clap/src/app/mod.rs

#[allow(dead_code)]
mod settings;
#[macro_use]
mod macros;
mod parser;
mod meta;

pub use self::settings::AppSettings;

use std::env;
use std::io::{self, BufRead, BufWriter, Write};
use std::path::Path;
use std::process;
use std::ffi::OsString;
use std::borrow::Borrow;

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

use args::{Arg, AnyArg, ArgGroup, ArgMatches, ArgMatcher};
use app::parser::Parser;
use errors::Error;
use errors::Result as ClapResult;

/// Used to create a representation of a command line program and all possible command line
/// arguments.
///
/// Application settings are set using the "builder pattern" with `.get_matches()` being the
/// terminal method that starts the runtime-parsing process and returns information about
/// the user supplied arguments (or lack there of).
///
/// There aren't any mandatory "options" that one must set. The "options" may also appear in any
/// order (so long as `.get_matches()` is the last method called).
///
///
/// # Examples
///
/// ```no_run
/// # use clap::{App, Arg};
/// let matches = App::new("myprog")
///                   .author("Me, me@mail.com")
///                   .version("1.0.2")
///                   .about("Explains in brief what the program does")
///                   .arg(
///                            Arg::with_name("in_file").index(1)
///                    )
///                   .after_help("Longer explaination to appear after the options when \
///                                displaying the help information from --help or -h")
///                   .get_matches();
///
/// // Your program logic starts here...
/// ```
#[allow(missing_debug_implementations)]
pub struct App<'a, 'b>(Parser<'a, 'b>) where 'a: 'b;

impl<'a, 'b> App<'a, 'b> {
    /// Creates a new instance of an application requiring a name (such as the binary). The name
    /// will be displayed to the user when they request to print version or help and usage
    /// information. The name should not contain spaces (hyphens '-' are ok).
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let prog = App::new("myprog")
    /// # .get_matches();
    /// ```
    pub fn new<S: Into<String>>(n: S) -> Self { App(Parser::with_name(n.into())) }

    /// Creates a new instace of `App` from a .yml (YAML) file. The YAML file must be properly
    /// formatted or this function will panic!(). A full example of supported YAML objects can be
    /// found in `examples/17_yaml.rs` and `examples/17_yaml.yml`.
    ///
    /// In order to use this function you must compile with the `features = ["yaml"]` in your
    /// settings for `[dependencies.clap]` table of your `Cargo.toml`
    ///
    /// Note, due to how the YAML objects are built there is a convienience macro for loading the
    /// YAML file (relative to the current file, like modules work). That YAML object can then be
    /// passed to this function.
    ///
    /// # Examples
    ///
    /// ```ignore
    /// # use clap::App;
    /// let yml = load_yaml!("app.yml");
    /// let app = App::from_yaml(yml);
    /// ```
    #[cfg(feature = "yaml")]
    pub fn from_yaml<'y>(mut yaml: &'y Yaml) -> App<'y, 'y, 'y, 'y, 'y, 'y> {
        // We WANT this to panic on error...so expect() is good.
        let mut is_sc = None;
        let mut a = if let Some(name) = yaml["name"].as_str() {
            App::new(name)
        } else {
            let yaml_hash = yaml.as_hash().unwrap();
            let sc_key = yaml_hash.keys().nth(0).unwrap();
            is_sc = Some(yaml_hash.get(sc_key).unwrap());
            App::new(sc_key.as_str().unwrap())
        };
        yaml = if let Some(sc) = is_sc {
            sc
        } else {
            yaml
        };
        if let Some(v) = yaml["version"].as_str() {
            a = a.version(v);
        }
        if let Some(v) = yaml["author"].as_str() {
            a = a.author(v);
        }
        if let Some(v) = yaml["bin_name"].as_str() {
            a = a.bin_name(v);
        }
        if let Some(v) = yaml["about"].as_str() {
            a = a.about(v);
        }
        if let Some(v) = yaml["after_help"].as_str() {
            a = a.after_help(v);
        }
        if let Some(v) = yaml["usage"].as_str() {
            a = a.usage(v);
        }
        if let Some(v) = yaml["help"].as_str() {
            a = a.help(v);
        }
        if let Some(v) = yaml["help_short"].as_str() {
            a = a.help_short(v);
        }
        if let Some(v) = yaml["version_short"].as_str() {
            a = a.version_short(v);
        }
        if let Some(v) = yaml["settings"].as_vec() {
            for ys in v {
                if let Some(s) = ys.as_str() {
                    a = a.setting(s.parse().ok().expect("unknown AppSetting found in YAML file"));
                }
            }
        }
        if let Some(v) = yaml["args"].as_vec() {
            for arg_yaml in v {
                a = a.arg(Arg::from_yaml(&arg_yaml.as_hash().unwrap()));
            }
        }
        if let Some(v) = yaml["subcommands"].as_vec() {
            for sc_yaml in v {
                a = a.subcommand(SubCommand::from_yaml(&sc_yaml));
            }
        }
        if let Some(v) = yaml["arg_groups"].as_vec() {
            for ag_yaml in v {
                a = a.arg_group(ArgGroup::from_yaml(&ag_yaml.as_hash().unwrap()));
            }
        }

