docopt.py

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

Now: with levenshtein based spellcheck, flag extension (de-abbreviation), and capitalization fixes.
(but only when unambiguous)

 * Licensed under terms of MIT license (see LICENSE-MIT)

Contributors (roughly in chronological order):

 * Copyright (c) 2012 Andrew Kassen <atkassen@ucdavis.edu>
 * Copyright (c) 2012 jeffrimko <jeffrimko@gmail.com>
 * COpyright (c) 2012 Andrew Sutton <met48@met48.com>
 * COpyright (c) 2012 Andrew Sutton <met48@met48.com>
 * Copyright (c) 2012 Nima Johari <nimajohari@gmail.com>
 * Copyright (c) 2012-2013 Vladimir Keleshev, vladimir@keleshev.com
 * Copyright (c) 2014-2018 Matt Boersma <matt@sprout.org>
 * Copyright (c) 2016 amir <ladsgroup@gmail.com>
 * Copyright (c) 2015 Benjamin Bach <benjaoming@gmail.com>
 * Copyright (c) 2017 Oleg Bulkin <o.bulkin@gmail.com>
 * Copyright (c) 2018 Iain Barnett <iainspeed@gmail.com>
 * Copyright (c) 2019 itdaniher, itdaniher@gmail.com

"""

import sys
import re

__all__ = ["docopt"]
__version__ = "0.6.3"


def levenshtein_norm(source, target):
    """Calculates the normalized Levenshtein distance between two string
    arguments. The result will be a float in the range [0.0, 1.0], with 1.0
    signifying the biggest possible distance between strings with these lengths
    """

    # Compute Levenshtein distance using helper function. The max is always
    # just the length of the longer string, so this is used to normalize result
    # before returning it
    distance = levenshtein(source, target)
    return float(distance) / max(len(source), len(target))


def levenshtein(source, target, rd_flag=False):
    """Computes the Levenshtein
    (https://en.wikipedia.org/wiki/Levenshtein_distance)
    and restricted Damerau-Levenshtein
    (https://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance)
    distances between two Unicode strings with given lengths using the
    Wagner-Fischer algorithm
    (https://en.wikipedia.org/wiki/Wagner%E2%80%93Fischer_algorithm).
    These distances are defined recursively, since the distance between two
    strings is just the cost of adjusting the last one or two characters plus
    the distance between the prefixes that exclude these characters (e.g. the
    distance between "tester" and "tested" is 1 + the distance between "teste"
    and "teste"). The Wagner-Fischer algorithm retains this idea but eliminates
    redundant computations by storing the distances between various prefixes in
    a matrix that is filled in iteratively.
    """

    # Create matrix of correct size (this is s_len + 1 * t_len + 1 so that the
    # empty prefixes "" can also be included). The leftmost column represents
    # transforming various source prefixes into an empty string, which can
    # always be done by deleting all characters in the respective prefix, and
    # the top row represents transforming the empty string into various target
    # prefixes, which can always be done by inserting every character in the
    # respective prefix. The ternary used to build the list should ensure that
    # this row and column are now filled correctly
    s_range = range(len(source) + 1)
    t_range = range(len(target) + 1)
    matrix = [[(i if j == 0 else j) for j in t_range] for i in s_range]

    # Iterate through rest of matrix, filling it in with Levenshtein
    # distances for the remaining prefix combinations
    for i in s_range[1:]:
        for j in t_range[1:]:
            # Applies the recursive logic outlined above using the values
            # stored in the matrix so far. The options for the last pair of
            # characters are deletion, insertion, and substitution, which
            # amount to dropping the source character, the target character,
            # or both and then calculating the distance for the resulting
            # prefix combo. If the characters at this point are the same, the
            # situation can be thought of as a free substitution
            del_dist = matrix[i - 1][j] + 1
            ins_dist = matrix[i][j - 1] + 1
            sub_trans_cost = 0 if source[i - 1] == target[j - 1] else 1
            sub_dist = matrix[i - 1][j - 1] + sub_trans_cost

            # Choose option that produces smallest distance
            matrix[i][j] = min(del_dist, ins_dist, sub_dist)

            # If restricted Damerau-Levenshtein was requested via the flag,
            # then there may be a fourth option: transposing the current and
            # previous characters in the source string. This can be thought of
            # as a double substitution and has a similar free case, where the
            # current and preceeding character in both strings is the same
            if rd_flag and i > 1 and j > 1 and source[i - 1] == target[j - 2] and source[i - 2] == target[j - 1]:
                trans_dist = matrix[i - 2][j - 2] + sub_trans_cost
                matrix[i][j] = min(matrix[i][j], trans_dist)

    # At this point, the matrix is full, and the biggest prefixes are just the
    # strings themselves, so this is the desired distance
    return matrix[len(source)][len(target)]


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="", collected=None, left=None):
        self.collected = collected if collected is not None else []
        self.left = left if left is not None else []
        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(r"(<\S*?>)", source)[0]
        value = re.findall(r"\[default: (.*)\]", 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(r"\[default: (.*)\]", 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
        original_collected = collected
        original_left = left
        for pattern in self.children:
            matched, left, collected = pattern.match(left, collected)
            if not matched:
                return False, original_left, original_collected
        return True, left, collected


