//! 跨平台路径操纵。
//!
//! 该模块提供两种类型，即 [`PathBuf`] 和 [`Path`] (类似于 [`String`] 和 [`str`])，用于抽象地处理路径。
//! 这些类型分别是围绕 [`OsString`] 和 [`OsStr`] 的薄包装器，这意味着它们根据本地平台的路径语法直接在字符串上工作。
//!
//! 通过遍历 [`Path`] 上 [`components`] 方法返回的结构体，可以将路径解析为 [`Component`]。[`Component`] 大致对应于路径分隔符 (`/` 或 `\`) 之间的子字符串。
//! 您可以使用 [`PathBuf`] 上的 [`push`] 方法从组件重建等效路径; 请注意，根据 [`components`] 方法文档中描述的规范化，路径可能在语法上有所不同。
//!
//!
//! ## 使用简单
//!
//! 路径操作既包括从切片中解析组件，也包括构建新的拥有的路径。
//!
//! 要解析路径，您可以从 [`str`] 切片创建 [`Path`] 切片并开始提出问题:
//!
//! ```
//! use std::path::Path;
//! use std::ffi::OsStr;
//!
//! let path = Path::new("/tmp/foo/bar.txt");
//!
//! let parent = path.parent();
//! assert_eq!(parent, Some(Path::new("/tmp/foo")));
//!
//! let file_stem = path.file_stem();
//! assert_eq!(file_stem, Some(OsStr::new("bar")));
//!
//! let extension = path.extension();
//! assert_eq!(extension, Some(OsStr::new("txt")));
//! ```
//!
//! 要构建或修改路径，请使用 [`PathBuf`]:
//!
//! ```
//! use std::path::PathBuf;
//!
//! // 这种方式有效...
//! let mut path = PathBuf::from("c:\\");
//!
//! path.push("windows");
//! path.push("system32");
//!
//! path.set_extension("dll");
//!
//! // ... 但是如果您不了解所有内容，则最好使用推送。
//! // 如果您这样做，则这种方法更好:
//! let path: PathBuf = ["c:\\", "windows", "system32.dll"].iter().collect();
//! ```
//!
//! [`components`]: Path::components
//! [`push`]: PathBuf::push
//!
//!
//!
//!
//!
//!
//!

#![stable(feature = "rust1", since = "1.0.0")]
#![deny(unsafe_op_in_unsafe_fn)]

#[cfg(test)]
mod tests;

use crate::borrow::{Borrow, Cow};
use crate::cmp;
use crate::error::Error;
use crate::fmt;
use crate::fs;
use crate::hash::{Hash, Hasher};
use crate::io;
use crate::iter::{self, FusedIterator};
use crate::ops::{self, Deref};
use crate::rc::Rc;
use crate::str::FromStr;
use crate::sync::Arc;

use crate::ffi::{OsStr, OsString};

use crate::sys::path::{is_sep_byte, is_verbatim_sep, parse_prefix, MAIN_SEP_STR};

////////////////////////////////////////////////////////////////////////////////
// 一般注意事项
////////////////////////////////////////////////////////////////////////////////
// 利用 OsStr 始终按原样编码 ASCII 字符这一事实，可以通过将 OsStr 直接转换为 [u8] slice 来完成此模块中的解析。
// 最终，应使用直接使用 OsStr API 进行解析来代替这种转换，但是要使这些转换可用需要一些时间。
//
//
//
//

////////////////////////////////////////////////////////////////////////////////
// Windows Prefixes
////////////////////////////////////////////////////////////////////////////////

/// Windows 路径前缀，例如 `C:` 或 `\\server\share`。
///
/// Windows 使用各种路径前缀样式，包括引用来驱动卷 (例如 `C:`)，网络共享文件夹 (例如 `\\server\share`) 以及其他。
/// 另外，某些路径前缀是 "verbatim" (即以 `\\?\` 前缀)，在这种情况下，*不* 将 `/` 视为分隔符，并且基本上不执行规范化。
///
///
/// # Examples
///
/// ```
/// use std::path::{Component, Path, Prefix};
/// use std::path::Prefix::*;
/// use std::ffi::OsStr;
///
/// fn get_path_prefix(s: &str) -> Prefix {
///     let path = Path::new(s);
///     match path.components().next().unwrap() {
///         Component::Prefix(prefix_component) => prefix_component.kind(),
///         _ => panic!(),
///     }
/// }
///
/// # if cfg!(windows) {
/// assert_eq!(Verbatim(OsStr::new("pictures")),
///            get_path_prefix(r"\\?\pictures\kittens"));
/// assert_eq!(VerbatimUNC(OsStr::new("server"), OsStr::new("share")),
///            get_path_prefix(r"\\?\UNC\server\share"));
/// assert_eq!(VerbatimDisk(b'C'), get_path_prefix(r"\\?\c:\"));
/// assert_eq!(DeviceNS(OsStr::new("BrainInterface")),
///            get_path_prefix(r"\\.\BrainInterface"));
/// assert_eq!(UNC(OsStr::new("server"), OsStr::new("share")),
///            get_path_prefix(r"\\server\share"));
/// assert_eq!(Disk(b'C'), get_path_prefix(r"C:\Users\Rust\Pictures\Ferris"));
/// # }
/// ```
///
///
#[derive(Copy, Clone, Debug, Hash, PartialOrd, Ord, PartialEq, Eq)]
#[stable(feature = "rust1", since = "1.0.0")]
pub enum Prefix<'a> {
    /// 逐字前缀，例如 `\\?\cat_pics`.
    ///
    /// 逐字前缀由 `\\?\` 组成，紧随其后是给定的组件。
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    Verbatim(#[stable(feature = "rust1", since = "1.0.0")] &'a OsStr),

    /// 使用 Windows 的 _**U** niform **N** aming **C** onvention_ 的逐字前缀，例如， `\\?\UNC\server\share`.
    ///
    /// Verbatim UNC 前缀由 `\\?\UNC\` 组成，其后紧跟服务器的主机名和共享名。
    ///
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    VerbatimUNC(
        #[stable(feature = "rust1", since = "1.0.0")] &'a OsStr,
        #[stable(feature = "rust1", since = "1.0.0")] &'a OsStr,
    ),

    /// 逐字磁盘前缀，例如， `\\?\C:`.
    ///
    /// 逐字磁盘前缀由 `\\?\` 紧随其后的驱动器号和 `:` 组成。
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    VerbatimDisk(#[stable(feature = "rust1", since = "1.0.0")] u8),

    /// 设备名称空间前缀，例如 `\\.\COM42`.
    ///
    /// 设备名称空间前缀由 `\\.\` 紧随其后的设备名称组成。
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    DeviceNS(#[stable(feature = "rust1", since = "1.0.0")] &'a OsStr),

    /// 使用 Windows 的 _**U** niform **N** aming **C** onvention_ 的前缀，例如
    /// `\\server\share`.
    ///
    /// UNC 前缀由服务器的主机名和共享名组成。
    #[stable(feature = "rust1", since = "1.0.0")]
    UNC(
        #[stable(feature = "rust1", since = "1.0.0")] &'a OsStr,
        #[stable(feature = "rust1", since = "1.0.0")] &'a OsStr,
    ),

    /// 给定磁盘驱动器的前缀 `C:`。
    #[stable(feature = "rust1", since = "1.0.0")]
    Disk(#[stable(feature = "rust1", since = "1.0.0")] u8),
}

impl<'a> Prefix<'a> {
    #[inline]
    fn len(&self) -> usize {
        use self::Prefix::*;
        fn os_str_len(s: &OsStr) -> usize {
            os_str_as_u8_slice(s).len()
        }
        match *self {
            Verbatim(x) => 4 + os_str_len(x),
            VerbatimUNC(x, y) => {
                8 + os_str_len(x) + if os_str_len(y) > 0 { 1 + os_str_len(y) } else { 0 }
            }
            VerbatimDisk(_) => 6,
            UNC(x, y) => 2 + os_str_len(x) + if os_str_len(y) > 0 { 1 + os_str_len(y) } else { 0 },
            DeviceNS(x) => 4 + os_str_len(x),
            Disk(_) => 2,
        }
    }

    /// 确定前缀是否为逐字形式，即以 `\\?\` 开头。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Prefix::*;
    /// use std::ffi::OsStr;
    ///
    /// assert!(Verbatim(OsStr::new("pictures")).is_verbatim());
    /// assert!(VerbatimUNC(OsStr::new("server"), OsStr::new("share")).is_verbatim());
    /// assert!(VerbatimDisk(b'C').is_verbatim());
    /// assert!(!DeviceNS(OsStr::new("BrainInterface")).is_verbatim());
    /// assert!(!UNC(OsStr::new("server"), OsStr::new("share")).is_verbatim());
    /// assert!(!Disk(b'C').is_verbatim());
    /// ```
    #[inline]
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn is_verbatim(&self) -> bool {
        use self::Prefix::*;
        matches!(*self, Verbatim(_) | VerbatimDisk(_) | VerbatimUNC(..))
    }

    #[inline]
    fn is_drive(&self) -> bool {
        matches!(*self, Prefix::Disk(_))
    }

    #[inline]
    fn has_implicit_root(&self) -> bool {
        !self.is_drive()
    }
}

////////////////////////////////////////////////////////////////////////////////
// 公开的解析助手
////////////////////////////////////////////////////////////////////////////////

/// 确定字符是否为当前平台允许的路径分隔符之一。
///
///
/// # Examples
///
/// ```
/// use std::path;
///
/// assert!(path::is_separator('/')); // '/' 适用于 Unix 和 Windows
/// assert!(!path::is_separator('❤'));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn is_separator(c: char) -> bool {
    c.is_ascii() && is_sep_byte(c as u8)
}

/// 当前平台的路径组件的主要分隔符。
///
/// 例如，Unix 上的 `/` 和 Windows 上的 `\`。
#[stable(feature = "rust1", since = "1.0.0")]
pub const MAIN_SEPARATOR: char = crate::sys::path::MAIN_SEP;

////////////////////////////////////////////////////////////////////////////////
// 杂项帮手
////////////////////////////////////////////////////////////////////////////////

// 与 `prefix` 匹配时遍历 `iter`; 如果 `prefix` 不是 `iter` 的前缀，则返回 `None`; 否则，在用完 `prefix` 后返回 `Some(iter_after_prefix)`，得到 `iter`。
//
//
fn iter_after<'a, 'b, I, J>(mut iter: I, mut prefix: J) -> Option<I>
where
    I: Iterator<Item = Component<'a>> + Clone,
    J: Iterator<Item = Component<'b>>,
{
    loop {
        let mut iter_next = iter.clone();
        match (iter_next.next(), prefix.next()) {
            (Some(ref x), Some(ref y)) if x == y => (),
            (Some(_), Some(_)) => return None,
            (Some(_), None) => return Some(iter),
            (None, None) => return Some(iter),
            (None, Some(_)) => return None,
        }
        iter = iter_next;
    }
}

