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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
use std::{
    any::{Any, TypeId},
    collections::HashMap,
    fmt,
    hash::{BuildHasherDefault, Hasher},
};

/// A hasher for `TypeId`s that takes advantage of its known characteristics.
///
/// Author of `anymap` crate has done research on the topic:
/// https://github.com/chris-morgan/anymap/blob/2e9a5704/src/lib.rs#L599
#[derive(Debug, Default)]
struct NoOpHasher(u64);

impl Hasher for NoOpHasher {
    fn write(&mut self, _bytes: &[u8]) {
        unimplemented!("This NoOpHasher can only handle u64s")
    }

    fn write_u64(&mut self, i: u64) {
        self.0 = i;
    }

    fn finish(&self) -> u64 {
        self.0
    }
}

/// A type map for request extensions.
///
/// All entries into this map must be owned types (or static references).
#[derive(Default)]
pub struct Extensions {
    /// Use AHasher with a std HashMap with for faster lookups on the small `TypeId` keys.
    map: HashMap<TypeId, Box<dyn Any>, BuildHasherDefault<NoOpHasher>>,
}

impl Extensions {
    /// Creates an empty `Extensions`.
    #[inline]
    pub fn new() -> Extensions {
        Extensions {
            map: HashMap::default(),
        }
    }

    /// Insert an item into the map.
    ///
    /// If an item of this type was already stored, it will be replaced and returned.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    /// assert_eq!(map.insert(""), None);
    /// assert_eq!(map.insert(1u32), None);
    /// assert_eq!(map.insert(2u32), Some(1u32));
    /// assert_eq!(*map.get::<u32>().unwrap(), 2u32);
    /// ```
    pub fn insert<T: 'static>(&mut self, val: T) -> Option<T> {
        self.map
            .insert(TypeId::of::<T>(), Box::new(val))
            .and_then(downcast_owned)
    }

    /// Check if map contains an item of a given type.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    /// assert!(!map.contains::<u32>());
    ///
    /// assert_eq!(map.insert(1u32), None);
    /// assert!(map.contains::<u32>());
    /// ```
    pub fn contains<T: 'static>(&self) -> bool {
        self.map.contains_key(&TypeId::of::<T>())
    }

    /// Get a reference to an item of a given type.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    /// map.insert(1u32);
    /// assert_eq!(map.get::<u32>(), Some(&1u32));
    /// ```
    pub fn get<T: 'static>(&self) -> Option<&T> {
        self.map
            .get(&TypeId::of::<T>())
            .and_then(|boxed| boxed.downcast_ref())
    }

    /// Get a mutable reference to an item of a given type.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    /// map.insert(1u32);
    /// assert_eq!(map.get_mut::<u32>(), Some(&mut 1u32));
    /// ```
    pub fn get_mut<T: 'static>(&mut self) -> Option<&mut T> {
        self.map
            .get_mut(&TypeId::of::<T>())
            .and_then(|boxed| boxed.downcast_mut())
    }

    /// Remove an item from the map of a given type.
    ///
    /// If an item of this type was already stored, it will be returned.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    ///
    /// map.insert(1u32);
    /// assert_eq!(map.get::<u32>(), Some(&1u32));
    ///
    /// assert_eq!(map.remove::<u32>(), Some(1u32));
    /// assert!(!map.contains::<u32>());
    /// ```
    pub fn remove<T: 'static>(&mut self) -> Option<T> {
        self.map.remove(&TypeId::of::<T>()).and_then(downcast_owned)
    }

    /// Clear the `Extensions` of all inserted extensions.
    ///
    /// ```
    /// # use actix_http::Extensions;
    /// let mut map = Extensions::new();
    ///
    /// map.insert(1u32);
    /// assert!(map.contains::<u32>());
    ///
    /// map.clear();
    /// assert!(!map.contains::<u32>());
    /// ```
    #[inline]
    pub fn clear(&mut self) {
        self.map.clear();
    }