        a
    }

    /// Sets a string of author(s) and will be displayed to the user when they request the help
    /// information with `--help` or `-h`.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///      .author("Me, me@mymain.com")
    /// # ;
    /// ```
    pub fn author<S: Into<&'b str>>(mut self, author: S) -> Self {
        self.0.meta.author = Some(author.into());
        self
    }

    /// Overrides the system-determined binary name. This should only be used when absolutely
    /// neccessary, such as the binary name for your application is misleading, or perhaps *not*
    /// how the user should invoke your program.
    ///
    /// **NOTE:** This command **should not** be used for SubCommands.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///      .bin_name("my_binary")
    /// # ;
    /// ```
    pub fn bin_name<S: Into<String>>(mut self, name: S) -> Self {
        self.0.meta.bin_name = Some(name.into());
        self
    }

    /// Sets a string briefly describing what the program does and will be displayed when
    /// displaying help information.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .about("Does really amazing things to great people")
    /// # ;
    /// ```
    pub fn about<S: Into<&'b str>>(mut self, about: S) -> Self {
        self.0.meta.about = Some(about.into());
        self
    }

    /// Adds additional help information to be displayed in addition to and directly after
    /// auto-generated help. This information is displayed **after** the auto-generated help
    /// information. This additional help is often used to describe how to use the arguments,
    /// or caveats to be noted.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::App;
    /// App::new("myprog")
    ///     .after_help("Does really amazing things to great people")
    /// # ;
    /// ```
    pub fn after_help<S: Into<&'b str>>(mut self, help: S) -> Self {
        self.0.meta.more_help = Some(help.into());
        self
    }

    /// Sets a string of the version number to be displayed when displaying version or help
    /// information.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .version("v0.1.24")
    /// # ;
    /// ```
    pub fn version<S: Into<&'b str>>(mut self, ver: S) -> Self {
        self.0.meta.version = Some(ver.into());
        self
    }

    /// Sets a custom usage string to override the auto-generated usage string.
    ///
    /// This will be displayed to the user when errors are found in argument parsing, or when you
    /// call `ArgMatcher::usage()`
    ///
    /// **NOTE:** You do not need to specify the "USAGE: \n\t" portion, as that will
    /// still be applied by `clap`, you only need to specify the portion starting
    /// with the binary name.
    ///
    /// **NOTE:** This will not replace the entire help message, *only* the portion
    /// showing the usage.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .usage("myapp [-clDas] <some_file>")
    /// # ;
    /// ```
    pub fn usage<S: Into<&'b str>>(mut self, usage: S) -> Self {
        self.0.meta.usage_str = Some(usage.into());
        self
    }

    /// Sets a custom help message and overrides the auto-generated one. This should only be used
    /// when the auto-generated message does not suffice.
    ///
    /// This will be displayed to the user when they use the default `--help` or `-h`
    ///
    /// **NOTE:** This replaces the **entire** help message, so nothing will be auto-generated.
    ///
    /// **NOTE:** This **only** replaces the help message for the current command, meaning if you
    /// are using subcommands, those help messages will still be auto-generated unless you
    /// specify a `.help()` for them as well.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myapp")
    ///     .help("myapp v1.0\n\
    ///            Does awesome things\n\
    ///            (C) me@mail.com\n\n\
    ///
    ///            USAGE: myapp <opts> <comamnd>\n\n\
    ///
    ///            Options:\n\
    ///            -h, --helpe      Dispay this message\n\
    ///            -V, --version    Display version info\n\
    ///            -s <stuff>       Do something with stuff\n\
    ///            -v               Be verbose\n\n\
    ///
    ///            Commmands:\n\
    ///            help             Prints this message\n\
    ///            work             Do some work")
    /// # ;
    /// ```
    pub fn help<S: Into<&'b str>>(mut self, help: S) -> Self {
        self.0.meta.help_str = Some(help.into());
        self
    }

