426 lines
14 KiB
Rust
426 lines
14 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
|
|
// file at the top-level directory of this distribution and at
|
|
// http://rust-lang.org/COPYRIGHT.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
|
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
|
|
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
|
|
// option. This file may not be copied, modified, or distributed
|
|
// except according to those terms.
|
|
|
|
//! Standard library macros
|
|
//!
|
|
//! This modules contains a set of macros which are exported from the standard
|
|
//! library. Each macro is available for use when linking against the standard
|
|
//! library.
|
|
|
|
#![unstable(feature = "std_misc")]
|
|
|
|
/// The entry point for panic of Rust tasks.
|
|
///
|
|
/// This macro is used to inject panic into a Rust task, causing the task to
|
|
/// unwind and panic entirely. Each task's panic can be reaped as the
|
|
/// `Box<Any>` type, and the single-argument form of the `panic!` macro will be
|
|
/// the value which is transmitted.
|
|
///
|
|
/// The multi-argument form of this macro panics with a string and has the
|
|
/// `format!` syntax for building a string.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```should_panic
|
|
/// # #![allow(unreachable_code)]
|
|
/// panic!();
|
|
/// panic!("this is a terrible mistake!");
|
|
/// panic!(4); // panic with the value of 4 to be collected elsewhere
|
|
/// panic!("this is a {} {message}", "fancy", message = "message");
|
|
/// ```
|
|
#[macro_export]
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
macro_rules! panic {
|
|
() => ({
|
|
panic!("explicit panic")
|
|
});
|
|
($msg:expr) => ({
|
|
$crate::rt::begin_unwind($msg, {
|
|
// static requires less code at runtime, more constant data
|
|
static _FILE_LINE: (&'static str, usize) = (file!(), line!() as usize);
|
|
&_FILE_LINE
|
|
})
|
|
});
|
|
($fmt:expr, $($arg:tt)+) => ({
|
|
$crate::rt::begin_unwind_fmt(format_args!($fmt, $($arg)+), {
|
|
// The leading _'s are to avoid dead code warnings if this is
|
|
// used inside a dead function. Just `#[allow(dead_code)]` is
|
|
// insufficient, since the user may have
|
|
// `#[forbid(dead_code)]` and which cannot be overridden.
|
|
static _FILE_LINE: (&'static str, usize) = (file!(), line!() as usize);
|
|
&_FILE_LINE
|
|
})
|
|
});
|
|
}
|
|
|
|
/// Macro for printing to the standard output.
|
|
///
|
|
/// Equivalent to the `println!` macro except that a newline is not printed at
|
|
/// the end of the message.
|
|
///
|
|
/// Note that stdout is frequently line-buffered by default so it may be
|
|
/// necessary to use `io::stdout().flush()` to ensure the output is emitted
|
|
/// immediately.
|
|
#[macro_export]
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
#[allow_internal_unstable]
|
|
macro_rules! print {
|
|
($($arg:tt)*) => ($crate::io::_print(format_args!($($arg)*)));
|
|
}
|
|
|
|
/// Macro for printing to the standard output.
|
|
///
|
|
/// Use the `format!` syntax to write data to the standard output.
|
|
/// See `std::fmt` for more information.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// println!("hello there!");
|
|
/// println!("format {} arguments", "some");
|
|
/// ```
|
|
#[macro_export]
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
macro_rules! println {
|
|
($fmt:expr) => (print!(concat!($fmt, "\n")));
|
|
($fmt:expr, $($arg:tt)*) => (print!(concat!($fmt, "\n"), $($arg)*));
|
|
}
|
|
|
|
/// Helper macro for unwrapping `Result` values while returning early with an
|
|
/// error if the value of the expression is `Err`.
|
|
#[macro_export]
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
macro_rules! try {
|
|
($expr:expr) => (match $expr {
|
|
$crate::result::Result::Ok(val) => val,
|
|
$crate::result::Result::Err(err) => {
|
|
return $crate::result::Result::Err($crate::convert::From::from(err))
|
|
}
|
|
})
|
|
}
|
|
|
|
/// A macro to select an event from a number of receivers.
