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
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
use rkyv::{Archive, Deserialize as RkyvDeserialize, Serialize as RkyvSerialize};
#[cfg(feature = "enable-serde")]
use serde::{Deserialize, Serialize};

/// Controls which experimental features will be enabled.
/// Features usually have a corresponding [WebAssembly proposal].
///
/// [WebAssembly proposal]: https://github.com/WebAssembly/proposals
#[derive(Clone, Debug, Eq, PartialEq)]
#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
#[derive(RkyvSerialize, RkyvDeserialize, Archive)]
#[archive(as = "Self")]
pub struct Features {
    /// Threads proposal should be enabled
    pub threads: bool,
    /// Reference Types proposal should be enabled
    pub reference_types: bool,
    /// SIMD proposal should be enabled
    pub simd: bool,
    /// Bulk Memory proposal should be enabled
    pub bulk_memory: bool,
    /// Multi Value proposal should be enabled
    pub multi_value: bool,
    /// Tail call proposal should be enabled
    pub tail_call: bool,
    /// Module Linking proposal should be enabled
    pub module_linking: bool,
    /// Multi Memory proposal should be enabled
    pub multi_memory: bool,
    /// 64-bit Memory proposal should be enabled
    pub memory64: bool,
    /// Wasm exceptions proposal should be enabled
    pub exceptions: bool,
    /// Relaxed SIMD proposal should be enabled
    pub relaxed_simd: bool,
    /// Extended constant expressions proposal should be enabled
    pub extended_const: bool,
}

impl Features {
    /// Create a new feature
    pub fn new() -> Self {
        Self {
            threads: true,
            // Reference types should be on by default
            reference_types: true,
            // SIMD should be on by default
            simd: true,
            // Bulk Memory should be on by default
            bulk_memory: true,
            // Multivalue should be on by default
            multi_value: true,
            tail_call: false,
            module_linking: false,
            multi_memory: false,
            memory64: false,
            exceptions: false,
            relaxed_simd: false,
            extended_const: false,
        }
    }

    /// Configures whether the WebAssembly threads proposal will be enabled.
    ///
    /// The [WebAssembly threads proposal][threads] is not currently fully
    /// standardized and is undergoing development. Support for this feature can
    /// be enabled through this method for appropriate WebAssembly modules.
    ///
    /// This feature gates items such as shared memories and atomic
    /// instructions.
    ///
    /// This is `false` by default.
    ///
    /// [threads]: https://github.com/webassembly/threads
    pub fn threads(&mut self, enable: bool) -> &mut Self {
        self.threads = enable;
        self
    }

    /// Configures whether the WebAssembly reference types proposal will be
    /// enabled.
    ///
    /// The [WebAssembly reference types proposal][proposal] is now
    /// fully standardized and enabled by default.
    ///
    /// This feature gates items such as the `externref` type and multiple tables
    /// being in a module. Note that enabling the reference types feature will
    /// also enable the bulk memory feature.
    ///
    /// This is `true` by default.
    ///
    /// [proposal]: https://github.com/webassembly/reference-types
    pub fn reference_types(&mut self, enable: bool) -> &mut Self {
        self.reference_types = enable;
        // The reference types proposal depends on the bulk memory proposal
        if enable {
            self.bulk_memory(true);
        }
        self
    }

    /// Configures whether the WebAssembly SIMD proposal will be
    /// enabled.
    ///
    /// The [WebAssembly SIMD proposal][proposal] is not currently
    /// fully standardized and is undergoing development. Support for this
    /// feature can be enabled through this method for appropriate WebAssembly
    /// modules.
    ///
    /// This feature gates items such as the `v128` type and all of its
    /// operators being in a module.
    ///
    /// This is `false` by default.
    ///
    /// [proposal]: https://github.com/webassembly/simd
    pub fn simd(&mut self, enable: bool) -> &mut Self {
        self.simd = enable;
        self
    }

    /// Configures whether the WebAssembly bulk memory operations proposal will
    /// be enabled.
    ///
    /// The [WebAssembly bulk memory operations proposal][proposal] is now
    /// fully standardized and enabled by default.
    ///
    /// This feature gates items such as the `memory.copy` instruction, passive
    /// data/table segments, etc, being in a module.
    ///
    /// This is `true` by default.
    ///
    /// [proposal]: https://github.com/webassembly/bulk-memory-operations
    pub fn bulk_memory(&mut self, enable: bool) -> &mut Self {
        self.bulk_memory = enable;
        // In case is false, we disable both threads and reference types
        // since they both depend on bulk memory
        if !enable {
            self.reference_types(false);
        }
        self
    }

