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    1019

    use std::iter::IntoIterator;
    #[cfg(feature = "yaml")]
    use std::collections::BTreeMap;
    use std::collections::BTreeSet;
    use std::rc::Rc;

    #[cfg(feature = "yaml")]
    use yaml_rust::Yaml;

    use usageparser::{UsageParser, UsageToken};

    /// The abstract representation of a command line argument used by the consumer of the library.
    /// Used to set all the options and relationships that define a valid argument for the program.
    ///
    /// This struct is used by the library consumer and describes the command line arguments for
    /// their program. Then evaluates the settings the consumer provided and determines the concret
    /// argument type to use when parsing.
    ///
    /// There are two methods for constructing `Arg`s, using the builder pattern and setting options
    /// manually, or using a usage string which is far less verbose. You can also use a combination
    /// of the two methods to achieve the best of both worlds.
    ///
    /// **NOTE*: Fields of this struct are **not** meant to be used directly unless absolutely
    /// required. 99.9% of the tasks can be performed without accessing these fields directly.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// # let matches = App::new("myprog")
    /// #                 .arg(
    /// // Using the traditional builder pattern and setting each option manually
    /// Arg::with_name("config")
    ///       .short("c")
    ///       .long("config")
    ///       .takes_value(true)
    ///       .help("Provides a config file to myprog")
    /// # ).arg(
    /// // Using a usage string (setting a similar argument to the one above)
    /// Arg::from_usage("-i --input=[input] 'Provides an input file to the program'")
    /// # ).get_matches();
    #[allow(missing_debug_implementations)]
    #[derive(Default)]
    pub struct Arg<'n, 'l, 'h, 'g, 'p, 'r> {
        /// The unique name of the argument
        pub name: &'n str,
        /// The short version (i.e. single character) of the argument, no preceding `-`
        /// **NOTE:** `short` is mutually exclusive with `index`
        pub short: Option<char>,
        /// The long version of the flag (i.e. word) without the preceding `--`
        /// **NOTE:** `long` is mutually exclusive with `index`
        pub long: Option<&'l str>,
        /// The string of text that will displayed to the user when the application's
        /// `help` text is displayed
        pub help: Option<&'h str>,
        /// If this is a required by default when using the command line program,
        /// e.g. a configuration file that's required for the program to function
        /// **NOTE:** required by default means it is required *until* mutually
        /// exclusive arguments are evaluated.
        pub required: bool,
        /// Determines if this argument is an option (as opposed to flag or positional) and
        /// is mutually exclusive with `index` and `multiple`
        pub takes_value: bool,
        /// The index of the argument. `index` is mutually exclusive with `takes_value`
        /// and `multiple`
        pub index: Option<u8>,
        /// Determines if multiple instances of the same flag are allowed. `multiple`
        /// is mutually exclusive with `index`.
        /// e.g. `-v -v -v` or `-vvv` or `--option foo --option bar`
        pub multiple: bool,
        /// A list of names for other arguments that *may not* be used with this flag
        pub blacklist: Option<Vec<&'r str>>,
        /// A list of possible values for an option or positional argument
        pub possible_vals: Option<Vec<&'p str>>,
        /// A list of names of other arguments that are *required* to be used when
        /// this flag is used
        pub requires: Option<Vec<&'r str>>,
        /// A name of the group the argument belongs to
        pub group: Option<&'g str>,
        /// A set of names (ordered) for the values to be displayed with the help message
        pub val_names: Option<BTreeSet<&'n str>>,
        /// The exact number of values to satisfy this argument
        pub num_vals: Option<u8>,
        /// The maximum number of values possible for this argument
        pub max_vals: Option<u8>,
        /// The minimum number of values possible to satisfy this argument
        pub min_vals: Option<u8>,
        /// Specifies whether or not this argument accepts explicit empty values such as `--option ""`
        pub empty_vals: bool,
        /// Specifies whether or not this argument is global and should be propagated through all
        /// child subcommands
        pub global: bool,
        /// A function used to check the validity of an argument value. Failing this validation results
        /// in failed argument parsing.
        pub validator: Option<Rc<Fn(String) -> Result<(), String>>>,
        /// A list of names for other arguments that *mutually override* this flag
        pub overrides: Option<Vec<&'r str>>,
        /// Specifies whether the argument should show up in the help message
        pub hidden: bool,
    }