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
        original_collected = collected
        original_left = left
        last_left = None
        matched = True
        times = 0
        while matched:
            # could it be that something didn't match but changed left or
            # collected?
            matched, left, collected = self.children[0].match(left, collected)
            times += 1 if matched else 0
            if last_left == left:
                break
            last_left = left
        if times >= 1:
            return True, left, collected
        return False, original_left, original_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, argv=False):
    """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 and long == o.long]
    start_collision = len([o for o in options if o.long and long in o.long and o.long.startswith(long)]) > 1
    if argv and not len(similar) and not start_collision:
        similar = [o for o in options if o.long and long in o.long and o.long.startswith(long)]
    if similar == []:  # if no exact match
        corrected = [(long, o) for o in options if o.long and levenshtein_norm(long, o.long) < 0.25]
        if corrected:
            print(f"NB: Corrected {corrected[0][0]} to {corrected[0][1].long}")
        similar = [correct for (original, correct) in corrected]
    if len(similar) > 1:
        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:]
        transformations = {None: lambda x: x, "lowercase": lambda x: x.lower(), "uppercase": lambda x: x.upper()}
        # try identity, lowercase, uppercase, iff such resolves uniquely (ie if upper and lowercase are not both defined)
        similar = []
        for transform_name, transform in transformations.items():
            transformed = list(set([transform(o.short) for o in options if o.short]))
            transform_unique = len([o for o in options if o.short and transformed.count(transform(o.short)) == 1]) == len(transformed)
            if transform_unique:
                similar = [o for o in options if o.short and transform(o.short) == transform(short)]
                if len(similar):
                    if transform_name:
                        print(f"NB: Corrected {short} to {similar[0].short} via {transform_name}")
                    break
            # if transformations do not resolve, try abbreviations of 'long' forms iff such resolves uniquely (ie if no two long forms begin with the same letter)
            if len(similar) == 0:
                abbreviated = [transform(o.long[1:3]) for o in options if o.long] + [transform(o.short) for o in options if o.short]
                abbreviated_unique = len([o for o in options if o.long and abbreviated.count(transform(o.long[1:3])) == 1])
                if abbreviated_unique:
                    for o in options:
                        if not o.short and o.long and transform(short) == transform(o.long[1:3]):
                            similar = [o]
                            print(f"NB: Corrected {short} to {similar[0].long} via abbreviation (case change: {transform_name})")
                            break
                if len(similar):
                    break
        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:
            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 "=" in value:
                    value = value.lstrip("=")
            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 ]* ] ;

    """

    def isanumber(x):
        try:
            float(x)
            return True
        except ValueError:
            return False

    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, argv=True)
        elif tokens.current().startswith("-") and tokens.current() != "-" and not isanumber(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, with_args=False):
    defaults = []
    for s in parse_section("options:", doc):
        options_literal, _, s = s.partition(":")
        if " " in options_literal:
            _, _, options_literal = options_literal.partition(" ")
        assert options_literal.lower().strip() == "options"
        split = re.split("\n[ \t]*(-\S+?)", "\n" + s)[1:]
        split = [s1 + s2 for s1, s2 in zip(split[::2], split[1::2])]
        for s in split:
            if s.startswith("-"):
                arg, _, description = s.partition("  ")
                flag, _, var = arg.replace("=", " ").partition(" ")
                option = Option.parse(s)
                defaults.append(option)
    return defaults


def parse_section(name, source):
    pattern = re.compile("^([^\n]*" + name + "[^\n]*\n?(?:[ \t].*?(?:\n|$))*)", re.IGNORECASE | re.MULTILINE)
    r = [s.strip() for s in pattern.findall(source) if s.strip().lower() != name.lower()]
    return r


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:" section (case-insensitive) not found. Perhaps missing indentation?')
    if len(usage_sections) > 1:
        raise DocoptLanguageError('More than one "usage:" (case-insensitive).')
    options_pattern = re.compile(r"\n\s*?options:", re.IGNORECASE)
    if options_pattern.search(usage_sections[0]):
        raise DocoptExit("Warning: options (case-insensitive) was found in usage." "Use a blank line between each section otherwise it behaves badly.")
    DocoptExit.usage = usage_sections[0]
    options = parse_defaults(doc)
    pattern = parse_pattern(formal_usage(DocoptExit.usage), options)
    pattern_options = set(pattern.flat(Option))
    for options_shortcut in pattern.flat(OptionsShortcut):
        doc_options = parse_defaults(doc)
        options_shortcut.children = [opt for opt in doc_options if opt not in pattern_options]
    names = [n.long or n.short for n in options]
    duplicated = [n for n in names if names.count(n) > 1]
    if any([duplicated]):
        raise DocoptLanguageError(f"duplicated token(s): {duplicated}")
    argv = parse_argv(Tokens(argv), list(options), options_first)
    extras(help, version, argv, doc)
    matched, left, collected = pattern.fix().match(argv)
    if matched and left == []:
        return Dict((a.name, a.value) for a in (pattern.flat() + collected))
    if left:
        raise DocoptExit(f"Warning: found unmatched (duplicate?) arguments {left}")
    raise DocoptExit(collected=collected, left=left)