add libcore from 2016-04-11 nightly

1 files changed, 366 insertions, 0 deletions

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