    impl<'n, 'l, 'h, 'g, 'p, 'r> Arg<'n, 'l, 'h, 'g, 'p, 'r> {
        /// Creates a new instance of `Arg` using a unique string name.
        /// The name will be used by the library consumer to get information about
        /// whether or not the argument was used at runtime.
        ///
        /// **NOTE:** in the case of arguments that take values (i.e. `takes_value(true)`)
        /// and positional arguments (i.e. those without a `-` or `--`) the name will also
        /// be displayed when the user prints the usage/help information of the program.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// Arg::with_name("config")
        /// # .short("c")
        /// # ).get_matches();
        pub fn with_name(n: &'n str) -> Self {
            Arg {
                name: n,
                empty_vals: true,
                ..Default::default()
            }
        }

        /// Creates a new instance of `Arg` from a .yml (YAML) file.
        ///
        /// # Examples
        ///
        /// ```ignore
        /// # use clap::Arg;
        /// let yml = load_yaml!("arg.yml");
        /// let arg = Arg::from_yaml(yml);
        /// ```
        #[cfg(feature = "yaml")]
        pub fn from_yaml<'y>(y: &'y BTreeMap<Yaml, Yaml>) -> Arg<'y, 'y, 'y, 'y, 'y, 'y> {
            // We WANT this to panic on error...so expect() is good.
            let name_yml = y.keys().nth(0).unwrap();
            let name_str = name_yml.as_str().unwrap();
            let mut a = Arg::with_name(name_str);
            let arg_settings = y.get(name_yml).unwrap().as_hash().unwrap();

            for (k, v) in arg_settings.iter() {
                a = match k.as_str().unwrap() {
                    "short" => a.short(v.as_str().unwrap()),
                    "long" => a.long(v.as_str().unwrap()),
                    "help" => a.help(v.as_str().unwrap()),
                    "required" => a.required(v.as_bool().unwrap()),
                    "takes_value" => a.takes_value(v.as_bool().unwrap()),
                    "index" => a.index(v.as_i64().unwrap() as u8),
                    "global" => a.global(v.as_bool().unwrap()),
                    "multiple" => a.multiple(v.as_bool().unwrap()),
                    "empty_values" => a.empty_values(v.as_bool().unwrap()),
                    "group" => a.group(v.as_str().unwrap()),
                    "number_of_values" => a.number_of_values(v.as_i64().unwrap() as u8),
                    "max_values" => a.max_values(v.as_i64().unwrap() as u8),
                    "min_values" => a.min_values(v.as_i64().unwrap() as u8),
                    "value_name" => a.value_name(v.as_str().unwrap()),
                    "value_names" => {
                        for ys in v.as_vec().unwrap() {
                            if let Some(s) = ys.as_str() {
                                a = a.value_name(s);
                            }
                        }
                        a
                    }
                    "requires" => {
                        for ys in v.as_vec().unwrap() {
                            if let Some(s) = ys.as_str() {
                                a = a.requires(s);
                            }
                        }
                        a
                    }
                    "conflicts_with" => {
                        for ys in v.as_vec().unwrap() {
                            if let Some(s) = ys.as_str() {
                                a = a.conflicts_with(s);
                            }
                        }
                        a
                    }
                    "mutually_overrides_with" => {
                        for ys in v.as_vec().unwrap() {
                            if let Some(s) = ys.as_str() {
                                a = a.mutually_overrides_with(s);
                            }
                        }
                        a
                    }
                    "possible_values" => {
                        for ys in v.as_vec().unwrap() {
                            if let Some(s) = ys.as_str() {
                                a = a.possible_value(s);
                            }
                        }
                        a
                    }
                    s => panic!("Unknown Arg setting '{}' in YAML file for arg '{}'",
                                s,
                                name_str),
                }
            }

