summaryrefslogtreecommitdiffstats
path: root/third_party/rust/quote/src/format.rs
blob: 3cddbd2819d65e1256f5387faae92b81fb63b05e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
/// Formatting macro for constructing `Ident`s.
///
/// <br>
///
/// # Syntax
///
/// Syntax is copied from the [`format!`] macro, supporting both positional and
/// named arguments.
///
/// Only a limited set of formatting traits are supported. The current mapping
/// of format types to traits is:
///
/// * `{}` ⇒ [`IdentFragment`]
/// * `{:o}` ⇒ [`Octal`](std::fmt::Octal)
/// * `{:x}` ⇒ [`LowerHex`](std::fmt::LowerHex)
/// * `{:X}` ⇒ [`UpperHex`](std::fmt::UpperHex)
/// * `{:b}` ⇒ [`Binary`](std::fmt::Binary)
///
/// See [`std::fmt`] for more information.
///
/// <br>
///
/// # IdentFragment
///
/// Unlike `format!`, this macro uses the [`IdentFragment`] formatting trait by
/// default. This trait is like `Display`, with a few differences:
///
/// * `IdentFragment` is only implemented for a limited set of types, such as
///    unsigned integers and strings.
/// * [`Ident`] arguments will have their `r#` prefixes stripped, if present.
///
/// [`IdentFragment`]: crate::IdentFragment
/// [`Ident`]: proc_macro2::Ident
///
/// <br>
///
/// # Hygiene
///
/// The [`Span`] of the first `Ident` argument is used as the span of the final
/// identifier, falling back to [`Span::call_site`] when no identifiers are
/// provided.
///
/// ```
/// # use quote::format_ident;
/// # let ident = format_ident!("Ident");
/// // If `ident` is an Ident, the span of `my_ident` will be inherited from it.
/// let my_ident = format_ident!("My{}{}", ident, "IsCool");
/// assert_eq!(my_ident, "MyIdentIsCool");
/// ```
///
/// Alternatively, the span can be overridden by passing the `span` named
/// argument.
///
/// ```
/// # use quote::format_ident;
/// # const IGNORE_TOKENS: &'static str = stringify! {
/// let my_span = /* ... */;
/// # };
/// # let my_span = proc_macro2::Span::call_site();
/// format_ident!("MyIdent", span = my_span);
/// ```
///
/// [`Span`]: proc_macro2::Span
/// [`Span::call_site`]: proc_macro2::Span::call_site
///
/// <p><br></p>
///
/// # Panics
///
/// This method will panic if the resulting formatted string is not a valid
/// identifier.
///
/// <br>
///
/// # Examples
///
/// Composing raw and non-raw identifiers:
/// ```
/// # use quote::format_ident;
/// let my_ident = format_ident!("My{}", "Ident");
/// assert_eq!(my_ident, "MyIdent");
///
/// let raw = format_ident!("r#Raw");
/// assert_eq!(raw, "r#Raw");
///
/// let my_ident_raw = format_ident!("{}Is{}", my_ident, raw);
/// assert_eq!(my_ident_raw, "MyIdentIsRaw");
/// ```
///
/// Integer formatting options:
/// ```
/// # use quote::format_ident;
/// let num: u32 = 10;
///
/// let decimal = format_ident!("Id_{}", num);
/// assert_eq!(decimal, "Id_10");
///
/// let octal = format_ident!("Id_{:o}", num);
/// assert_eq!(octal, "Id_12");
///
/// let binary = format_ident!("Id_{:b}", num);
/// assert_eq!(binary, "Id_1010");
///
/// let lower_hex = format_ident!("Id_{:x}", num);
/// assert_eq!(lower_hex, "Id_a");
///
/// let upper_hex = format_ident!("Id_{:X}", num);
/// assert_eq!(upper_hex, "Id_A");
/// ```
#[macro_export]
macro_rules! format_ident {
    ($fmt:expr) => {
        $crate::format_ident_impl!([
            $crate::__private::Option::None,
            $fmt
        ])
    };

    ($fmt:expr, $($rest:tt)*) => {
        $crate::format_ident_impl!([
            $crate::__private::Option::None,
            $fmt
        ] $($rest)*)
    };
}

#[macro_export]
#[doc(hidden)]
macro_rules! format_ident_impl {
    // Final state
    ([$span:expr, $($fmt:tt)*]) => {
        $crate::__private::mk_ident(
            &$crate::__private::format!($($fmt)*),
            $span,
        )
    };

    // Span argument
    ([$old:expr, $($fmt:tt)*] span = $span:expr) => {
        $crate::format_ident_impl!([$old, $($fmt)*] span = $span,)
    };
    ([$old:expr, $($fmt:tt)*] span = $span:expr, $($rest:tt)*) => {
        $crate::format_ident_impl!([
            $crate::__private::Option::Some::<$crate::__private::Span>($span),
            $($fmt)*
        ] $($rest)*)
    };

    // Named argument
    ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr) => {
        $crate::format_ident_impl!([$span, $($fmt)*] $name = $arg,)
    };
    ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr, $($rest:tt)*) => {
        match $crate::__private::IdentFragmentAdapter(&$arg) {
            arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, $name = arg] $($rest)*),
        }
    };

    // Positional argument
    ([$span:expr, $($fmt:tt)*] $arg:expr) => {
        $crate::format_ident_impl!([$span, $($fmt)*] $arg,)
    };
    ([$span:expr, $($fmt:tt)*] $arg:expr, $($rest:tt)*) => {
        match $crate::__private::IdentFragmentAdapter(&$arg) {
            arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, arg] $($rest)*),
        }
    };
}