// 请参见本模块顶部的说明以了解为什么使用它们:
//
// 这些强制转换是安全的，因为 OsStr 在内部是所有平台上 [u8] 的包装。
//
// 请注意，当前这依赖于 libstd 拥有的特殊知识。
// 这些类型是单一元素结构体，但未标记为 repr(transparent) 或 repr(C)，这会使这些转换在 std 之外是允许的。
//
//
fn os_str_as_u8_slice(s: &OsStr) -> &[u8] {
    unsafe { &*(s as *const OsStr as *const [u8]) }
}
unsafe fn u8_slice_as_os_str(s: &[u8]) -> &OsStr {
    // SAFETY: 查看 `os_str_as_u8_slice` 的评论
    unsafe { &*(s as *const [u8] as *const OsStr) }
}

// `Redox` 检测方案
fn has_redox_scheme(s: &[u8]) -> bool {
    cfg!(target_os = "redox") && s.contains(&b':')
}

////////////////////////////////////////////////////////////////////////////////
// 跨平台，独立于迭代器的解析
////////////////////////////////////////////////////////////////////////////////

/// 说前缀之后的第一个字节是否为分隔符。
fn has_physical_root(s: &[u8], prefix: Option<Prefix<'_>>) -> bool {
    let path = if let Some(p) = prefix { &s[p.len()..] } else { s };
    !path.is_empty() && is_sep_byte(path[0])
}

// 分裂茎和伸展的基本力量
fn split_file_at_dot(file: &OsStr) -> (Option<&OsStr>, Option<&OsStr>) {
    if os_str_as_u8_slice(file) == b".." {
        return (Some(file), None);
    }

    // 这里的不安全性源于 &OsStr 和 &[u8] and 之间的转换。
    // 这样做是安全的，因为 (1) 我们仅查看编码的 ASCII 内容，而 (2) 新的 &OsStr 值仅从现有 &OsStr values 的 ASCII 限制切片中产生。
    //
    //
    let mut iter = os_str_as_u8_slice(file).rsplitn(2, |b| *b == b'.');
    let after = iter.next();
    let before = iter.next();
    if before == Some(b"") {
        (Some(file), None)
    } else {
        unsafe { (before.map(|s| u8_slice_as_os_str(s)), after.map(|s| u8_slice_as_os_str(s))) }
    }
}

////////////////////////////////////////////////////////////////////////////////
// core 迭代器
////////////////////////////////////////////////////////////////////////////////

/// 组件解析由双端状态机完成; 路径前面和后面的游标都记录了到目前为止路径的哪些部分被消耗了。
///
///
/// 从前到后，路径由前缀，起始目录组件和主体组成 (由常规组件组成)
///
///
#[derive(Copy, Clone, PartialEq, PartialOrd, Debug)]
enum State {
    Prefix = 0,   // c:
    StartDir = 1, // / 或者。或者什么都没有
    Body = 2,     // foo/bar/baz
    Done = 3,
}

/// 包裹 Windows 路径前缀及其未解析的字符串表示形式的结构体。
///
/// 除了由 [`kind`] 返回的已解析 [`Prefix`] 信息外，`PrefixComponent` 还保存由 [`as_os_str`] 返回的原始和未解析的 [`OsStr`] 切片。
///
///
/// 可以通过与 [`Component`] 上的 [`Prefix` variant] 匹配来获得此 `struct` 的实例。
///
/// 在 Unix 上不会发生。
///
/// # Examples
///
/// ```
/// # if cfg!(windows) {
/// use std::path::{Component, Path, Prefix};
/// use std::ffi::OsStr;
///
/// let path = Path::new(r"c:\you\later\");
/// match path.components().next().unwrap() {
///     Component::Prefix(prefix_component) => {
///         assert_eq!(Prefix::Disk(b'C'), prefix_component.kind());
///         assert_eq!(OsStr::new("c:"), prefix_component.as_os_str());
///     }
///     _ => unreachable!(),
/// }
/// # }
/// ```
///
/// [`as_os_str`]: PrefixComponent::as_os_str
/// [`kind`]: PrefixComponent::kind
/// [`Prefix` variant]: Component::Prefix
///
///
///
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(Copy, Clone, Eq, Debug)]
pub struct PrefixComponent<'a> {
    /// 前缀为未解析的 `OsStr` 切片。
    raw: &'a OsStr,

    /// 解析的前缀数据。
    parsed: Prefix<'a>,
}

impl<'a> PrefixComponent<'a> {
    /// 返回已解析的前缀数据。
    ///
    /// 有关不同种类的前缀的更多信息，请参见 [`Prefix`] 的文档。
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn kind(&self) -> Prefix<'a> {
        self.parsed
    }

    /// 返回此前缀的原始 [`OsStr`] 切片。
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn as_os_str(&self) -> &'a OsStr {
        self.raw
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> cmp::PartialEq for PrefixComponent<'a> {
    #[inline]
    fn eq(&self, other: &PrefixComponent<'a>) -> bool {
        cmp::PartialEq::eq(&self.parsed, &other.parsed)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> cmp::PartialOrd for PrefixComponent<'a> {
    #[inline]
    fn partial_cmp(&self, other: &PrefixComponent<'a>) -> Option<cmp::Ordering> {
        cmp::PartialOrd::partial_cmp(&self.parsed, &other.parsed)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Ord for PrefixComponent<'_> {
    #[inline]
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        cmp::Ord::cmp(&self.parsed, &other.parsed)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Hash for PrefixComponent<'_> {
    fn hash<H: Hasher>(&self, h: &mut H) {
        self.parsed.hash(h);
    }
}

/// 路径的单个组成部分。
///
/// `Component` 大致对应于路径分隔符 (`/` 或 `\`) 之间的子字符串。
///
/// 该 `enum` 是通过迭代 [`Components`] 来创建的，而 [`Components`] 又是通过 [`Path`] 上的 [`components`](Path::components) 方法创建的。
///
///
/// # Examples
///
/// ```rust
/// use std::path::{Component, Path};
///
/// let path = Path::new("/tmp/foo/bar.txt");
/// let components = path.components().collect::<Vec<_>>();
/// assert_eq!(&components, &[
///     Component::RootDir,
///     Component::Normal("tmp".as_ref()),
///     Component::Normal("foo".as_ref()),
///     Component::Normal("bar.txt".as_ref()),
/// ]);
/// ```
///
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub enum Component<'a> {
    /// Windows 路径前缀，例如 `C:` 或 `\\server\share`。
    ///
    /// 前缀类型种类繁多，有关更多信息，请参见 [`Prefix`] 的文档。
    ///
    ///
    /// 在 Unix 上不会发生。
    #[stable(feature = "rust1", since = "1.0.0")]
    Prefix(#[stable(feature = "rust1", since = "1.0.0")] PrefixComponent<'a>),

    /// 根目录组件出现在任何前缀之后和其他任何内容之前。
    ///
    /// 它代表一个分隔符，它指定路径从根开始。
    #[stable(feature = "rust1", since = "1.0.0")]
    RootDir,

    /// 对当前目录的引用，即 `.`.
    #[stable(feature = "rust1", since = "1.0.0")]
    CurDir,

    /// 对父目录的引用，即 `..`.
    #[stable(feature = "rust1", since = "1.0.0")]
    ParentDir,

    /// 正常组件，例如 `a/b` 中的 `a` 和 `b`。
    ///
    /// 这个成员是最常见的一个，它代表对文件或目录的引用。
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    Normal(#[stable(feature = "rust1", since = "1.0.0")] &'a OsStr),
}

impl<'a> Component<'a> {
    /// 提取基础的 [`OsStr`] 切片。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("./tmp/foo/bar.txt");
    /// let components: Vec<_> = path.components().map(|comp| comp.as_os_str()).collect();
    /// assert_eq!(&components, &[".", "tmp", "foo", "bar.txt"]);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn as_os_str(self) -> &'a OsStr {
        match self {
            Component::Prefix(p) => p.as_os_str(),
            Component::RootDir => OsStr::new(MAIN_SEP_STR),
            Component::CurDir => OsStr::new("."),
            Component::ParentDir => OsStr::new(".."),
            Component::Normal(path) => path,
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<OsStr> for Component<'_> {
    #[inline]
    fn as_ref(&self) -> &OsStr {
        self.as_os_str()
    }
}

#[stable(feature = "path_component_asref", since = "1.25.0")]
impl AsRef<Path> for Component<'_> {
    #[inline]
    fn as_ref(&self) -> &Path {
        self.as_os_str().as_ref()
    }
}

/// [`Path`] 的 [`Component`] 上的迭代器。
///
/// 该 `struct` 是通过 [`Path`] 上的 [`components`] 方法创建的。
/// 有关更多信息，请参见其文档。
///
/// # Examples
///
/// ```
/// use std::path::Path;
///
/// let path = Path::new("/tmp/foo/bar.txt");
///
/// for component in path.components() {
///     println!("{:?}", component);
/// }
/// ```
///
/// [`components`]: Path::components
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Components<'a> {
    // 解析组件所剩下的路径
    path: &'a [u8],

    // 最初解析的前缀 (如果有)
    prefix: Option<Prefix<'a>>,

    // 如果 path *物理* 具有根分隔符，则为 true; 否则为 true。对于大多数 Windows 前缀，为了规范化的目的，它可能有一个 "logical" 根分隔符，例如，\\server\share == \\server\share\。
    //
    //
    has_physical_root: bool,

    // 迭代器是双端的，这两个状态跟踪从两端产生的结果
    //
    front: State,
    back: State,
}

/// [`Path`] 的 [`Component`] 上的迭代器，作为 [`OsStr`] 切片。
///
/// 该 `struct` 是通过 [`Path`] 上的 [`iter`] 方法创建的。
/// 有关更多信息，请参见其文档。
///
/// [`iter`]: Path::iter
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a> {
    inner: Components<'a>,
}

#[stable(feature = "path_components_debug", since = "1.13.0")]
impl fmt::Debug for Components<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        struct DebugHelper<'a>(&'a Path);

        impl fmt::Debug for DebugHelper<'_> {
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                f.debug_list().entries(self.0.components()).finish()
            }
        }

        f.debug_tuple("Components").field(&DebugHelper(self.as_path())).finish()
    }
}

impl<'a> Components<'a> {
    // 前缀多长时间 (如果有) ?
    #[inline]
    fn prefix_len(&self) -> usize {
        self.prefix.as_ref().map(Prefix::len).unwrap_or(0)
    }

    #[inline]
    fn prefix_verbatim(&self) -> bool {
        self.prefix.as_ref().map(Prefix::is_verbatim).unwrap_or(false)
    }

    /// 从迭代的角度来看，还剩下多少前缀?
    #[inline]
    fn prefix_remaining(&self) -> usize {
        if self.front == State::Prefix { self.prefix_len() } else { 0 }
    }

    // 给定到目前为止的迭代，还剩下多少 pre-State::Body 路径?
    #[inline]
    fn len_before_body(&self) -> usize {
        let root = if self.front <= State::StartDir && self.has_physical_root { 1 } else { 0 };
        let cur_dir = if self.front <= State::StartDir && self.include_cur_dir() { 1 } else { 0 };
        self.prefix_remaining() + root + cur_dir
    }

