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
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
//! A map implemented by searching linearly in a vector.
//!
//! See the [`LinearMap`](struct.LinearMap.html) type for details.

#![deny(missing_docs)]

// Optional Serde support
#[cfg(feature = "serde_impl")]
pub mod serde;
pub mod set;

use std::borrow::Borrow;
use std::fmt::{self, Debug};
use std::iter;
use std::mem;
use std::ops;
use std::slice;
use std::vec;

use self::Entry::{Occupied, Vacant};

// TODO: Unzip the vectors?
// Consideration: When unzipped, the compiler will not be able to understand
// that both of the `Vec`s have the same length, thus stuff like `iter` and so
// on should probably be implemented in unsafe code.

/// A map implemented by searching linearly in a vector.
///
/// `LinearMap`'s keys are compared using the [`Eq`][eq] trait. All search operations
/// (`contains_key`, `get`, `get_mut`, `insert`, and `remove`) run in `O(n)` time, making this
/// implementation suitable only for small numbers of keys. The ordering of the keys in the
/// underlying vector is arbitrary.
///
/// It is a logic error for a key to be modified in such a way that the key's equality, as
/// determined by the [`Eq`][eq] trait, changes while it is in the map. This is normally only
/// possible through [`Cell`][cell], [`RefCell`][ref_cell], global state, I/O, or unsafe code.
///
/// [cell]: https://doc.rust-lang.org/nightly/std/cell/struct.Cell.html
/// [eq]: https://doc.rust-lang.org/nightly/std/cmp/trait.Eq.html
/// [ref_cell]: https://doc.rust-lang.org/nightly/std/cell/struct.RefCell.html
///
/// # Example
///
/// ```
/// use linear_map::LinearMap;
///
/// // type inference lets us omit an explicit type signature (which
/// // would be `LinearMap<&str, &str>` in this example).
/// let mut book_reviews = LinearMap::new();
///
/// // review some books.
/// book_reviews.insert("Adventures of Huckleberry Finn",    "My favorite book.");
/// book_reviews.insert("Grimms' Fairy Tales",               "Masterpiece.");
/// book_reviews.insert("Pride and Prejudice",               "Very enjoyable.");
/// book_reviews.insert("The Adventures of Sherlock Holmes", "Eye lyked it alot.");
///
/// // check for a specific one.
/// if !book_reviews.contains_key("Les Misérables") {
///     println!("We've got {} reviews, but Les Misérables ain't one.",
///              book_reviews.len());
/// }
///
/// // oops, this review has a lot of spelling mistakes. let's delete it.
/// book_reviews.remove("The Adventures of Sherlock Holmes");
///
/// // look up the values associated with some keys.
/// let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
/// for book in &to_find {
///     match book_reviews.get(book) {
///         Some(review) => println!("{}: {}", book, review),
///         None => println!("{} is unreviewed.", book)
///     }
/// }
///
/// // iterate over everything.
/// for (book, review) in &book_reviews {
///     println!("{}: \"{}\"", book, review);
/// }
/// ```
pub struct LinearMap<K, V> {
    storage: Vec<(K, V)>,
}

impl<K: Eq, V> LinearMap<K, V> {
    /// Creates an empty map. This method does not allocate.
    pub fn new() -> Self {
        LinearMap { storage: vec![] }
    }

    /// Creates an empty map with the given initial capacity.
    pub fn with_capacity(capacity: usize) -> Self {
        LinearMap { storage: Vec::with_capacity(capacity) }
    }

    /// Returns the number of elements the map can hold without reallocating.
    pub fn capacity(&self) -> usize {
        self.storage.capacity()
    }

    /// Reserves capacity for at least `additional` more to be inserted in the
    /// map. The collection may reserve more space to avoid frequent
    /// reallocations.
    ///
    /// # Panics
    ///
    /// Panics if the new allocation size overflows `usize`.
    pub fn reserve(&mut self, additional: usize) {
        self.storage.reserve(additional);
    }

