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use crate::fmt;
/// 包含有关 panic 位置信息的结构体。
///
/// 该结构体由 [`PanicInfo::location()`] 创建。
///
/// [`PanicInfo::location()`]: crate::panic::PanicInfo::location
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(location) = panic_info.location() {
/// println!("panic occurred in file '{}' at line {}", location.file(), location.line());
/// } else {
/// println!("panic occurred but can't get location information...");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
///
/// # Comparisons
///
/// 在文件,行和列优先级中进行相等性和顺序的比较。
/// 文件被比较为字符串,而不是 `Path`,这可能是意外的。
/// 有关更多讨论,请参见 [`Location::file`] 的文档。
#[lang = "panic_location"]
#[derive(Copy, Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub struct Location<'a> {
file: &'a str,
line: u32,
col: u32,
}
impl<'a> Location<'a> {
/// 返回此函数的调用者的源位置。
/// 如果该函数的调用者被注释,那么它的调用位置将被返回,以此类推,直到堆栈中第一个未被跟踪的函数体中的调用。
///
///
/// # Examples
///
/// ```
/// use std::panic::Location;
///
/// /// 返回调用它的 [`Location`]。
/// #[track_caller]
/// fn get_caller_location() -> &'static Location<'static> {
/// Location::caller()
/// }
///
/// /// 从此函数的定义中返回 [`Location`]。
/// fn get_just_one_location() -> &'static Location<'static> {
/// get_caller_location()
/// }
///
/// let fixed_location = get_just_one_location();
/// assert_eq!(fixed_location.file(), file!());
/// assert_eq!(fixed_location.line(), 14);
/// assert_eq!(fixed_location.column(), 5);
///
/// // 在不同的位置运行相同的未跟踪函数会得到相同的结果
/// let second_fixed_location = get_just_one_location();
/// assert_eq!(fixed_location.file(), second_fixed_location.file());
/// assert_eq!(fixed_location.line(), second_fixed_location.line());
/// assert_eq!(fixed_location.column(), second_fixed_location.column());
///
/// let this_location = get_caller_location();
/// assert_eq!(this_location.file(), file!());
/// assert_eq!(this_location.line(), 28);
/// assert_eq!(this_location.column(), 21);
///
/// // 在其他位置运行跟踪的函数会产生不同的值
/// let another_location = get_caller_location();
/// assert_eq!(this_location.file(), another_location.file());
/// assert_ne!(this_location.line(), another_location.line());
/// assert_ne!(this_location.column(), another_location.column());
/// ```
#[must_use]
#[stable(feature = "track_caller", since = "1.46.0")]
#[rustc_const_unstable(feature = "const_caller_location", issue = "76156")]
#[track_caller]
#[inline]
pub const fn caller() -> &'static Location<'static> {
crate::intrinsics::caller_location()
}
/// 返回 panic 源自的源文件的名称。
///
/// # `&str`,不是 `&Path`
///
/// 返回的名称指向编译系统上的源路径,但是将其直接表示为 `&Path` 是无效的。
/// 与提供内容的系统相比,编译后的代码可以在具有不同 `Path` 实现的不同系统上运行,并且此库当前没有不同的 "host path" 类型。
///
/// 当通过模块系统中的多个路径可访问 "the same" 文件时 (通常使用 `#[path = "..."]` 属性或类似属性),会发生最令人惊讶的行为,这可能导致看似相同的代码返回与此函数不同的值。
///
///
/// # Cross-compilation
///
/// 当主机平台和目标平台不同时,此值不适合传递给 `Path::new` 或类似的构造函数。
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(location) = panic_info.location() {
/// println!("panic occurred in file '{}'", location.file());
/// } else {
/// println!("panic occurred but can't get location information...");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
///
///
///
///
#[must_use]
#[stable(feature = "panic_hooks", since = "1.10.0")]
#[rustc_const_unstable(feature = "const_location_fields", issue = "102911")]
#[inline]
pub const fn file(&self) -> &str {
self.file
}
/// 返回 panic 起源的行号。
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(location) = panic_info.location() {
/// println!("panic occurred at line {}", location.line());
/// } else {
/// println!("panic occurred but can't get location information...");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
#[must_use]
#[stable(feature = "panic_hooks", since = "1.10.0")]
#[rustc_const_unstable(feature = "const_location_fields", issue = "102911")]
#[inline]
pub const fn line(&self) -> u32 {
self.line
}
/// 返回 panic 起源的列。
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(location) = panic_info.location() {
/// println!("panic occurred at column {}", location.column());
/// } else {
/// println!("panic occurred but can't get location information...");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
#[must_use]
#[stable(feature = "panic_col", since = "1.25.0")]
#[rustc_const_unstable(feature = "const_location_fields", issue = "102911")]
#[inline]
pub const fn column(&self) -> u32 {
self.col
}
}
#[unstable(
feature = "panic_internals",
reason = "internal details of the implementation of the `panic!` and related macros",
issue = "none"
)]
impl<'a> Location<'a> {
#[doc(hidden)]
pub const fn internal_constructor(file: &'a str, line: u32, col: u32) -> Self {
Location { file, line, col }
}
}
#[stable(feature = "panic_hook_display", since = "1.26.0")]
impl fmt::Display for Location<'_> {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(formatter, "{}:{}:{}", self.file, self.line, self.col)
}
}