From Jason Turner

[iterators.counted]

C++23 → Trunk 6.6 KB 50 lines
Current Draft | LaTeX Source
Archived: C++23
Markdown: C++23 | Trunk
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  1. tmp/tmp56jzqjb6/{from.md → to.md} +19 -19
tmp/tmp56jzqjb6/{from.md → to.md} RENAMED
@@ -34,13 +34,13 @@ namespace std {
34
  public:
35
  using iterator_type = I;
36
  using value_type = iter_value_t<I>; // present only
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  // if I models indirectly_readable
38
  using difference_type = iter_difference_t<I>;
39
- using iterator_concept = typename I::iterator_concept; // present only
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  // if the qualified-id I::iterator_concept is valid and denotes a type
41
- using iterator_category = typename I::iterator_category; // present only
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  // if the qualified-id I::iterator_category is valid and denotes a type
43
  constexpr counted_iterator() requires default_initializable<I> = default;
44
  constexpr counted_iterator(I x, iter_difference_t<I> n);
45
  template<class I2>
46
  requires convertible_to<const I2&, I>
@@ -81,30 +81,30 @@ namespace std {
81
  requires random_access_iterator<I>;
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  template<common_with<I> I2>
83
  friend constexpr iter_difference_t<I2> operator-(
84
  const counted_iterator& x, const counted_iterator<I2>& y);
85
  friend constexpr iter_difference_t<I> operator-(
86
- const counted_iterator& x, default_sentinel_t);
87
  friend constexpr iter_difference_t<I> operator-(
88
- default_sentinel_t, const counted_iterator& y);
89
  constexpr counted_iterator& operator-=(iter_difference_t<I> n)
90
  requires random_access_iterator<I>;
91
 
92
  constexpr decltype(auto) operator[](iter_difference_t<I> n) const
93
  requires random_access_iterator<I>;
94
 
95
  template<common_with<I> I2>
96
  friend constexpr bool operator==(
97
  const counted_iterator& x, const counted_iterator<I2>& y);
98
  friend constexpr bool operator==(
99
- const counted_iterator& x, default_sentinel_t);
100
 
101
  template<common_with<I> I2>
102
  friend constexpr strong_ordering operator<=>(
103
  const counted_iterator& x, const counted_iterator<I2>& y);
104
 
105
- friend constexpr iter_rvalue_reference_t<I> iter_move(const counted_iterator& i)
106
  noexcept(noexcept(ranges::iter_move(i.current)))
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  requires input_iterator<I>;
108
  template<indirectly_swappable<I> I2>
109
  friend constexpr void iter_swap(const counted_iterator& x, const counted_iterator<I2>& y)
110
  noexcept(noexcept(ranges::iter_swap(x.current, y.current)));
@@ -127,11 +127,11 @@ namespace std {
127
 
128
  ``` cpp
129
  constexpr counted_iterator(I i, iter_difference_t<I> n);
130
  ```
131
 
132
- *Preconditions:* `n >= 0`.
133
 
134
  *Effects:* Initializes `current` with `std::move(i)` and `length` with
135
  `n`.
136
 
137
  ``` cpp
@@ -179,11 +179,11 @@ constexpr iter_difference_t<I> count() const noexcept;
179
  constexpr decltype(auto) operator*();
180
  constexpr decltype(auto) operator*() const
181
  requires dereferenceable<const I>;
182
  ```
183
 
184
- *Preconditions:* `length > 0` is `true`.
185
 
186
  *Effects:* Equivalent to: `return *current;`
187
 
188
  ``` cpp
189
  constexpr auto operator->() const noexcept
@@ -195,21 +195,21 @@ constexpr auto operator->() const noexcept
195
  ``` cpp
196
  constexpr decltype(auto) operator[](iter_difference_t<I> n) const
197
  requires random_access_iterator<I>;
198
  ```
199
 
200
- *Preconditions:* `n < length`.
201
 
202
  *Effects:* Equivalent to: `return current[n];`
203
 
204
  #### Navigation <a id="counted.iter.nav">[[counted.iter.nav]]</a>
205
 
206
  ``` cpp
207
  constexpr counted_iterator& operator++();
208
  ```
209
 
210
- *Preconditions:* `length > 0`.
211
 
212
  *Effects:* Equivalent to:
213
 
214
  ``` cpp
215
  ++current;
@@ -219,11 +219,11 @@ return *this;
219
 