    /// Reserves the minimum capacity for exactly `additional` more elemnnts to
    /// be inserted in the map.
    ///
    /// Note that the allocator may give the collection more space than it
    /// requests. Therefore capacity cannot be relied upon to be precisely
    /// minimal. Prefer `reserve` if future insertions are expected.
    ///
    /// # Panics
    ///
    /// Panics if the new capacity overflows `usize`.
    pub fn reserve_exact(&mut self, additional: usize) {
        self.storage.reserve_exact(additional);
    }

    /// Shrinks the capacity of the map as much as possible.
    ///
    /// It will drop down as close as possible to the current length but the
    /// allocator may still inform the map that there is more space than
    /// necessary. Therefore capacity cannot be relid upon to be minimal.
    pub fn shrink_to_fit(&mut self) {
        self.storage.shrink_to_fit();
    }

    /// Returns the number of elements in the map.
    pub fn len(&self) -> usize {
        self.storage.len()
    }

    /// Returns true if the map contains no elements.
    pub fn is_empty(&self) -> bool {
        self.storage.is_empty()
    }

    /// Clears the map, removing all elements. Keeps the allocated memory for
    /// reuse.
    pub fn clear(&mut self) {
        self.storage.clear();
    }

    /// Removes all key-value pairs from the map and returns an iterator that yields them in
    /// arbitrary order.
    ///
    /// All key-value pairs are removed even if the iterator is not exhausted. However, the
    /// behavior of this method is unspecified if the iterator is leaked.
    ///
    /// The iterator's item type is `(K, V)`.
    pub fn drain(&mut self) -> Drain<K, V> {
        Drain { iter: self.storage.drain(..) }
    }

    /// Returns an iterator yielding references to the map's keys and their corresponding values in
    /// arbitrary order.
    ///
    /// The iterator's item type is `(&K, &V)`.
    pub fn iter(&self) -> Iter<K, V> {
        Iter { iter: self.storage.iter() }
    }

    /// Returns an iterator yielding references to the map's keys and mutable references to their
    /// corresponding values in arbitrary order.
    ///
    /// The iterator's item type is `(&K, &mut V)`.
    pub fn iter_mut(&mut self) -> IterMut<K, V> {
        IterMut { iter: self.storage.iter_mut() }
    }

    /// Returns an iterator yielding references to the map's keys in arbitrary order.
    ///
    /// The iterator's item type is `&K`.
    pub fn keys(&self) -> Keys<K, V> {
        Keys { iter: self.iter() }
    }

    /// Returns an iterator yielding references to the map's values in arbitrary order.
    ///
    /// The iterator's item type is `&V`.
    pub fn values(&self) -> Values<K, V> {
        Values { iter: self.iter() }
    }

    /// Returns a reference to the value in the map whose key is equal to the given key.
    ///
    /// Returns `None` if the map contains no such key.
    ///
    /// The given key may be any borrowed form of the map's key type, but `Eq` on the borrowed form
    /// *must* match that of the key type.
    pub fn get<Q: ?Sized + Eq>(&self, key: &Q) -> Option<&V> where K: Borrow<Q> {
        for (k, v) in self {
            if key == k.borrow() {
                return Some(v);
            }
        }
        None
    }

    /// Returns a mutable reference to the value in the map whose key is equal to the given key.
    ///
    /// Returns `None` if the map contains no such key.
    ///
    /// The given key may be any borrowed form of the map's key type, but `Eq` on the borrowed form
    /// *must* match that of the key type.
    pub fn get_mut<Q: ?Sized + Eq>(&mut self, key: &Q) -> Option<&mut V> where K: Borrow<Q> {
        for (k, v) in self {
            if key == k.borrow() {
                return Some(v);
            }
        }
        None
    }

    /// Checks if the map contains a key that is equal to the given key.
    ///
    /// The given key may be any borrowed form of the map's key type, but `Eq` on the borrowed form
    /// *must* match that of the key type.
    pub fn contains_key<Q: ?Sized + Eq>(&self, key: &Q) -> bool where K: Borrow<Q> {
        self.get(key).is_some()
    }

