bitflags/
internal.rs

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1//! Generate the internal `bitflags`-facing flags type.
2//!
3//! The code generated here is owned by `bitflags`, but still part of its public API.
4//! Changes to the types generated here need to be considered like any other public API change.
5
6/// Declare the `bitflags`-facing bitflags struct.
7///
8/// This type is part of the `bitflags` crate's public API, but not part of the user's.
9#[macro_export]
10#[doc(hidden)]
11macro_rules! __declare_internal_bitflags {
12    (
13        $vis:vis struct $InternalBitFlags:ident: $T:ty
14    ) => {
15        // NOTE: The ABI of this type is _guaranteed_ to be the same as `T`
16        // This is relied on by some external libraries like `bytemuck` to make
17        // its `unsafe` trait impls sound.
18        #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
19        #[repr(transparent)]
20        $vis struct $InternalBitFlags($T);
21    };
22}
23
24/// Implement functions on the private (bitflags-facing) bitflags type.
25///
26/// Methods and trait implementations can be freely added here without breaking end-users.
27/// If we want to expose new functionality to `#[derive]`, this is the place to do it.
28#[macro_export]
29#[doc(hidden)]
30macro_rules! __impl_internal_bitflags {
31    (
32        $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident {
33            $(
34                $(#[$inner:ident $($args:tt)*])*
35                const $Flag:tt = $value:expr;
36            )*
37        }
38    ) => {
39        // NOTE: This impl is also used to prevent using bits types from non-primitive types
40        // in the `bitflags` macro. If this approach is changed, this guard will need to be
41        // retained somehow
42        impl $crate::__private::PublicFlags for $PublicBitFlags {
43            type Primitive = $T;
44            type Internal = $InternalBitFlags;
45        }
46
47        impl $crate::__private::core::default::Default for $InternalBitFlags {
48            #[inline]
49            fn default() -> Self {
50                $InternalBitFlags::empty()
51            }
52        }
53
54        impl $crate::__private::core::fmt::Debug for $InternalBitFlags {
55            fn fmt(&self, f: &mut $crate::__private::core::fmt::Formatter<'_>) -> $crate::__private::core::fmt::Result {
56                if self.is_empty() {
57                    // If no flags are set then write an empty hex flag to avoid
58                    // writing an empty string. In some contexts, like serialization,
59                    // an empty string is preferable, but it may be unexpected in
60                    // others for a format not to produce any output.
61                    //
62                    // We can remove this `0x0` and remain compatible with `FromStr`,
63                    // because an empty string will still parse to an empty set of flags,
64                    // just like `0x0` does.
65                    $crate::__private::core::write!(f, "{:#x}", <$T as $crate::Bits>::EMPTY)
66                } else {
67                    $crate::__private::core::fmt::Display::fmt(self, f)
68                }
69            }
70        }
71
72        impl $crate::__private::core::fmt::Display for $InternalBitFlags {
73            fn fmt(&self, f: &mut $crate::__private::core::fmt::Formatter<'_>) -> $crate::__private::core::fmt::Result {
74                $crate::parser::to_writer(&$PublicBitFlags(*self), f)
75            }
76        }
77
78        impl $crate::__private::core::str::FromStr for $InternalBitFlags {
79            type Err = $crate::parser::ParseError;
80
81            fn from_str(s: &str) -> $crate::__private::core::result::Result<Self, Self::Err> {
82                $crate::parser::from_str::<$PublicBitFlags>(s).map(|flags| flags.0)
83            }
84        }
85
86        impl $crate::__private::core::convert::AsRef<$T> for $InternalBitFlags {
87            fn as_ref(&self) -> &$T {
88                &self.0
89            }
90        }
91
92        impl $crate::__private::core::convert::From<$T> for $InternalBitFlags {
93            fn from(bits: $T) -> Self {
94                Self::from_bits_retain(bits)
95            }
96        }
97
98        // The internal flags type offers a similar API to the public one
99
100        $crate::__impl_public_bitflags! {
101            $InternalBitFlags: $T, $PublicBitFlags {
102                $(
103                    $(#[$inner $($args)*])*
104                    const $Flag = $value;
105                )*
106            }
107        }
108
109        $crate::__impl_public_bitflags_ops! {
110            $InternalBitFlags
111        }
112
113        $crate::__impl_public_bitflags_iter! {
114            $InternalBitFlags: $T, $PublicBitFlags
115        }
116
117        impl $InternalBitFlags {
118            /// Returns a mutable reference to the raw value of the flags currently stored.
119            #[inline]
120            pub fn bits_mut(&mut self) -> &mut $T {
121                &mut self.0
122            }
123        }
124    };
125}
bitflags/internal.rs

bitflags/
internal.rs