220
  ``` cpp
221
  constexpr decltype(auto) operator++(int);
222
  ```
223
 
224
- *Preconditions:* `length > 0`.
225
 
226
  *Effects:* Equivalent to:
227
 
228
  ``` cpp
229
  --length;
@@ -289,11 +289,11 @@ friend constexpr counted_iterator operator+(
289
  ``` cpp
290
  constexpr counted_iterator& operator+=(iter_difference_t<I> n)
291
  requires random_access_iterator<I>;
292
  ```
293
 
294
- *Preconditions:* `n <= length`.
295
 
296
  *Effects:* Equivalent to:
297
 
298
  ``` cpp
299
  current += n;
@@ -320,28 +320,28 @@ sequence [[counted.iterator]].
320
 
321
  *Effects:* Equivalent to: `return y.length - x.length;`
322
 
323
  ``` cpp
324
  friend constexpr iter_difference_t<I> operator-(
325
- const counted_iterator& x, default_sentinel_t);
326
  ```
327
 
328
  *Effects:* Equivalent to: `return -x.length;`
329
 
330
  ``` cpp
331
  friend constexpr iter_difference_t<I> operator-(
332
- default_sentinel_t, const counted_iterator& y);
333
  ```
334
 
335
  *Effects:* Equivalent to: `return y.length;`
336
 
337
  ``` cpp
338
  constexpr counted_iterator& operator-=(iter_difference_t<I> n)
339
  requires random_access_iterator<I>;
340
  ```
341
 
342
- *Preconditions:* `-n <= length`.
343
 
344
  *Effects:* Equivalent to:
345
 
346
  ``` cpp
347
  current -= n;
@@ -362,11 +362,11 @@ sequence [[counted.iterator]].
362
 
363
  *Effects:* Equivalent to: `return x.length == y.length;`
364
 
365
  ``` cpp
366
  friend constexpr bool operator==(
367
- const counted_iterator& x, default_sentinel_t);
368
  ```
369
 
370
  *Effects:* Equivalent to: `return x.length == 0;`
371
 
372
  ``` cpp
@@ -384,26 +384,26 @@ sequence [[counted.iterator]].
384
  because `length` counts down, not up. — *end note*]
385
 
386
  #### Customizations <a id="counted.iter.cust">[[counted.iter.cust]]</a>
387
 
388
  ``` cpp
389
- friend constexpr iter_rvalue_reference_t<I>
390
  iter_move(const counted_iterator& i)
391
  noexcept(noexcept(ranges::iter_move(i.current)))
392
  requires input_iterator<I>;
393
  ```
394
 
395
- *Preconditions:* `i.length > 0` is `true`.
396
 
397
  *Effects:* Equivalent to: `return ranges::iter_move(i.current);`
398
 
399
  ``` cpp
400
  template<indirectly_swappable<I> I2>
401
  friend constexpr void
402
  iter_swap(const counted_iterator& x, const counted_iterator<I2>& y)
403
  noexcept(noexcept(ranges::iter_swap(x.current, y.current)));
404
  ```
405
 
406
- *Preconditions:* Both `x.length > 0` and `y.length > 0` are `true`.
407
 
408
  *Effects:* Equivalent to `ranges::iter_swap(x.current, y.current)`.
409
 
 
34
  public:
35
  using iterator_type = I;
36
  using value_type = iter_value_t<I>; // present only
37
  // if I models indirectly_readable
38
  using difference_type = iter_difference_t<I>;
39
+ using iterator_concept = I::iterator_concept; // present only
40
  // if the qualified-id I::iterator_concept is valid and denotes a type
41
+ using iterator_category = I::iterator_category; // present only
42
  // if the qualified-id I::iterator_category is valid and denotes a type
43
  constexpr counted_iterator() requires default_initializable<I> = default;
44
  constexpr counted_iterator(I x, iter_difference_t<I> n);
45
  template<class I2>
46
  requires convertible_to<const I2&, I>
 
81
  requires random_access_iterator<I>;
82
  template<common_with<I> I2>
83
  friend constexpr iter_difference_t<I2> operator-(
84
  const counted_iterator& x, const counted_iterator<I2>& y);
85
  friend constexpr iter_difference_t<I> operator-(
86
+ const counted_iterator& x, default_sentinel_t) noexcept;
87
  friend constexpr iter_difference_t<I> operator-(
88
+ default_sentinel_t, const counted_iterator& y) noexcept;
89
  constexpr counted_iterator& operator-=(iter_difference_t<I> n)
90
  requires random_access_iterator<I>;
91
 
92
  constexpr decltype(auto) operator[](iter_difference_t<I> n) const
93
  requires random_access_iterator<I>;
94
 
95
  template<common_with<I> I2>
96
  friend constexpr bool operator==(
97
  const counted_iterator& x, const counted_iterator<I2>& y);
98
  friend constexpr bool operator==(
99
+ const counted_iterator& x, default_sentinel_t) noexcept;
100
 
101
  template<common_with<I> I2>
102
  friend constexpr strong_ordering operator<=>(
103
  const counted_iterator& x, const counted_iterator<I2>& y);
104
 
