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// Unlike `impl Into<Option<T>>` or `Option<impl Into<T>>`, this isn't ambiguous for the `None`
// case.
use crate::builder::ArgAction;
use crate::builder::OsStr;
use crate::builder::Str;
use crate::builder::StyledStr;
use crate::builder::ValueHint;
use crate::builder::ValueParser;
use crate::builder::ValueRange;
/// Clearable builder value
///
/// This allows a builder function to both accept any value that can [`Into::into`] `T` (like
/// `&str` into `OsStr`) as well as `None` to reset it to the default. This is needed to
/// workaround a limitation where you can't have a function argument that is `impl Into<Option<T>>`
/// where `T` is `impl Into<S>` accept `None` as its type is ambiguous.
///
/// # Example
///
/// ```rust
/// # use clap_builder as clap;
/// # use clap::Command;
/// # use clap::Arg;
/// fn common() -> Command {
/// Command::new("cli")
/// .arg(Arg::new("input").short('i').long("input"))
/// }
/// let mut command = common();
/// command.mut_arg("input", |arg| arg.short(None));
/// ```
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum Resettable<T> {
/// Overwrite builder value
Value(T),
/// Reset builder value
Reset,
}
impl<T> Resettable<T> {
pub(crate) fn into_option(self) -> Option<T> {
match self {
Self::Value(t) => Some(t),
Self::Reset => None,
}
}
}
impl<T> From<T> for Resettable<T> {
fn from(other: T) -> Self {
Self::Value(other)
}
}
impl<T> From<Option<T>> for Resettable<T> {
fn from(other: Option<T>) -> Self {
match other {
Some(inner) => Self::Value(inner),
None => Self::Reset,
}
}
}
/// Convert to the intended resettable type
pub trait IntoResettable<T> {
/// Convert to the intended resettable type
fn into_resettable(self) -> Resettable<T>;
}
impl IntoResettable<char> for Option<char> {
fn into_resettable(self) -> Resettable<char> {
match self {
Some(s) => Resettable::Value(s),
None => Resettable::Reset,
}
}
}
impl IntoResettable<usize> for Option<usize> {
fn into_resettable(self) -> Resettable<usize> {
match self {
Some(s) => Resettable::Value(s),
None => Resettable::Reset,
}
}
}
impl IntoResettable<ArgAction> for Option<ArgAction> {
fn into_resettable(self) -> Resettable<ArgAction> {
match self {
Some(s) => Resettable::Value(s),
None => Resettable::Reset,
}
}
}
impl IntoResettable<ValueHint> for Option<ValueHint> {
fn into_resettable(self) -> Resettable<ValueHint> {
match self {
Some(s) => Resettable::Value(s),
None => Resettable::Reset,
}
}
}
impl IntoResettable<ValueParser> for Option<ValueParser> {
fn into_resettable(self) -> Resettable<ValueParser> {
match self {
Some(s) => Resettable::Value(s),
None => Resettable::Reset,
}
}
}
impl IntoResettable<StyledStr> for Option<&'static str> {
fn into_resettable(self) -> Resettable<StyledStr> {
match self {
Some(s) => Resettable::Value(s.into()),
None => Resettable::Reset,
}
}
}
impl IntoResettable<OsStr> for Option<&'static str> {
fn into_resettable(self) -> Resettable<OsStr> {
match self {
Some(s) => Resettable::Value(s.into()),
None => Resettable::Reset,
}
}
}
impl IntoResettable<Str> for Option<&'static str> {
fn into_resettable(self) -> Resettable<Str> {
match self {
Some(s) => Resettable::Value(s.into()),
None => Resettable::Reset,
}
}
}
impl<T> IntoResettable<T> for Resettable<T> {
fn into_resettable(self) -> Resettable<T> {
self
}
}
impl IntoResettable<char> for char {
fn into_resettable(self) -> Resettable<char> {
Resettable::Value(self)
}
}
impl IntoResettable<usize> for usize {
fn into_resettable(self) -> Resettable<usize> {
Resettable::Value(self)
}
}
impl IntoResettable<ArgAction> for ArgAction {
fn into_resettable(self) -> Resettable<ArgAction> {
Resettable::Value(self)
}
}
impl IntoResettable<ValueHint> for ValueHint {
fn into_resettable(self) -> Resettable<ValueHint> {
Resettable::Value(self)
}
}
impl<I: Into<ValueRange>> IntoResettable<ValueRange> for I {
fn into_resettable(self) -> Resettable<ValueRange> {
Resettable::Value(self.into())
}
}
impl<I: Into<ValueParser>> IntoResettable<ValueParser> for I {
fn into_resettable(self) -> Resettable<ValueParser> {
Resettable::Value(self.into())
}
}
impl<I: Into<String>> IntoResettable<String> for I {
fn into_resettable(self) -> Resettable<String> {
Resettable::Value(self.into())
}
}
impl<I: Into<StyledStr>> IntoResettable<StyledStr> for I {
fn into_resettable(self) -> Resettable<StyledStr> {
Resettable::Value(self.into())
}
}
impl<I: Into<OsStr>> IntoResettable<OsStr> for I {
fn into_resettable(self) -> Resettable<OsStr> {
Resettable::Value(self.into())
}
}
impl<I: Into<Str>> IntoResettable<Str> for I {
fn into_resettable(self) -> Resettable<Str> {
Resettable::Value(self.into())
}
}
impl<I: Into<crate::Id>> IntoResettable<crate::Id> for I {
fn into_resettable(self) -> Resettable<crate::Id> {
Resettable::Value(self.into())
}
}