    /// Inserts a key-value pair into the map.
    ///
    /// Returns `None` if the map did not contain a key that is equal to the given key.
    ///
    /// If the map did contain such a key, its corresponding value is replaced with the given
    /// value, and the old value is returned. The key is not updated, though. This matters for
    /// values that can be `==` without being identical. See the [standard library's documentation]
    /// [std] for more details.
    ///
    /// [std]: https://doc.rust-lang.org/nightly/std/collections/index.html#insert-and-complex-keys
    pub fn insert(&mut self, key: K, value: V) -> Option<V> {
        match self.entry(key) {
            Occupied(mut e) => Some(e.insert(value)),
            Vacant(e) => { e.insert(value); None }
        }
    }

    /// Removes the key in the map that is equal to the given key and returns its corresponding
    /// value.
    ///
    /// Returns `None` if the map contained no such key.
    ///
    /// The given key may be any borrowed form of the map's key type, but `Eq` on the borrowed form
    /// *must* match that of the key type.
    pub fn remove<Q: ?Sized + Eq>(&mut self, key: &Q) -> Option<V> where K: Borrow<Q> {
        for i in 0..self.storage.len() {
            if self.storage[i].0.borrow() == key {
                return Some(self.storage.swap_remove(i).1);
            }
        }
        None
    }

    /// Returns the given key's corresponding entry in the map for in-place manipulation.
    pub fn entry(&mut self, key: K) -> Entry<K, V> {
        match self.storage.iter().position(|&(ref k, _)| key == *k) {
            None => Vacant(VacantEntry {
                map: self,
                key: key
            }),
            Some(index) => Occupied(OccupiedEntry {
                map: self,
                index: index
            })
        }
    }
}

impl<K: Clone, V: Clone> Clone for LinearMap<K, V> {
    fn clone(&self) -> Self {
        LinearMap { storage: self.storage.clone() }
    }

    fn clone_from(&mut self, other: &Self) {
        self.storage.clone_from(&other.storage);
    }
}

impl<K: Eq + Debug, V: Debug> Debug for LinearMap<K, V> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_map().entries(self).finish()
    }
}

impl<K: Eq, V> Default for LinearMap<K, V> {
    fn default() -> Self {
        Self::new()
    }
}

impl<K: Eq, V> Extend<(K, V)> for LinearMap<K, V> {
    fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, key_values: I) {
        for (key, value) in key_values { self.insert(key, value); }
    }
}

impl<K: Eq, V> iter::FromIterator<(K, V)> for LinearMap<K, V> {
    fn from_iter<I: IntoIterator<Item = (K, V)>>(key_values: I) -> Self {
        let mut map = Self::new();
        map.extend(key_values);
        map
    }
}

impl<'a, K: Eq + Borrow<Q>, V, Q: ?Sized + Eq> ops::Index<&'a Q> for LinearMap<K, V> {
    type Output = V;

    fn index(&self, key: &'a Q) -> &V {
        self.get(key).expect("key not found")
    }
}

impl<K: Eq, V: PartialEq> PartialEq for LinearMap<K, V> {
    fn eq(&self, other: &Self) -> bool {
        if self.len() != other.len() {
            return false;
        }

        for (key, value) in self {
            if other.get(key) != Some(value) {
                return false;
            }
        }

        true
    }
}

impl<K: Eq, V: Eq> Eq for LinearMap<K, V> {}

impl<K: Eq, V> Into<Vec<(K, V)>> for LinearMap<K, V> {
    fn into(self) -> Vec<(K, V)> {
        self.storage
    }
}

/// Creates a `LinearMap` from a list of key-value pairs.
///
/// The created `LinearMap` has a capacity set to the number of entries provided.
///
/// # Example
///
/// ```
/// #[macro_use] extern crate linear_map;
/// # fn main() {
///
/// let map = linear_map!{
///     "a" => 1,
///     "b" => 2,
/// };
/// assert_eq!(map["a"], 1);
/// assert_eq!(map["b"], 2);
/// assert_eq!(map.get("c"), None);
/// # }
/// ```
#[macro_export]
macro_rules! linear_map {
    ($($key:expr => $value:expr,)+) => { linear_map!($($key => $value),+) };
    ($($key:expr => $value:expr),*) => {
        {
            let _cap = <[&str]>::len(&[$(stringify!($key)),*]);
            let mut _map = $crate::LinearMap::with_capacity(_cap);
            $(
                _map.insert($key, $value);
            )*
            _map
        }
    };
}