    // 迭代完成了吗?
    #[inline]
    fn finished(&self) -> bool {
        self.front == State::Done || self.back == State::Done || self.front > self.back
    }

    #[inline]
    fn is_sep_byte(&self, b: u8) -> bool {
        if self.prefix_verbatim() { is_verbatim_sep(b) } else { is_sep_byte(b) }
    }

    /// 提取与迭代剩余路径部分相对应的切片。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let mut components = Path::new("/tmp/foo/bar.txt").components();
    /// components.next();
    /// components.next();
    ///
    /// assert_eq!(Path::new("foo/bar.txt"), components.as_path());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn as_path(&self) -> &'a Path {
        let mut comps = self.clone();
        if comps.front == State::Body {
            comps.trim_left();
        }
        if comps.back == State::Body {
            comps.trim_right();
        }
        unsafe { Path::from_u8_slice(comps.path) }
    }

    /// *原始* 路径是否扎根?
    fn has_root(&self) -> bool {
        if self.has_physical_root {
            return true;
        }
        if let Some(p) = self.prefix {
            if p.has_implicit_root() {
                return true;
            }
        }
        false
    }

    /// 规范化路径是否应包含前导。?
    fn include_cur_dir(&self) -> bool {
        if self.has_root() {
            return false;
        }
        let mut iter = self.path[self.prefix_len()..].iter();
        match (iter.next(), iter.next()) {
            (Some(&b'.'), None) => true,
            (Some(&b'.'), Some(&b)) => self.is_sep_byte(b),
            _ => false,
        }
    }

    // 将给定的字节序列解析为相应的路径组件
    fn parse_single_component<'b>(&self, comp: &'b [u8]) -> Option<Component<'b>> {
        match comp {
            b"." if self.prefix_verbatim() => Some(Component::CurDir),
            b"." => None, // . 组件被标准化掉，除了在
            // 路径的开始，通过 `include_cur_dir` 进行单独处理
            //
            b".." => Some(Component::ParentDir),
            b"" => None,
            _ => Some(Component::Normal(unsafe { u8_slice_as_os_str(comp) })),
        }
    }

    // 从左侧解析一个组件，说出删除该组件要消耗多少字节
    //
    fn parse_next_component(&self) -> (usize, Option<Component<'a>>) {
        debug_assert!(self.front == State::Body);
        let (extra, comp) = match self.path.iter().position(|b| self.is_sep_byte(*b)) {
            None => (0, self.path),
            Some(i) => (1, &self.path[..i]),
        };
        (comp.len() + extra, self.parse_single_component(comp))
    }

    // 从右边解析一个组件，说出删除该组件要消耗多少字节
    //
    fn parse_next_component_back(&self) -> (usize, Option<Component<'a>>) {
        debug_assert!(self.back == State::Body);
        let start = self.len_before_body();
        let (extra, comp) = match self.path[start..].iter().rposition(|b| self.is_sep_byte(*b)) {
            None => (0, &self.path[start..]),
            Some(i) => (1, &self.path[start + i + 1..]),
        };
        (comp.len() + extra, self.parse_single_component(comp))
    }

    // 在左侧修剪掉重复的分隔符 (即空组件)
    fn trim_left(&mut self) {
        while !self.path.is_empty() {
            let (size, comp) = self.parse_next_component();
            if comp.is_some() {
                return;
            } else {
                self.path = &self.path[size..];
            }
        }
    }

    // 在右侧修剪掉重复的分隔符 (即空组件)
    fn trim_right(&mut self) {
        while self.path.len() > self.len_before_body() {
            let (size, comp) = self.parse_next_component_back();
            if comp.is_some() {
                return;
            } else {
                self.path = &self.path[..self.path.len() - size];
            }
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for Components<'_> {
    #[inline]
    fn as_ref(&self) -> &Path {
        self.as_path()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<OsStr> for Components<'_> {
    #[inline]
    fn as_ref(&self) -> &OsStr {
        self.as_path().as_os_str()
    }
}

#[stable(feature = "path_iter_debug", since = "1.13.0")]
impl fmt::Debug for Iter<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        struct DebugHelper<'a>(&'a Path);

        impl fmt::Debug for DebugHelper<'_> {
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                f.debug_list().entries(self.0.iter()).finish()
            }
        }

        f.debug_tuple("Iter").field(&DebugHelper(self.as_path())).finish()
    }
}

impl<'a> Iter<'a> {
    /// 提取与迭代剩余路径部分相对应的切片。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let mut iter = Path::new("/tmp/foo/bar.txt").iter();
    /// iter.next();
    /// iter.next();
    ///
    /// assert_eq!(Path::new("foo/bar.txt"), iter.as_path());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn as_path(&self) -> &'a Path {
        self.inner.as_path()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for Iter<'_> {
    #[inline]
    fn as_ref(&self) -> &Path {
        self.as_path()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<OsStr> for Iter<'_> {
    #[inline]
    fn as_ref(&self) -> &OsStr {
        self.as_path().as_os_str()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Iter<'a> {
    type Item = &'a OsStr;

    #[inline]
    fn next(&mut self) -> Option<&'a OsStr> {
        self.inner.next().map(Component::as_os_str)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> DoubleEndedIterator for Iter<'a> {
    #[inline]
    fn next_back(&mut self) -> Option<&'a OsStr> {
        self.inner.next_back().map(Component::as_os_str)
    }
}

#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for Iter<'_> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Components<'a> {
    type Item = Component<'a>;

    fn next(&mut self) -> Option<Component<'a>> {
        while !self.finished() {
            match self.front {
                State::Prefix if self.prefix_len() > 0 => {
                    self.front = State::StartDir;
                    debug_assert!(self.prefix_len() <= self.path.len());
                    let raw = &self.path[..self.prefix_len()];
                    self.path = &self.path[self.prefix_len()..];
                    return Some(Component::Prefix(PrefixComponent {
                        raw: unsafe { u8_slice_as_os_str(raw) },
                        parsed: self.prefix.unwrap(),
                    }));
                }
                State::Prefix => {
                    self.front = State::StartDir;
                }
                State::StartDir => {
                    self.front = State::Body;
                    if self.has_physical_root {
                        debug_assert!(!self.path.is_empty());
                        self.path = &self.path[1..];
                        return Some(Component::RootDir);
                    } else if let Some(p) = self.prefix {
                        if p.has_implicit_root() && !p.is_verbatim() {
                            return Some(Component::RootDir);
                        }
                    } else if self.include_cur_dir() {
                        debug_assert!(!self.path.is_empty());
                        self.path = &self.path[1..];
                        return Some(Component::CurDir);
                    }
                }
                State::Body if !self.path.is_empty() => {
                    let (size, comp) = self.parse_next_component();
                    self.path = &self.path[size..];
                    if comp.is_some() {
                        return comp;
                    }
                }
                State::Body => {
                    self.front = State::Done;
                }
                State::Done => unreachable!(),
            }
        }
        None
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> DoubleEndedIterator for Components<'a> {
    fn next_back(&mut self) -> Option<Component<'a>> {
        while !self.finished() {
            match self.back {
                State::Body if self.path.len() > self.len_before_body() => {
                    let (size, comp) = self.parse_next_component_back();
                    self.path = &self.path[..self.path.len() - size];
                    if comp.is_some() {
                        return comp;
                    }
                }
                State::Body => {
                    self.back = State::StartDir;
                }
                State::StartDir => {
                    self.back = State::Prefix;
                    if self.has_physical_root {
                        self.path = &self.path[..self.path.len() - 1];
                        return Some(Component::RootDir);
                    } else if let Some(p) = self.prefix {
                        if p.has_implicit_root() && !p.is_verbatim() {
                            return Some(Component::RootDir);
                        }
                    } else if self.include_cur_dir() {
                        self.path = &self.path[..self.path.len() - 1];
                        return Some(Component::CurDir);
                    }
                }
                State::Prefix if self.prefix_len() > 0 => {
                    self.back = State::Done;
                    return Some(Component::Prefix(PrefixComponent {
                        raw: unsafe { u8_slice_as_os_str(self.path) },
                        parsed: self.prefix.unwrap(),
                    }));
                }
                State::Prefix => {
                    self.back = State::Done;
                    return None;
                }
                State::Done => unreachable!(),
            }
        }
        None
    }
}

#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for Components<'_> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> cmp::PartialEq for Components<'a> {
    #[inline]
    fn eq(&self, other: &Components<'a>) -> bool {
        Iterator::eq(self.clone().rev(), other.clone().rev())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Eq for Components<'_> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> cmp::PartialOrd for Components<'a> {
    #[inline]
    fn partial_cmp(&self, other: &Components<'a>) -> Option<cmp::Ordering> {
        Iterator::partial_cmp(self.clone(), other.clone())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Ord for Components<'_> {
    #[inline]
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        Iterator::cmp(self.clone(), other.clone())
    }
}

/// [`Path`] 及其祖先上的迭代器。
///
/// 该 `struct` 是通过 [`Path`] 上的 [`ancestors`] 方法创建的。
/// 有关更多信息，请参见其文档。
///
/// # Examples
///
/// ```
/// use std::path::Path;
///
/// let path = Path::new("/foo/bar");
///
/// for ancestor in path.ancestors() {
///     println!("{}", ancestor.display());
/// }
/// ```
///
/// [`ancestors`]: Path::ancestors
#[derive(Copy, Clone, Debug)]
#[stable(feature = "path_ancestors", since = "1.28.0")]
pub struct Ancestors<'a> {
    next: Option<&'a Path>,
}

#[stable(feature = "path_ancestors", since = "1.28.0")]
impl<'a> Iterator for Ancestors<'a> {
    type Item = &'a Path;

    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        let next = self.next;
        self.next = next.and_then(Path::parent);
        next
    }
}

#[stable(feature = "path_ancestors", since = "1.28.0")]
impl FusedIterator for Ancestors<'_> {}

////////////////////////////////////////////////////////////////////////////////
// 基本类型和 traits
////////////////////////////////////////////////////////////////////////////////

