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use crate::fmt;
use crate::hash::Hash;
/// 无限制范围 (`..`)。
///
/// `RangeFull` 主要用作 [切片索引][slicing index],其简写为 `..`。
/// 它不能用作 [`Iterator`],因为它没有起点。
///
/// # Examples
///
/// `..` 语法是一个 `RangeFull`:
///
/// ```
/// assert_eq!((..), std::ops::RangeFull);
/// ```
///
/// 它没有 [`IntoIterator`] 实现,因此不能直接在 `for` 循环中使用它。
/// 这不会编译:
///
/// ```compile_fail,E0277
/// for i in .. {
/// // ...
/// }
/// ```
///
/// 用作 [切片索引][slicing index] 时,`RangeFull` 产生完整的阵列作为切片。
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]); // 这是 `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
#[lang = "RangeFull"]
#[doc(alias = "..")]
#[derive(Copy, Clone, Default, PartialEq, Eq, Hash)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RangeFull;
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for RangeFull {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(fmt, "..")
}
}
/// (half-open) 范围包括在 (`start..end`) 之下和仅在 (`start..end`) 之上。
///
///
/// 范围 `start..end` 包含 `start <= x < end` 的所有值。
/// 如果为 `start >= end`,则为空。
///
/// # Examples
///
/// `start..end` 语法是 `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 ]); // 这是 `Range`
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
#[lang = "Range"]
#[doc(alias = "..")]
#[derive(Clone, Default, PartialEq, Eq, Hash)] // 没有 Copy - 请参见 #27186
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Range<Idx> {
/// 范围的下限 (包括)。
#[stable(feature = "rust1", since = "1.0.0")]
pub start: Idx,
/// 范围 (exclusive) 的上限。
#[stable(feature = "rust1", since = "1.0.0")]
pub end: Idx,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<Idx: fmt::Debug> fmt::Debug for Range<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
self.start.fmt(fmt)?;
write!(fmt, "..")?;
self.end.fmt(fmt)?;
Ok(())
}
}
impl<Idx: PartialOrd<Idx>> Range<Idx> {
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!(!(3..5).contains(&2));
/// assert!( (3..5).contains(&3));
/// assert!( (3..5).contains(&4));
/// assert!(!(3..5).contains(&5));
///
/// assert!(!(3..3).contains(&3));
/// assert!(!(3..2).contains(&3));
///
/// assert!( (0.0..1.0).contains(&0.5));
/// assert!(!(0.0..1.0).contains(&f32::NAN));
/// assert!(!(0.0..f32::NAN).contains(&0.5));
/// assert!(!(f32::NAN..1.0).contains(&0.5));
/// ```
#[stable(feature = "range_contains", since = "1.35.0")]
pub fn contains<U>(&self, item: &U) -> bool
where
Idx: PartialOrd<U>,
U: ?Sized + PartialOrd<Idx>,
{
<Self as RangeBounds<Idx>>::contains(self, item)
}
/// 如果范围不包含任何项,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!(!(3..5).is_empty());
/// assert!( (3..3).is_empty());
/// assert!( (3..2).is_empty());
/// ```
///
/// 如果任何一方都无法比拟,则范围为空:
///
/// ```
/// assert!(!(3.0..5.0).is_empty());
/// assert!( (3.0..f32::NAN).is_empty());
/// assert!( (f32::NAN..5.0).is_empty());
/// ```
#[stable(feature = "range_is_empty", since = "1.47.0")]
pub fn is_empty(&self) -> bool {
!(self.start < self.end)
}
}
/// 范围仅包括 (`start..`) 以下的范围。
///
/// `RangeFrom` `start..` 包含 `x >= start` 的所有值。
///
/// *Note*: [`Iterator`] 实现中的溢出 (当所包含的数据类型达到其数值限制时) 允许 panic,自动换行或饱和。
/// 此行为由 [`Step`] trait 的实现定义。
/// 对于原始整数,这遵循正常规则,并遵守溢出检查配置文件 (调试中为 panic,释放中为包装)。
/// 还要注意,溢出发生的时间比您想像的要早:溢出发生在 `next` 的调用中,该调用会产生最大值,因为必须将范围设置为产生下一个值的状态。
///
///
/// [`Step`]: crate::iter::Step
///
/// # Examples
///
/// `start..` 语法是 `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]); // 这是 `RangeFrom`
/// assert_eq!(arr[1.. 3], [ 1, 2 ]);
/// assert_eq!(arr[1..=3], [ 1, 2, 3 ]);
/// ```
///
///
///
#[lang = "RangeFrom"]
#[doc(alias = "..")]