            a
        }

        /// Creates a new instance of `Arg` from a usage string. Allows creation of basic settings
        /// for Arg (i.e. everything except relational rules). The syntax is flexible, but there are
        /// some rules to follow.
        ///
        /// **NOTE**: only properties which you wish to set must be present
        ///
        /// 1. Name (arguments with a `long` or that take a value can omit this if desired),
        ///    use `[]` for non-required arguments, or `<>` for required arguments.
        /// 2. Short preceded by a `-`
        /// 3. Long preceded by a `--` (this may be used as the name, if the name is omitted. If the
        ///    name is *not* omitted, the name takes precedence over the `long`)
        /// 4. Value (this can be used as the name if the name is not manually specified. If the name
        ///    is manually specified, it takes precedence. If this value is used as the name, it uses
        ///    the same `[]` and `<>` requirement specification rules. If it is *not* used as the name,
        ///    it still needs to be surrounded by either `[]` or `<>` but there is no requirement
        ///    effect, as the requirement rule is determined by the real name. This value may follow
        ///    the `short` or `long`, it doesn't matter. If it follows the `long`, it may follow either
        ///    a `=` or ` ` there is no difference, just personal preference. If this follows a `short`
        ///    it can only be after a ` `) i.e. `-c [name]`, `--config [name]`, `--config=[name]`, etc.
        /// 5. Multiple specifier `...` (the `...` may follow the name, `short`, `long`, or value
        ///    *without* a ` ` space) i.e. `<name>... -c`, `--config <name>...`, `[name] -c...`, etc.
        /// 6. The help info surrounded by `'`s (single quotes)
        /// 7. The index of a positional argument will be the next available index (you don't need to
        ///    specify one) i.e. all arguments without a `short` or `long` will be treated as
        ///    positional
        /// 8. If the value names are all the same, and their multiple ones (i.e `-o <val> <val>`)
        ///    they are counted and used as the number of values. If they are different, they are used
        ///    as the value names (i.e. `--opt <file> <mode>`). In this case, if no name was specified
        ///    prior to the value names, the long is used as the name by which to access the argument.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        ///                  .args(vec![
        ///
        /// // A option argument with a long, named "conf" (note: because the name was specified
        /// // the portion after the long can be called anything, only the first name will be displayed
        /// // to the user. Also, requirement is set with the *name*, so the portion after the long
        /// // could be either <> or [] and it wouldn't matter, so long as it's one of them. Had the
        /// // name been omitted, the name would have been derived from the portion after the long and
        /// // those rules would have mattered)
        /// Arg::from_usage("[conf] --config=[c] 'a required file for the configuration'"),
        ///
        /// // A flag with a short, a long, named "debug", and accepts multiple values
        /// Arg::from_usage("-d --debug... 'turns on debugging information"),
        ///
        /// // A required positional argument named "input"
        /// Arg::from_usage("<input> 'the input file to use'")
        /// ])
        /// # .get_matches();
        pub fn from_usage(u: &'n str) -> Arg<'n, 'n, 'n, 'g, 'p, 'r> {
            assert!(u.len() > 0,
                    "Arg::from_usage() requires a non-zero-length usage string but none \
                was provided");

            let mut name = None;
            let mut short = None;
            let mut long = None;
            let mut help = None;
            let mut required = false;
            let mut takes_value = false;
            let mut multiple = false;
            let mut num_names = 1;
            let mut name_first = false;
            let mut consec_names = false;
            let mut val_names = BTreeSet::new();

            let parser = UsageParser::with_usage(u);
            for_match!{ parser,
                UsageToken::Name(n, req) => {
                    if consec_names {
                        num_names += 1;
                    }
                    let mut use_req = false;
                    let mut use_name = false;
                    if name.is_none() && long.is_none() && short.is_none() {
                        name_first = true;
                        use_name = true;
                        use_req = true;
                    } else if let Some(l) = long {
                        if l == name.unwrap_or("") {
                            if !name_first {
                                use_name = true;
                                use_req = true;
                            }
                        }
                    } else {
            // starting with short
                        if !name_first {
                            use_name = true;
                            use_req = true;
                        }
                    }
                    if use_name && !consec_names {
                        name = Some(n);
                    }
                    if use_req && !consec_names {
                        if let Some(r) = req {
                            required = r;
                        }
                    }
                    if short.is_some() || long.is_some() {
                        val_names.insert(n);
                        takes_value = true;
                    }
                    consec_names = true;
                },
                UsageToken::Short(s)     => {
                    consec_names = false;
                    short = Some(s);
                },
                UsageToken::Long(l)      => {
                    consec_names = false;
                    long = Some(l);
                    if name.is_none() {
                        name = Some(l);
                    }
                },
                UsageToken::Help(h)      => {
                    help = Some(h);
                },
                UsageToken::Multiple     => {
                    multiple = true;
                }
            }

            if let Some(l) = long {
                val_names.remove(l);
                if (val_names.len() > 1) && (name.unwrap() != l && !name_first) {
                    name = Some(l);
                }
            }

