ee9921aaed
This reverts commit f031671c6e.
Conflicts:
src/libcollections/slice.rs
src/libcore/iter.rs
src/libstd/sync/mpsc/mod.rs
src/libstd/sync/rwlock.rs
613 lines
19 KiB
Rust
613 lines
19 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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//! Standard library macros
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//!
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//! This modules contains a set of macros which are exported from the standard
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//! library. Each macro is available for use when linking against the standard
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//! library.
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#![experimental]
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/// The entry point for panic of Rust tasks.
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///
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/// This macro is used to inject panic into a Rust task, causing the task to
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/// unwind and panic entirely. Each task's panic can be reaped as the
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/// `Box<Any>` type, and the single-argument form of the `panic!` macro will be
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/// the value which is transmitted.
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///
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/// The multi-argument form of this macro panics with a string and has the
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/// `format!` syntax for building a string.
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///
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/// # Example
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///
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/// ```should_fail
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/// # #![allow(unreachable_code)]
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/// panic!();
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/// panic!("this is a terrible mistake!");
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/// panic!(4i); // panic with the value of 4 to be collected elsewhere
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/// panic!("this is a {} {message}", "fancy", message = "message");
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/// ```
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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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($msg:expr) => ({
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// static requires less code at runtime, more constant data
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static _FILE_LINE: (&'static str, uint) = (file!(), line!());
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::std::rt::begin_unwind($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, uint) = (file!(), line!());
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::std::rt::begin_unwind_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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/// # fn some_computation() -> bool { true }
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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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/// # let a = 3i; let b = 27i;
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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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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:expr),+) => (
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if !$cond {
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panic!($($arg),+)
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}
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);
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}
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/// Asserts that two expressions are equal to each other, testing equality in
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/// both directions.
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///
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/// On panic, this macro will print the values of the expressions.
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///
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/// # Example
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///
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/// ```
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/// let a = 3i;
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/// let b = 1i + 2i;
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/// assert_eq!(a, b);
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/// ```
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#[macro_export]
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macro_rules! assert_eq {
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($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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/// # fn some_expensive_computation() -> bool { true }
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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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/// # let a = 3i; let b = 27i;
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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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macro_rules! debug_assert {
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($($arg:tt)*) => (if cfg!(not(ndebug)) { assert!($($arg)*); })
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}
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/// Asserts that two expressions are equal to each other, testing equality in
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/// both directions.
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///
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/// On panic, this macro will print the values of the expressions.
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///
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/// Unlike `assert_eq!`, `debug_assert_eq!` statements can be disabled by
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/// passing `--cfg ndebug` to the compiler. This makes `debug_assert_eq!`
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/// useful for checks that are too expensive to be present in a release build
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/// but may be helpful during development.
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///
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/// # Example
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///
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/// ```
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/// let a = 3i;
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/// let b = 1i + 2i;
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/// debug_assert_eq!(a, b);
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/// ```
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#[macro_export]
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macro_rules! debug_assert_eq {
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($($arg:tt)*) => (if cfg!(not(ndebug)) { assert_eq!($($arg)*); })
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}
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/// 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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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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macro_rules! unimplemented {
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() => (panic!("not yet implemented"))
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}
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/// Use the syntax described in `std::fmt` to create a value of type `String`.
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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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/// format!("test");
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/// format!("hello {}", "world!");
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/// format!("x = {}, y = {y}", 10i, y = 30i);
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/// ```
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#[macro_export]
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#[stable]
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macro_rules! format {
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($($arg:tt)*) => (::std::fmt::format(format_args!($($arg)*)))
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}
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/// Equivalent to the `println!` macro except that a newline is not printed at
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/// the end of the message.
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#[macro_export]
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#[stable]
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macro_rules! print {
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($($arg:tt)*) => (::std::io::stdio::print_args(format_args!($($arg)*)))
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}
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/// Macro for printing to a task's stdout handle.
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///
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/// Each task can override its stdout handle via `std::io::stdio::set_stdout`.
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/// The syntax of this macro is the same as that used for `format!`. For more
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/// information, see `std::fmt` and `std::io::stdio`.
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///
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/// # Example
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///
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/// ```
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/// println!("hello there!");
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/// println!("format {} arguments", "some");
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/// ```
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#[macro_export]
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#[stable]
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macro_rules! println {
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($($arg:tt)*) => (::std::io::stdio::println_args(format_args!($($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`. For more information, see
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/// `std::io`.
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#[macro_export]
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macro_rules! try {
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($expr:expr) => ({
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use $crate::result::Result::{Ok, Err};
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match $expr {
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Ok(val) => val,
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Err(err) => return Err($crate::error::FromError::from_error(err)),
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}
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})
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}
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/// A macro to select an event from a number of receivers.
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///
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/// This macro is used to wait for the first event to occur on a number of
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/// receivers. It places no restrictions on the types of receivers given to
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/// this macro, this can be viewed as a heterogeneous select.