    /// Sets the short version of the `help` argument without the preceding `-`.
    ///
    /// By default `clap` automatically assigns `h`, but this can be overridden
    ///
    /// **NOTE:** Any leading `-` characters will be stripped, and only the first
    /// non `-` chacter will be used as the `short` version
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     // Using an uppercase `H` instead of the default lowercase `h`
    ///     .help_short("H")
    /// # ;
    pub fn help_short<S: AsRef<str> + 'b>(mut self, s: S) -> Self {
        self.0.help_short(s.as_ref());
        self
    }

    /// Sets the short version of the `version` argument without the preceding `-`.
    ///
    /// By default `clap` automatically assigns `V`, but this can be overridden
    ///
    /// **NOTE:** Any leading `-` characters will be stripped, and only the first
    /// non `-` chacter will be used as the `short` version
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     // Using a lowercase `v` instead of the default capital `V`
    ///     .version_short("v")
    /// # ;
    pub fn version_short<S: AsRef<str>>(mut self, s: S) -> Self {
        self.0.version_short(s.as_ref());
        self
    }

    /// Enables Application level settings, passed as argument
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg, AppSettings};
    /// App::new("myprog")
    ///     .setting(AppSettings::SubcommandRequired)
    ///     .setting(AppSettings::WaitOnError)
    /// # ;
    /// ```
    pub fn setting(mut self, setting: AppSettings) -> Self {
        self.0.set(setting);
        self
    }

    /// Enables multiple Application level settings, passed as argument
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg, AppSettings};
    /// App::new("myprog")
    ///     .settings( &[AppSettings::SubcommandRequired,
    ///                  AppSettings::WaitOnError])
    /// # ;
    /// ```
    pub fn settings(mut self, settings: &[AppSettings]) -> Self {
        for s in settings {
            self.0.set(*s);
        }
        self
    }

    /// Adds an argument to the list of valid possibilties manually. This method allows you full
    /// control over the arguments settings and options (as well as dynamic generation). It also
    /// allows you specify several more advanced configuration options such as relational rules
    /// (exclusions and requirements).
    ///
    /// The only disadvantage to this method is that it's more verbose, and arguments must be added
    /// one at a time. Using `Arg::from_usage` helps with the verbosity, and still allows full
    /// control over the advanced configuration options.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     // Adding a single "flag" argument with a short and help text, using Arg::with_name()
    ///     .arg(
    ///         Arg::with_name("debug")
    ///            .short("d")
    ///            .help("turns on debugging mode")
    ///     )
    ///     // Adding a single "option" argument with a short, a long, and help text using the less
    ///     // verbose Arg::from_usage()
    ///     .arg(
    ///         Arg::from_usage("-c --config=[CONFIG] 'Optionally sets a config file to use'")
    ///     )
    /// # ;
    /// ```
    pub fn arg<A: Borrow<Arg<'a, 'b>> + 'a>(mut self, a: A) -> Self {
        self.0.add_arg(a.borrow());
        self
    }

    /// Adds multiple arguments to the list of valid possibilties by iterating over a Vec of Args
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .args(
    ///         vec![Arg::from_usage("[debug] -d 'turns on debugging info"),
    ///              Arg::with_name("input").index(1).help("the input file to use")]
    ///     )
    /// # ;
    /// ```
    pub fn args(mut self, args: &[Arg<'a, 'b>]) -> Self {
        for arg in args {
            self.0.add_arg(arg);
        }
        self
    }

    /// A convienience method for adding a single basic argument (one without advanced
    /// relational rules) from a usage type string. The string used follows the same rules and
    /// syntax as `Arg::from_usage()`
    ///
    /// The downside to using this method is that you can not set any additional properties of the
    /// `Arg` other than what `Arg::from_usage()` supports.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .arg_from_usage("-c --conf=<config> 'Sets a configuration file to use'")
    /// # ;
    /// ```
    pub fn arg_from_usage(mut self, usage: &'a str) -> Self {
        self.0.add_arg(&Arg::from_usage(usage));
        self
    }

