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
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
use std::boxed::Box;
use std::ops::Deref;

use rustc_serialize_crate::{Encodable, Encoder, Decodable, Decoder};

use serde_crate as serde;

/// A struct for encoding nested reference types.
///
/// Encoding large objects by reference is really handy.  For example,
/// `encode(&large_hashmap, ...)` encodes the large structure without having to
/// own the hashmap.  However, it is impossible to serialize a reference if that
/// reference is inside of a struct.
///
/// ```ignore rust
/// // Not possible, rustc can not decode the reference.
/// #[derive(RustcEncoding, RustcDecoding)]
/// struct Message<'a>  {
///   big_map: &'a HashMap<u32, u32>,
///   message_type: String,
/// }
/// ```
///
/// This is because on the decoding side, you can't create the Message struct
/// because it needs to have a reference to a HashMap, which is impossible because
/// during deserialization, all members need to be owned by the deserialized
/// object.
///
/// This is where RefBox comes in.  During serialization, it serializs a reference,
/// but during deserialization, it puts that sub-object into a box!
///
/// ```ignore rust
/// // This works!
/// #[derive(RustcEncoding, RustcDecoding)]
/// struct Message<'a> {
///     big_map: RefBox<'a, HashMap<u32, u32>>,
///     message_type: String
/// }
/// ```
///
/// Now we can write
///
/// ```ignore rust
/// let my_map = HashMap::new();
/// let my_msg = Message {
///     big_map: RefBox::new(&my_map),
///     message_type: "foo".to_string()
/// };
///
/// let encoded = encode(&my_msg, ...).unwrap();
/// let decoded: Message<'static> = decode(&encoded[]).unwrap();
/// ```
///
/// Notice that we managed to encode and decode a struct with a nested reference
/// and that the decoded message has the lifetime `'static` which shows us
/// that the message owns everything inside it completely.
///
/// Please don't stick RefBox inside deep data structures.  It is much better
/// suited in the outermost layer of whatever it is that you are encoding.
#[derive(Debug, PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
pub struct RefBox<'a, T: 'a> {
    inner:  RefBoxInner<'a, T, Box<T>>
}

/// Like a RefBox, but encoding from a `str` and decoedes to a `String`.
#[derive(Debug, PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
pub struct StrBox<'a> {
    inner: RefBoxInner<'a, str, String>
}

/// Like a RefBox, but encodes from a `[T]` and encodes to a `Vec<T>`.
#[derive(Debug, PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
pub struct SliceBox<'a, T: 'a> {
    inner: RefBoxInner<'a, [T], Vec<T>>
}

#[derive(Debug, PartialEq, PartialOrd, Eq, Ord, Hash)]
enum RefBoxInner<'a, A: 'a + ?Sized, B> {
    Ref(&'a A),
    Box(B)
}

impl<'a, T> Clone for RefBoxInner<'a, T, Box<T>> where T: Clone {
    fn clone(&self) -> RefBoxInner<'a, T, Box<T>> {
        match *self {
            RefBoxInner::Ref(reff) => RefBoxInner::Box(Box::new(reff.clone())),
            RefBoxInner::Box(ref boxed) => RefBoxInner::Box(boxed.clone())
        }
    }
}

impl<'a> Clone for RefBoxInner<'a, str, String> {
    fn clone(&self) -> RefBoxInner<'a, str, String> {
        match *self {
            RefBoxInner::Ref(reff) => RefBoxInner::Box(String::from(reff)),
            RefBoxInner::Box(ref boxed) => RefBoxInner::Box(boxed.clone())
        }
    }
}

impl<'a, T> Clone for RefBoxInner<'a, [T], Vec<T>> where T: Clone {
    fn clone(&self) -> RefBoxInner<'a, [T], Vec<T>> {
        match *self {
            RefBoxInner::Ref(reff) => RefBoxInner::Box(Vec::from(reff)),
            RefBoxInner::Box(ref boxed) => RefBoxInner::Box(boxed.clone())
        }
    }
}

impl <'a, T> RefBox<'a, T> {
    /// Creates a new RefBox that looks at a borrowed value.
    pub fn new(v: &'a T) -> RefBox<'a, T> {
        RefBox {
            inner: RefBoxInner::Ref(v)
        }
    }
}

impl <T> RefBox<'static, T>  {
    /// Takes the value out of this refbox.
    ///
    /// Fails if this refbox was not created out of a deserialization.
    ///
    /// Unless you are doing some really weird things with static references,
    /// this function will never fail.
    pub fn take(self) -> Box<T> {
        match self.inner {
            RefBoxInner::Box(b) => b,
            _ => unreachable!()
        }
    }