|
|
///
|
|
/// This macro is used to wait for the first event to occur on a number of
|
|
/// receivers. It places no restrictions on the types of receivers given to
|
|
/// this macro, this can be viewed as a heterogeneous select.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(std_misc)]
|
|
/// use std::thread;
|
|
/// use std::sync::mpsc;
|
|
///
|
|
/// // two placeholder functions for now
|
|
/// fn long_running_task() {}
|
|
/// fn calculate_the_answer() -> u32 { 42 }
|
|
///
|
|
/// let (tx1, rx1) = mpsc::channel();
|
|
/// let (tx2, rx2) = mpsc::channel();
|
|
///
|
|
/// thread::spawn(move|| { long_running_task(); tx1.send(()).unwrap(); });
|
|
/// thread::spawn(move|| { tx2.send(calculate_the_answer()).unwrap(); });
|
|
///
|
|
/// select! (
|
|
/// _ = rx1.recv() => println!("the long running task finished first"),
|
|
/// answer = rx2.recv() => {
|
|
/// println!("the answer was: {}", answer.unwrap());
|
|
/// }
|
|
/// )
|
|
/// ```
|
|
///
|
|
/// For more information about select, see the `std::sync::mpsc::Select` structure.
|
|
#[macro_export]
|
|
#[unstable(feature = "std_misc")]
|
|
macro_rules! select {
|
|
(
|
|
$($name:pat = $rx:ident.$meth:ident() => $code:expr),+
|
|
) => ({
|
|
use $crate::sync::mpsc::Select;
|
|
let sel = Select::new();
|
|
$( let mut $rx = sel.handle(&$rx); )+
|
|
unsafe {
|
|
$( $rx.add(); )+
|
|
}
|
|
let ret = sel.wait();
|
|
$( if ret == $rx.id() { let $name = $rx.$meth(); $code } else )+
|
|
{ unreachable!() }
|
|
})
|
|
}
|
|
|
|
// When testing the standard library, we link to the liblog crate to get the
|
|
// logging macros. In doing so, the liblog crate was linked against the real
|
|
// version of libstd, and uses a different std::fmt module than the test crate
|
|
// uses. To get around this difference, we redefine the log!() macro here to be
|
|
// just a dumb version of what it should be.
|
|
#[cfg(test)]
|
|
macro_rules! log {
|
|
($lvl:expr, $($args:tt)*) => (
|
|
if log_enabled!($lvl) { println!($($args)*) }
|
|
)
|
|
}
|
|
|
|
/// Built-in macros to the compiler itself.
|
|
///
|
|
/// These macros do not have any corresponding definition with a `macro_rules!`
|
|
/// macro, but are documented here. Their implementations can be found hardcoded
|
|
/// into libsyntax itself.
|
|
#[cfg(dox)]
|
|
pub mod builtin {
|
|
/// The core macro for formatted string creation & output.
|
|
///
|
|
/// This macro produces a value of type `fmt::Arguments`. This value can be
|
|
/// passed to the functions in `std::fmt` for performing useful functions.
|
|
/// All other formatting macros (`format!`, `write!`, `println!`, etc) are
|
|
/// proxied through this one.
|
|
///
|
|
/// For more information, see the documentation in `std::fmt`.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::fmt;
|
|
///
|
|
/// let s = fmt::format(format_args!("hello {}", "world"));
|
|
/// assert_eq!(s, format!("hello {}", "world"));
|
|
///
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! format_args { ($fmt:expr, $($args:tt)*) => ({
|
|
/* compiler built-in */
|
|
}) }
|
|
|
|
/// Inspect an environment variable at compile time.
|
|
///
|
|
/// This macro will expand to the value of the named environment variable at
|
|
/// compile time, yielding an expression of type `&'static str`.
|
|
///
|
|
/// If the environment variable is not defined, then a compilation error
|
|
/// will be emitted. To not emit a compile error, use the `option_env!`
|
|
/// macro instead.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let path: &'static str = env!("PATH");
|
|
/// println!("the $PATH variable at the time of compiling was: {}", path);
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! env { ($name:expr) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Optionally inspect an environment variable at compile time.