/// 拥有的可变路径 (类似于 [`String`])。
///
/// 这种类型提供了 [`push`] 和 [`set_extension`] 之类的方法，这些方法会改变路径。
/// 它还实现了 [`Deref`] 到 [`Path`]，这意味着 [`Path`] 切片上的所有方法也可以在 `PathBuf` 值上使用。
///
///
/// [`push`]: PathBuf::push
/// [`set_extension`]: PathBuf::set_extension
///
/// 有关整体方法的更多详细信息，请参见 [module documentation](self)。
///
/// # Examples
///
/// 您可以使用 [`push`] 从组件构建 `PathBuf`:
///
/// ```
/// use std::path::PathBuf;
///
/// let mut path = PathBuf::new();
///
/// path.push(r"C:\");
/// path.push("windows");
/// path.push("system32");
///
/// path.set_extension("dll");
/// ```
///
/// 但是，[`push`] 最适合用于动态情况。
/// 当您提前了解所有组件时，这是一种更好的方法:
///
/// ```
/// use std::path::PathBuf;
///
/// let path: PathBuf = [r"C:\", "windows", "system32.dll"].iter().collect();
/// ```
///
/// 我们仍然可以做得更好! 由于这些都是字符串，因此我们可以使用
/// `From::from`:
///
/// ```
/// use std::path::PathBuf;
///
/// let path = PathBuf::from(r"C:\windows\system32.dll");
/// ```
///
/// 哪种方法最有效取决于您所处的情况。
///
///
#[cfg_attr(not(test), rustc_diagnostic_item = "PathBuf")]
#[stable(feature = "rust1", since = "1.0.0")]
// FIXME:
// `PathBuf::as_mut_vec` 当前的实现依赖于 `PathBuf` 与 `Vec<u8>` 在布局上兼容。
// 实现属性隐私时，应将 `PathBuf` 注解为 `#[repr(transparent)]`。
// 无论如何，`PathBuf` 表示形式和布局被视为实现细节，没有文档记录，因此不能依赖。
//
//
pub struct PathBuf {
    inner: OsString,
}

impl PathBuf {
    #[inline]
    fn as_mut_vec(&mut self) -> &mut Vec<u8> {
        unsafe { &mut *(self as *mut PathBuf as *mut Vec<u8>) }
    }

    /// 分配一个空的 `PathBuf`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let path = PathBuf::new();
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn new() -> PathBuf {
        PathBuf { inner: OsString::new() }
    }

    /// 创建具有给定容量的新 `PathBuf`，用于创建内部 [`OsString`]。
    /// 请参见在 [`OsString`] 上定义的 [`with_capacity`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let mut path = PathBuf::with_capacity(10);
    /// let capacity = path.capacity();
    ///
    /// // 无需重新分配即可完成此推送
    /// path.push(r"C:\");
    ///
    /// assert_eq!(capacity, path.capacity());
    /// ```
    ///
    /// [`with_capacity`]: OsString::with_capacity
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn with_capacity(capacity: usize) -> PathBuf {
        PathBuf { inner: OsString::with_capacity(capacity) }
    }

    /// 强制转换为 [`Path`] 切片。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let p = PathBuf::from("/test");
    /// assert_eq!(Path::new("/test"), p.as_path());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn as_path(&self) -> &Path {
        self
    }

    /// 用 `path` 扩展 `self`。
    ///
    /// 如果 `path` 是绝对路径，它将替换当前路径。
    ///
    /// 在 Windows 上:
    ///
    /// * 如果 `path` 具有根但没有前缀 (例如 `\windows`)，它将替换 `self` 的前缀 (如果有) 之外的所有内容。
    ///
    /// * 如果 `path` 有前缀但没有根，它将替换 `self`。
    ///
    /// # Examples
    ///
    /// 推动相对路径可扩展现有路径:
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let mut path = PathBuf::from("/tmp");
    /// path.push("file.bk");
    /// assert_eq!(path, PathBuf::from("/tmp/file.bk"));
    /// ```
    ///
    /// 推送绝对路径将替换现有路径:
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let mut path = PathBuf::from("/tmp");
    /// path.push("/etc");
    /// assert_eq!(path, PathBuf::from("/etc"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn push<P: AsRef<Path>>(&mut self, path: P) {
        self._push(path.as_ref())
    }

    fn _push(&mut self, path: &Path) {
        // 通常，如果最右边的字节不是分隔符，则需要分隔符
        let mut need_sep = self.as_mut_vec().last().map(|c| !is_sep_byte(*c)).unwrap_or(false);

        // 在 Windows 上的 `C:` 的特殊情况下，请 *不要* 添加分隔符
        {
            let comps = self.components();
            if comps.prefix_len() > 0
                && comps.prefix_len() == comps.path.len()
                && comps.prefix.unwrap().is_drive()
            {
                need_sep = false
            }
        }

        // 绝对 `path` 替代 `self`
        if path.is_absolute() || path.prefix().is_some() {
            self.as_mut_vec().truncate(0);

        // `path` 具有根但没有前缀，例如 `\windows` (仅 Windows)
        } else if path.has_root() {
            let prefix_len = self.components().prefix_remaining();
            self.as_mut_vec().truncate(prefix_len);

        // `path` 是一条纯粹的相对路径
        } else if need_sep {
            self.inner.push(MAIN_SEP_STR);
        }

        self.inner.push(path);
    }

    /// 将 `self` 截断为 [`self.parent`]。
    ///
    /// 返回 `false`，如果 [`self.parent`] 为 [`None`]，则不执行任何操作。
    /// 否则，返回 `true`。
    ///
    /// [`self.parent`]: Path::parent
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let mut p = PathBuf::from("/spirited/away.rs");
    ///
    /// p.pop();
    /// assert_eq!(Path::new("/spirited"), p);
    /// p.pop();
    /// assert_eq!(Path::new("/"), p);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn pop(&mut self) -> bool {
        match self.parent().map(|p| p.as_u8_slice().len()) {
            Some(len) => {
                self.as_mut_vec().truncate(len);
                true
            }
            None => false,
        }
    }

    /// 将 [`self.file_name`] 更新为 `file_name`。
    ///
    /// 如果 [`self.file_name`] 是 [`None`]，则等效于按下 `file_name`。
    ///
    ///
    /// 否则，这等效于调用 [`pop`]，然后按 `file_name`。
    /// 新路径将是原始路径的同级。
    /// (也就是说，它将具有相同的父对象。)
    ///
    /// [`self.file_name`]: Path::file_name
    /// [`pop`]: PathBuf::pop
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let mut buf = PathBuf::from("/");
    /// assert!(buf.file_name() == None);
    /// buf.set_file_name("bar");
    /// assert!(buf == PathBuf::from("/bar"));
    /// assert!(buf.file_name().is_some());
    /// buf.set_file_name("baz.txt");
    /// assert!(buf == PathBuf::from("/baz.txt"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn set_file_name<S: AsRef<OsStr>>(&mut self, file_name: S) {
        self._set_file_name(file_name.as_ref())
    }

    fn _set_file_name(&mut self, file_name: &OsStr) {
        if self.file_name().is_some() {
            let popped = self.pop();
            debug_assert!(popped);
        }
        self.push(file_name);
    }

    /// 将 [`self.extension`] 更新为 `extension`。
    ///
    /// 返回 `false`，如果 [`self.file_name`] 为 [`None`]，则不执行任何操作，否则返回 `true`，并更新扩展名。
    ///
    ///
    /// 如果 [`self.extension`] 为 [`None`]，则添加扩展名; 否则将被替换。
    ///
    /// [`self.file_name`]: Path::file_name
    /// [`self.extension`]: Path::extension
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let mut p = PathBuf::from("/feel/the");
    ///
    /// p.set_extension("force");
    /// assert_eq!(Path::new("/feel/the.force"), p.as_path());
    ///
    /// p.set_extension("dark_side");
    /// assert_eq!(Path::new("/feel/the.dark_side"), p.as_path());
    /// ```
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn set_extension<S: AsRef<OsStr>>(&mut self, extension: S) -> bool {
        self._set_extension(extension.as_ref())
    }

    fn _set_extension(&mut self, extension: &OsStr) -> bool {
        let file_stem = match self.file_stem() {
            None => return false,
            Some(f) => os_str_as_u8_slice(f),
        };

        // 截断直到文件干之后
        let end_file_stem = file_stem[file_stem.len()..].as_ptr() as usize;
        let start = os_str_as_u8_slice(&self.inner).as_ptr() as usize;
        let v = self.as_mut_vec();
        v.truncate(end_file_stem.wrapping_sub(start));

        // 添加新的扩展名 (如果有)
        let new = os_str_as_u8_slice(extension);
        if !new.is_empty() {
            v.reserve_exact(new.len() + 1);
            v.push(b'.');
            v.extend_from_slice(new);
        }

        true
    }

    /// 消耗 `PathBuf`，产生其内部 [`OsString`] 存储。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::PathBuf;
    ///
    /// let p = PathBuf::from("/the/head");
    /// let os_str = p.into_os_string();
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn into_os_string(self) -> OsString {
        self.inner
    }

    /// 将此 `PathBuf` 转换为 [boxed](Box) [`Path`]。
    #[stable(feature = "into_boxed_path", since = "1.20.0")]
    #[inline]
    pub fn into_boxed_path(self) -> Box<Path> {
        let rw = Box::into_raw(self.inner.into_boxed_os_str()) as *mut Path;
        unsafe { Box::from_raw(rw) }
    }

    /// 在 [`OsString`] 的基础实例上调用 [`capacity`]。
    ///
    /// [`capacity`]: OsString::capacity
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn capacity(&self) -> usize {
        self.inner.capacity()
    }

    /// 在 [`OsString`] 的基础实例上调用 [`clear`]。
    ///
    /// [`clear`]: OsString::clear
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn clear(&mut self) {
        self.inner.clear()
    }

    /// 在 [`OsString`] 的基础实例上调用 [`reserve`]。
    ///
    /// [`reserve`]: OsString::reserve
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn reserve(&mut self, additional: usize) {
        self.inner.reserve(additional)
    }

    /// 在 [`OsString`] 的基础实例上调用 [`reserve_exact`]。
    ///
    /// [`reserve_exact`]: OsString::reserve_exact
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn reserve_exact(&mut self, additional: usize) {
        self.inner.reserve_exact(additional)
    }

    /// 在 [`OsString`] 的基础实例上调用 [`shrink_to_fit`]。
    ///
    /// [`shrink_to_fit`]: OsString::shrink_to_fit
    #[stable(feature = "path_buf_capacity", since = "1.44.0")]
    #[inline]
    pub fn shrink_to_fit(&mut self) {
        self.inner.shrink_to_fit()
    }

    /// 在 [`OsString`] 的基础实例上调用 [`shrink_to`]。
    ///
    /// [`shrink_to`]: OsString::shrink_to
    #[unstable(feature = "shrink_to", issue = "56431")]
    #[inline]
    pub fn shrink_to(&mut self, min_capacity: usize) {
        self.inner.shrink_to(min_capacity)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Clone for PathBuf {
    #[inline]
    fn clone(&self) -> Self {
        PathBuf { inner: self.inner.clone() }
    }

    #[inline]
    fn clone_from(&mut self, source: &Self) {
        self.inner.clone_from(&source.inner)
    }
}

#[stable(feature = "box_from_path", since = "1.17.0")]
impl From<&Path> for Box<Path> {
    /// 从引用创建一个 boxed [`Path`]。
    ///
    /// 这将为它分配和克隆 `path`。
    fn from(path: &Path) -> Box<Path> {
        let boxed: Box<OsStr> = path.inner.into();
        let rw = Box::into_raw(boxed) as *mut Path;
        unsafe { Box::from_raw(rw) }
    }
}

#[stable(feature = "box_from_cow", since = "1.45.0")]
impl From<Cow<'_, Path>> for Box<Path> {
    /// 从写时克隆指针创建一个 boxed [`Path`]。
    ///
    /// 从 `Cow::Owned` 转换不会克隆或分配。
    #[inline]
    fn from(cow: Cow<'_, Path>) -> Box<Path> {
        match cow {
            Cow::Borrowed(path) => Box::from(path),
            Cow::Owned(path) => Box::from(path),
        }
    }
}