            Arg {
                name: name.unwrap_or_else(|| {
                    panic!("Missing flag name in \"{}\", check from_usage call", u)
                }),
                short: short,
                long: long,
                help: help,
                required: required,
                takes_value: takes_value,
                multiple: multiple,
                empty_vals: true,
                num_vals: if num_names > 1 {
                    Some(num_names)
                } else {
                    None
                },
                val_names: if val_names.len() > 1 {
                    Some(val_names)
                } else {
                    None
                },
                ..Default::default()
            }
        }

        /// Sets the short version of the argument without the preceding `-`.
        ///
        ///
        /// By default `clap` automatically assigns `V` and `h` to display version and help information
        /// respectively. You may use `V` or `h` for your own purposes, in which case `clap` simply
        /// will not assign those to the displaying of version or help.
        ///
        /// **NOTE:** Any leading `-` characters will be stripped, and only the first
        /// non `-` character will be used as the `short` version
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .short("c")
        /// # ).get_matches();
        pub fn short(mut self, s: &str) -> Self {
            self.short = s.trim_left_matches(|c| c == '-').chars().nth(0);
            self
        }

        /// Sets the long version of the argument without the preceding `--`.
        ///
        /// By default `clap` automatically assigns `version` and `help` to display version and help
        /// information respectively. You may use `version` or `help` for your own purposes, in which
        /// case `clap` simply will not assign those to the displaying of version or help automatically,
        /// and you will have to do so manually.
        ///
        /// **NOTE:** Any leading `-` characters will be stripped
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .long("config")
        /// # ).get_matches();
        pub fn long(mut self, l: &'l str) -> Self {
            self.long = Some(l.trim_left_matches(|c| c == '-'));
            self
        }

        /// Sets the help text of the argument that will be displayed to the user
        /// when they print the usage/help information.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .help("The config file used by the myprog")
        /// # ).get_matches();
        pub fn help(mut self, h: &'h str) -> Self {
            self.help = Some(h);
            self
        }

        /// Sets whether or not the argument is required by default. Required by
        /// default means it is required, when no other mutually exclusive rules have
        /// been evaluated. Mutually exclusive rules take precedence over being required
        /// by default.
        ///
        /// **NOTE:** Flags (i.e. not positional, or arguments that take values)
        /// cannot be required by default.
        /// when they print the usage/help information.
        ///
        ///
        /// #Example
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .required(true)
        /// # ).get_matches();
        pub fn required(mut self, r: bool) -> Self {
            self.required = r;
            self
        }

        /// Sets a mutually exclusive argument by name. I.e. when using this argument,
        /// the following argument can't be present.
        ///
        /// **NOTE:** Mutually exclusive rules take precedence over being required
        /// by default. Mutually exclusive rules only need to be set for one of the two
        /// arguments, they do not need to be set for each.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .conflicts_with("debug")
        /// # ).get_matches();
        pub fn conflicts_with(mut self, name: &'r str) -> Self {
            if let Some(ref mut vec) = self.blacklist {
                vec.push(name);
            } else {
                self.blacklist = Some(vec![name]);
            }
            self
        }

        /// Sets mutually exclusive arguments by names. I.e. when using this argument,
        /// the following argument can't be present.
        ///
        /// **NOTE:** Mutually exclusive rules take precedence over being required
        /// by default. Mutually exclusive rules only need to be set for one of the two
        /// arguments, they do not need to be set for each.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// let config_conflicts = ["debug", "input"];
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .conflicts_with_all(&config_conflicts)
        /// # ).get_matches();
        pub fn conflicts_with_all<T, I>(mut self, names: I) -> Self
            where T: AsRef<str> + 'r,
                  I: IntoIterator<Item = &'r T>
        {
            if let Some(ref mut vec) = self.blacklist {
                for s in names {
                    vec.push(s.as_ref());
                }
            } else {
                self.blacklist = Some(names.into_iter().map(|s| s.as_ref()).collect::<Vec<_>>());
            }
            self
        }

        /// Sets a mutually overridable argument by name. I.e. this argument and
        /// the following argument will override each other in POSIX style
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .mutually_overrides_with("debug")
        /// # ).get_matches();
        pub fn mutually_overrides_with(mut self, name: &'r str) -> Self {
            if let Some(ref mut vec) = self.overrides {
                vec.push(name);
            } else {
                self.overrides = Some(vec![name]);
            }
            self
        }

