1use std::any::{Any, TypeId};
2use std::collections::HashMap;
3use std::fmt;
4use std::hash::{BuildHasherDefault, Hasher};
5
6type AnyMap = HashMap<TypeId, Box<dyn Any + Send + Sync>, BuildHasherDefault<IdHasher>>;
7
8// With TypeIds as keys, there's no need to hash them. They are already hashes
9// themselves, coming from the compiler. The IdHasher just holds the u64 of
10// the TypeId, and then returns it, instead of doing any bit fiddling.
11#[derive(Default)]
12struct IdHasher(u64);
13
14impl Hasher for IdHasher {
15 fn write(&mut self, _: &[u8]) {
16 unreachable!("TypeId calls write_u64");
17 }
18
19 #[inline]
20 fn write_u64(&mut self, id: u64) {
21 self.0 = id;
22 }
23
24 #[inline]
25 fn finish(&self) -> u64 {
26 self.0
27 }
28}
29
30/// A type map of protocol extensions.
31///
32/// `Extensions` can be used by `Request` and `Response` to store
33/// extra data derived from the underlying protocol.
34#[derive(Default)]
35pub struct Extensions {
36 // If extensions are never used, no need to carry around an empty HashMap.
37 // That's 3 words. Instead, this is only 1 word.
38 map: Option<Box<AnyMap>>,
39}
40
41impl Extensions {
42 /// Create an empty `Extensions`.
43 #[inline]
44 pub fn new() -> Extensions {
45 Extensions { map: None }
46 }
47
48 /// Insert a type into this `Extensions`.
49 ///
50 /// If a extension of this type already existed, it will
51 /// be returned.
52 ///
53 /// # Example
54 ///
55 /// ```
56 /// # use http::Extensions;
57 /// let mut ext = Extensions::new();
58 /// assert!(ext.insert(5i32).is_none());
59 /// assert!(ext.insert(4u8).is_none());
60 /// assert_eq!(ext.insert(9i32), Some(5i32));
61 /// ```
62 pub fn insert<T: Send + Sync + 'static>(&mut self, val: T) -> Option<T> {
63 self.map
64 .get_or_insert_with(|| Box::new(HashMap::default()))
65 .insert(TypeId::of::<T>(), Box::new(val))
66 .and_then(|boxed| {
67 (boxed as Box<dyn Any + 'static>)
68 .downcast()
69 .ok()
70 .map(|boxed| *boxed)
71 })
72 }
73
74 /// Get a reference to a type previously inserted on this `Extensions`.
75 ///
76 /// # Example
77 ///
78 /// ```
79 /// # use http::Extensions;
80 /// let mut ext = Extensions::new();
81 /// assert!(ext.get::<i32>().is_none());
82 /// ext.insert(5i32);
83 ///
84 /// assert_eq!(ext.get::<i32>(), Some(&5i32));
85 /// ```
86 pub fn get<T: Send + Sync + 'static>(&self) -> Option<&T> {
87 self.map
88 .as_ref()
89 .and_then(|map| map.get(&TypeId::of::<T>()))
90 .and_then(|boxed| (&**boxed as &(dyn Any + 'static)).downcast_ref())
91 }
92
93 /// Get a mutable reference to a type previously inserted on this `Extensions`.
94 ///
95 /// # Example
96 ///
97 /// ```
98 /// # use http::Extensions;
99 /// let mut ext = Extensions::new();
100 /// ext.insert(String::from("Hello"));
101 /// ext.get_mut::<String>().unwrap().push_str(" World");
102 ///
103 /// assert_eq!(ext.get::<String>().unwrap(), "Hello World");
104 /// ```
105 pub fn get_mut<T: Send + Sync + 'static>(&mut self) -> Option<&mut T> {
106 self.map
107 .as_mut()
108 .and_then(|map| map.get_mut(&TypeId::of::<T>()))
109 .and_then(|boxed| (&mut **boxed as &mut (dyn Any + 'static)).downcast_mut())
110 }
111
112 /// Remove a type from this `Extensions`.
113 ///
114 /// If a extension of this type existed, it will be returned.