    /// Extends self with the items from another `Extensions`.
    pub fn extend(&mut self, other: Extensions) {
        self.map.extend(other.map);
    }
}

impl fmt::Debug for Extensions {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Extensions").finish()
    }
}

fn downcast_owned<T: 'static>(boxed: Box<dyn Any>) -> Option<T> {
    boxed.downcast().ok().map(|boxed| *boxed)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_remove() {
        let mut map = Extensions::new();

        map.insert::<i8>(123);
        assert!(map.get::<i8>().is_some());

        map.remove::<i8>();
        assert!(map.get::<i8>().is_none());
    }

    #[test]
    fn test_clear() {
        let mut map = Extensions::new();

        map.insert::<i8>(8);
        map.insert::<i16>(16);
        map.insert::<i32>(32);

        assert!(map.contains::<i8>());
        assert!(map.contains::<i16>());
        assert!(map.contains::<i32>());

        map.clear();

        assert!(!map.contains::<i8>());
        assert!(!map.contains::<i16>());
        assert!(!map.contains::<i32>());

        map.insert::<i8>(10);
        assert_eq!(*map.get::<i8>().unwrap(), 10);
    }

    #[test]
    fn test_integers() {
        static A: u32 = 8;

        let mut map = Extensions::new();

        map.insert::<i8>(8);
        map.insert::<i16>(16);
        map.insert::<i32>(32);
        map.insert::<i64>(64);
        map.insert::<i128>(128);
        map.insert::<u8>(8);
        map.insert::<u16>(16);
        map.insert::<u32>(32);
        map.insert::<u64>(64);
        map.insert::<u128>(128);
        map.insert::<&'static u32>(&A);
        assert!(map.get::<i8>().is_some());
        assert!(map.get::<i16>().is_some());
        assert!(map.get::<i32>().is_some());
        assert!(map.get::<i64>().is_some());
        assert!(map.get::<i128>().is_some());
        assert!(map.get::<u8>().is_some());
        assert!(map.get::<u16>().is_some());
        assert!(map.get::<u32>().is_some());
        assert!(map.get::<u64>().is_some());
        assert!(map.get::<u128>().is_some());
        assert!(map.get::<&'static u32>().is_some());
    }

    #[test]
    fn test_composition() {
        struct Magi<T>(pub T);

        struct Madoka {
            pub god: bool,
        }

        struct Homura {
            pub attempts: usize,
        }

        struct Mami {
            pub guns: usize,
        }

        let mut map = Extensions::new();

        map.insert(Magi(Madoka { god: false }));
        map.insert(Magi(Homura { attempts: 0 }));
        map.insert(Magi(Mami { guns: 999 }));

        assert!(!map.get::<Magi<Madoka>>().unwrap().0.god);
        assert_eq!(0, map.get::<Magi<Homura>>().unwrap().0.attempts);
        assert_eq!(999, map.get::<Magi<Mami>>().unwrap().0.guns);
    }

    #[test]
    fn test_extensions() {
        #[derive(Debug, PartialEq)]
        struct MyType(i32);

        let mut extensions = Extensions::new();

        extensions.insert(5i32);
        extensions.insert(MyType(10));

        assert_eq!(extensions.get(), Some(&5i32));
        assert_eq!(extensions.get_mut(), Some(&mut 5i32));

        assert_eq!(extensions.remove::<i32>(), Some(5i32));
        assert!(extensions.get::<i32>().is_none());

        assert_eq!(extensions.get::<bool>(), None);
        assert_eq!(extensions.get(), Some(&MyType(10)));
    }

    #[test]
    fn test_extend() {
        #[derive(Debug, PartialEq)]
        struct MyType(i32);

        let mut extensions = Extensions::new();

        extensions.insert(5i32);
        extensions.insert(MyType(10));

        let mut other = Extensions::new();

        other.insert(15i32);
        other.insert(20u8);

        extensions.extend(other);

        assert_eq!(extensions.get(), Some(&15i32));
        assert_eq!(extensions.get_mut(), Some(&mut 15i32));

        assert_eq!(extensions.remove::<i32>(), Some(15i32));
        assert!(extensions.get::<i32>().is_none());

        assert_eq!(extensions.get::<bool>(), None);
        assert_eq!(extensions.get(), Some(&MyType(10)));

        assert_eq!(extensions.get(), Some(&20u8));
        assert_eq!(extensions.get_mut(), Some(&mut 20u8));
    }
}