    /// Adds multiple arguments at once from a usage string, one per line. See `Arg::from_usage()`
    /// for details on the syntax and rules supported.
    ///
    /// Like `App::arg_from_usage()` the downside is you only set properties for the `Arg`s which
    /// `Arg::from_usage()` supports. But here the benefit is pretty strong, as the readability is
    /// greatly enhanced, especially if you don't need any of the more advanced configuration
    /// options.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// App::new("myprog")
    ///     .args_from_usage(
    ///         "-c --conf=[config] 'Sets a configuration file to use'
    ///          [debug]... -d 'Sets the debugging level'
    ///          <input> 'The input file to use'"
    ///     )
    /// # ;
    /// ```
    pub fn args_from_usage(mut self, usage: &'a str) -> Self {
        for l in usage.lines() {
            self.0.add_arg(&Arg::from_usage(l.trim()));
        }
        self
    }

    /// Adds an ArgGroup to the application. ArgGroups are a family of related arguments. By
    /// placing them in a logical group, you make easier requirement and exclusion rules. For
    /// instance, you can make an ArgGroup required, this means that one (and *only* one) argument
    /// from that group must be present. Using more than one argument from an ArgGroup causes a
    /// failure (graceful exit).
    ///
    /// You can also do things such as name an ArgGroup as a confliction, meaning any of the
    /// arguments that belong to that group will cause a failure if present.
    ///
    /// Perhaps the most common use of ArgGroups is to require one and *only* one argument to be
    /// present out of a given set. For example, lets say that you were building an application
    /// where one could set a given version number by supplying a string using an option argument,
    /// such as `--set-ver v1.2.3`, you also wanted to support automatically using a previous
    /// version numer and simply incrementing one of the three numbers, so you create three flags
    /// `--major`, `--minor`, and `--patch`. All of these arguments shouldn't be used at one time
    /// but perhaps you want to specify that *at least one* of them is used. You can create a
    /// group
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, ArgGroup};
    /// # App::new("app")
    /// .args_from_usage("--set-ver [ver] 'set the version manually'
    ///                   --major         'auto increase major'
    ///                   --minor         'auto increase minor'
    ///                   --patch         'auto increase patch")
    /// .arg_group(ArgGroup::with_name("vers")
    ///                     .add_all(&["ver", "major", "minor","patch"])
    ///                     .required(true))
    /// # ;
    pub fn group(mut self, group: ArgGroup<'a>) -> Self {
        self.0.add_group(group);
        self
    }

    /// Adds a ArgGroups to the application. ArgGroups are a family of related arguments. By
    /// placing them in a logical group, you make easier requirement and exclusion rules. For
    /// instance, you can make an ArgGroup required, this means that one (and *only* one) argument
    /// from that group must be present. Using more than one argument from an ArgGroup causes a
    /// failure (graceful exit).
    ///
    /// You can also do things such as name an ArgGroup as a confliction, meaning any of the
    /// arguments that belong to that group will cause a failure if present.
    ///
    /// Perhaps the most common use of ArgGroups is to require one and *only* one argument to be
    /// present out of a given set. For example, lets say that you were building an application
    /// where one could set a given version number by supplying a string using an option argument,
    /// such as `--set-ver v1.2.3`, you also wanted to support automatically using a previous
    /// version numer and simply incrementing one of the three numbers, so you create three flags
    /// `--major`, `--minor`, and `--patch`. All of these arguments shouldn't be used at one time
    /// but perhaps you want to specify that *at least one* of them is used. You can create a
    /// group
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, ArgGroup};
    /// # App::new("app")
    /// .args_from_usage("--set-ver [ver] 'set the version manually'
    ///                   --major         'auto increase major'
    ///                   --minor         'auto increase minor'
    ///                   --patch         'auto increase patch")
    /// .arg_group(ArgGroup::with_name("vers")
    ///                     .add_all(&["ver", "major", "minor","patch"])
    ///                     .required(true))
    /// # ;
    pub fn groups(mut self, groups: &[ArgGroup<'a>]) -> Self {
        for g in groups {
            self = self.group(g.into());
        }
        self
    }

    /// Adds a subcommand to the list of valid possibilties. Subcommands are effectively sub apps,
    /// because they can contain their own arguments, subcommands, version, usage, etc. They also
    /// function just like apps, in that they get their own auto generated help, version, and
    /// usage.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg, SubCommand};
    /// # App::new("myprog")
    /// .subcommand(SubCommand::with_name("config")
    ///                .about("Controls configuration features")
    ///                .arg_from_usage("<config> 'Required configuration file to use'"))
    ///             // Additional subcommand configuration goes here, such as other arguments...
    /// # ;
    /// ```
    pub fn subcommand(mut self, subcmd: App<'a, 'b>) -> Self {
        self.0.add_subcommand(subcmd);
        self
    }