|
|
///
|
|
/// If the named environment variable is present at compile time, this will
|
|
/// expand into an expression of type `Option<&'static str>` whose value is
|
|
/// `Some` of the value of the environment variable. If the environment
|
|
/// variable is not present, then this will expand to `None`.
|
|
///
|
|
/// A compile time error is never emitted when using this macro regardless
|
|
/// of whether the environment variable is present or not.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let key: Option<&'static str> = option_env!("SECRET_KEY");
|
|
/// println!("the secret key might be: {:?}", key);
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! option_env { ($name:expr) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Concatenate identifiers into one identifier.
|
|
///
|
|
/// This macro takes any number of comma-separated identifiers, and
|
|
/// concatenates them all into one, yielding an expression which is a new
|
|
/// identifier. Note that hygiene makes it such that this macro cannot
|
|
/// capture local variables, and macros are only allowed in item,
|
|
/// statement or expression position, meaning this macro may be difficult to
|
|
/// use in some situations.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// #![feature(concat_idents)]
|
|
///
|
|
/// # fn main() {
|
|
/// fn foobar() -> u32 { 23 }
|
|
///
|
|
/// let f = concat_idents!(foo, bar);
|
|
/// println!("{}", f());
|
|
/// # }
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! concat_idents {
|
|
($($e:ident),*) => ({ /* compiler built-in */ })
|
|
}
|
|
|
|
/// Concatenates literals into a static string slice.
|
|
///
|
|
/// This macro takes any number of comma-separated literals, yielding an
|
|
/// expression of type `&'static str` which represents all of the literals
|
|
/// concatenated left-to-right.
|
|
///
|
|
/// Integer and floating point literals are stringified in order to be
|
|
/// concatenated.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let s = concat!("test", 10, 'b', true);
|
|
/// assert_eq!(s, "test10btrue");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! concat { ($($e:expr),*) => ({ /* compiler built-in */ }) }
|
|
|
|
/// A macro which expands to the line number on which it was invoked.
|
|
///
|
|
/// The expanded expression has type `usize`, and the returned line is not
|
|
/// the invocation of the `line!()` macro itself, but rather the first macro
|
|
/// invocation leading up to the invocation of the `line!()` macro.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let current_line = line!();
|
|
/// println!("defined on line: {}", current_line);
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! line { () => ({ /* compiler built-in */ }) }
|
|
|
|
/// A macro which expands to the column number on which it was invoked.
|
|
///
|
|
/// The expanded expression has type `usize`, and the returned column is not
|
|
/// the invocation of the `column!()` macro itself, but rather the first macro
|
|
/// invocation leading up to the invocation of the `column!()` macro.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let current_col = column!();
|
|
/// println!("defined on column: {}", current_col);
|
|
/// ```
|
|
#[macro_export]
|
|
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.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// 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.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// 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),
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```rust,ignore
|
|
/// let secret_key = include_str!("secret-key.ascii");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! include_str { ($file:expr) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Includes a file as a byte slice.
|
|
///
|
|
/// This macro will yield an expression of type `&'static [u8]` which is
|
|
/// the contents of the filename specified. The file is located relative to
|
|
/// the current file (similarly to how modules are found),
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```rust,ignore
|
|
/// let secret_key = include_bytes!("secret-key.bin");
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! include_bytes { ($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.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// 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.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let my_directory = if cfg!(windows) {
|
|
/// "windows-specific-directory"
|
|
/// } else {
|
|
/// "unix-directory"
|
|
/// };
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! cfg { ($cfg:tt) => ({ /* compiler built-in */ }) }
|
|
|
|
/// Parse the current given file as an expression.
|
|
///
|
|
/// This is generally a bad idea, because it's going to behave unhygenically.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```ignore
|
|
/// fn foo() {
|
|
/// include!("/path/to/a/file")
|
|
/// }
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! include { ($cfg:tt) => ({ /* compiler built-in */ }) }
|
|
}
|