#[derive(Clone, PartialEq, Eq, Hash)] // 没有 Copy - 请参见 #27186
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RangeFrom<Idx> {
/// 范围的下限 (包括)。
#[stable(feature = "rust1", since = "1.0.0")]
pub start: Idx,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<Idx: fmt::Debug> fmt::Debug for RangeFrom<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
self.start.fmt(fmt)?;
write!(fmt, "..")?;
Ok(())
}
}
impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!(!(3..).contains(&2));
/// assert!( (3..).contains(&3));
/// assert!( (3..).contains(&1_000_000_000));
///
/// assert!( (0.0..).contains(&0.5));
/// assert!(!(0.0..).contains(&f32::NAN));
/// assert!(!(f32::NAN..).contains(&0.5));
/// ```
#[stable(feature = "range_contains", since = "1.35.0")]
pub fn contains<U>(&self, item: &U) -> bool
where
Idx: PartialOrd<U>,
U: ?Sized + PartialOrd<Idx>,
{
<Self as RangeBounds<Idx>>::contains(self, item)
}
}
/// 范围仅排在 (`..end`) 之上。
///
/// `RangeTo` `..end` 包含 `x < end` 的所有值。
/// 它不能用作 [`Iterator`],因为它没有起点。
///
/// # Examples
///
/// `..end` 语法是 `RangeTo`:
///
/// ```
/// assert_eq!((..5), std::ops::RangeTo { end: 5 });
/// ```
///
/// 它没有 [`IntoIterator`] 实现,因此不能直接在 `for` 循环中使用它。
/// 这不会编译:
///
/// ```compile_fail,E0277
/// // error[E0277]: the trait bound `std::ops::RangeTo<{integer}>:
/// // std::Iterator` 不满足
/// for i in ..5 {
/// // ...
/// }
/// ```
///
/// 当用作 [切片索引][slicing index] 时,`RangeTo` 会在 `end` 所指示的索引之前生成所有数组元素的切片。
///
///
/// ```
/// let arr = [0, 1, 2, 3, 4];
/// assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
/// assert_eq!(arr[ .. 3], [0, 1, 2 ]); // 这是 `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
#[lang = "RangeTo"]
#[doc(alias = "..")]
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RangeTo<Idx> {
/// 范围 (exclusive) 的上限。
#[stable(feature = "rust1", since = "1.0.0")]
pub end: Idx,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<Idx: fmt::Debug> fmt::Debug for RangeTo<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(fmt, "..")?;
self.end.fmt(fmt)?;
Ok(())
}
}
impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!( (..5).contains(&-1_000_000_000));
/// assert!( (..5).contains(&4));
/// assert!(!(..5).contains(&5));
///
/// assert!( (..1.0).contains(&0.5));
/// assert!(!(..1.0).contains(&f32::NAN));
/// assert!(!(..f32::NAN).contains(&0.5));
/// ```
#[stable(feature = "range_contains", since = "1.35.0")]
pub fn contains<U>(&self, item: &U) -> bool
where
Idx: PartialOrd<U>,
U: ?Sized + PartialOrd<Idx>,
{
<Self as RangeBounds<Idx>>::contains(self, item)
}
}
/// 范围包括 (`start..=end`) 的上下边界。
///
/// `RangeInclusive` `start..=end` 包含 `x >= start` 和 `x <= end` 的所有值。除非 `start <= end`,否则为空。
///
/// 这个迭代器是 [fused],但是迭代完成后 `start` 和 `end` 的特定值是未指定的,除了 [`.is_empty()`] 之外,一旦不再产生值,就会返回 `true`。