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///
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/// # Example
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///
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/// ```
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/// use std::thread::Thread;
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/// use std::sync::mpsc::channel;
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///
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/// let (tx1, rx1) = channel();
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/// let (tx2, rx2) = channel();
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/// # fn long_running_task() {}
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/// # fn calculate_the_answer() -> int { 42i }
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///
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/// Thread::spawn(move|| { long_running_task(); tx1.send(()) }).detach();
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/// Thread::spawn(move|| { tx2.send(calculate_the_answer()) }).detach();
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///
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/// select! (
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/// _ = rx1.recv() => println!("the long running task finished first"),
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/// answer = rx2.recv() => {
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/// println!("the answer was: {}", answer.unwrap());
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/// }
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/// )
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/// ```
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///
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/// For more information about select, see the `std::sync::mpsc::Select` structure.
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#[macro_export]
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#[experimental]
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macro_rules! select {
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(
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$($name:pat = $rx:ident.$meth:ident() => $code:expr),+
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) => ({
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use $crate::sync::mpsc::Select;
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let sel = Select::new();
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$( let mut $rx = sel.handle(&$rx); )+
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unsafe {
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$( $rx.add(); )+
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}
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let ret = sel.wait();
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$( if ret == $rx.id() { let $name = $rx.$meth(); $code } else )+
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{ unreachable!() }
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})
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}
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// When testing the standard library, we link to the liblog crate to get the
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// logging macros. In doing so, the liblog crate was linked against the real
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// version of libstd, and uses a different std::fmt module than the test crate
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// uses. To get around this difference, we redefine the log!() macro here to be
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// just a dumb version of what it should be.
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#[cfg(test)]
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macro_rules! log {
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($lvl:expr, $($args:tt)*) => (
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if log_enabled!($lvl) { println!($($args)*) }
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)
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}
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/// Built-in macros to the compiler itself.
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///
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/// These macros do not have any corresponding definition with a `macro_rules!`
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/// macro, but are documented here. Their implementations can be found hardcoded
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/// into libsyntax itself.
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#[cfg(dox)]
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pub mod builtin {
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/// The core macro for formatted string creation & output.
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///
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/// This macro produces a value of type `fmt::Arguments`. This value can be
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/// passed to the functions in `std::fmt` for performing useful functions.
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/// All other formatting macros (`format!`, `write!`, `println!`, etc) are
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/// proxied through this one.
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///
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/// For more information, see the documentation in `std::fmt`.
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///
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/// # Example
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///
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/// ```rust
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/// use std::fmt;
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///
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/// let s = fmt::format(format_args!("hello {}", "world"));
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/// assert_eq!(s, format!("hello {}", "world"));
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///
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/// ```
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#[macro_export]
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macro_rules! format_args { ($fmt:expr $($args:tt)*) => ({
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/* compiler built-in */
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}) }
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/// Inspect an environment variable at compile time.
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///
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/// This macro will expand to the value of the named environment variable at
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/// compile time, yielding an expression of type `&'static str`.
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///
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/// If the environment variable is not defined, then a compilation error
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/// will be emitted. To not emit a compile error, use the `option_env!`
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/// macro instead.
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///
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/// # Example
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///
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/// ```rust
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/// let path: &'static str = env!("PATH");
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/// println!("the $PATH variable at the time of compiling was: {}", path);
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/// ```
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#[macro_export]
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macro_rules! env { ($name:expr) => ({ /* compiler built-in */ }) }
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/// Optionally inspect an environment variable at compile time.
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///
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/// If the named environment variable is present at compile time, this will
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/// expand into an expression of type `Option<&'static str>` whose value is
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/// `Some` of the value of the environment variable. If the environment
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/// variable is not present, then this will expand to `None`.
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///
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/// A compile time error is never emitted when using this macro regardless
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/// of whether the environment variable is present or not.
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///
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/// # Example
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///
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/// ```rust
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/// let key: Option<&'static str> = option_env!("SECRET_KEY");
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/// println!("the secret key might be: {}", key);
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/// ```
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#[macro_export]
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macro_rules! option_env { ($name:expr) => ({ /* compiler built-in */ }) }
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/// Concatenate literals into a static byte slice.
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///
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/// This macro takes any number of comma-separated literal expressions,
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/// yielding an expression of type `&'static [u8]` which is the
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/// concatenation (left to right) of all the literals in their byte format.
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///
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/// This extension currently only supports string literals, character
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/// literals, and integers less than 256. The byte slice returned is the
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/// utf8-encoding of strings and characters.
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///
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/// # Example
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///
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/// ```
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/// let rust = bytes!("r", 'u', "st", 255);
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/// assert_eq!(rust[1], b'u');
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/// assert_eq!(rust[4], 255);
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/// ```
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#[macro_export]
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macro_rules! bytes { ($($e:expr),*) => ({ /* compiler built-in */ }) }
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/// Concatenate identifiers into one identifier.
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///
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/// This macro takes any number of comma-separated identifiers, and
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/// concatenates them all into one, yielding an expression which is a new
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/// identifier. Note that hygiene makes it such that this macro cannot
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/// capture local variables, and macros are only allowed in item,
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/// statement or expression position, meaning this macro may be difficult to
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/// use in some situations.
