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Oct 19, 2020
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Improve range docs #77874

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92 changes: 52 additions & 40 deletions library/core/src/ops/range.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,20 +19,20 @@ use crate::hash::Hash;
///
/// ```compile_fail,E0277
/// for i in .. {
/// // ...
/// // ...
/// }
/// ```
///
/// Used as a [slicing index], `RangeFull` produces the full array as a slice.
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]); // RangeFull
/// assert_eq!(arr[ .. 3], [0,1,2 ]);
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]);
/// assert_eq!(arr[1.. ], [ 1,2,3,4]);
/// assert_eq!(arr[1.. 3], [ 1,2 ]);
/// assert_eq!(arr[1..=3], [ 1,2,3 ]);
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]); // This is the `RangeFull`
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]);
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]);
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]);
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
///
/// [slicing index]: crate::slice::SliceIndex
Expand All @@ -52,22 +52,26 @@ impl fmt::Debug for RangeFull {
/// A (half-open) range bounded inclusively below and exclusively above
/// (`start..end`).
///
/// The `Range` `start..end` contains all values with `x >= start` and
/// `x < end`. It is empty unless `start < end`.
/// The range `start..end` contains all values with `start <= x < end`.
/// It is empty if `start >= end`.
///
/// # Examples
///
/// The `start..end` syntax is a `Range`:
///
/// ```
/// assert_eq!((3..5), std::ops::Range { start: 3, end: 5 });
/// assert_eq!(3 + 4 + 5, (3..6).sum());
/// ```
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]);
/// assert_eq!(arr[ .. 3], [0,1,2 ]);
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]);
/// assert_eq!(arr[1.. ], [ 1,2,3,4]);
/// assert_eq!(arr[1.. 3], [ 1,2 ]); // Range
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I'm not sure why the comment // Range was here; it didn't make sense to me, so I removed it.

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It looks like these must have been copy-pasted to all the Range* types? So the comment is probably to emphasize that that particular line is the one for this type.

Seems like this example should be maybe somewhere where we reference it from all the types, and call-out Range, RangeTo, etc on every line. I guess there's not a core::range module to put it on...

Maybe this example could go on RangeBounds, and all the Range* types could link over there as a way to jump between them?

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So the comment is probably to emphasize that that particular line is the one for this type.

Ah, I see; thanks for clearing that up :)

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For now I just updated all the examples to make them consistent.

/// assert_eq!(arr[1..=3], [ 1,2,3 ]);
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]);
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]);
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]);
/// assert_eq!(arr[1.. 3], [ 1, 2 ]); // This is a `Range`
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
#[lang = "Range"]
#[doc(alias = "..")]
Expand Down Expand Up @@ -160,17 +164,21 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> {
///
/// # Examples
///
/// The `start..` syntax is a `RangeFrom`:
///
/// ```
/// assert_eq!((2..), std::ops::RangeFrom { start: 2 });
/// assert_eq!(2 + 3 + 4, (2..).take(3).sum());
/// ```
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]);
/// assert_eq!(arr[ .. 3], [0,1,2 ]);
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]);
/// assert_eq!(arr[1.. ], [ 1,2,3,4]); // RangeFrom
/// assert_eq!(arr[1.. 3], [ 1,2 ]);
/// assert_eq!(arr[1..=3], [ 1,2,3 ]);
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]);
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]);
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]); // This is a `RangeFrom`
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
#[lang = "RangeFrom"]
#[doc(alias = "..")]
Expand Down Expand Up @@ -244,12 +252,12 @@ impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]);
/// assert_eq!(arr[ .. 3], [0,1,2 ]); // RangeTo
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]);
/// assert_eq!(arr[1.. ], [ 1,2,3,4]);
/// assert_eq!(arr[1.. 3], [ 1,2 ]);
/// assert_eq!(arr[1..=3], [ 1,2,3 ]);
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]); // This is a `RangeTo`
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]);
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]);
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
///
/// [slicing index]: crate::slice::SliceIndex
Expand Down Expand Up @@ -310,17 +318,21 @@ impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
///
/// # Examples
///
/// The `start..=end` syntax is a `RangeInclusive`:
///
/// ```
/// assert_eq!((3..=5), std::ops::RangeInclusive::new(3, 5));
/// assert_eq!(3 + 4 + 5, (3..=5).sum());
/// ```
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]);
/// assert_eq!(arr[ .. 3], [0,1,2 ]);
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]);
/// assert_eq!(arr[1.. ], [ 1,2,3,4]);
/// assert_eq!(arr[1.. 3], [ 1,2 ]);
/// assert_eq!(arr[1..=3], [ 1,2,3 ]); // RangeInclusive
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]);
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]);
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]);
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]); // This is a `RangeInclusive`
/// ```
#[lang = "RangeInclusive"]
#[doc(alias = "..=")]
Expand Down Expand Up @@ -534,12 +546,12 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0,1,2,3,4]);
/// assert_eq!(arr[ .. 3], [0,1,2 ]);
/// assert_eq!(arr[ ..=3], [0,1,2,3 ]); // RangeToInclusive
/// assert_eq!(arr[1.. ], [ 1,2,3,4]);
/// assert_eq!(arr[1.. 3], [ 1,2 ]);
/// assert_eq!(arr[1..=3], [ 1,2,3 ]);
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]);
/// assert_eq!(arr[ ..=3], [0, 1, 2, 3 ]); // This is a `RangeToInclusive`
/// assert_eq!(arr[1.. ], [ 1, 2, 3, 4]);
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
///
/// [slicing index]: crate::slice::SliceIndex
Expand Down Expand Up @@ -661,9 +673,9 @@ impl<T: Clone> Bound<&T> {
}
}

#[stable(feature = "collections_range", since = "1.28.0")]
/// `RangeBounds` is implemented by Rust's built-in range types, produced
/// by range syntax like `..`, `a..`, `..b`, `..=c`, `d..e`, or `f..=g`.
#[stable(feature = "collections_range", since = "1.28.0")]
pub trait RangeBounds<T: ?Sized> {
/// Start index bound.
///
Expand Down