///
///
/// [fused]: crate::iter::FusedIterator
/// [`.is_empty()`]: RangeInclusive::is_empty
///
/// # Examples
///
/// `start..=end` 语法是 `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 ]); // 这是 `RangeInclusive`
/// ```
///
///
#[lang = "RangeInclusive"]
#[doc(alias = "..=")]
#[derive(Clone, PartialEq, Eq, Hash)] // 没有 Copy - 请参见 #27186
#[stable(feature = "inclusive_range", since = "1.26.0")]
pub struct RangeInclusive<Idx> {
// 请注意,此处的字段不是公开的,以允许更改 future 中的表示形式。尤其是,尽管我们可能公开 start/end,但在不更改 (future/current) 私有字段的情况下对其进行修改可能会导致错误的行为,因此我们不希望支持该模式。
//
//
//
//
pub(crate) start: Idx,
pub(crate) end: Idx,
// 该字段是:
// - 构建时为 `false`
// - `false` 当迭代产生一个元素并且迭代器没有耗尽时
// - `true` 当迭代已被用于耗尽迭代器时
//
// 这是支持 PartialEq 和 Hash 而没有 PartialOrd 绑定或特殊化所必需的。
pub(crate) exhausted: bool,
}
impl<Idx> RangeInclusive<Idx> {
/// 创建一个新的包含范围。等同于编写 `start..=end`。
///
/// # Examples
///
/// ```
/// use std::ops::RangeInclusive;
///
/// assert_eq!(3..=5, RangeInclusive::new(3, 5));
/// ```
#[lang = "range_inclusive_new"]
#[stable(feature = "inclusive_range_methods", since = "1.27.0")]
#[inline]
#[rustc_promotable]
#[rustc_const_stable(feature = "const_range_new", since = "1.32.0")]
pub const fn new(start: Idx, end: Idx) -> Self {
Self { start, end, exhausted: false }
}
/// 返回范围的下限 (包括下限)。
///
/// 当使用包含范围进行迭代时,在迭代结束后未指定 `start()` 和 [`end()`] 的值。
/// 若要确定包含范围是否为空,请使用 [`is_empty()`] 方法而不是比较 `start() > end()`。
///
/// Note: 范围迭代到穷竭之后,此方法返回的值是不确定的。
///
/// [`end()`]: RangeInclusive::end
/// [`is_empty()`]: RangeInclusive::is_empty
///
/// # Examples
///
/// ```
/// assert_eq!((3..=5).start(), &3);
/// ```
///
///
///
#[stable(feature = "inclusive_range_methods", since = "1.27.0")]
#[rustc_const_stable(feature = "const_inclusive_range_methods", since = "1.32.0")]
#[inline]
pub const fn start(&self) -> &Idx {
&self.start
}
/// 返回范围的上限 (包括上限)。
///
/// 当使用包含范围进行迭代时,在迭代结束后未指定 [`start()`] 和 `end()` 的值。
/// 若要确定包含范围是否为空,请使用 [`is_empty()`] 方法而不是比较 `start() > end()`。
///
/// Note: 范围迭代到穷竭之后,此方法返回的值是不确定的。
///
/// [`start()`]: RangeInclusive::start
/// [`is_empty()`]: RangeInclusive::is_empty
///
/// # Examples
///
/// ```
/// assert_eq!((3..=5).end(), &5);
/// ```
///
///
///
#[stable(feature = "inclusive_range_methods", since = "1.27.0")]
#[rustc_const_stable(feature = "const_inclusive_range_methods", since = "1.32.0")]
#[inline]
pub const fn end(&self) -> &Idx {
&self.end
}
/// 将 `RangeInclusive` 分解为 (下限,上限 (含上限))。
///
/// Note: 范围迭代到穷竭之后,此方法返回的值是不确定的。
///
///
/// # Examples
///
/// ```
/// assert_eq!((3..=5).into_inner(), (3, 5));
/// ```
#[stable(feature = "inclusive_range_methods", since = "1.27.0")]
#[inline]
#[rustc_const_unstable(feature = "const_range_bounds", issue = "108082")]
pub const fn into_inner(self) -> (Idx, Idx) {