#[stable(feature = "path_buf_from_box", since = "1.18.0")]
impl From<Box<Path>> for PathBuf {
    /// 将 `Box<Path>` 转换为 `PathBuf`
    ///
    /// 此转换不会分配或复制内存。
    #[inline]
    fn from(boxed: Box<Path>) -> PathBuf {
        boxed.into_path_buf()
    }
}

#[stable(feature = "box_from_path_buf", since = "1.20.0")]
impl From<PathBuf> for Box<Path> {
    /// 将 `PathBuf` 转换为 `Box<Path>`
    ///
    /// 此转换当前不应该分配内存，但是不能在所有平台上或所有 future 版本中都保证此行为。
    ///
    #[inline]
    fn from(p: PathBuf) -> Box<Path> {
        p.into_boxed_path()
    }
}

#[stable(feature = "more_box_slice_clone", since = "1.29.0")]
impl Clone for Box<Path> {
    #[inline]
    fn clone(&self) -> Self {
        self.to_path_buf().into_boxed_path()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized + AsRef<OsStr>> From<&T> for PathBuf {
    /// 将借用的 `OsStr` 转换为 `PathBuf`。
    ///
    /// 分配一个 [`PathBuf`] 并将数据复制到其中。
    #[inline]
    fn from(s: &T) -> PathBuf {
        PathBuf::from(s.as_ref().to_os_string())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl From<OsString> for PathBuf {
    /// 将 [`OsString`] 转换为 [`PathBuf`]
    ///
    /// 此转换不会分配或复制内存。
    #[inline]
    fn from(s: OsString) -> PathBuf {
        PathBuf { inner: s }
    }
}

#[stable(feature = "from_path_buf_for_os_string", since = "1.14.0")]
impl From<PathBuf> for OsString {
    /// 将 [`PathBuf`] 转换为 [`OsString`]
    ///
    /// 此转换不会分配或复制内存。
    #[inline]
    fn from(path_buf: PathBuf) -> OsString {
        path_buf.inner
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl From<String> for PathBuf {
    /// 将 [`String`] 转换为 [`PathBuf`]
    ///
    /// 此转换不会分配或复制内存。
    #[inline]
    fn from(s: String) -> PathBuf {
        PathBuf::from(OsString::from(s))
    }
}

#[stable(feature = "path_from_str", since = "1.32.0")]
impl FromStr for PathBuf {
    type Err = core::convert::Infallible;

    #[inline]
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Ok(PathBuf::from(s))
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<P: AsRef<Path>> iter::FromIterator<P> for PathBuf {
    fn from_iter<I: IntoIterator<Item = P>>(iter: I) -> PathBuf {
        let mut buf = PathBuf::new();
        buf.extend(iter);
        buf
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<P: AsRef<Path>> iter::Extend<P> for PathBuf {
    fn extend<I: IntoIterator<Item = P>>(&mut self, iter: I) {
        iter.into_iter().for_each(move |p| self.push(p.as_ref()));
    }

    #[inline]
    fn extend_one(&mut self, p: P) {
        self.push(p.as_ref());
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for PathBuf {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&**self, formatter)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl ops::Deref for PathBuf {
    type Target = Path;
    #[inline]
    fn deref(&self) -> &Path {
        Path::new(&self.inner)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Borrow<Path> for PathBuf {
    #[inline]
    fn borrow(&self) -> &Path {
        self.deref()
    }
}

#[stable(feature = "default_for_pathbuf", since = "1.17.0")]
impl Default for PathBuf {
    #[inline]
    fn default() -> Self {
        PathBuf::new()
    }
}

#[stable(feature = "cow_from_path", since = "1.6.0")]
impl<'a> From<&'a Path> for Cow<'a, Path> {
    /// 创建一个从引用到 [`Path`] 的写时克隆指针。
    ///
    ///
    /// 此转换不会克隆或分配。
    #[inline]
    fn from(s: &'a Path) -> Cow<'a, Path> {
        Cow::Borrowed(s)
    }
}

#[stable(feature = "cow_from_path", since = "1.6.0")]
impl<'a> From<PathBuf> for Cow<'a, Path> {
    /// 从 [`PathBuf`] 的拥有实例创建一个写时克隆指针。
    ///
    ///
    /// 此转换不会克隆或分配。
    #[inline]
    fn from(s: PathBuf) -> Cow<'a, Path> {
        Cow::Owned(s)
    }
}

#[stable(feature = "cow_from_pathbuf_ref", since = "1.28.0")]
impl<'a> From<&'a PathBuf> for Cow<'a, Path> {
    /// 创建一个从引用到 [`PathBuf`] 的写时克隆指针。
    ///
    ///
    /// 此转换不会克隆或分配。
    #[inline]
    fn from(p: &'a PathBuf) -> Cow<'a, Path> {
        Cow::Borrowed(p.as_path())
    }
}

#[stable(feature = "pathbuf_from_cow_path", since = "1.28.0")]
impl<'a> From<Cow<'a, Path>> for PathBuf {
    /// 将写时克隆指针转换为拥有所有权的路径。
    ///
    /// 从 `Cow::Owned` 转换不会克隆或分配。
    #[inline]
    fn from(p: Cow<'a, Path>) -> Self {
        p.into_owned()
    }
}

#[stable(feature = "shared_from_slice2", since = "1.24.0")]
impl From<PathBuf> for Arc<Path> {
    /// 通过将 [`PathBuf`] 数据移动到新的 [`Arc`] 缓冲区，将 [`PathBuf`] 转换为 [`Arc`]。
    #[inline]
    fn from(s: PathBuf) -> Arc<Path> {
        let arc: Arc<OsStr> = Arc::from(s.into_os_string());
        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Path) }
    }
}

#[stable(feature = "shared_from_slice2", since = "1.24.0")]
impl From<&Path> for Arc<Path> {
    /// 通过将 [`Path`] 数据复制到新的 [`Arc`] 缓冲区，将 [`Path`] 转换为 [`Arc`]。
    #[inline]
    fn from(s: &Path) -> Arc<Path> {
        let arc: Arc<OsStr> = Arc::from(s.as_os_str());
        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Path) }
    }
}

#[stable(feature = "shared_from_slice2", since = "1.24.0")]
impl From<PathBuf> for Rc<Path> {
    /// 通过将 [`PathBuf`] 数据移动到新的 `Rc` 缓冲区，将 [`PathBuf`] 转换为 [`Rc`]。
    #[inline]
    fn from(s: PathBuf) -> Rc<Path> {
        let rc: Rc<OsStr> = Rc::from(s.into_os_string());
        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Path) }
    }
}

#[stable(feature = "shared_from_slice2", since = "1.24.0")]
impl From<&Path> for Rc<Path> {
    /// 通过将 [`Path`] 数据复制到新的 `Rc` 缓冲区，将 [`Path`] 转换为 [`Rc`]。
    #[inline]
    fn from(s: &Path) -> Rc<Path> {
        let rc: Rc<OsStr> = Rc::from(s.as_os_str());
        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Path) }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl ToOwned for Path {
    type Owned = PathBuf;
    #[inline]
    fn to_owned(&self) -> PathBuf {
        self.to_path_buf()
    }
    #[inline]
    fn clone_into(&self, target: &mut PathBuf) {
        self.inner.clone_into(&mut target.inner);
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::PartialEq for PathBuf {
    #[inline]
    fn eq(&self, other: &PathBuf) -> bool {
        self.components() == other.components()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Hash for PathBuf {
    fn hash<H: Hasher>(&self, h: &mut H) {
        self.as_path().hash(h)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Eq for PathBuf {}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::PartialOrd for PathBuf {
    #[inline]
    fn partial_cmp(&self, other: &PathBuf) -> Option<cmp::Ordering> {
        self.components().partial_cmp(other.components())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Ord for PathBuf {
    #[inline]
    fn cmp(&self, other: &PathBuf) -> cmp::Ordering {
        self.components().cmp(other.components())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<OsStr> for PathBuf {
    #[inline]
    fn as_ref(&self) -> &OsStr {
        &self.inner[..]
    }
}

/// 路径的切片 (类似于 [`str`])。
///
/// 此类型支持许多检查路径的操作，包括将路径分为其各个组成部分 (由 Unix 上的 `/` 和 Windows 上的 `/` 或 `\` 分隔)，提取文件名，确定路径是否为绝对路径，等等。。
///
///
/// 这是未定义大小的类型，表示必须始终在 `&` 或 [`Box`] 之类的指针后面使用它。
/// 有关此类型的拥有版本，请参见 [`PathBuf`]。
///
/// 有关整体方法的更多详细信息，请参见 [module documentation](self)。
///
/// # Examples
///
/// ```
/// use std::path::Path;
/// use std::ffi::OsStr;
///
/// // Note: 这个例子可以在 Windows 上使用
/// let path = Path::new("./foo/bar.txt");
///
/// let parent = path.parent();
/// assert_eq!(parent, Some(Path::new("./foo")));
///
/// let file_stem = path.file_stem();
/// assert_eq!(file_stem, Some(OsStr::new("bar")));
///
/// let extension = path.extension();
/// assert_eq!(extension, Some(OsStr::new("txt")));
/// ```
///
///
///
///
#[cfg_attr(not(test), rustc_diagnostic_item = "Path")]
#[stable(feature = "rust1", since = "1.0.0")]
// FIXME:
// `Path::new` 当前的实现依赖于 `Path` 与 `OsStr` 在布局上兼容。
// 实现属性隐私时，应将 `Path` 注解为 `#[repr(transparent)]`。
// 无论如何，`Path` 表示形式和布局被视为实现细节，没有文档记录，因此不能依赖。
//
//
pub struct Path {
    inner: OsStr,
}

/// 如果找不到前缀，则从 [`Path::strip_prefix`] 返回错误。
///
/// 该 `struct` 是通过 [`Path`] 上的 [`strip_prefix`] 方法创建的。
/// 有关更多信息，请参见其文档。
///
/// [`strip_prefix`]: Path::strip_prefix
#[derive(Debug, Clone, PartialEq, Eq)]
#[stable(since = "1.7.0", feature = "strip_prefix")]
pub struct StripPrefixError(());

impl Path {
    // 以下 (private!) 函数允许从 u8 切片构造路径，仅当已知遵循 OsStr 编码时，此路径才是安全的。
    //
    unsafe fn from_u8_slice(s: &[u8]) -> &Path {
        unsafe { Path::new(u8_slice_as_os_str(s)) }
    }
    // 以下 (private!) 函数揭示了用于 OsStr 的字节编码。
    fn as_u8_slice(&self) -> &[u8] {
        os_str_as_u8_slice(&self.inner)
    }