105
+ friend constexpr decltype(auto) iter_move(const counted_iterator& i)
106
  noexcept(noexcept(ranges::iter_move(i.current)))
107
  requires input_iterator<I>;
108
  template<indirectly_swappable<I> I2>
109
  friend constexpr void iter_swap(const counted_iterator& x, const counted_iterator<I2>& y)
110
  noexcept(noexcept(ranges::iter_swap(x.current, y.current)));
 
127
 
128
  ``` cpp
129
  constexpr counted_iterator(I i, iter_difference_t<I> n);
130
  ```
131
 
132
+ `n >= 0` is `true`.
133
 
134
  *Effects:* Initializes `current` with `std::move(i)` and `length` with
135
  `n`.
136
 
137
  ``` cpp
 
179
  constexpr decltype(auto) operator*();
180
  constexpr decltype(auto) operator*() const
181
  requires dereferenceable<const I>;
182
  ```
183
 
184
+ `length > 0` is `true`.
185
 
186
  *Effects:* Equivalent to: `return *current;`
187
 
188
  ``` cpp
189
  constexpr auto operator->() const noexcept
 
195
  ``` cpp
196
  constexpr decltype(auto) operator[](iter_difference_t<I> n) const
197
  requires random_access_iterator<I>;
198
  ```
199
 
200
+ `n < length` is `true`.
201
 
202
  *Effects:* Equivalent to: `return current[n];`
203
 
204
  #### Navigation <a id="counted.iter.nav">[[counted.iter.nav]]</a>
205
 
206
  ``` cpp
207
  constexpr counted_iterator& operator++();
208
  ```
209
 
210
+ `length > 0` is `true`.
211
 
212
  *Effects:* Equivalent to:
213
 
214
  ``` cpp
215
  ++current;
 
219
 
220
  ``` cpp
221
  constexpr decltype(auto) operator++(int);
222
  ```
223
 
224
+ `length > 0` is `true`.
225
 
226
  *Effects:* Equivalent to:
227
 
228
  ``` cpp
229
  --length;
 
289
  ``` cpp
290
  constexpr counted_iterator& operator+=(iter_difference_t<I> n)
291
  requires random_access_iterator<I>;
292
  ```
293
 
294
+ `n <= length` is `true`.
295
 
296
  *Effects:* Equivalent to:
297
 
298
  ``` cpp
299
  current += n;
 
320
 
321
  *Effects:* Equivalent to: `return y.length - x.length;`
322
 
323
  ``` cpp
324
  friend constexpr iter_difference_t<I> operator-(
325
+ const counted_iterator& x, default_sentinel_t) noexcept;
326
  ```
327
 
328
  *Effects:* Equivalent to: `return -x.length;`
329
 
330
  ``` cpp
331
  friend constexpr iter_difference_t<I> operator-(
332
+ default_sentinel_t, const counted_iterator& y) noexcept;
333
  ```
334
 
335
  *Effects:* Equivalent to: `return y.length;`
336
 
337
  ``` cpp
338
  constexpr counted_iterator& operator-=(iter_difference_t<I> n)
339
  requires random_access_iterator<I>;
340
  ```
341
 
342
+ `-n <= length` is `true`.
343
 
344
  *Effects:* Equivalent to:
345
 
346
  ``` cpp
347
  current -= n;
 
362
 
363
  *Effects:* Equivalent to: `return x.length == y.length;`
364
 
365
  ``` cpp
366
  friend constexpr bool operator==(
367
+ const counted_iterator& x, default_sentinel_t) noexcept;
368
  ```
369
 
370
  *Effects:* Equivalent to: `return x.length == 0;`
371
 
372
  ``` cpp
 
384
  because `length` counts down, not up. — *end note*]
385
 
386
  #### Customizations <a id="counted.iter.cust">[[counted.iter.cust]]</a>
387
 
388
  ``` cpp
389
+ friend constexpr decltype(auto)
390
  iter_move(const counted_iterator& i)
391
  noexcept(noexcept(ranges::iter_move(i.current)))
392
  requires input_iterator<I>;
393
  ```
394
 
395
+ `i.length > 0` is `true`.
396
 
397
  *Effects:* Equivalent to: `return ranges::iter_move(i.current);`
398
 
399
  ``` cpp
400
  template<indirectly_swappable<I> I2>
401
  friend constexpr void
402
  iter_swap(const counted_iterator& x, const counted_iterator<I2>& y)
403
  noexcept(noexcept(ranges::iter_swap(x.current, y.current)));
404
  ```
405
 
406
+ Both `x.length > 0` and `y.length > 0` are `true`.
407
 
408
  *Effects:* Equivalent to `ranges::iter_swap(x.current, y.current)`.
409