(self.start, self.end)
}
}
impl RangeInclusive<usize> {
/// 转换为 `SliceIndex` 实现的专用 `Range`。
/// 调用者负责处理 `end == usize::MAX`。
#[inline]
pub(crate) const fn into_slice_range(self) -> Range<usize> {
// 如果我们不筋疲力尽,我们只想切片 `start..end + 1`。
// 如果我们筋疲力尽,则使用 `end + 1..end + 1` 切片会为我们提供一个空范围,该范围仍受该端点的边界检查的影响。
//
let exclusive_end = self.end + 1;
let start = if self.exhausted { exclusive_end } else { self.start };
start..exclusive_end
}
}
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl<Idx: fmt::Debug> fmt::Debug for RangeInclusive<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
self.start.fmt(fmt)?;
write!(fmt, "..=")?;
self.end.fmt(fmt)?;
if self.exhausted {
write!(fmt, " (exhausted)")?;
}
Ok(())
}
}
impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!(!(3..=5).contains(&2));
/// assert!( (3..=5).contains(&3));
/// assert!( (3..=5).contains(&4));
/// assert!( (3..=5).contains(&5));
/// assert!(!(3..=5).contains(&6));
///
/// assert!( (3..=3).contains(&3));
/// assert!(!(3..=2).contains(&3));
///
/// assert!( (0.0..=1.0).contains(&1.0));
/// assert!(!(0.0..=1.0).contains(&f32::NAN));
/// assert!(!(0.0..=f32::NAN).contains(&0.0));
/// assert!(!(f32::NAN..=1.0).contains(&1.0));
/// ```
///
/// 迭代完成后,此方法总是返回 `false`:
///
/// ```
/// let mut r = 3..=5;
/// assert!(r.contains(&3) && r.contains(&5));
/// for _ in r.by_ref() {}
/// // 此处未指定精确的字段值
/// assert!(!r.contains(&3) && !r.contains(&5));
/// ```
#[stable(feature = "range_contains", since = "1.35.0")]
pub fn contains<U>(&self, item: &U) -> bool
where
Idx: PartialOrd<U>,
U: ?Sized + PartialOrd<Idx>,
{
<Self as RangeBounds<Idx>>::contains(self, item)
}
/// 如果范围不包含任何项,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!(!(3..=5).is_empty());
/// assert!(!(3..=3).is_empty());
/// assert!( (3..=2).is_empty());
/// ```
///
/// 如果任何一方都无法比拟,则范围为空:
///
/// ```
/// assert!(!(3.0..=5.0).is_empty());
/// assert!( (3.0..=f32::NAN).is_empty());
/// assert!( (f32::NAN..=5.0).is_empty());
/// ```
///
/// 迭代完成后,此方法返回 `true`:
///
/// ```
/// let mut r = 3..=5;
/// for _ in r.by_ref() {}
/// // 此处未指定精确的字段值
/// assert!(r.is_empty());
/// ```
#[stable(feature = "range_is_empty", since = "1.47.0")]
#[inline]
pub fn is_empty(&self) -> bool {
self.exhausted || !(self.start <= self.end)
}
}
/// 范围仅包括 (`..=end`) 以上的范围。
///
/// `RangeToInclusive` `..=end` 包含 `x <= end` 的所有值。
/// 它不能用作 [`Iterator`],因为它没有起点。
///
/// # Examples
///
/// `..=end` 语法是 `RangeToInclusive`:
///
/// ```
/// assert_eq!((..=5), std::ops::RangeToInclusive{ end: 5 });
/// ```
///
/// 它没有 [`IntoIterator`] 实现,因此不能直接在 `for` 循环中使用它。这不会编译:
///
/// ```compile_fail,E0277
/// // error[E0277]: the trait bound `std::ops::RangeToInclusive<{integer}>:
/// // std::Iterator` 不满足
/// for i in ..=5 {
/// // ...
