...     my_program tcp <host> <port> [--timeout=<seconds>]
    ...     my_program serial <port> [--baud=<n>] [--timeout=<seconds>]
    ...     my_program (-h | --help | --version)
    ...
    ... Options:
    ...     -h, --help  Show this screen and exit.
    ...     --baud=<n>  Baudrate [default: 9600]
    ... '''
    >>> argv = ['tcp', '127.0.0.1', '80', '--timeout', '30']
    >>> docopt(doc, argv)
    {'--baud': '9600',
     '--help': False,
     '--timeout': '30',
     '--version': False,
     '<host>': '127.0.0.1',
     '<port>': '80',
     'serial': False,
     'tcp': True}

    See also
    --------
    * For video introduction see http://docopt.org
    * Full documentation is available in README.rst as well as online
      at https://github.com/docopt/docopt#readme

    """
    argv = sys.argv[1:] if argv is None else argv

    usage_sections = parse_section('usage:', doc)
    if len(usage_sections) == 0:
        raise DocoptLanguageError('"usage:" (case-insensitive) not found.')
    if len(usage_sections) > 1:
        raise DocoptLanguageError('More than one "usage:" (case-insensitive).')
    DocoptExit.usage = usage_sections[0]

    options = parse_defaults(doc)
    pattern = parse_pattern(formal_usage(DocoptExit.usage), options)
    # [default] syntax for argument is disabled
    #for a in pattern.flat(Argument):
    #    same_name = [d for d in arguments if d.name == a.name]
    #    if same_name:
    #        a.value = same_name[0].value
    argv = parse_argv(Tokens(argv), list(options), options_first)
    pattern_options = set(pattern.flat(Option))
    for options_shortcut in pattern.flat(OptionsShortcut):
        doc_options = parse_defaults(doc)
        options_shortcut.children = list(set(doc_options) - pattern_options)
        #if any_options:
        #    options_shortcut.children += [Option(o.short, o.long, o.argcount)
        #                    for o in argv if type(o) is Option]
    extras(help, version, argv, doc)
    matched, left, collected = pattern.fix().match(argv)
    if matched and left == []:  # better error message if left?
        return Dict((a.name, a.value) for a in (pattern.flat() + collected))
    raise DocoptExit()