    /// Tries to take the value out of this refbox.
    pub fn try_take(self) -> Result<Box<T>, RefBox<'static, T>> {
        match self.inner {
            RefBoxInner::Box(b) => Ok(b),
            o => Err(RefBox{ inner: o})
        }
    }
}


impl <'a, T: Encodable> Encodable for RefBox<'a, T> {
    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
        self.inner.encode(s)
    }
}

impl <T: Decodable> Decodable for RefBox<'static, T> {
    fn decode<D: Decoder>(d: &mut D) -> Result<RefBox<'static, T>, D::Error> {
        let inner = try!(Decodable::decode(d));
        Ok(RefBox{inner: inner})
    }
}

impl<'a, T> serde::Serialize for RefBox<'a, T>
    where T: serde::Serialize,
{
    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
        where S: serde::Serializer
    {
        serde::Serialize::serialize(&self.inner, serializer)
    }
}

impl<T: serde::Deserialize> serde::Deserialize for RefBox<'static, T> {
    fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
        where D: serde::Deserializer
    {
        let inner = try!(serde::Deserialize::deserialize(deserializer));
        Ok(RefBox{ inner: inner })
    }
}

impl<'a> StrBox<'a> {
    /// Creates a new StrBox that looks at a borrowed value.
    pub fn new(s: &'a str) -> StrBox<'a> {
        StrBox {
            inner: RefBoxInner::Ref(s)
        }
    }

    /// Extract a String from a StrBox.
    pub fn into_string(self) -> String {
        match self.inner {
            RefBoxInner::Ref(s) => String::from(s),
            RefBoxInner::Box(s) => s
        }
    }

    /// Convert to an Owned `SliceBox`.
    pub fn to_owned(self) -> StrBox<'static> {
        match self.inner {
            RefBoxInner::Ref(s) => StrBox::boxed(String::from(s)),
            RefBoxInner::Box(s) => StrBox::boxed(s)
        }
    }
}

impl<'a> AsRef<str> for StrBox<'a> {
    fn as_ref(&self) -> &str {
        match self.inner {
            RefBoxInner::Ref(ref s) => s,
            RefBoxInner::Box(ref s) => s
        }
    }
}

impl StrBox<'static>  {
    /// Creates a new StrBox made from an allocated String.
    pub fn boxed(s: String) -> StrBox<'static> {
        StrBox { inner: RefBoxInner::Box(s) }
    }

    /// Takes the value out of this refbox.
    ///
    /// Fails if this refbox was not created out of a deserialization.
    ///
    /// Unless you are doing some really weird things with static references,
    /// this function will never fail.
    pub fn take(self) -> String {
        match self.inner {
            RefBoxInner::Box(b) => b,
            RefBoxInner::Ref(b) => String::from(b)
        }
    }

    /// Tries to take the value out of this refbox.
    pub fn try_take(self) -> Result<String, StrBox<'static>> {
        match self.inner {
            RefBoxInner::Box(b) => Ok(b),
            o => Err(StrBox{ inner: o})
        }
    }
}

impl <'a> Encodable for StrBox<'a> {
    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
        self.inner.encode(s)
    }
}

impl Decodable for StrBox<'static> {
    fn decode<D: Decoder>(d: &mut D) -> Result<StrBox<'static>, D::Error> {
        let inner: RefBoxInner<'static, str, String> = try!(Decodable::decode(d));
        Ok(StrBox{inner: inner})
    }
}

impl<'a> serde::Serialize for StrBox<'a> {
    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
        where S: serde::Serializer
    {
        serde::Serialize::serialize(&self.inner, serializer)
    }
}

impl serde::Deserialize for StrBox<'static> {
    fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
        where D: serde::Deserializer
    {
        let inner = try!(serde::Deserialize::deserialize(deserializer));
        Ok(StrBox{ inner: inner })
    }
}

//
// SliceBox
//

impl <'a, T> SliceBox<'a, T> {
    /// Creates a new RefBox that looks at a borrowed value.
    pub fn new(v: &'a [T]) -> SliceBox<'a, T> {
        SliceBox {
            inner: RefBoxInner::Ref(v)
        }
    }