/// }
/// ```
///
/// 当用作 [切片索引][slicing index] 时,`RangeToInclusive` 会生成所有数组元素的切片,直到并包括 `end` 指示的索引。
///
///
/// ```
/// 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 ]); // 这是 `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
///
#[lang = "RangeToInclusive"]
#[doc(alias = "..=")]
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
#[stable(feature = "inclusive_range", since = "1.26.0")]
pub struct RangeToInclusive<Idx> {
/// 范围的上限 (包含上限)
#[stable(feature = "inclusive_range", since = "1.26.0")]
pub end: Idx,
}
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl<Idx: fmt::Debug> fmt::Debug for RangeToInclusive<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(fmt, "..=")?;
self.end.fmt(fmt)?;
Ok(())
}
}
impl<Idx: PartialOrd<Idx>> RangeToInclusive<Idx> {
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!( (..=5).contains(&-1_000_000_000));
/// assert!( (..=5).contains(&5));
/// assert!(!(..=5).contains(&6));
///
/// assert!( (..=1.0).contains(&1.0));
/// assert!(!(..=1.0).contains(&f32::NAN));
/// assert!(!(..=f32::NAN).contains(&0.5));
/// ```
#[stable(feature = "range_contains", since = "1.35.0")]
pub fn contains<U>(&self, item: &U) -> bool
where
Idx: PartialOrd<U>,
U: ?Sized + PartialOrd<Idx>,
{
<Self as RangeBounds<Idx>>::contains(self, item)
}
}
// RangeToInclusive<Idx> 不能 impl From<RangeTo<Idx>> 因为下溢可能使用 (..0).into ()
//
/// 一系列键的端点。
///
/// # Examples
///
/// 边界是范围端点:
///
/// ```
/// use std::ops::Bound::*;
/// use std::ops::RangeBounds;
///
/// assert_eq!((..100).start_bound(), Unbounded);
/// assert_eq!((1..12).start_bound(), Included(&1));
/// assert_eq!((1..12).end_bound(), Excluded(&12));
/// ```
///
/// 使用 `Bound`s 的元组作为 [`BTreeMap::range`] 的参数。
/// 请注意,在大多数情况下,最好改用范围语法 (`1..5`)。
///
/// ```
/// use std::collections::BTreeMap;
/// use std::ops::Bound::{Excluded, Included, Unbounded};
///
/// let mut map = BTreeMap::new();
/// map.insert(3, "a");
/// map.insert(5, "b");
/// map.insert(8, "c");
///
/// for (key, value) in map.range((Excluded(3), Included(8))) {
/// println!("{key}: {value}");
/// }
///
/// assert_eq!(Some((&3, &"a")), map.range((Unbounded, Included(5))).next());
/// ```
///
/// [`BTreeMap::range`]: ../../std/collections/btree_map/struct.BTreeMap.html#method.range
#[stable(feature = "collections_bound", since = "1.17.0")]
#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
pub enum Bound<T> {
/// 包容性范围。
#[stable(feature = "collections_bound", since = "1.17.0")]
Included(#[stable(feature = "collections_bound", since = "1.17.0")] T),
/// 排他性约束。
#[stable(feature = "collections_bound", since = "1.17.0")]
Excluded(#[stable(feature = "collections_bound", since = "1.17.0")] T),
/// 无限端点。指示此方向没有界限。
#[stable(feature = "collections_bound", since = "1.17.0")]
Unbounded,
}
impl<T> Bound<T> {
/// 从 `&Bound<T>` 转换为 `Bound<&T>`。
#[inline]
#[stable(feature = "bound_as_ref_shared", since = "1.65.0")]
pub fn as_ref(&self) -> Bound<&T> {
match *self {
Included(ref x) => Included(x),
Excluded(ref x) => Excluded(x),
Unbounded => Unbounded,
}
}
/// 从 `&mut Bound<T>` 转换为 `Bound<&mut T>`。
#[inline]
#[unstable(feature = "bound_as_ref", issue = "80996")]
pub fn as_mut(&mut self) -> Bound<&mut T> {
match *self {
Included(ref mut x) => Included(x),