        /// Sets a mutually overridable arguments by name. I.e. this argument and
        /// the following argument will override each other in POSIX style
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// let config_overrides = ["debug", "input"];
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .mutually_overrides_with_all(&config_overrides)
        /// # ).get_matches();
        pub fn mutually_overrides_with_all<T, I>(mut self, names: I) -> Self
            where T: AsRef<str> + 'r,
                  I: IntoIterator<Item = &'r T>
        {
            if let Some(ref mut vec) = self.overrides {
                for s in names {
                    vec.push(s.as_ref());
                }
            } else {
                self.overrides = Some(names.into_iter().map(|s| s.as_ref()).collect::<Vec<_>>());
            }
            self
        }

        /// Sets an argument by name that is required when this one is present I.e. when
        /// using this argument, the following argument *must* be present.
        ///
        /// **NOTE:** Mutually exclusive and override rules take precedence over being required
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .requires("debug")
        /// # ).get_matches();
        pub fn requires(mut self, name: &'r str) -> Self {
            if let Some(ref mut vec) = self.requires {
                vec.push(name);
            } else {
                self.requires = Some(vec![name]);
            }
            self
        }

        /// Sets arguments by names that are required when this one is present I.e. when
        /// using this argument, the following arguments *must* be present.
        ///
        /// **NOTE:** Mutually exclusive and override rules take precedence over being required
        /// by default.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// let config_reqs = ["debug", "input"];
        /// # let myprog = App::new("myprog").arg(Arg::with_name("config")
        /// .requires_all(&config_reqs)
        /// # ).get_matches();
        pub fn requires_all<T, I>(mut self, names: I) -> Self
            where T: AsRef<str> + 'r,
                  I: IntoIterator<Item = &'r T>
        {
            if let Some(ref mut vec) = self.requires {
                for s in names {
                    vec.push(s.as_ref());
                }
            } else {
                self.requires = Some(names.into_iter().map(|s| s.as_ref()).collect::<Vec<_>>());
            }
            self
        }

        /// Specifies that the argument takes an additional value at run time.
        ///
        /// **NOTE:** When setting this to `true` the `name` of the argument
        /// will be used when printing the help/usage information to the user.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .takes_value(true)
        /// # ).get_matches();
        pub fn takes_value(mut self, tv: bool) -> Self {
            self.takes_value = tv;
            self
        }

        /// Specifies the index of a positional argument starting at 1.
        ///
        /// **NOTE:** When setting this,  any `short` or `long` values you set
        /// are ignored as positional arguments cannot have a `short` or `long`.
        /// Also, the name will be used when printing the help/usage information
        /// to the user.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("config")
        /// .index(1)
        /// # ).get_matches();
        pub fn index(mut self, idx: u8) -> Self {
            self.index = Some(idx);
            self
        }

        /// Specifies that the flag or option may appear more than once. For flags, this results
        /// in the number of occurrences of the flag being recorded. For example `-ddd` would count as
        /// three occurrences. The form `-d -d -d` would also be recognized as three occurrences. For
        /// options, more than one value may be provided. The forms `--optional foo --optional bar`,
        /// `--optional foo bar` and `-ofoo -obar` are all recognized, assuming the relevant `short`
        /// and `long` option names have been set.
        ///
        /// **NOTE:** When setting this, `index` is ignored as it only makes sense for positional
        /// arguments.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug")
        /// .multiple(true)
        /// # ).get_matches();
        pub fn multiple(mut self, multi: bool) -> Self {
            self.multiple = multi;
            self
        }

        /// Specifies that an argument can be matched to all child subcommands.
        ///
        /// **NOTE:** Global arguments *only* propagate down, **not** up (to parent commands)
        ///
        /// **NOTE:** Global arguments *cannot* be required.
        ///
        /// **NOTE:** Global arguments, when matched, *only* exist in the command's matches that they
        /// were matched to. For example, if you defined a `--flag` global argument in the top most
        /// parent command, but the user supplied the arguments `top cmd1 cmd2 --flag` *only* `cmd2`'s
        /// `ArgMatches` would return `true` if tested for `.is_present("flag")`.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug")
        /// .global(true)
        /// # ).get_matches();
        pub fn global(mut self, g: bool) -> Self {
            self.global = g;
            self
        }