    /// 将字符串切片直接包装为 `Path` 切片。
    ///
    /// 这是一个免费的转换。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// Path::new("foo.txt");
    /// ```
    ///
    /// 您可以从 `String` 甚至其他 `Path`s 创建 `Path`s:
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let string = String::from("foo.txt");
    /// let from_string = Path::new(&string);
    /// let from_path = Path::new(&from_string);
    /// assert_eq!(from_string, from_path);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn new<S: AsRef<OsStr> + ?Sized>(s: &S) -> &Path {
        unsafe { &*(s.as_ref() as *const OsStr as *const Path) }
    }

    /// 产生基础的 [`OsStr`] 切片。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let os_str = Path::new("foo.txt").as_os_str();
    /// assert_eq!(os_str, std::ffi::OsStr::new("foo.txt"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn as_os_str(&self) -> &OsStr {
        &self.inner
    }

    /// 如果 `Path` 是有效的 unicode，则产生 [`&str`] 切片。
    ///
    /// 此转换可能需要检查 UTF-8 有效性。
    /// 请注意，执行验证是因为非 UTF-8 字符串对于某些 OS 完全有效。
    ///
    ///
    /// [`&str`]: str
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("foo.txt");
    /// assert_eq!(path.to_str(), Some("foo.txt"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn to_str(&self) -> Option<&str> {
        self.inner.to_str()
    }

    /// 将 `Path` 转换为 [`Cow<str>`]。
    ///
    /// 任何非 Unicode 序列都将替换为 [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD]。
    ///
    /// [U+FFFD]: super::char::REPLACEMENT_CHARACTER
    ///
    /// # Examples
    ///
    /// 使用有效的 Unicode 在 `Path` 上调用 `to_string_lossy`:
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("foo.txt");
    /// assert_eq!(path.to_string_lossy(), "foo.txt");
    /// ```
    ///
    /// 如果 `path` 包含无效的 unicode，则 `to_string_lossy` 调用可能已返回 `"fo.txt"`。
    ///
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn to_string_lossy(&self) -> Cow<'_, str> {
        self.inner.to_string_lossy()
    }

    /// 将 `Path` 转换为拥有的 [`PathBuf`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path_buf = Path::new("foo.txt").to_path_buf();
    /// assert_eq!(path_buf, std::path::PathBuf::from("foo.txt"));
    /// ```
    #[rustc_conversion_suggestion]
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn to_path_buf(&self) -> PathBuf {
        PathBuf::from(self.inner.to_os_string())
    }

    /// 如果 `Path` 是绝对的，即独立于当前目录，则返回 `true`。
    ///
    /// * 在 Unix 上，如果路径以根开头，则它是绝对的，因此 `is_absolute` 和 [`has_root`] 是等效的。
    ///
    /// * 在 Windows 上，如果路径具有前缀并以根开头，则它是绝对路径: `c:\windows` 是绝对路径，而 `c:temp` 和 `\temp` 不是。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// assert!(!Path::new("foo.txt").is_absolute());
    /// ```
    ///
    /// [`has_root`]: Path::has_root
    ///
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    #[allow(deprecated)]
    pub fn is_absolute(&self) -> bool {
        if cfg!(target_os = "redox") {
            // FIXME: 允许 `Redox` 前缀
            self.has_root() || has_redox_scheme(self.as_u8_slice())
        } else {
            self.has_root() && (cfg!(any(unix, target_os = "wasi")) || self.prefix().is_some())
        }
    }

    /// 如果 `Path` 是相对的，即不是绝对的，则返回 `true`。
    ///
    /// 有关更多详细信息，请参见 [`is_absolute`] 的文档。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// assert!(Path::new("foo.txt").is_relative());
    /// ```
    ///
    /// [`is_absolute`]: Path::is_absolute
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn is_relative(&self) -> bool {
        !self.is_absolute()
    }

    fn prefix(&self) -> Option<Prefix<'_>> {
        self.components().prefix
    }

    /// 如果 `Path` 具有根，则返回 `true`。
    ///
    /// * 在 Unix 上，如果路径以 `/` 开头，则该路径具有根。
    ///
    /// * 在 Windows 上，如果路径具有根，则它是:
    ///     * 没有前缀，并以分隔符开头，例如， `\windows`
    ///     * 有一个前缀，后跟一个分隔符，例如 `c:\windows`，但没有 `c:windows`
    ///     * 具有任何非磁盘前缀，例如 `\\server\share`
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// assert!(Path::new("/etc/passwd").has_root());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn has_root(&self) -> bool {
        self.components().has_root()
    }

    /// 如果没有 `Path`，则返回不包含其最终组成部分的 `Path`。
    ///
    /// 如果路径以根或前缀结尾，则返回 [`None`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("/foo/bar");
    /// let parent = path.parent().unwrap();
    /// assert_eq!(parent, Path::new("/foo"));
    ///
    /// let grand_parent = parent.parent().unwrap();
    /// assert_eq!(grand_parent, Path::new("/"));
    /// assert_eq!(grand_parent.parent(), None);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn parent(&self) -> Option<&Path> {
        let mut comps = self.components();
        let comp = comps.next_back();
        comp.and_then(|p| match p {
            Component::Normal(_) | Component::CurDir | Component::ParentDir => {
                Some(comps.as_path())
            }
            _ => None,
        })
    }

    /// 在 `Path` 及其祖先上生成一个迭代器。
    ///
    /// 如果 [`parent`] 方法使用了 0 次或多次，则迭代器将产生返回的 `Path`。
    /// 这意味着，迭代器将产生 `&self`，`&self.parent().unwrap()`，`&self.parent().unwrap().parent().unwrap()` 等。如果 [`parent`] 方法返回 [`None`]，则迭代器也将这样做。
    ///
    /// 迭代器将始终产生至少一个值，即 `&self`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let mut ancestors = Path::new("/foo/bar").ancestors();
    /// assert_eq!(ancestors.next(), Some(Path::new("/foo/bar")));
    /// assert_eq!(ancestors.next(), Some(Path::new("/foo")));
    /// assert_eq!(ancestors.next(), Some(Path::new("/")));
    /// assert_eq!(ancestors.next(), None);
    ///
    /// let mut ancestors = Path::new("../foo/bar").ancestors();
    /// assert_eq!(ancestors.next(), Some(Path::new("../foo/bar")));
    /// assert_eq!(ancestors.next(), Some(Path::new("../foo")));
    /// assert_eq!(ancestors.next(), Some(Path::new("..")));
    /// assert_eq!(ancestors.next(), Some(Path::new("")));
    /// assert_eq!(ancestors.next(), None);
    /// ```
    ///
    /// [`parent`]: Path::parent
    ///
    #[stable(feature = "path_ancestors", since = "1.28.0")]
    #[inline]
    pub fn ancestors(&self) -> Ancestors<'_> {
        Ancestors { next: Some(&self) }
    }

    /// 返回 `Path` 的最后一个组件 (如果有)。
    ///
    /// 如果路径是普通文件，则为文件名。
    /// 如果是目录路径，则为目录名称。
    ///
    /// 如果路径以 `..` 结尾，则返回 [`None`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    /// use std::ffi::OsStr;
    ///
    /// assert_eq!(Some(OsStr::new("bin")), Path::new("/usr/bin/").file_name());
    /// assert_eq!(Some(OsStr::new("foo.txt")), Path::new("tmp/foo.txt").file_name());
    /// assert_eq!(Some(OsStr::new("foo.txt")), Path::new("foo.txt/.").file_name());
    /// assert_eq!(Some(OsStr::new("foo.txt")), Path::new("foo.txt/.//").file_name());
    /// assert_eq!(None, Path::new("foo.txt/..").file_name());
    /// assert_eq!(None, Path::new("/").file_name());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn file_name(&self) -> Option<&OsStr> {
        self.components().next_back().and_then(|p| match p {
            Component::Normal(p) => Some(p),
            _ => None,
        })
    }

    /// 返回连接到 `base` 时产生 `self` 的路径。
    ///
    /// # Errors
    ///
    /// 如果 `base` 不是 `self` 的前缀 (即 [`starts_with`] 返回 `false`)，则返回 [`Err`]。
    ///
    ///
    /// [`starts_with`]: Path::starts_with
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let path = Path::new("/test/haha/foo.txt");
    ///
    /// assert_eq!(path.strip_prefix("/"), Ok(Path::new("test/haha/foo.txt")));
    /// assert_eq!(path.strip_prefix("/test"), Ok(Path::new("haha/foo.txt")));
    /// assert_eq!(path.strip_prefix("/test/"), Ok(Path::new("haha/foo.txt")));
    /// assert_eq!(path.strip_prefix("/test/haha/foo.txt"), Ok(Path::new("")));
    /// assert_eq!(path.strip_prefix("/test/haha/foo.txt/"), Ok(Path::new("")));
    ///
    /// assert!(path.strip_prefix("test").is_err());
    /// assert!(path.strip_prefix("/haha").is_err());
    ///
    /// let prefix = PathBuf::from("/test/");
    /// assert_eq!(path.strip_prefix(prefix), Ok(Path::new("haha/foo.txt")));
    /// ```
    #[stable(since = "1.7.0", feature = "path_strip_prefix")]
    pub fn strip_prefix<P>(&self, base: P) -> Result<&Path, StripPrefixError>
    where
        P: AsRef<Path>,
    {
        self._strip_prefix(base.as_ref())
    }

    fn _strip_prefix(&self, base: &Path) -> Result<&Path, StripPrefixError> {
        iter_after(self.components(), base.components())
            .map(|c| c.as_path())
            .ok_or(StripPrefixError(()))
    }

    /// 确定 `base` 是否为 `self` 的前缀。
    ///
    /// 仅考虑整个路径组件匹配。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("/etc/passwd");
    ///
    /// assert!(path.starts_with("/etc"));
    /// assert!(path.starts_with("/etc/"));
    /// assert!(path.starts_with("/etc/passwd"));
    /// assert!(path.starts_with("/etc/passwd/")); // 额外的斜线是可以的
    /// assert!(path.starts_with("/etc/passwd///")); // multiple extra slashes are okay
    ///
    /// assert!(!path.starts_with("/e"));
    /// assert!(!path.starts_with("/etc/passwd.txt"));
    ///
    /// assert!(!Path::new("/etc/foo.rs").starts_with("/etc/foo"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn starts_with<P: AsRef<Path>>(&self, base: P) -> bool {
        self._starts_with(base.as_ref())
    }

    fn _starts_with(&self, base: &Path) -> bool {
        iter_after(self.components(), base.components()).is_some()
    }

    /// 确定 `child` 是否为 `self` 的后缀。
    ///
    /// 仅考虑整个路径组件匹配。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("/etc/resolv.conf");
    ///
    /// assert!(path.ends_with("resolv.conf"));
    /// assert!(path.ends_with("etc/resolv.conf"));
    /// assert!(path.ends_with("/etc/resolv.conf"));
    ///
    /// assert!(!path.ends_with("/resolv.conf"));
    /// assert!(!path.ends_with("conf")); // 改用 .extension()
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn ends_with<P: AsRef<Path>>(&self, child: P) -> bool {
        self._ends_with(child.as_ref())
    }

    fn _ends_with(&self, child: &Path) -> bool {
        iter_after(self.components().rev(), child.components().rev()).is_some()
    }

