378 lines
11 KiB
Rust
378 lines
11 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/// Entry point of thread panic, for details, see std::macros
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#[macro_export]
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#[allow_internal_unstable]
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#[stable(feature = "core", since = "1.6.0")]
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macro_rules! panic {
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() => (
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panic!("explicit panic")
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);
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($msg:expr) => ({
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static _MSG_FILE_LINE: (&'static str, &'static str, u32) = ($msg, file!(), line!());
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$crate::panicking::panic(&_MSG_FILE_LINE)
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});
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($fmt:expr, $($arg:tt)*) => ({
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// The leading _'s are to avoid dead code warnings if this is
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// used inside a dead function. Just `#[allow(dead_code)]` is
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// insufficient, since the user may have
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// `#[forbid(dead_code)]` and which cannot be overridden.
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static _FILE_LINE: (&'static str, u32) = (file!(), line!());
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$crate::panicking::panic_fmt(format_args!($fmt, $($arg)*), &_FILE_LINE)
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});
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}
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/// Ensure that a boolean expression is `true` at runtime.
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///
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/// This will invoke the `panic!` macro if the provided expression cannot be
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/// evaluated to `true` at runtime.
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///
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/// This macro has a second version, where a custom panic message can be provided.
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///
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/// # Examples
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///
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/// ```
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/// // the panic message for these assertions is the stringified value of the
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/// // expression given.
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/// assert!(true);
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///
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/// fn some_computation() -> bool { true } // a very simple function
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///
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/// assert!(some_computation());
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///
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/// // assert with a custom message
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/// let x = true;
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/// assert!(x, "x wasn't true!");
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///
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/// let a = 3; let b = 27;
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/// assert!(a + b == 30, "a = {}, b = {}", a, b);
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! assert {
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($cond:expr) => (
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if !$cond {
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panic!(concat!("assertion failed: ", stringify!($cond)))
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}
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);
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($cond:expr, $($arg:tt)+) => (
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if !$cond {
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panic!($($arg)+)
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}
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);
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}
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/// Asserts that two expressions are equal to each other.
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///
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/// On panic, this macro will print the values of the expressions with their
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/// debug representations.
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///
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/// # Examples
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///
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/// ```
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/// let a = 3;
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/// let b = 1 + 2;
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/// assert_eq!(a, b);
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! assert_eq {
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($left:expr , $right:expr) => ({
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match (&$left, &$right) {
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(left_val, right_val) => {
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if !(*left_val == *right_val) {
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panic!("assertion failed: `(left == right)` \
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(left: `{:?}`, right: `{:?}`)", left_val, right_val)
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}
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}
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}
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});
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($left:expr , $right:expr, $($arg:tt)*) => ({
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match (&($left), &($right)) {
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(left_val, right_val) => {
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if !(*left_val == *right_val) {
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panic!("assertion failed: `(left == right)` \
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(left: `{:?}`, right: `{:?}`): {}", left_val, right_val,
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format_args!($($arg)*))
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}
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}
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}
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});
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}
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/// Ensure that a boolean expression is `true` at runtime.
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///
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/// This will invoke the `panic!` macro if the provided expression cannot be
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/// evaluated to `true` at runtime.
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///
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/// Like `assert!`, this macro also has a second version, where a custom panic
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/// message can be provided.
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///
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/// Unlike `assert!`, `debug_assert!` statements are only enabled in non
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/// optimized builds by default. An optimized build will omit all
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/// `debug_assert!` statements unless `-C debug-assertions` is passed to the
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/// compiler. This makes `debug_assert!` useful for checks that are too
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/// expensive to be present in a release build but may be helpful during
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/// development.
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///
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/// # Examples
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///
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/// ```
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/// // the panic message for these assertions is the stringified value of the
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/// // expression given.
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/// debug_assert!(true);
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///
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/// fn some_expensive_computation() -> bool { true } // a very simple function
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/// debug_assert!(some_expensive_computation());
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///
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/// // assert with a custom message
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/// let x = true;
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/// debug_assert!(x, "x wasn't true!");
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///
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/// let a = 3; let b = 27;
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/// debug_assert!(a + b == 30, "a = {}, b = {}", a, b);
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! debug_assert {
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($($arg:tt)*) => (if cfg!(debug_assertions) { assert!($($arg)*); })
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}
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/// Asserts that two expressions are equal to each other.
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///
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/// On panic, this macro will print the values of the expressions with their
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/// debug representations.
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///
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/// Unlike `assert_eq!`, `debug_assert_eq!` statements are only enabled in non
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/// optimized builds by default. An optimized build will omit all
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/// `debug_assert_eq!` statements unless `-C debug-assertions` is passed to the
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/// compiler. This makes `debug_assert_eq!` useful for checks that are too
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/// expensive to be present in a release build but may be helpful during
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/// development.
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///
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/// # Examples
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///
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/// ```
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/// let a = 3;
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/// let b = 1 + 2;
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/// debug_assert_eq!(a, b);
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! debug_assert_eq {
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($($arg:tt)*) => (if cfg!(debug_assertions) { assert_eq!($($arg)*); })
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}
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/// Helper macro for unwrapping `Result` values while returning early with an
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/// error if the value of the expression is `Err`. Can only be used in
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/// functions that return `Result` because of the early return of `Err` that
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/// it provides.