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///
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/// # Example
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///
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/// ```
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/// #![feature(concat_idents)]
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///
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/// # fn main() {
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/// fn foobar() -> int { 23 }
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///
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/// let f = concat_idents!(foo, bar);
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/// println!("{}", f());
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/// # }
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/// ```
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#[macro_export]
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macro_rules! concat_idents {
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($($e:ident),*) => ({ /* compiler built-in */ })
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}
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/// Concatenates literals into a static string slice.
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///
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/// This macro takes any number of comma-separated literals, yielding an
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/// expression of type `&'static str` which represents all of the literals
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/// concatenated left-to-right.
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///
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/// Integer and floating point literals are stringified in order to be
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/// concatenated.
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///
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/// # Example
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///
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/// ```
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/// let s = concat!("test", 10i, 'b', true);
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/// assert_eq!(s, "test10btrue");
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/// ```
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#[macro_export]
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macro_rules! concat { ($($e:expr),*) => ({ /* compiler built-in */ }) }
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/// A macro which expands to the line number on which it was invoked.
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///
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/// The expanded expression has type `uint`, and the returned line is not
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/// the invocation of the `line!()` macro itself, but rather the first macro
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/// invocation leading up to the invocation of the `line!()` macro.
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///
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/// # Example
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///
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/// ```
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/// let current_line = line!();
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/// println!("defined on line: {}", current_line);
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/// ```
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#[macro_export]
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macro_rules! line { () => ({ /* compiler built-in */ }) }
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/// A macro which expands to the column number on which it was invoked.
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///
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/// The expanded expression has type `uint`, and the returned column is not
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/// the invocation of the `column!()` macro itself, but rather the first macro
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/// invocation leading up to the invocation of the `column!()` macro.
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///
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/// # Example
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///
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/// ```
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/// let current_col = column!();
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/// println!("defined on column: {}", current_col);
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/// ```
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|
#[macro_export]
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|
macro_rules! column { () => ({ /* compiler built-in */ }) }
|
|
|
|
/// A macro which expands to the file name from which it was invoked.
|
|
///
|
|
/// The expanded expression has type `&'static str`, and the returned file
|
|
/// is not the invocation of the `file!()` macro itself, but rather the
|
|
/// first macro invocation leading up to the invocation of the `file!()`
|
|
/// macro.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// let this_file = file!();
|
|
/// println!("defined in file: {}", this_file);
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! file { () => ({ /* compiler built-in */ }) }
|
|
|
|
/// A macro which stringifies its argument.
|
|
///
|
|
/// This macro will yield an expression of type `&'static str` which is the
|
|
/// stringification of all the tokens passed to the macro. No restrictions
|
|
/// are placed on the syntax of the macro invocation itself.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// let one_plus_one = stringify!(1 + 1);
|
|
/// assert_eq!(one_plus_one, "1 + 1");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! stringify { ($t:tt) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Includes a utf8-encoded file as a string.
|
|
///
|
|
/// This macro will yield an expression of type `&'static str` which is the
|
|
/// contents of the filename specified. The file is located relative to the
|
|
/// current file (similarly to how modules are found),
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```rust,ignore
|
|
/// let secret_key = include_str!("secret-key.ascii");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! include_str { ($file:expr) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Includes a file as a byte slice.
|
|
///
|
|
/// This macro will yield an expression of type `&'static [u8]` which is
|
|
/// the contents of the filename specified. The file is located relative to
|
|
/// the current file (similarly to how modules are found),
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```rust,ignore
|
|
/// let secret_key = include_bytes!("secret-key.bin");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! include_bytes { ($file:expr) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Deprecated alias for `include_bytes!()`.
|
|
#[macro_export]
|
|
macro_rules! include_bin { ($file:expr) => ({ /* compiler built-in */}) }
|
|
|
|
/// Expands to a string that represents the current module path.
|
|
///
|
|
/// The current module path can be thought of as the hierarchy of modules
|
|
/// leading back up to the crate root. The first component of the path
|
|
/// returned is the name of the crate currently being compiled.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```rust
|
|
/// mod test {
|
|
/// pub fn foo() {
|
|
/// assert!(module_path!().ends_with("test"));
|
|
/// }
|
|
/// }
|
|
///
|
|
/// test::foo();
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! module_path { () => ({ /* compiler built-in */ }) }
|
|
|
|
/// Boolean evaluation of configuration flags.
|
|
///
|
|
/// In addition to the `#[cfg]` attribute, this macro is provided to allow
|
|
/// boolean expression evaluation of configuration flags. This frequently
|
|
/// leads to less duplicated code.
|
|
///
|
|
/// The syntax given to this macro is the same syntax as the `cfg`
|
|
/// attribute.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```rust
|
|
/// let my_directory = if cfg!(windows) {
|
|
/// "windows-specific-directory"
|
|
/// } else {
|
|
/// "unix-directory"
|
|
/// };
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! cfg { ($cfg:tt) => ({ /* compiler built-in */ }) }
|
|
}
|