        /// Allows an argument to accept explicit empty values. An empty value must be specified at the
        /// command line with an explicit `""`, or `''`
        ///
        /// **NOTE:** Defaults to `true` (Explicit empty values are allowed)
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug")
        /// .empty_values(true)
        /// # ).get_matches();
        pub fn empty_values(mut self, ev: bool) -> Self {
            self.empty_vals = ev;
            self
        }

        /// Hides an argument from help message output.
        ///
        /// **NOTE:** This does **not** hide the argument from usage strings on error
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug")
        /// .hidden(true)
        /// # ).get_matches();
        pub fn hidden(mut self, h: bool) -> Self {
            self.hidden = h;
            self
        }

        /// Specifies a list of possible values for this argument. At runtime, clap verifies that only
        /// one of the specified values was used, or fails with a usage string.
        ///
        /// **NOTE:** This setting only applies to options and positional arguments
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// let mode_vals = ["fast", "slow"];
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .possible_values(&mode_vals)
        /// # ).get_matches();
        pub fn possible_values<T, I>(mut self, names: I) -> Self
            where T: AsRef<str> + 'p,
                  I: IntoIterator<Item = &'p T>
        {
            if let Some(ref mut vec) = self.possible_vals {
                for s in names {
                    vec.push(s.as_ref());
                }
            } else {
                self.possible_vals = Some(names.into_iter().map(|s| s.as_ref()).collect::<Vec<_>>());
            }
            self
        }

        /// Specifies a possible value for this argument. At runtime, clap verifies that only
        /// one of the specified values was used, or fails with a usage string.
        ///
        /// **NOTE:** This setting only applies to options and positional arguments
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .possible_value("fast")
        /// .possible_value("slow")
        /// # ).get_matches();
        pub fn possible_value(mut self, name: &'p str) -> Self {
            if let Some(ref mut vec) = self.possible_vals {
                vec.push(name);
            } else {
                self.possible_vals = Some(vec![name]);
            }
            self
        }

        /// Specifies the name of the group the argument belongs to.
        ///
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .group("mode")
        /// # ).get_matches();
        pub fn group(mut self, name: &'g str) -> Self {
            self.group = Some(name);
            self
        }

        /// Specifies how many values are required to satisfy this argument. For example, if you had a
        /// `-f <file>` argument where you wanted exactly 3 'files' you would set
        /// `.number_of_values(3)`, and this argument wouldn't be satisfied unless the user provided
        /// 3 and only 3 values.
        ///
        /// **NOTE:** Does *not* require `.multiple(true)` to be set. Setting `.multiple(true)` would
        /// allow `-f <file> <file> <file> -f <file> <file> <file>` where as *not* setting
        /// `.multiple(true)` would only allow one occurrence of this argument.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .number_of_values(3)
        /// # ).get_matches();
        pub fn number_of_values(mut self, qty: u8) -> Self {
            self.num_vals = Some(qty);
            self
        }

        /// Allows one to perform a validation on the argument value. You provide a closure which
        /// accepts a `String` value, a `Result` where the `Err(String)` is a message displayed to the
        /// user.
        ///
        /// **NOTE:** The error message does *not* need to contain the `error:` portion, only the
        /// message.
        ///
        /// **NOTE:** There is a small performance hit for using validators, as they are implemented
        /// with `Rc` pointers. And the value to be checked will be allocated an extra time in order to
        /// to be passed to the closure.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .validator(|val| {
        ///     if val.contains("@") {
        ///         Ok(())
        ///     } else {
        ///         Err(String::from("the value must contain at least one '@' character"))
        ///     }
        /// })
        /// # ).get_matches();
        pub fn validator<F>(mut self, f: F) -> Self
            where F: Fn(String) -> Result<(), String> + 'static
        {
            self.validator = Some(Rc::new(f));
            self
        }

        /// Specifies the *maximum* number of values are for this argument. For example, if you had a
        /// `-f <file>` argument where you wanted up to 3 'files' you would set
        /// `.max_values(3)`, and this argument would be satisfied if the user provided, 1, 2, or 3
        /// values.
        ///
        /// **NOTE:** `qty` must be > 1
        ///
        /// **NOTE:** This implicitly sets `.multiple(true)`
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .max_values(3)
        /// # ).get_matches();
        pub fn max_values(mut self, qty: u8) -> Self {
            if qty < 2 {
                panic!("Arguments with max_values(qty) qty must be > 1. Prefer \
                    takes_value(true) for arguments with only one value, or flags for arguments \
                    with 0 values.");
            }
            self.max_vals = Some(qty);
            self.multiple = true;
            self
        }

