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/// Command line argument parser kind of error
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
#[non_exhaustive]
pub enum ErrorKind {
/// Occurs when an [`Arg`][crate::Arg] has a set of possible values,
/// and the user provides a value which isn't in that set.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .arg(Arg::new("speed")
/// .value_parser(["fast", "slow"]))
/// .try_get_matches_from(vec!["prog", "other"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::InvalidValue);
/// ```
InvalidValue,
/// Occurs when a user provides a flag, option, argument or subcommand which isn't defined.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .arg(arg!(--flag "some flag"))
/// .try_get_matches_from(vec!["prog", "--other"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::UnknownArgument);
/// ```
UnknownArgument,
/// Occurs when the user provides an unrecognized [`Subcommand`] which meets the threshold for
/// being similar enough to an existing subcommand.
/// If it doesn't meet the threshold, or the 'suggestions' feature is disabled,
/// the more general [`UnknownArgument`] error is returned.
///
/// # Examples
///
#[cfg_attr(not(feature = "suggestions"), doc = " ```no_run")]
#[cfg_attr(feature = "suggestions", doc = " ```")]
/// # use clap::{Command, Arg, error::ErrorKind, };
/// let result = Command::new("prog")
/// .subcommand(Command::new("config")
/// .about("Used for configuration")
/// .arg(Arg::new("config_file")
/// .help("The configuration file to use")))
/// .try_get_matches_from(vec!["prog", "confi"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::InvalidSubcommand);
/// ```
///
/// [`Subcommand`]: crate::Subcommand
/// [`UnknownArgument`]: ErrorKind::UnknownArgument
InvalidSubcommand,
/// Occurs when the user doesn't use equals for an option that requires equal
/// sign to provide values.
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind, ArgAction};
/// let res = Command::new("prog")
/// .arg(Arg::new("color")
/// .action(ArgAction::Set)
/// .require_equals(true)
/// .long("color"))
/// .try_get_matches_from(vec!["prog", "--color", "red"]);
/// assert!(res.is_err());
/// assert_eq!(res.unwrap_err().kind(), ErrorKind::NoEquals);
/// ```
NoEquals,
/// Occurs when the user provides a value for an argument with a custom validation and the
/// value fails that validation.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind, value_parser};
/// fn is_numeric(val: &str) -> Result<(), String> {
/// match val.parse::<i64>() {
/// Ok(..) => Ok(()),
/// Err(..) => Err(String::from("Value wasn't a number!")),
/// }
/// }
///
/// let result = Command::new("prog")
/// .arg(Arg::new("num")
/// .value_parser(value_parser!(u8)))
/// .try_get_matches_from(vec!["prog", "NotANumber"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::ValueValidation);
/// ```
ValueValidation,
/// Occurs when a user provides more values for an argument than were defined by setting
/// [`Arg::num_args`].
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .arg(Arg::new("arg")
/// .num_args(1..=2))
/// .try_get_matches_from(vec!["prog", "too", "many", "values"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::TooManyValues);
/// ```
/// [`Arg::num_args`]: crate::Arg::num_args()
TooManyValues,
/// Occurs when the user provides fewer values for an argument than were defined by setting
/// [`Arg::num_args`].
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .arg(Arg::new("some_opt")
/// .long("opt")
/// .num_args(3..))
/// .try_get_matches_from(vec!["prog", "--opt", "too", "few"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::TooFewValues);
/// ```
/// [`Arg::num_args`]: crate::Arg::num_args()
TooFewValues,
/// Occurs when the user provides a different number of values for an argument than what's
/// been defined by setting [`Arg::num_args`] or than was implicitly set by
/// [`Arg::value_names`].
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind, ArgAction};
/// let result = Command::new("prog")
/// .arg(Arg::new("some_opt")
/// .long("opt")
/// .action(ArgAction::Set)
/// .num_args(2))
/// .try_get_matches_from(vec!["prog", "--opt", "wrong"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::WrongNumberOfValues);
/// ```
///
/// [`Arg::num_args`]: crate::Arg::num_args()
/// [`Arg::value_names`]: crate::Arg::value_names()
WrongNumberOfValues,
/// Occurs when the user provides two values which conflict with each other and can't be used
/// together.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind, ArgAction};
/// let result = Command::new("prog")
/// .arg(Arg::new("debug")
/// .long("debug")
/// .action(ArgAction::SetTrue)
/// .conflicts_with("color"))
/// .arg(Arg::new("color")
/// .long("color")
/// .action(ArgAction::SetTrue))
/// .try_get_matches_from(vec!["prog", "--debug", "--color"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::ArgumentConflict);
/// ```
ArgumentConflict,
/// Occurs when the user does not provide one or more required arguments.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .arg(Arg::new("debug")
/// .required(true))
/// .try_get_matches_from(vec!["prog"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);
/// ```
MissingRequiredArgument,
/// Occurs when a subcommand is required (as defined by [`Command::subcommand_required`]),
/// but the user does not provide one.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, error::ErrorKind};
/// let err = Command::new("prog")
/// .subcommand_required(true)
/// .subcommand(Command::new("test"))
/// .try_get_matches_from(vec![
/// "myprog",
/// ]);
/// assert!(err.is_err());
/// assert_eq!(err.unwrap_err().kind(), ErrorKind::MissingSubcommand);
/// # ;
/// ```
///
/// [`Command::subcommand_required`]: crate::Command::subcommand_required
MissingSubcommand,
/// Occurs when the user provides a value containing invalid UTF-8.