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///
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/// # Examples
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///
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/// ```
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/// use std::io;
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/// use std::fs::File;
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/// use std::io::prelude::*;
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///
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/// fn write_to_file_using_try() -> Result<(), io::Error> {
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/// let mut file = try!(File::create("my_best_friends.txt"));
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/// try!(file.write_all(b"This is a list of my best friends."));
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/// println!("I wrote to the file");
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/// Ok(())
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/// }
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/// // This is equivalent to:
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/// fn write_to_file_using_match() -> Result<(), io::Error> {
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/// let mut file = try!(File::create("my_best_friends.txt"));
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/// match file.write_all(b"This is a list of my best friends.") {
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/// Ok(v) => v,
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/// Err(e) => return Err(e),
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/// }
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/// println!("I wrote to the file");
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/// Ok(())
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/// }
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! try {
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($expr:expr) => (match $expr {
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$crate::result::Result::Ok(val) => val,
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$crate::result::Result::Err(err) => {
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return $crate::result::Result::Err($crate::convert::From::from(err))
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}
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})
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}
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/// Use the `format!` syntax to write data into a buffer.
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///
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/// This macro is typically used with a buffer of `&mut `[`Write`][write].
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///
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/// See [`std::fmt`][fmt] for more information on format syntax.
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///
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/// [fmt]: ../std/fmt/index.html
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/// [write]: ../std/io/trait.Write.html
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///
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/// # Examples
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///
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/// ```
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/// use std::io::Write;
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///
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/// let mut w = Vec::new();
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/// write!(&mut w, "test").unwrap();
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/// write!(&mut w, "formatted {}", "arguments").unwrap();
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///
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/// assert_eq!(w, b"testformatted arguments");
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/// ```
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#[macro_export]
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#[stable(feature = "core", since = "1.6.0")]
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macro_rules! write {
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($dst:expr, $($arg:tt)*) => ($dst.write_fmt(format_args!($($arg)*)))
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}
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/// Use the `format!` syntax to write data into a buffer, appending a newline.
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///
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/// This macro is typically used with a buffer of `&mut `[`Write`][write].
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///
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/// See [`std::fmt`][fmt] for more information on format syntax.
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///
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/// [fmt]: ../std/fmt/index.html
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/// [write]: ../std/io/trait.Write.html
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///
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/// # Examples
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///
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/// ```
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/// use std::io::Write;
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///
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/// let mut w = Vec::new();
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/// writeln!(&mut w, "test").unwrap();
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/// writeln!(&mut w, "formatted {}", "arguments").unwrap();
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///
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/// assert_eq!(&w[..], "test\nformatted arguments\n".as_bytes());
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! writeln {
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($dst:expr, $fmt:expr) => (
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write!($dst, concat!($fmt, "\n"))
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);
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($dst:expr, $fmt:expr, $($arg:tt)*) => (
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write!($dst, concat!($fmt, "\n"), $($arg)*)
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);
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}
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/// A utility macro for indicating unreachable code.
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///
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/// This is useful any time that the compiler can't determine that some code is unreachable. For
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/// example:
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///
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/// * Match arms with guard conditions.
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/// * Loops that dynamically terminate.
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/// * Iterators that dynamically terminate.
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///
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/// # Panics
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///
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/// This will always panic.
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///
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/// # Examples
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///
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/// Match arms:
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///
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/// ```
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/// # #[allow(dead_code)]
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/// fn foo(x: Option<i32>) {
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/// match x {
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/// Some(n) if n >= 0 => println!("Some(Non-negative)"),
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/// Some(n) if n < 0 => println!("Some(Negative)"),
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/// Some(_) => unreachable!(), // compile error if commented out
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/// None => println!("None")
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/// }
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/// }
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/// ```
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///
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/// Iterators:
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///
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/// ```
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/// # #[allow(dead_code)]
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/// fn divide_by_three(x: u32) -> u32 { // one of the poorest implementations of x/3
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/// for i in 0.. {
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/// if 3*i < i { panic!("u32 overflow"); }
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/// if x < 3*i { return i-1; }
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/// }
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/// unreachable!();
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/// }
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/// ```
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#[macro_export]
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#[stable(feature = "core", since = "1.6.0")]
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macro_rules! unreachable {
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() => ({
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panic!("internal error: entered unreachable code")
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});
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($msg:expr) => ({
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unreachable!("{}", $msg)
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});
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($fmt:expr, $($arg:tt)*) => ({
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panic!(concat!("internal error: entered unreachable code: ", $fmt), $($arg)*)
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});
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}
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/// A standardized placeholder for marking unfinished code. It panics with the
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/// message `"not yet implemented"` when executed.
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///
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/// This can be useful if you are prototyping and are just looking to have your
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/// code typecheck, or if you're implementing a trait that requires multiple
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/// methods, and you're only planning on using one of them.
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///
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/// # Examples
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///
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/// Here's an example of some in-progress code. We have a trait `Foo`:
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///
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/// ```
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/// trait Foo {
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/// fn bar(&self);
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/// fn baz(&self);
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/// }
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/// ```
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///
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/// We want to implement `Foo` on one of our types, but we also want to work on
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/// just `bar()` first. In order for our code to compile, we need to implement
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/// `baz()`, so we can use `unimplemented!`:
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///
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/// ```
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/// # trait Foo {
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/// # fn bar(&self);
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/// # fn baz(&self);
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/// # }
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/// struct MyStruct;
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///
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/// impl Foo for MyStruct {
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/// fn bar(&self) {
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/// // implementation goes here
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/// }
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///
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/// fn baz(&self) {
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/// // let's not worry about implementing baz() for now
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/// unimplemented!();
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/// }
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/// }
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///
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/// fn main() {
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/// let s = MyStruct;
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/// s.bar();
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///
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/// // we aren't even using baz() yet, so this is fine.
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/// }
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/// ```
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#[macro_export]
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#[stable(feature = "core", since = "1.6.0")]
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macro_rules! unimplemented {
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() => (panic!("not yet implemented"))
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}
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