        /// Specifies the *minimum* number of values are for this argument. For example, if you had a
        /// `-f <file>` argument where you wanted at least 2 'files' you would set
        /// `.min_values(2)`, and this argument would be satisfied if the user provided, 2 or more
        /// values.
        ///
        /// **NOTE:** This implicitly sets `.multiple(true)`
        ///
        /// **NOTE:** `qty` must be > 0
        ///
        /// **NOTE:** `qty` *must* be > 0. If you wish to have an argument with 0 or more values prefer
        /// two separate arguments (a flag, and an option with multiple values).
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// .min_values(2)
        /// # ).get_matches();
        pub fn min_values(mut self, qty: u8) -> Self {
            if qty < 1 {
                panic!("Arguments with min_values(qty) qty must be > 0. Prefer flags for arguments \
                    with 0 values.");
            }
            self.min_vals = Some(qty);
            self.multiple = true;
            self
        }

        /// Specifies names for values of option arguments. These names are cosmetic only, used for
        /// help and usage strings only. The names are **not** used to access arguments. The values of
        /// the arguments are accessed in numeric order (i.e. if you specify two names `one` and `two`
        /// `one` will be the first matched value, `two` will be the second).
        ///
        /// **NOTE:** This implicitly sets `.number_of_values()` so there is no need to set that, but
        /// be aware that the number of "names" you set for the values, will be the *exact* number of
        /// values required to satisfy this argument
        ///
        /// **NOTE:** Does *not* require `.multiple(true)` to be set. Setting `.multiple(true)` would
        /// allow `-f <file> <file> <file> -f <file> <file> <file>` where as *not* setting
        /// `.multiple(true)` would only allow one occurrence of this argument.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// let val_names = ["one", "two"];
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// # Arg::with_name("debug").index(1)
        /// // ...
        /// .value_names(&val_names)
        /// # ).get_matches();
        pub fn value_names<T, I>(mut self, names: I) -> Self
            where T: AsRef<str> + 'n,
                  I: IntoIterator<Item = &'n T>
        {
            if let Some(ref mut vec) = self.val_names {
                for s in names {
                    vec.insert(s.as_ref());
                }
            } else {
                self.val_names = Some(names.into_iter().map(|s| s.as_ref()).collect::<BTreeSet<_>>());
            }
            self
        }

        /// Specifies the name for value of option or positional arguments. This name is cosmetic only,
        /// used for help and usage strings. The name is **not** used to access arguments.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg};
        /// # let matches = App::new("myprog")
        /// #                 .arg(
        /// Arg::with_name("debug")
        ///     .index(1)
        ///     .value_name("file")
        /// # ).get_matches();
        pub fn value_name(mut self, name: &'n str) -> Self {
            if let Some(ref mut vec) = self.val_names {
                vec.insert(name);
            } else {
                let mut bts = BTreeSet::new();
                bts.insert(name);
                self.val_names = Some(bts);
            }
            self
        }
    }

    impl<'n, 'l, 'h, 'g, 'p, 'r, 'z> From<&'z Arg<'n, 'l, 'h, 'g, 'p, 'r>>
        for Arg<'n, 'l, 'h, 'g, 'p, 'r> {
        fn from(a: &'z Arg<'n, 'l, 'h, 'g, 'p, 'r>) -> Self {
            Arg {
                name: a.name,
                short: a.short,
                long: a.long,
                help: a.help,
                required: a.required,
                takes_value: a.takes_value,
                multiple: a.multiple,
                index: a.index,
                possible_vals: a.possible_vals.clone(),
                blacklist: a.blacklist.clone(),
                requires: a.requires.clone(),
                num_vals: a.num_vals,
                min_vals: a.min_vals,
                max_vals: a.max_vals,
                val_names: a.val_names.clone(),
                group: a.group,
                global: a.global,
                empty_vals: a.empty_vals,
                validator: a.validator.clone(),
                overrides: a.overrides.clone(),
                hidden: a.hidden,
            }
        }
    }

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## Keyboard Shortcuts

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  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
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⏎
  Go to active search result

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)