/// A view into a single occupied location in a `LinearMap`.
///
/// See [`LinearMap::entry`](struct.LinearMap.html#method.entry) for details.
pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
    map: &'a mut LinearMap<K, V>,
    index: usize,
}

/// A view into a single vacant location in a `LinearMap`.
///
/// See [`LinearMap::entry`](struct.LinearMap.html#method.entry) for details.
pub struct VacantEntry<'a, K: 'a, V: 'a> {
    map: &'a mut LinearMap<K, V>,
    key: K,
}

/// A view into a single entry in a `LinearMap`.
///
/// See [`LinearMap::entry`](struct.LinearMap.html#method.entry) for details.
pub enum Entry<'a, K: 'a, V: 'a> {
    /// An occupied entry.
    Occupied(OccupiedEntry<'a, K, V>),

    /// A vacant entry.
    Vacant(VacantEntry<'a, K, V>)
}

impl<'a, K, V> Entry<'a, K, V> {
    /// Ensures that the entry is occupied by inserting the given value if it is vacant.
    ///
    /// Returns a mutable reference to the entry's value.
    pub fn or_insert(self, default: V) -> &'a mut V {
        match self {
            Occupied(entry) => entry.into_mut(),
            Vacant(entry) => entry.insert(default)
        }
    }

    /// Ensures that the entry is occupied by inserting the the result of the given function if it
    /// is vacant.
    ///
    /// Returns a mutable reference to the entry's value.
    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
        match self {
            Occupied(entry) => entry.into_mut(),
            Vacant(entry) => entry.insert(default())
        }
    }
}

impl<'a, K, V> OccupiedEntry<'a, K, V> {
    /// Returns a reference to the entry's value.
    pub fn get(&self) -> &V {
        &self.map.storage[self.index].1
    }

    /// Returns a mutable reference to the entry's value.
    pub fn get_mut(&mut self) -> &mut V {
        &mut self.map.storage[self.index].1
    }

    /// Returns a mutable reference to the entry's value with the same lifetime as the map.
    pub fn into_mut(self) -> &'a mut V {
        &mut self.map.storage[self.index].1
    }

    /// Replaces the entry's value with the given one and returns the previous value.
    pub fn insert(&mut self, value: V) -> V {
        mem::replace(self.get_mut(), value)
    }

    /// Removes the entry from the map and returns its value.
    pub fn remove(self) -> V {
        self.map.storage.swap_remove(self.index).1
    }
}

impl<'a, K, V> VacantEntry<'a, K, V> {
    /// Inserts the entry into the map with the given value.
    ///
    /// Returns a mutable reference to the entry's value with the same lifetime as the map.
    pub fn insert(self, value: V) -> &'a mut V {
        self.map.storage.push((self.key, value));
        &mut self.map.storage.last_mut().unwrap().1
    }
}

/// A consuming iterator over a `LinearMap`.
///
/// The iterator's order is arbitrary.
///
/// Acquire through [`IntoIterator`](struct.LinearMap.html#method.into_iter).
pub struct IntoIter<K, V> {
    iter: vec::IntoIter<(K, V)>,
}

impl<K, V> Iterator for IntoIter<K, V> {
    type Item = (K, V);

    fn next(&mut self) -> Option<(K, V)> {
        self.iter.next()
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.iter.size_hint()
    }
}

impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
    fn next_back(&mut self) -> Option<(K, V)> {
        self.iter.next_back()
    }
}

impl<K, V> ExactSizeIterator for IntoIter<K, V> {
    fn len(&self) -> usize {
        self.iter.len()
    }
}

/// A draining iterator over a `LinearMap`.
///
/// See [`LinearMap::drain`](struct.LinearMap.html#method.drain) for details.
pub struct Drain<'a, K: 'a, V: 'a> {
    iter: vec::Drain<'a, (K, V)>,
}

/// An iterator yielding references to a `LinearMap`'s keys and their corresponding values.
///
/// See [`LinearMap::iter`](struct.LinearMap.html#method.iter) for details.
pub struct Iter<'a, K: 'a, V: 'a> {
    iter: slice::Iter<'a, (K, V)>,
}