    /// 提取 [`self.file_name`] 的茎 (non-extension) 部分。
    ///
    /// [`self.file_name`]: Path::file_name
    ///
    /// 词干为:
    ///
    /// * [`None`], 如果没有文件名;
    /// * 如果没有嵌入式 `.`，则为整个文件名; 否则为 0。
    /// * 如果文件名以 `.` 开头且内部没有其他 `.`，则为整个文件名;
    /// * 否则，文件名中最后 `.` 之前的部分
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// assert_eq!("foo", Path::new("foo.rs").file_stem().unwrap());
    /// assert_eq!("foo.tar", Path::new("foo.tar.gz").file_stem().unwrap());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn file_stem(&self) -> Option<&OsStr> {
        self.file_name().map(split_file_at_dot).and_then(|(before, after)| before.or(after))
    }

    /// 如果可能，提取 [`self.file_name`] 的扩展名。
    ///
    /// 扩展名是:
    ///
    /// * [`None`], 如果没有文件名;
    /// * [`None`], 如果没有嵌入式 `.`;
    /// * [`None`], 如果文件名以 `.` 开头，并且里面没有其他 `.`;
    /// * 否则，文件名中最后一个 `.` 之后的部分
    ///
    /// [`self.file_name`]: Path::file_name
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// assert_eq!("rs", Path::new("foo.rs").extension().unwrap());
    /// assert_eq!("gz", Path::new("foo.tar.gz").extension().unwrap());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn extension(&self) -> Option<&OsStr> {
        self.file_name().map(split_file_at_dot).and_then(|(before, after)| before.and(after))
    }

    /// 创建一个拥有的 [`PathBuf`]，并将 `path` 附加到 `self`。
    ///
    /// 有关连接路径的含义的更多详细信息，请参见 [`PathBuf::push`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// assert_eq!(Path::new("/etc").join("passwd"), PathBuf::from("/etc/passwd"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[must_use]
    pub fn join<P: AsRef<Path>>(&self, path: P) -> PathBuf {
        self._join(path.as_ref())
    }

    fn _join(&self, path: &Path) -> PathBuf {
        let mut buf = self.to_path_buf();
        buf.push(path);
        buf
    }

    /// 创建一个拥有的 [`PathBuf`]，例如 `self`，但具有给定的文件名。
    ///
    /// 有关更多详细信息，请参见 [`PathBuf::set_file_name`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let path = Path::new("/tmp/foo.txt");
    /// assert_eq!(path.with_file_name("bar.txt"), PathBuf::from("/tmp/bar.txt"));
    ///
    /// let path = Path::new("/tmp");
    /// assert_eq!(path.with_file_name("var"), PathBuf::from("/var"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn with_file_name<S: AsRef<OsStr>>(&self, file_name: S) -> PathBuf {
        self._with_file_name(file_name.as_ref())
    }

    fn _with_file_name(&self, file_name: &OsStr) -> PathBuf {
        let mut buf = self.to_path_buf();
        buf.set_file_name(file_name);
        buf
    }

    /// 创建一个拥有的 [`PathBuf`]，例如 `self`，但具有给定的扩展名。
    ///
    /// 有关更多详细信息，请参见 [`PathBuf::set_extension`]。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, PathBuf};
    ///
    /// let path = Path::new("foo.rs");
    /// assert_eq!(path.with_extension("txt"), PathBuf::from("foo.txt"));
    ///
    /// let path = Path::new("foo.tar.gz");
    /// assert_eq!(path.with_extension(""), PathBuf::from("foo.tar"));
    /// assert_eq!(path.with_extension("xz"), PathBuf::from("foo.tar.xz"));
    /// assert_eq!(path.with_extension("").with_extension("txt"), PathBuf::from("foo.txt"));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn with_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf {
        self._with_extension(extension.as_ref())
    }

    fn _with_extension(&self, extension: &OsStr) -> PathBuf {
        let mut buf = self.to_path_buf();
        buf.set_extension(extension);
        buf
    }

    /// 生成路径的 [`Component`] 上的迭代器。
    ///
    /// 解析路径时，需要进行少量标准化:
    ///
    /// * 重复的分隔符将被忽略，因此 `a/b` 和 `a//b` 都具有 `a` 和 `b` 作为组件。
    ///
    /// * `.` 的出现被归一化，除非它们位于路径的开头。
    /// 例如，`a/./b`，`a/b/`，`a/b/.` 和 `a/b` 都具有 `a` 和 `b` 作为组件，但是 `./a/b` 以附加的 [`CurDir`] 组件开头。
    ///
    /// * 尾部的斜杠已标准化，`/a/b` 和 `/a/b/` 是等效的。
    ///
    /// 请注意，没有其他标准化发生。特别是，`a/c` 和 `a/b/../c` 是不同的，以考虑到 `b` 是符号链接 (因此其父代不是 `a`) 的可能性。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{Path, Component};
    /// use std::ffi::OsStr;
    ///
    /// let mut components = Path::new("/tmp/foo.txt").components();
    ///
    /// assert_eq!(components.next(), Some(Component::RootDir));
    /// assert_eq!(components.next(), Some(Component::Normal(OsStr::new("tmp"))));
    /// assert_eq!(components.next(), Some(Component::Normal(OsStr::new("foo.txt"))));
    /// assert_eq!(components.next(), None)
    /// ```
    ///
    /// [`CurDir`]: Component::CurDir
    ///
    ///
    ///
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn components(&self) -> Components<'_> {
        let prefix = parse_prefix(self.as_os_str());
        Components {
            path: self.as_u8_slice(),
            prefix,
            has_physical_root: has_physical_root(self.as_u8_slice(), prefix)
                || has_redox_scheme(self.as_u8_slice()),
            front: State::Prefix,
            back: State::Body,
        }
    }

    /// 在视为 [`OsStr`] slice 的路径的组件上生成迭代器。
    ///
    /// 有关如何将路径分成多个组件的详细信息，请参见 [`components`]。
    ///
    ///
    /// [`components`]: Path::components
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::{self, Path};
    /// use std::ffi::OsStr;
    ///
    /// let mut it = Path::new("/tmp/foo.txt").iter();
    /// assert_eq!(it.next(), Some(OsStr::new(&path::MAIN_SEPARATOR.to_string())));
    /// assert_eq!(it.next(), Some(OsStr::new("tmp")));
    /// assert_eq!(it.next(), Some(OsStr::new("foo.txt")));
    /// assert_eq!(it.next(), None)
    /// ```
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn iter(&self) -> Iter<'_> {
        Iter { inner: self.components() }
    }

    /// 返回实现 [`Display`] 的 object，以安全地打印可能包含非 Unicode 数据的路径。
    ///
    /// 根据平台的不同，这可能会执行有损转换。
    /// 如果您想要一个转义路径的实现，请改用 [`Debug`]。
    ///
    /// [`Display`]: fmt::Display
    ///
    /// # Examples
    ///
    /// ```
    /// use std::path::Path;
    ///
    /// let path = Path::new("/tmp/foo.rs");
    ///
    /// println!("{}", path.display());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub fn display(&self) -> Display<'_> {
        Display { path: self }
    }

    /// 查询文件系统以获取有关文件，目录等的信息。
    ///
    /// 该函数将遍历符号链接以查询有关目标文件的信息。
    ///
    ///
    /// 这是 [`fs::metadata`] 的别名。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    ///
    /// let path = Path::new("/Minas/tirith");
    /// let metadata = path.metadata().expect("metadata call failed");
    /// println!("{:?}", metadata.file_type());
    /// ```
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn metadata(&self) -> io::Result<fs::Metadata> {
        fs::metadata(self)
    }

    /// 查询有关文件的元数据，而无需遵循符号链接。
    ///
    /// 这是 [`fs::symlink_metadata`] 的别名。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    ///
    /// let path = Path::new("/Minas/tirith");
    /// let metadata = path.symlink_metadata().expect("symlink_metadata call failed");
    /// println!("{:?}", metadata.file_type());
    /// ```
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn symlink_metadata(&self) -> io::Result<fs::Metadata> {
        fs::symlink_metadata(self)
    }

    /// 返回路径的规范，绝对形式，所有中间组件均已标准化，符号链接已解析。
    ///
    ///
    /// 这是 [`fs::canonicalize`] 的别名。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::{Path, PathBuf};
    ///
    /// let path = Path::new("/foo/test/../test/bar.rs");
    /// assert_eq!(path.canonicalize().unwrap(), PathBuf::from("/foo/test/bar.rs"));
    /// ```
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn canonicalize(&self) -> io::Result<PathBuf> {
        fs::canonicalize(self)
    }

    /// 读取符号链接，返回链接指向的文件。
    ///
    /// 这是 [`fs::read_link`] 的别名。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    ///
    /// let path = Path::new("/laputa/sky_castle.rs");
    /// let path_link = path.read_link().expect("read_link call failed");
    /// ```
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn read_link(&self) -> io::Result<PathBuf> {
        fs::read_link(self)
    }

    /// 返回目录中条目的迭代器。
    ///
    /// 迭代器将产生 [`io::Result`]`<`[`fs::DirEntry`]`>` 的实例。
    /// 最初构造迭代器后，可能会遇到新的错误。
    ///
    /// 这是 [`fs::read_dir`] 的别名。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    ///
    /// let path = Path::new("/laputa");
    /// for entry in path.read_dir().expect("read_dir call failed") {
    ///     if let Ok(entry) = entry {
    ///         println!("{:?}", entry.path());
    ///     }
    /// }
    /// ```
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn read_dir(&self) -> io::Result<fs::ReadDir> {
        fs::read_dir(self)
    }

    /// 如果路径指向现有实体，则返回 `true`。
    ///
    /// 该函数将遍历符号链接以查询有关目标文件的信息。
    ///
    ///
    /// 如果您无法访问文件的元数据，例如
    /// 由于权限错误或损坏的符号链接，这将返回 `false`。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    /// assert!(!Path::new("does_not_exist.txt").exists());
    /// ```
    ///
    /// # 也可以看看
    ///
    /// 这是一个方便的函数，可将错误强制为 false。
    /// 如果要检查错误，请调用 [`fs::metadata`]。
    #[stable(feature = "path_ext", since = "1.5.0")]
    #[inline]
    pub fn exists(&self) -> bool {
        fs::metadata(self).is_ok()
    }

    /// 如果路径指向现有实体，则返回 `Ok(true)`。
    ///
    /// 该函数将遍历符号链接以查询有关目标文件的信息。
    /// 如果符号链接断开，则将返回 `Ok(false)`。
    ///
    /// 与 `exists()` 方法相反，此方法不会默默地忽略与不存在的路径无关的错误。
    /// (E.g.
    /// 如果某些父目录的权限被拒绝，它将返回 `Err(_)`。)
    ///
    /// # Examples
    ///
    /// ```no_run
    /// #![feature(path_try_exists)]
    ///
    /// use std::path::Path;
    /// assert!(!Path::new("does_not_exist.txt").try_exists().expect("Can't check existence of file does_not_exist.txt"));
    /// assert!(Path::new("/root/secret_file.txt").try_exists().is_err());
    /// ```
    // FIXME: 稳定性应修改 `exists()` 的文档以推荐此方法。
    //
    #[unstable(feature = "path_try_exists", issue = "83186")]
    #[inline]
    pub fn try_exists(&self) -> io::Result<bool> {
        fs::try_exists(self)
    }