Excluded(ref mut x) => Excluded(x),
Unbounded => Unbounded,
}
}
/// 映射一个 `Bound` 通过将函数应用于包含的值 (包括 `Included` 和 `Excluded`),返回相同类型的 `Bound`。
///
///
/// # Examples
///
/// ```
/// #![feature(bound_map)]
/// use std::ops::Bound::*;
///
/// let bound_string = Included("Hello, World!");
///
/// assert_eq!(bound_string.map(|s| s.len()), Included(13));
/// ```
///
/// ```
/// #![feature(bound_map)]
/// use std::ops::Bound;
/// use Bound::*;
///
/// let unbounded_string: Bound<String> = Unbounded;
///
/// assert_eq!(unbounded_string.map(|s| s.len()), Unbounded);
/// ```
#[inline]
#[unstable(feature = "bound_map", issue = "86026")]
pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Bound<U> {
match self {
Unbounded => Unbounded,
Included(x) => Included(f(x)),
Excluded(x) => Excluded(f(x)),
}
}
}
impl<T: Clone> Bound<&T> {
/// Map 通过克隆绑定的内容将 `Bound<&T>` 更改为 `Bound<T>`。
///
/// # Examples
///
/// ```
/// use std::ops::Bound::*;
/// use std::ops::RangeBounds;
///
/// assert_eq!((1..12).start_bound(), Included(&1));
/// assert_eq!((1..12).start_bound().cloned(), Included(1));
/// ```
#[must_use = "`self` will be dropped if the result is not used"]
#[stable(feature = "bound_cloned", since = "1.55.0")]
pub fn cloned(self) -> Bound<T> {
match self {
Bound::Unbounded => Bound::Unbounded,
Bound::Included(x) => Bound::Included(x.clone()),
Bound::Excluded(x) => Bound::Excluded(x.clone()),
}
}
}
/// `RangeBounds` 由 Rust 的内置范围类型实现,由 `..`、`a..`、`..b`、`..=c`、`d..e` 或 `f..=g` 等范围语法生成。
///
#[stable(feature = "collections_range", since = "1.28.0")]
pub trait RangeBounds<T: ?Sized> {
/// 开始索引绑定。
///
/// 以 `Bound` 形式返回起始值。
///
/// # Examples
///
/// ```
/// # fn main() {
/// use std::ops::Bound::*;
/// use std::ops::RangeBounds;
///
/// assert_eq!((..10).start_bound(), Unbounded);
/// assert_eq!((3..10).start_bound(), Included(&3));
/// # }
/// ```
#[stable(feature = "collections_range", since = "1.28.0")]
fn start_bound(&self) -> Bound<&T>;
/// 结束索引绑定。
///
/// 将结束值返回为 `Bound`。
///
/// # Examples
///
/// ```
/// # fn main() {
/// use std::ops::Bound::*;
/// use std::ops::RangeBounds;
///
/// assert_eq!((3..).end_bound(), Unbounded);
/// assert_eq!((3..10).end_bound(), Excluded(&10));
/// # }
/// ```
#[stable(feature = "collections_range", since = "1.28.0")]
fn end_bound(&self) -> Bound<&T>;
/// 如果范围中包含 `item`,则返回 `true`。
///
/// # Examples
///
/// ```
/// assert!( (3..5).contains(&4));
/// assert!(!(3..5).contains(&2));
///
/// assert!( (0.0..1.0).contains(&0.5));
/// assert!(!(0.0..1.0).contains(&f32::NAN));
/// assert!(!(0.0..f32::NAN).contains(&0.5));
/// assert!(!(f32::NAN..1.0).contains(&0.5));
#[stable(feature = "range_contains", since = "1.35.0")]
fn contains<U>(&self, item: &U) -> bool
where
T: PartialOrd<U>,
U: ?Sized + PartialOrd<T>,
{
(match self.start_bound() {
Included(start) => start <= item,
Excluded(start) => start < item,
Unbounded => true,
}) && (match self.end_bound() {
Included(end) => item <= end,
Excluded(end) => item < end,
Unbounded => true,
})
}
}
use self::Bound::{Excluded, Included, Unbounded};
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T: ?Sized> RangeBounds<T> for RangeFull {
fn start_bound(&self) -> Bound<&T> {
Unbounded
}
fn end_bound(&self) -> Bound<&T> {
Unbounded
