260 lines
7.4 KiB
Rust
260 lines
7.4 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 task panic, for details, see std::macros
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#[macro_export]
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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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::core::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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::core::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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/// # Example
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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 !$cond {
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panic!($($arg)+)
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}
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);
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}
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/// Asserts that two expressions are equal to each other, testing equality in
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/// both directions.
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///
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/// On panic, this macro will print the values of the expressions.
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///
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/// # Example
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///
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/// ```
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/// let a = 3;
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/// let b = 1 + 2;
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/// assert_eq!(a, b);
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/// ```
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! assert_eq {
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($left:expr , $right:expr) => ({
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match (&($left), &($right)) {
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(left_val, right_val) => {
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// check both directions of equality....
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if !((*left_val == *right_val) &&
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(*right_val == *left_val)) {
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panic!("assertion failed: `(left == right) && (right == left)` \
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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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}
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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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/// Unlike `assert!`, `debug_assert!` statements can be disabled by passing
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/// `--cfg ndebug` to the compiler. This makes `debug_assert!` useful for
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/// checks that are too expensive to be present in a release build but may be
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/// helpful during development.
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///
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/// # Example
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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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($($arg:tt)*) => (if cfg!(not(ndebug)) { assert!($($arg)*); })
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}
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/// Asserts that two expressions are equal to each other, testing equality in
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/// both directions.
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///
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/// On panic, this macro will print the values of the expressions.
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///
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/// Unlike `assert_eq!`, `debug_assert_eq!` statements can be disabled by
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/// passing `--cfg ndebug` to the compiler. This makes `debug_assert_eq!`
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/// useful for checks that are too expensive to be present in a release build
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/// but may be helpful during development.
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///
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/// # Example
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///
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/// ```
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/// let a = 3;
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/// let b = 1 + 2;
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/// debug_assert_eq!(a, b);
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/// ```
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#[macro_export]
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macro_rules! debug_assert_eq {
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($($arg:tt)*) => (if cfg!(not(ndebug)) { assert_eq!($($arg)*); })
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}
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/// Short circuiting evaluation on Err
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///
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/// `libstd` contains a more general `try!` macro that uses `FromError`.
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#[macro_export]
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macro_rules! try {
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($e:expr) => ({
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use $crate::result::Result::{Ok, Err};
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match $e {
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Ok(e) => e,
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Err(e) => return Err(e),
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}
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})
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}
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/// Use the `format!` syntax to write data into a buffer of type `&mut Writer`.
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/// See `std::fmt` for more information.
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///
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/// # Example
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///
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/// ```
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/// # #![allow(unused_must_use)]
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///
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/// let mut w = Vec::new();
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/// write!(&mut w, "test");
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/// write!(&mut w, "formatted {}", "arguments");
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/// ```
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#[macro_export]
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macro_rules! write {
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($dst:expr, $($arg:tt)*) => ((&mut *$dst).write_fmt(format_args!($($arg)*)))
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}
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/// Equivalent to the `write!` macro, except that a newline is appended after
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/// the message is written.
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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macro_rules! writeln {
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($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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/// ```rust
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/// fn foo(x: Option<int>) {
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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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/// ```rust
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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 std::iter::count(0_u32, 1) {
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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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#[unstable(feature = "core",
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reason = "relationship with panic is unclear")]
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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 standardised placeholder for marking unfinished code. It panics with the
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/// message `"not yet implemented"` when executed.
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#[macro_export]
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#[unstable(feature = "core",
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reason = "relationship with panic is unclear")]
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macro_rules! unimplemented {
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() => (panic!("not yet implemented"))
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}
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