    /// Configures whether the WebAssembly multi-value proposal will
    /// be enabled.
    ///
    /// The [WebAssembly multi-value proposal][proposal] is now fully
    /// standardized and enabled by default, except with the singlepass
    /// compiler which does not support it.
    ///
    /// This feature gates functions and blocks returning multiple values in a
    /// module, for example.
    ///
    /// This is `true` by default.
    ///
    /// [proposal]: https://github.com/webassembly/multi-value
    pub fn multi_value(&mut self, enable: bool) -> &mut Self {
        self.multi_value = enable;
        self
    }

    /// Configures whether the WebAssembly tail-call proposal will
    /// be enabled.
    ///
    /// The [WebAssembly tail-call proposal][proposal] is not
    /// currently fully standardized and is undergoing development.
    /// Support for this feature can be enabled through this method for
    /// appropriate WebAssembly modules.
    ///
    /// This feature gates tail-call functions in WebAssembly.
    ///
    /// This is `false` by default.
    ///
    /// [proposal]: https://github.com/webassembly/tail-call
    pub fn tail_call(&mut self, enable: bool) -> &mut Self {
        self.tail_call = enable;
        self
    }

    /// Configures whether the WebAssembly module linking proposal will
    /// be enabled.
    ///
    /// The [WebAssembly module linking proposal][proposal] is not
    /// currently fully standardized and is undergoing development.
    /// Support for this feature can be enabled through this method for
    /// appropriate WebAssembly modules.
    ///
    /// This feature allows WebAssembly modules to define, import and
    /// export modules and instances.
    ///
    /// This is `false` by default.
    ///
    /// [proposal]: https://github.com/webassembly/module-linking
    pub fn module_linking(&mut self, enable: bool) -> &mut Self {
        self.module_linking = enable;
        self
    }

    /// Configures whether the WebAssembly multi-memory proposal will
    /// be enabled.
    ///
    /// The [WebAssembly multi-memory proposal][proposal] is not
    /// currently fully standardized and is undergoing development.
    /// Support for this feature can be enabled through this method for
    /// appropriate WebAssembly modules.
    ///
    /// This feature adds the ability to use multiple memories within a
    /// single Wasm module.
    ///
    /// This is `false` by default.
    ///
    /// [proposal]: https://github.com/WebAssembly/multi-memory
    pub fn multi_memory(&mut self, enable: bool) -> &mut Self {
        self.multi_memory = enable;
        self
    }

    /// Configures whether the WebAssembly 64-bit memory proposal will
    /// be enabled.
    ///
    /// The [WebAssembly 64-bit memory proposal][proposal] is not
    /// currently fully standardized and is undergoing development.
    /// Support for this feature can be enabled through this method for
    /// appropriate WebAssembly modules.
    ///
    /// This feature gates support for linear memory of sizes larger than
    /// 2^32 bits.
    ///
    /// This is `false` by default.
    ///
    /// [proposal]: https://github.com/WebAssembly/memory64
    pub fn memory64(&mut self, enable: bool) -> &mut Self {
        self.memory64 = enable;
        self
    }
}

impl Default for Features {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod test_features {
    use super::*;
    #[test]
    fn default_features() {
        let default = Features::default();
        assert_eq!(
            default,
            Features {
                threads: true,
                reference_types: true,
                simd: true,
                bulk_memory: true,
                multi_value: true,
                tail_call: false,
                module_linking: false,
                multi_memory: false,
                memory64: false,
                exceptions: false,
                relaxed_simd: false,
                extended_const: false,
            }
        );
    }

    #[test]
    fn enable_threads() {
        let mut features = Features::new();
        features.bulk_memory(false).threads(true);

        assert!(features.threads);
    }

    #[test]
    fn enable_reference_types() {
        let mut features = Features::new();
        features.bulk_memory(false).reference_types(true);
        assert!(features.reference_types);
        assert!(features.bulk_memory);
    }

    #[test]
    fn enable_simd() {
        let mut features = Features::new();
        features.simd(true);
        assert!(features.simd);
    }

    #[test]
    fn enable_multi_value() {
        let mut features = Features::new();
        features.multi_value(true);
        assert!(features.multi_value);
    }

    #[test]
    fn enable_bulk_memory() {
        let mut features = Features::new();
        features.bulk_memory(true);
        assert!(features.bulk_memory);
    }

    #[test]
    fn disable_bulk_memory() {
        let mut features = Features::new();
        features
            .threads(true)
            .reference_types(true)
            .bulk_memory(false);
        assert!(!features.bulk_memory);
        assert!(!features.reference_types);
    }

    #[test]
    fn enable_tail_call() {
        let mut features = Features::new();
        features.tail_call(true);
        assert!(features.tail_call);
    }

    #[test]
    fn enable_module_linking() {
        let mut features = Features::new();
        features.module_linking(true);
        assert!(features.module_linking);
    }

    #[test]
    fn enable_multi_memory() {
        let mut features = Features::new();
        features.multi_memory(true);
        assert!(features.multi_memory);
    }

    #[test]
    fn enable_memory64() {
        let mut features = Features::new();
        features.memory64(true);
        assert!(features.memory64);
    }
}