1// Unlike `impl Into<Option<T>>` or `Option<impl Into<T>>`, this isn't ambiguous for the `None`
2// case.
3
4use crate::builder::ArgAction;
5use crate::builder::OsStr;
6use crate::builder::Str;
7use crate::builder::StyledStr;
8use crate::builder::ValueHint;
9use crate::builder::ValueParser;
10use crate::builder::ValueRange;
11
12/// Clearable builder value
13///
14/// This allows a builder function to both accept any value that can [`Into::into`] `T` (like
15/// `&str` into `OsStr`) as well as `None` to reset it to the default. This is needed to
16/// workaround a limitation where you can't have a function argument that is `impl Into<Option<T>>`
17/// where `T` is `impl Into<S>` accept `None` as its type is ambiguous.
18///
19/// # Example
20///
21/// ```rust
22/// # use clap_builder as clap;
23/// # use clap::Command;
24/// # use clap::Arg;
25/// fn common() -> Command {
26/// Command::new("cli")
27/// .arg(Arg::new("input").short('i').long("input"))
28/// }
29/// let mut command = common();
30/// command.mut_arg("input", |arg| arg.short(None));
31/// ```
32#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
33pub enum Resettable<T> {
34 /// Overwrite builder value
35 Value(T),
36 /// Reset builder value
37 Reset,
38}
39
40impl<T> Resettable<T> {
41 pub(crate) fn into_option(self) -> Option<T> {
42 match self {
43 Self::Value(t: T) => Some(t),
44 Self::Reset => None,
45 }
46 }
47}
48
49impl<T> From<T> for Resettable<T> {
50 fn from(other: T) -> Self {
51 Self::Value(other)
52 }
53}
54
55impl<T> From<Option<T>> for Resettable<T> {
56 fn from(other: Option<T>) -> Self {
57 match other {
58 Some(inner: T) => Self::Value(inner),
59 None => Self::Reset,
60 }
61 }
62}
63
64/// Convert to the intended resettable type
65pub trait IntoResettable<T> {
66 /// Convert to the intended resettable type
67 fn into_resettable(self) -> Resettable<T>;
68}
69
70impl IntoResettable<char> for Option<char> {
71 fn into_resettable(self) -> Resettable<char> {
72 match self {
73 Some(s: char) => Resettable::Value(s),
74 None => Resettable::Reset,
75 }
76 }
77}
78
79impl IntoResettable<usize> for Option<usize> {
80 fn into_resettable(self) -> Resettable<usize> {
81 match self {
82 Some(s: usize) => Resettable::Value(s),
83 None => Resettable::Reset,
84 }
85 }
86}
87
88impl IntoResettable<ArgAction> for Option<ArgAction> {
89 fn into_resettable(self) -> Resettable<ArgAction> {
90 match self {
91 Some(s: ArgAction) => Resettable::Value(s),
92 None => Resettable::Reset,
93 }
94 }
95}
96
97impl IntoResettable<ValueHint> for Option<ValueHint> {
98 fn into_resettable(self) -> Resettable<ValueHint> {
99 match self {
100 Some(s: ValueHint) => Resettable::Value(s),
101 None => Resettable::Reset,
102 }
103 }
104}
105
106impl IntoResettable<ValueParser> for Option<ValueParser> {
107 fn into_resettable(self) -> Resettable<ValueParser> {
108 match self {
109 Some(s: ValueParser) => Resettable::Value(s),
110 None => Resettable::Reset,
111 }
112 }
113}
114
115impl IntoResettable<StyledStr> for Option<&'static str> {
116 fn into_resettable(self) -> Resettable<StyledStr> {
117 match self {
118 Some(s: &'static str) => Resettable::Value(s.into()),
119 None => Resettable::Reset,
120 }
121 }
122}
123
124impl IntoResettable<OsStr> for Option<&'static str> {
125 fn into_resettable(self) -> Resettable<OsStr> {
126 match self {
127 Some(s: &'static str) => Resettable::Value(s.into()),
128 None => Resettable::Reset,
129 }
130 }
131}
132
133impl IntoResettable<Str> for Option<&'static str> {
134 fn into_resettable(self) -> Resettable<Str> {
135 match self {
136 Some(s: &'static str) => Resettable::Value(s.into()),
137 None => Resettable::Reset,
138 }
139 }
140}
141
142impl<T> IntoResettable<T> for Resettable<T> {
143 fn into_resettable(self) -> Resettable<T> {
144 self
145 }
146}
147
148impl IntoResettable<char> for char {
149 fn into_resettable(self) -> Resettable<char> {
150 Resettable::Value(self)
151 }
152}
153
154impl IntoResettable<usize> for usize {
155 fn into_resettable(self) -> Resettable<usize> {
156 Resettable::Value(self)
157 }
158}
159
160impl IntoResettable<ArgAction> for ArgAction {
161 fn into_resettable(self) -> Resettable<ArgAction> {
162 Resettable::Value(self)
163 }
164}
165
166impl IntoResettable<ValueHint> for ValueHint {
167 fn into_resettable(self) -> Resettable<ValueHint> {
168 Resettable::Value(self)
169 }
170}
171
172impl<I: Into<ValueRange>> IntoResettable<ValueRange> for I {
173 fn into_resettable(self) -> Resettable<ValueRange> {
174 Resettable::Value(self.into())
175 }
176}
177
178impl<I: Into<ValueParser>> IntoResettable<ValueParser> for I {
179 fn into_resettable(self) -> Resettable<ValueParser> {
180 Resettable::Value(self.into())
181 }
182}
183
184impl<I: Into<String>> IntoResettable<String> for I {
185 fn into_resettable(self) -> Resettable<String> {
186 Resettable::Value(self.into())
187 }
188}
189
190impl<I: Into<StyledStr>> IntoResettable<StyledStr> for I {
191 fn into_resettable(self) -> Resettable<StyledStr> {
192 Resettable::Value(self.into())
193 }
194}
195
196impl<I: Into<OsStr>> IntoResettable<OsStr> for I {
197 fn into_resettable(self) -> Resettable<OsStr> {
198 Resettable::Value(self.into())
199 }
200}
201
202impl<I: Into<Str>> IntoResettable<Str> for I {
203 fn into_resettable(self) -> Resettable<Str> {
204 Resettable::Value(self.into())
205 }
206}
207
208impl<I: Into<crate::Id>> IntoResettable<crate::Id> for I {
209 fn into_resettable(self) -> Resettable<crate::Id> {
210 Resettable::Value(self.into())
211 }
212}
213