    /// Extract a `Vec<T>` from a `SliceBox`.
    pub fn into_vec(self) -> Vec<T> where T: Clone {
        match self.inner {
            RefBoxInner::Ref(s) => s.to_vec(),
            RefBoxInner::Box(s) => s
        }
    }

    /// Convert to an Owned `SliceBox`.
    pub fn to_owned(self) -> SliceBox<'static, T> where T: Clone {
        match self.inner {
            RefBoxInner::Ref(s) => SliceBox::boxed(s.to_vec()),
            RefBoxInner::Box(s) => SliceBox::boxed(s)
        }
    }
}

impl <T> SliceBox<'static, T>  {
    /// Creates a new SliceBox made from an allocated `Vec<T>`.
    pub fn boxed(s: Vec<T>) -> SliceBox<'static, T> {
        SliceBox { inner: RefBoxInner::Box(s) }
    }

    /// Takes the value out of this refbox.
    ///
    /// Fails if this refbox was not created out of a deserialization.
    ///
    /// Unless you are doing some really weird things with static references,
    /// this function will never fail.
    pub fn take(self) -> Vec<T> {
        match self.inner {
            RefBoxInner::Box(b) => b,
            _ => unreachable!()
        }
    }

    /// Tries to take the value out of this refbox.
    pub fn try_take(self) -> Result<Vec<T>, SliceBox<'static, T>> {
        match self.inner {
            RefBoxInner::Box(b) => Ok(b),
            o => Err(SliceBox{ inner: o})
        }
    }
}

impl <'a, T: Encodable> Encodable for SliceBox<'a, T> {
    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
        self.inner.encode(s)
    }
}

impl <T: Decodable> Decodable for SliceBox<'static, T> {
    fn decode<D: Decoder>(d: &mut D) -> Result<SliceBox<'static, T>, D::Error> {
        let inner: RefBoxInner<'static, [T], Vec<T>> = try!(Decodable::decode(d));
        Ok(SliceBox{inner: inner})
    }
}

impl<'a, T> serde::Serialize for SliceBox<'a, T>
    where T: serde::Serialize,
{
    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
        where S: serde::Serializer
    {
        serde::Serialize::serialize(&self.inner, serializer)
    }
}

impl<T: serde::Deserialize> serde::Deserialize for SliceBox<'static, T> {
    fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
        where D: serde::Deserializer
    {
        let inner = try!(serde::Deserialize::deserialize(deserializer));
        Ok(SliceBox{ inner: inner })
    }
}

impl <'a, A: Encodable + ?Sized, B: Encodable> Encodable for RefBoxInner<'a, A, B> {
    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
        match self {
            &RefBoxInner::Ref(ref r) => r.encode(s),
            &RefBoxInner::Box(ref b) => b.encode(s)
        }
    }
}

impl<'a, A: ?Sized, B> serde::Serialize for RefBoxInner<'a, A, B>
    where A: serde::Serialize,
          B: serde::Serialize,
{
    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
        where S: serde::Serializer
    {
        match self {
            &RefBoxInner::Ref(ref r) => serde::Serialize::serialize(r, serializer),
            &RefBoxInner::Box(ref b) => serde::Serialize::serialize(b, serializer),
        }
    }
}


impl <A: ?Sized, B: Decodable> Decodable for RefBoxInner<'static, A, B> {
    fn decode<D: Decoder>(d: &mut D) -> Result<RefBoxInner<'static, A, B>, D::Error> {
        let decoded = try!(Decodable::decode(d));
        Ok(RefBoxInner::Box(decoded))
    }
}

impl<A: ?Sized, B> serde::Deserialize for RefBoxInner<'static, A, B>
    where B: serde::Deserialize,
{
    fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
        where D: serde::Deserializer
    {
        let deserialized = try!(serde::Deserialize::deserialize(deserializer));
        Ok(RefBoxInner::Box(deserialized))
    }
}

impl <'a, T> Deref for RefBox<'a, T> {
    type Target = T;

    fn deref(&self) -> &T {
        match &self.inner {
            &RefBoxInner::Ref(ref t) => t,
            &RefBoxInner::Box(ref b) => b.deref()
        }
    }
}

impl <'a, T> Deref for SliceBox<'a, T> {
    type Target = [T];

    fn deref(&self) -> &[T] {
        match &self.inner {
            &RefBoxInner::Ref(ref t) => t,
            &RefBoxInner::Box(ref b) => b.deref()
        }
    }
}