    /// 如果路径在磁盘上并且指向常规文件，则返回 `true`。
    ///
    /// 该函数将遍历符号链接以查询有关目标文件的信息。
    ///
    /// 如果您无法访问文件的元数据，例如由于权限错误或损坏的符号链接，这将返回 `false`。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    /// assert_eq!(Path::new("./is_a_directory/").is_file(), false);
    /// assert_eq!(Path::new("a_file.txt").is_file(), true);
    /// ```
    ///
    /// # 也可以看看
    ///
    /// 这是一个方便的函数，可将错误强制为 false。如果要检查错误，请调用 [`fs::metadata`] 并处理其 [`Result`]。
    /// 如果是 [`Ok`]，则调用 [`fs::Metadata::is_file`]。
    ///
    /// 当目标只是读取 (或写入) 源时，可以读取 (或写入) 最可靠的测试源方法是打开它。
    ///
    /// 例如，仅使用 `is_file` 才能中断类似 Unix 的系统上的工作流，例如 `diff <( prog_a )`。
    /// 有关更多信息，请参见 [`fs::File::open`] 或 [`fs::OpenOptions::open`]。
    ///
    ///
    ///
    ///
    #[stable(feature = "path_ext", since = "1.5.0")]
    pub fn is_file(&self) -> bool {
        fs::metadata(self).map(|m| m.is_file()).unwrap_or(false)
    }

    /// 如果路径在磁盘上并且指向目录，则返回 `true`。
    ///
    /// 该函数将遍历符号链接以查询有关目标文件的信息。
    ///
    ///
    /// 如果您无法访问文件的元数据，例如
    /// 由于权限错误或损坏的符号链接，这将返回 `false`。
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::path::Path;
    /// assert_eq!(Path::new("./is_a_directory/").is_dir(), true);
    /// assert_eq!(Path::new("a_file.txt").is_dir(), false);
    /// ```
    ///
    /// # 也可以看看
    ///
    /// 这是一个方便的函数，可将错误强制为 false。
    /// 如果要检查错误，请调用 [`fs::metadata`] 并处理其 [`Result`]。
    /// 如果是 [`Ok`]，则调用 [`fs::Metadata::is_dir`]。
    #[stable(feature = "path_ext", since = "1.5.0")]
    pub fn is_dir(&self) -> bool {
        fs::metadata(self).map(|m| m.is_dir()).unwrap_or(false)
    }

    /// 如果路径存在于磁盘上并且指向符号链接，则返回 true。
    ///
    /// 这个函数不会遍历符号链接。
    /// 如果符号链接损坏，这也将返回 true。
    ///
    /// 如果您无法访问包含该文件的目录，例如，由于权限错误，这将返回 false。
    ///
    ///
    /// # Examples
    ///
    #[cfg_attr(unix, doc = "```no_run")]
    #[cfg_attr(not(unix), doc = "```ignore")]
    /// #![feature(is_symlink)]
    /// use std::path::Path;
    /// use std::os::unix::fs::symlink;
    ///
    /// let link_path = Path::new("link");
    /// symlink("/origin_does_not_exists/", link_path).unwrap();
    /// assert_eq!(link_path.is_symlink(), true);
    /// assert_eq!(link_path.exists(), false);
    /// ```
    #[unstable(feature = "is_symlink", issue = "85748")]
    pub fn is_symlink(&self) -> bool {
        fs::symlink_metadata(self).map(|m| m.is_symlink()).unwrap_or(false)
    }

    /// 无需复制或分配即可将 [`Box<Path>`](Box) 转换为 [`PathBuf`]。
    ///
    #[stable(feature = "into_boxed_path", since = "1.20.0")]
    pub fn into_path_buf(self: Box<Path>) -> PathBuf {
        let rw = Box::into_raw(self) as *mut OsStr;
        let inner = unsafe { Box::from_raw(rw) };
        PathBuf { inner: OsString::from(inner) }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<OsStr> for Path {
    #[inline]
    fn as_ref(&self) -> &OsStr {
        &self.inner
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for Path {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&self.inner, formatter)
    }
}

/// Helper 结构体，用于使用 [`format!`] 和 `{}` 安全地打印路径。
///
/// [`Path`] 可能包含非 Unicode 数据。
/// 该 `struct` 可以减轻 [`Display`] trait 的负担。
/// 它是通过 [`Path`] 上的 [`display`](Path::display) 方法创建的。
/// 根据平台的不同，这可能会执行有损转换。
/// 如果您想要一个转义路径的实现，请改用 [`Debug`]。
///
/// # Examples
///
/// ```
/// use std::path::Path;
///
/// let path = Path::new("/tmp/foo.rs");
///
/// println!("{}", path.display());
/// ```
///
/// [`Display`]: fmt::Display
/// [`format!`]: crate::format
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Display<'a> {
    path: &'a Path,
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for Display<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&self.path, f)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for Display<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.path.inner.display(f)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::PartialEq for Path {
    #[inline]
    fn eq(&self, other: &Path) -> bool {
        self.components().eq(other.components())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Hash for Path {
    fn hash<H: Hasher>(&self, h: &mut H) {
        for component in self.components() {
            component.hash(h);
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Eq for Path {}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::PartialOrd for Path {
    #[inline]
    fn partial_cmp(&self, other: &Path) -> Option<cmp::Ordering> {
        self.components().partial_cmp(other.components())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl cmp::Ord for Path {
    #[inline]
    fn cmp(&self, other: &Path) -> cmp::Ordering {
        self.components().cmp(other.components())
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for Path {
    #[inline]
    fn as_ref(&self) -> &Path {
        self
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for OsStr {
    #[inline]
    fn as_ref(&self) -> &Path {
        Path::new(self)
    }
}

#[stable(feature = "cow_os_str_as_ref_path", since = "1.8.0")]
impl AsRef<Path> for Cow<'_, OsStr> {
    #[inline]
    fn as_ref(&self) -> &Path {
        Path::new(self)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for OsString {
    #[inline]
    fn as_ref(&self) -> &Path {
        Path::new(self)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for str {
    #[inline]
    fn as_ref(&self) -> &Path {
        Path::new(self)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for String {
    #[inline]
    fn as_ref(&self) -> &Path {
        Path::new(self)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<Path> for PathBuf {
    #[inline]
    fn as_ref(&self) -> &Path {
        self
    }
}

#[stable(feature = "path_into_iter", since = "1.6.0")]
impl<'a> IntoIterator for &'a PathBuf {
    type Item = &'a OsStr;
    type IntoIter = Iter<'a>;
    #[inline]
    fn into_iter(self) -> Iter<'a> {
        self.iter()
    }
}

#[stable(feature = "path_into_iter", since = "1.6.0")]
impl<'a> IntoIterator for &'a Path {
    type Item = &'a OsStr;
    type IntoIter = Iter<'a>;
    #[inline]
    fn into_iter(self) -> Iter<'a> {
        self.iter()
    }
}

macro_rules! impl_cmp {
    ($lhs:ty, $rhs: ty) => {
        #[stable(feature = "partialeq_path", since = "1.6.0")]
        impl<'a, 'b> PartialEq<$rhs> for $lhs {
            #[inline]
            fn eq(&self, other: &$rhs) -> bool {
                <Path as PartialEq>::eq(self, other)
            }
        }

        #[stable(feature = "partialeq_path", since = "1.6.0")]
        impl<'a, 'b> PartialEq<$lhs> for $rhs {
            #[inline]
            fn eq(&self, other: &$lhs) -> bool {
                <Path as PartialEq>::eq(self, other)
            }
        }

        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialOrd<$rhs> for $lhs {
            #[inline]
            fn partial_cmp(&self, other: &$rhs) -> Option<cmp::Ordering> {
                <Path as PartialOrd>::partial_cmp(self, other)
            }
        }

        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialOrd<$lhs> for $rhs {
            #[inline]
            fn partial_cmp(&self, other: &$lhs) -> Option<cmp::Ordering> {
                <Path as PartialOrd>::partial_cmp(self, other)
            }
        }
    };
}

impl_cmp!(PathBuf, Path);
impl_cmp!(PathBuf, &'a Path);
impl_cmp!(Cow<'a, Path>, Path);
impl_cmp!(Cow<'a, Path>, &'b Path);
impl_cmp!(Cow<'a, Path>, PathBuf);

macro_rules! impl_cmp_os_str {
    ($lhs:ty, $rhs: ty) => {
        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialEq<$rhs> for $lhs {
            #[inline]
            fn eq(&self, other: &$rhs) -> bool {
                <Path as PartialEq>::eq(self, other.as_ref())
            }
        }

        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialEq<$lhs> for $rhs {
            #[inline]
            fn eq(&self, other: &$lhs) -> bool {
                <Path as PartialEq>::eq(self.as_ref(), other)
            }
        }

        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialOrd<$rhs> for $lhs {
            #[inline]
            fn partial_cmp(&self, other: &$rhs) -> Option<cmp::Ordering> {
                <Path as PartialOrd>::partial_cmp(self, other.as_ref())
            }
        }

        #[stable(feature = "cmp_path", since = "1.8.0")]
        impl<'a, 'b> PartialOrd<$lhs> for $rhs {
            #[inline]
            fn partial_cmp(&self, other: &$lhs) -> Option<cmp::Ordering> {
                <Path as PartialOrd>::partial_cmp(self.as_ref(), other)
            }
        }
    };
}

impl_cmp_os_str!(PathBuf, OsStr);
impl_cmp_os_str!(PathBuf, &'a OsStr);
impl_cmp_os_str!(PathBuf, Cow<'a, OsStr>);
impl_cmp_os_str!(PathBuf, OsString);
impl_cmp_os_str!(Path, OsStr);
impl_cmp_os_str!(Path, &'a OsStr);
impl_cmp_os_str!(Path, Cow<'a, OsStr>);
impl_cmp_os_str!(Path, OsString);
impl_cmp_os_str!(&'a Path, OsStr);
impl_cmp_os_str!(&'a Path, Cow<'b, OsStr>);
impl_cmp_os_str!(&'a Path, OsString);
impl_cmp_os_str!(Cow<'a, Path>, OsStr);
impl_cmp_os_str!(Cow<'a, Path>, &'b OsStr);
impl_cmp_os_str!(Cow<'a, Path>, OsString);

#[stable(since = "1.7.0", feature = "strip_prefix")]
impl fmt::Display for StripPrefixError {
    #[allow(deprecated, deprecated_in_future)]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.description().fmt(f)
    }
}

#[stable(since = "1.7.0", feature = "strip_prefix")]
impl Error for StripPrefixError {
    #[allow(deprecated)]
    fn description(&self) -> &str {
        "prefix not found"
    }
}