115 ///
116 /// # Example
117 ///
118 /// ```
119 /// # use http::Extensions;
120 /// let mut ext = Extensions::new();
121 /// ext.insert(5i32);
122 /// assert_eq!(ext.remove::<i32>(), Some(5i32));
123 /// assert!(ext.get::<i32>().is_none());
124 /// ```
125 pub fn remove<T: Send + Sync + 'static>(&mut self) -> Option<T> {
126 self.map
127 .as_mut()
128 .and_then(|map| map.remove(&TypeId::of::<T>()))
129 .and_then(|boxed| {
130 (boxed as Box<dyn Any + 'static>)
131 .downcast()
132 .ok()
133 .map(|boxed| *boxed)
134 })
135 }
136
137 /// Clear the `Extensions` of all inserted extensions.
138 ///
139 /// # Example
140 ///
141 /// ```
142 /// # use http::Extensions;
143 /// let mut ext = Extensions::new();
144 /// ext.insert(5i32);
145 /// ext.clear();
146 ///
147 /// assert!(ext.get::<i32>().is_none());
148 /// ```
149 #[inline]
150 pub fn clear(&mut self) {
151 if let Some(ref mut map) = self.map {
152 map.clear();
153 }
154 }
155
156 /// Check whether the extension set is empty or not.
157 ///
158 /// # Example
159 ///
160 /// ```
161 /// # use http::Extensions;
162 /// let mut ext = Extensions::new();
163 /// assert!(ext.is_empty());
164 /// ext.insert(5i32);
165 /// assert!(!ext.is_empty());
166 /// ```
167 #[inline]
168 pub fn is_empty(&self) -> bool {
169 self.map
170 .as_ref()
171 .map_or(true, |map| map.is_empty())
172 }
173
174 /// Get the numer of extensions available.
175 ///
176 /// # Example
177 ///
178 /// ```
179 /// # use http::Extensions;
180 /// let mut ext = Extensions::new();
181 /// assert_eq!(ext.len(), 0);
182 /// ext.insert(5i32);
183 /// assert_eq!(ext.len(), 1);
184 /// ```
185 #[inline]
186 pub fn len(&self) -> usize {
187 self.map
188 .as_ref()
189 .map_or(0, |map| map.len())
190 }
191
192 /// Extends `self` with another `Extensions`.
193 ///
194 /// If an instance of a specific type exists in both, the one in `self` is overwritten with the
195 /// one from `other`.
196 ///
197 /// # Example
198 ///
199 /// ```
200 /// # use http::Extensions;
201 /// let mut ext_a = Extensions::new();
202 /// ext_a.insert(8u8);
203 /// ext_a.insert(16u16);
204 ///
205 /// let mut ext_b = Extensions::new();
206 /// ext_b.insert(4u8);
207 /// ext_b.insert("hello");
208 ///
209 /// ext_a.extend(ext_b);
210 /// assert_eq!(ext_a.len(), 3);
211 /// assert_eq!(ext_a.get::<u8>(), Some(&4u8));
212 /// assert_eq!(ext_a.get::<u16>(), Some(&16u16));
213 /// assert_eq!(ext_a.get::<&'static str>().copied(), Some("hello"));
214 /// ```
215 pub fn extend(&mut self, other: Self) {
216 if let Some(other) = other.map {
217 if let Some(map) = &mut self.map {
218 map.extend(*other);
219 } else {
220 self.map = Some(other);
221 }
222 }
223 }
224}
225
226impl fmt::Debug for Extensions {
227 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
228 f.debug_struct("Extensions").finish()
229 }
230}
231
232#[test]
233fn test_extensions() {
234 #[derive(Debug, PartialEq)]
235 struct MyType(i32);
236
237 let mut extensions = Extensions::new();
238
239 extensions.insert(5i32);
240 extensions.insert(MyType(10));
241
242 assert_eq!(extensions.get(), Some(&5i32));
243 assert_eq!(extensions.get_mut(), Some(&mut 5i32));
244
245 assert_eq!(extensions.remove::<i32>(), Some(5i32));
246 assert!(extensions.get::<i32>().is_none());
247
248 assert_eq!(extensions.get::<bool>(), None);
249 assert_eq!(extensions.get(), Some(&MyType(10)));
250}
251