    /// Adds multiple subcommands to the list of valid possibilties by iterating over a Vec of
    /// `SubCommand`s
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg, SubCommand};
    /// # App::new("myprog")
    /// .subcommands( vec![
    ///        SubCommand::with_name("config").about("Controls configuration functionality")
    ///                                 .arg(Arg::with_name("config_file").index(1)),
    ///        SubCommand::with_name("debug").about("Controls debug functionality")])
    /// # ;
    /// ```
    pub fn subcommands(mut self, subcmds: Vec<App<'a, 'b>>) -> Self {
        for subcmd in subcmds.into_iter() {
            self.0.add_subcommand(subcmd);
        }
        self
    }


    /// Prints the full help message to `io::stdout()` using a `BufWriter`
    ///
    /// # Examples
    /// ```no_run
    /// # use clap::App;
    /// # use std::io;
    /// let app = App::new("myprog");
    /// app.print_help();
    /// ```
    pub fn print_help(&self) -> ClapResult<()> {
        let out = io::stdout();
        let mut buf_w = BufWriter::new(out.lock());
        self.write_help(&mut buf_w)
    }

    /// Writes the full help message to the user to a `io::Write` object
    ///
    /// ```no_run
    /// # use clap::App;
    /// # use std::io;
    /// let mut app = App::new("myprog");
    /// let mut out = io::stdout();
    /// app.write_help(&mut out).ok().expect("failed to write to stdout");
    /// ```
    pub fn write_help<W: Write>(&self, w: &mut W) -> ClapResult<()> {
        self.0.write_help(w)
    }

    /// Starts the parsing process. Called on top level parent app **ONLY** then recursively calls
    /// the real parsing function for all subcommands
    ///
    /// # Panics
    ///
    /// If any arguments contain invalid unicode characters. If this is not desired it is
    /// recommended to use the `*_safe()` or `*_lossy()` versions of this method.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let matches = App::new("myprog")
    ///     // Args and options go here...
    ///     .get_matches();
    /// ```
    pub fn get_matches<U>(self) -> ArgMatches<'a> {
        // Start the parsing
        self.get_matches_from(&mut env::args_os())
    }

    /// Starts the parsing process. Called on top level parent app **ONLY** then recursively calls
    /// the real parsing function for all subcommands
    ///
    /// **NOTE:** This method WILL NOT exit when `--help` or `--version` (or short versions) are
    /// used. It will return an error, where the `kind` is a `ErrorKind::HelpDisplayed`
    /// or `ErrorKind::VersionDisplayed` respectively. You must call `error.exit()` or
    /// perform a `std::process::exit` yourself.
    ///
    /// **NOTE:** This method should only be used when is absolutely necessary to handle errors
    /// manually.
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let matches = App::new("myprog")
    ///     // Args and options go here...
    ///     .get_matches_safe()
    ///     .unwrap_or_else( |e| { panic!("An error occurs: {}", e) });
    /// ```
    pub fn get_matches_safe(self) -> ClapResult<ArgMatches<'a>> {
        // Start the parsing
        self.get_matches_from_safe(&mut env::args_os())
    }

    /// Starts the parsing process. Called on top level parent app **ONLY** then recursively calls
    /// the real parsing function for all subcommands
    ///
    /// **NOTE:** The first argument will be parsed as the binary name.
    ///
    /// **NOTE:** This method should only be used when absolutely necessary, such as needing to
    /// parse arguments from something other than `std::env::args()`. If you are unsure, use
    /// `App::get_matches()`
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let arg_vec = vec!["my_prog", "some", "args", "to", "parse"];
    ///
    /// let matches = App::new("myprog")
    ///     // Args and options go here...
    ///     .get_matches_from(arg_vec);
    /// ```
    pub fn get_matches_from<I, T>(mut self, itr: &mut I) -> ArgMatches<'a>
        where I: Iterator<Item = T>,
              T: Into<OsString>
    {
        self.get_matches_from_safe_borrow(itr).unwrap_or_else(|e| {
            // Otherwise, write to stderr and exit
            self.maybe_wait_for_exit(e);
        })
    }

