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Added the grammar for inclusive ranges #265

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Added the grammar for inclusive ranges #265

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23 changes: 19 additions & 4 deletions src/expressions/range-expr.md
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@
>    | _RangeFromExpr_
>    | _RangeToExpr_
>    | _RangeFullExpr_
>    | _RangeInclusiveExpr_
>    | _RangeToInclusiveExpr_
>
> _RangeExpr_ :
>    [_Expression_] `..` [_Expression_]
Expand All @@ -18,6 +20,12 @@
>
> _RangeFullExpr_ :
>    `..`
>
> _RangeInclusiveExpr_ :
>    [_Expression_] `..=` [_Expression_]
>
> _RangeToInclusiveExpr_ :
>    `..=` [_Expression_]

The `..` operator will construct an object of one of the `std::ops::Range` (or
`core::ops::Range`) variants, according to the following table:
Expand All @@ -28,14 +36,18 @@ The `..` operator will construct an object of one of the `std::ops::Range` (or
| _RangeFromExpr_ | start`..` | [std::ops::RangeFrom] | start ≤ x |
| _RangeToExpr_ | `..`end | [std::ops::RangeTo] | x < end |
| _RangeFullExpr_ | `..` | [std::ops::RangeFull] | - |
| _RangeInclusiveExpr_ | start`..=`end | [std::ops::RangeInclusive] | start ≤ x ≤ end |
| _RangeToInclusiveExpr_ | `..=`end | [std::ops::RangeToInclusive] | x ≤ end |

Examples:

```rust
1..2; // std::ops::Range
3..; // std::ops::RangeFrom
..4; // std::ops::RangeTo
..; // std::ops::RangeFull
let a = 1..2; // std::ops::Range
let a = 3..; // std::ops::RangeFrom
let a = ..4; // std::ops::RangeTo
let a = ..; // std::ops::RangeFull
let a = 1..=2; // std::ops::RangeInclusive
let a = ..=10; // std::ops::RangeToInclusive
```

The following expressions are equivalent.
Expand All @@ -61,3 +73,6 @@ for i in 1..11 {
[std::ops::RangeFrom]: https://doc.rust-lang.org/std/ops/struct.RangeFrom.html
[std::ops::RangeTo]: https://doc.rust-lang.org/std/ops/struct.RangeTo.html
[std::ops::RangeFull]: https://doc.rust-lang.org/std/ops/struct.RangeFull.html
[std::ops::RangeInclusive]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html
[std::ops::RangeToInclusive]: https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html