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeFrom<T> {
fn start_bound(&self) -> Bound<&T> {
Included(&self.start)
}
fn end_bound(&self) -> Bound<&T> {
Unbounded
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeTo<T> {
fn start_bound(&self) -> Bound<&T> {
Unbounded
}
fn end_bound(&self) -> Bound<&T> {
Excluded(&self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for Range<T> {
fn start_bound(&self) -> Bound<&T> {
Included(&self.start)
}
fn end_bound(&self) -> Bound<&T> {
Excluded(&self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeInclusive<T> {
fn start_bound(&self) -> Bound<&T> {
Included(&self.start)
}
fn end_bound(&self) -> Bound<&T> {
if self.exhausted {
// 当迭代器用尽时,我们通常有 start == end,但我们希望范围显示为空,不包含任何内容。
//
Excluded(&self.end)
} else {
Included(&self.end)
}
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeToInclusive<T> {
fn start_bound(&self) -> Bound<&T> {
Unbounded
}
fn end_bound(&self) -> Bound<&T> {
Included(&self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for (Bound<T>, Bound<T>) {
fn start_bound(&self) -> Bound<&T> {
match *self {
(Included(ref start), _) => Included(start),
(Excluded(ref start), _) => Excluded(start),
(Unbounded, _) => Unbounded,
}
}
fn end_bound(&self) -> Bound<&T> {
match *self {
(_, Included(ref end)) => Included(end),
(_, Excluded(ref end)) => Excluded(end),
(_, Unbounded) => Unbounded,
}
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<'a, T: ?Sized + 'a> RangeBounds<T> for (Bound<&'a T>, Bound<&'a T>) {
fn start_bound(&self) -> Bound<&T> {
self.0
}
fn end_bound(&self) -> Bound<&T> {
self.1
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeFrom<&T> {
fn start_bound(&self) -> Bound<&T> {
Included(self.start)
}
fn end_bound(&self) -> Bound<&T> {
Unbounded
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeTo<&T> {
fn start_bound(&self) -> Bound<&T> {
Unbounded
}
fn end_bound(&self) -> Bound<&T> {
Excluded(self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for Range<&T> {
fn start_bound(&self) -> Bound<&T> {
Included(self.start)
}
fn end_bound(&self) -> Bound<&T> {
Excluded(self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeInclusive<&T> {
fn start_bound(&self) -> Bound<&T> {
Included(self.start)
}
fn end_bound(&self) -> Bound<&T> {
Included(self.end)
}
}
#[stable(feature = "collections_range", since = "1.28.0")]
impl<T> RangeBounds<T> for RangeToInclusive<&T> {
fn start_bound(&self) -> Bound<&T> {
Unbounded
}
fn end_bound(&self) -> Bound<&T> {
Included(self.end)
}
}
/// `OneSidedRange` 是为一侧无界的内置范围类型实现的。
/// 例如,`a..`、`..b` 和 `..=c` 实现了 `OneSidedRange`,而 `..`、`d..e` 和 `f..=g` 则没有。
///
/// 实现 `OneSidedRange<T>` 的类型必须从 `RangeBounds::start_bound` 或 `RangeBounds::end_bound` 之一返回 `Bound::Unbounded`。
///
///
#[unstable(feature = "one_sided_range", issue = "69780")]
pub trait OneSidedRange<T: ?Sized>: RangeBounds<T> {}
#[unstable(feature = "one_sided_range", issue = "69780")]
impl<T> OneSidedRange<T> for RangeTo<T> where Self: RangeBounds<T> {}
#[unstable(feature = "one_sided_range", issue = "69780")]
impl<T> OneSidedRange<T> for RangeFrom<T> where Self: RangeBounds<T> {}
#[unstable(feature = "one_sided_range", issue = "69780")]
impl<T> OneSidedRange<T> for RangeToInclusive<T> where Self: RangeBounds<T> {}