    /// Starts the parsing process. Called on top level parent app **ONLY** then recursively calls
    /// the real parsing function for all subcommands
    ///
    /// **NOTE:** This method WILL NOT exit when `--help` or `--version` (or short versions) are
    /// used. It will return an error, where the `kind` is a `ErrorKind::HelpDisplayed`
    /// or `ErrorKind::VersionDisplayed` respectively. You must call `error.exit()` or
    /// perform a `std::process::exit` yourself.
    ///
    /// **NOTE:** The first argument will be parsed as the binary name.
    ///
    /// **NOTE:** This method should only be used when absolutely necessary, such as needing to
    /// parse arguments from something other than `std::env::args()`. If you are unsure, use
    /// `App::get_matches_safe()`
    ///
    /// **NOTE:** This method should only be used when is absolutely necessary to handle errors
    /// manually.
    ///
    /// **NOTE:** Invalid unicode characters will result in an `Err` with type
    /// `ErrorKind::InvalidUtf8`
    ///
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let arg_vec = vec!["my_prog", "some", "args", "to", "parse"];
    ///
    /// let matches = App::new("myprog")
    ///     // Args and options go here...
    ///     .get_matches_from_safe(arg_vec)
    ///     .unwrap_or_else( |e| { panic!("An error occurs: {}", e) });
    /// ```
    pub fn get_matches_from_safe<I, T>(mut self, itr: &mut I) -> ClapResult<ArgMatches<'a>>
        where I: Iterator<Item = T>,
              T: Into<OsString>
    {
        self.get_matches_from_safe_borrow(itr)
    }

    /// Starts the parsing process without consuming the `App` struct `self`. This is normally not
    /// the desired functionality, instead prefer `App::get_matches_from_safe` which *does*
    /// consume `self`.
    ///
    /// **NOTE:** The first argument will be parsed as the binary name.
    ///
    /// **NOTE:** This method should only be used when absolutely necessary, such as needing to
    /// parse arguments from something other than `std::env::args()`. If you are unsure, use
    /// `App::get_matches_safe()`
    ///
    /// **NOTE:** This method should only be used when is absolutely necessary to handle errors
    /// manually.
    ///
    /// **NOTE:** Invalid unicode characters will result in an `Err` with type
    /// `ErrorKind::InvalidUtf8`
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let arg_vec = vec!["my_prog", "some", "args", "to", "parse"];
    ///
    /// let mut app = App::new("myprog");
    ///     // Args and options go here...
    /// let matches = app.get_matches_from_safe_borrow(arg_vec)
    ///     .unwrap_or_else( |e| { panic!("An error occurs: {}", e) });
    /// ```
    fn get_matches_from_safe_borrow<I, T>(&mut self, itr: &mut I) -> ClapResult<ArgMatches<'a>>
        where I: Iterator<Item = T>,
              T: Into<OsString>
    {
        // Verify all positional assertions pass
        self.0.verify_positionals();
        // If there are global arguments, we need to propgate them down to subcommands
        // before parsing incase we run into a subcommand
        self.0.propogate_globals();

        let mut matcher = ArgMatcher::new();

        let mut it = itr.into_iter();
        // Get the name of the program (argument 1 of env::args()) and determine the
        // actual file
        // that was used to execute the program. This is because a program called
        // ./target/release/my_prog -a
        // will have two arguments, './target/release/my_prog', '-a' but we don't want
        // to display
        // the full path when displaying help messages and such
        if !self.0.is_set(AppSettings::NoBinaryName) {
            if let Some(name) = it.next() {
                let bn_os = name.into();
                let p = Path::new(&*bn_os);
                if let Some(f) = p.file_name() {
                    if let Some(s) = f.to_os_string().to_str() {
                        if let None = self.0.meta.bin_name {
                            self.0.meta.bin_name = Some(s.to_owned());
                        }
                    }
                }
            }
        }

        // do the real parsing
        if let Err(e) = self.0.get_matches_with(&mut matcher, &mut it) {
            return Err(e);
        }

        Ok(matcher.into())
    }

    // Re-implements ClapError::exit except it checks if we should wait for input before exiting
    // since ClapError doesn't have that info and the error message must be printed before exiting
    fn maybe_wait_for_exit(&self, e: Error) -> ! {
        if e.use_stderr() {
            wlnerr!("{}", e.message);
            if self.0.is_set(AppSettings::WaitOnError) {
                wlnerr!("\nPress [ENTER] / [RETURN] to continue...");
                let mut s = String::new();
                let i = io::stdin();
                i.lock().read_line(&mut s).unwrap();
            }
            process::exit(1);
        }

        e.exit()
    }
}