maplibre/util/
label.rs

1//! Traits used by label implementations
2
3use std::{
4    any::Any,
5    hash::{Hash, Hasher},
6};
7
8pub trait DynEq: Any {
9    fn as_any(&self) -> &dyn Any;
10
11    fn dyn_eq(&self, other: &dyn DynEq) -> bool;
12}
13
14impl<T> DynEq for T
15where
16    T: Any + Eq,
17{
18    fn as_any(&self) -> &dyn Any {
19        self
20    }
21
22    fn dyn_eq(&self, other: &dyn DynEq) -> bool {
23        if let Some(other) = other.as_any().downcast_ref::<T>() {
24            return self == other;
25        }
26        false
27    }
28}
29
30pub trait DynHash: DynEq {
31    fn as_dyn_eq(&self) -> &dyn DynEq;
32
33    fn dyn_hash(&self, state: &mut dyn Hasher);
34}
35
36impl<T> DynHash for T
37where
38    T: DynEq + Hash,
39{
40    fn as_dyn_eq(&self) -> &dyn DynEq {
41        self
42    }
43
44    fn dyn_hash(&self, mut state: &mut dyn Hasher) {
45        T::hash(self, &mut state);
46        self.type_id().hash(&mut state);
47    }
48}
49
50/// Macro to define a new label trait
51///
52/// # Example
53///
54/// ```
55/// # use maplibre::define_label;
56/// define_label!(MyNewLabelTrait);
57/// ```
58#[macro_export]
59macro_rules! define_label {
60    ($label_trait_name:ident) => {
61        /// Defines a set of strongly-typed labels for a class of objects
62        pub trait $label_trait_name:
63            $crate::util::label::DynHash + ::std::fmt::Debug + Send + Sync + 'static
64        {
65            #[doc(hidden)]
66            fn dyn_clone(&self) -> Box<dyn $label_trait_name>;
67        }
68
69        impl PartialEq for dyn $label_trait_name {
70            fn eq(&self, other: &Self) -> bool {
71                self.dyn_eq(other.as_dyn_eq())
72            }
73        }
74
75        impl Eq for dyn $label_trait_name {}
76
77        impl ::std::hash::Hash for dyn $label_trait_name {
78            fn hash<H: ::std::hash::Hasher>(&self, state: &mut H) {
79                self.dyn_hash(state);
80            }
81        }
82
83        impl Clone for Box<dyn $label_trait_name> {
84            fn clone(&self) -> Self {
85                self.dyn_clone()
86            }
87        }
88
89        impl $label_trait_name for ::std::borrow::Cow<'static, str> {
90            fn dyn_clone(&self) -> Box<dyn $label_trait_name> {
91                Box::new(self.clone())
92            }
93        }
94
95        impl $label_trait_name for &'static str {
96            fn dyn_clone(&self) -> Box<dyn $label_trait_name> {
97                Box::new(<&str>::clone(self))
98            }
99        }
100    };
101}
maplibre/util/label.rs

maplibre/util/
label.rs