///
/// To allow arbitrary data
/// - Set [`Arg::value_parser(value_parser!(OsString))`] for argument values
/// - Set [`Command::external_subcommand_value_parser`] for external-subcommand
/// values
///
/// # Platform Specific
///
/// Non-Windows platforms only (such as Linux, Unix, OSX, etc.)
///
/// # Examples
///
#[cfg_attr(not(unix), doc = " ```ignore")]
#[cfg_attr(unix, doc = " ```")]
/// # use clap::{Command, Arg, error::ErrorKind, ArgAction};
/// # use std::os::unix::ffi::OsStringExt;
/// # use std::ffi::OsString;
/// let result = Command::new("prog")
/// .arg(Arg::new("utf8")
/// .short('u')
/// .action(ArgAction::Set))
/// .try_get_matches_from(vec![OsString::from("myprog"),
/// OsString::from("-u"),
/// OsString::from_vec(vec![0xE9])]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::InvalidUtf8);
/// ```
///
/// [`Arg::allow_invalid_utf8`]: crate::Arg::allow_invalid_utf8
/// [`Command::external_subcommand_value_parser`]: crate::Command::external_subcommand_value_parser
InvalidUtf8,
/// Not a true "error" as it means `--help` or similar was used.
/// The help message will be sent to `stdout`.
///
/// **Note**: If the help is displayed due to an error (such as missing subcommands) it will
/// be sent to `stderr` instead of `stdout`.
///
/// # Examples
///
#[cfg_attr(not(feature = "help"), doc = " ```ignore")]
#[cfg_attr(feature = "help", doc = " ```")]
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .try_get_matches_from(vec!["prog", "--help"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::DisplayHelp);
/// ```
DisplayHelp,
/// Occurs when either an argument or a [`Subcommand`] is required, as defined by
/// [`Command::arg_required_else_help`] , but the user did not provide
/// one.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind, };
/// let result = Command::new("prog")
/// .arg_required_else_help(true)
/// .subcommand(Command::new("config")
/// .about("Used for configuration")
/// .arg(Arg::new("config_file")
/// .help("The configuration file to use")))
/// .try_get_matches_from(vec!["prog"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::DisplayHelpOnMissingArgumentOrSubcommand);
/// ```
///
/// [`Subcommand`]: crate::Subcommand
/// [`Command::arg_required_else_help`]: crate::Command::arg_required_else_help
DisplayHelpOnMissingArgumentOrSubcommand,
/// Not a true "error" as it means `--version` or similar was used.
/// The message will be sent to `stdout`.
///
/// # Examples
///
/// ```rust
/// # use clap::{Command, Arg, error::ErrorKind};
/// let result = Command::new("prog")
/// .version("3.0")
/// .try_get_matches_from(vec!["prog", "--version"]);
/// assert!(result.is_err());
/// assert_eq!(result.unwrap_err().kind(), ErrorKind::DisplayVersion);
/// ```
DisplayVersion,
/// Represents an [I/O error].
/// Can occur when writing to `stderr` or `stdout` or reading a configuration file.
///
/// [I/O error]: std::io::Error
Io,
/// Represents a [Format error] (which is a part of [`Display`]).
/// Typically caused by writing to `stderr` or `stdout`.
///
/// [`Display`]: std::fmt::Display
/// [Format error]: std::fmt::Error
Format,
}
impl ErrorKind {
/// End-user description of the error case, where relevant
pub fn as_str(self) -> Option<&'static str> {
match self {
Self::InvalidValue => Some("One of the values isn't valid for an argument"),
Self::UnknownArgument => {
Some("Found an argument which wasn't expected or isn't valid in this context")
}
Self::InvalidSubcommand => Some("A subcommand wasn't recognized"),
Self::NoEquals => Some("Equal is needed when assigning values to one of the arguments"),
Self::ValueValidation => Some("Invalid value for one of the arguments"),
Self::TooManyValues => Some("An argument received an unexpected value"),
Self::TooFewValues => Some("An argument requires more values"),
Self::WrongNumberOfValues => Some("An argument received too many or too few values"),
Self::ArgumentConflict => {
Some("An argument cannot be used with one or more of the other specified arguments")
}
Self::MissingRequiredArgument => {
Some("One or more required arguments were not provided")
}
Self::MissingSubcommand => Some("A subcommand is required but one was not provided"),
Self::InvalidUtf8 => Some("Invalid UTF-8 was detected in one or more arguments"),
Self::DisplayHelp => None,
Self::DisplayHelpOnMissingArgumentOrSubcommand => None,
Self::DisplayVersion => None,
Self::Io => None,
Self::Format => None,
}
}
}
impl std::fmt::Display for ErrorKind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.as_str().unwrap_or_default().fmt(f)
}
}