/// An iterator yielding references to a `LinearMap`'s keys and mutable references to their
/// corresponding values.
///
/// See [`LinearMap::iter_mut`](struct.LinearMap.html#method.iter_mut) for details.
pub struct IterMut<'a, K: 'a, V: 'a> {
    iter: slice::IterMut<'a, (K, V)>,
}

/// An iterator yielding references to a `LinearMap`'s keys in arbitrary order.
///
/// See [`LinearMap::keys`](struct.LinearMap.html#method.keys) for details.
pub struct Keys<'a, K: 'a, V: 'a> {
    iter: Iter<'a, K, V>,
}

/// An iterator yielding references to a `LinearMap`'s values in arbitrary order.
///
/// See [`LinearMap::values`](struct.LinearMap.html#method.values) for details.
pub struct Values<'a, K: 'a, V: 'a> {
    iter: Iter<'a, K, V>,
}

macro_rules! impl_iter {($typ:ty, $item:ty, $map:expr) => {
    impl<'a, K, V> Iterator for $typ {
        type Item = $item;

        fn next(&mut self) -> Option<Self::Item> {
            self.iter.next().map($map)
        }

        fn size_hint(&self) -> (usize, Option<usize>) {
            self.iter.size_hint()
        }
    }

    impl<'a, K, V> DoubleEndedIterator for $typ {
        fn next_back(&mut self) -> Option<Self::Item> {
            self.iter.next_back().map($map)
        }
    }

    impl<'a, K, V> ExactSizeIterator for $typ {
        fn len(&self) -> usize {
            self.iter.len()
        }
    }
}}
impl_iter!{Drain<'a,K,V>,  (K,V),  |e| e }
impl_iter!{Iter<'a,K,V>,  (&'a K, &'a V),  |e| (&e.0, &e.1) }
impl_iter!{IterMut<'a,K,V>,  (&'a K, &'a mut V),  |e| (&e.0, &mut e.1) }
impl_iter!{Keys<'a,K,V>,  &'a K,  |e| e.0 }
impl_iter!{Values<'a,K,V>,  &'a V,  |e| e.1 }

impl<'a, K, V> Clone for Iter<'a, K, V> {
    fn clone(&self) -> Self {
        Iter { iter: self.iter.clone() }
    }
}

impl<'a, K, V> Clone for Keys<'a, K, V> {
    fn clone(&self) -> Self {
        Keys { iter: self.iter.clone() }
    }
}

impl<'a, K, V> Clone for Values<'a, K, V> {
    fn clone(&self) -> Self {
        Values { iter: self.iter.clone() }
    }
}

impl<K: Eq, V> IntoIterator for LinearMap<K, V> {
    type Item = (K, V);
    type IntoIter = IntoIter<K, V>;

    fn into_iter(self) -> IntoIter<K, V> {
        IntoIter { iter: self.storage.into_iter() }
    }
}

impl<'a, K: Eq, V> IntoIterator for &'a LinearMap<K, V> {
    type Item = (&'a K, &'a V);
    type IntoIter = Iter<'a, K, V>;

    fn into_iter(self) -> Iter<'a, K, V> {
        self.iter()
    }
}

impl<'a, K: Eq, V> IntoIterator for &'a mut LinearMap<K, V> {
    type Item = (&'a K, &'a mut V);
    type IntoIter = IterMut<'a, K, V>;

    fn into_iter(self) -> IterMut<'a, K, V> {
        self.iter_mut()
    }
}

#[allow(dead_code)]
fn assert_covariance() {
    fn a<'a, K, V>(x: LinearMap<&'static K, &'static V>) -> LinearMap<&'a K, &'a V> { x }

    fn b<'a, K, V>(x: IntoIter<&'static K, &'static V>) -> IntoIter<&'a K, &'a V> { x }

    fn c<'i, 'a, K, V>(x: Iter<'i, &'static K, &'static V>) -> Iter<'i, &'a K, &'a V> { x }

    fn d<'i, 'a, K, V>(x: Keys<'i, &'static K, &'static V>) -> Keys<'i, &'a K, &'a V> { x }

    fn e<'i, 'a, K, V>(x: Values<'i, &'static K, &'static V>) -> Values<'i, &'a K, &'a V> { x }
}