102 lines
2.8 KiB
Rust
102 lines
2.8 KiB
Rust
// Copyright 2013 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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#![allow(missing_doc)]
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#![experimental]
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//! Contains struct definitions for the layout of compiler built-in types.
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//!
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//! They can be used as targets of transmutes in unsafe code for manipulating
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//! the raw representations directly.
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//!
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//! Their definition should always match the ABI defined in `rustc::back::abi`.
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use mem;
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/// The representation of a Rust managed box
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pub struct Box<T> {
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pub ref_count: uint,
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pub drop_glue: fn(ptr: *mut u8),
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pub prev: *mut Box<T>,
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pub next: *mut Box<T>,
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pub data: T,
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}
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/// The representation of a Rust slice
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pub struct Slice<T> {
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pub data: *const T,
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pub len: uint,
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}
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/// The representation of a Rust closure
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pub struct Closure {
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pub code: *mut (),
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pub env: *mut (),
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}
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/// The representation of a Rust procedure (`proc()`)
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pub struct Procedure {
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pub code: *mut (),
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pub env: *mut (),
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}
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/// The representation of a Rust trait object.
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///
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/// This struct does not have a `Repr` implementation
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/// because there is no way to refer to all trait objects generically.
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pub struct TraitObject {
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pub vtable: *mut (),
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pub data: *mut (),
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}
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/// This trait is meant to map equivalences between raw structs and their
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/// corresponding rust values.
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pub trait Repr<T> {
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/// This function "unwraps" a rust value (without consuming it) into its raw
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/// struct representation. This can be used to read/write different values
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/// for the struct. This is a safe method because by default it does not
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/// enable write-access to the fields of the return value in safe code.
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#[inline]
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fn repr(&self) -> T { unsafe { mem::transmute_copy(self) } }
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}
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impl<'a, T> Repr<Slice<T>> for &'a [T] {}
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impl<'a> Repr<Slice<u8>> for &'a str {}
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#[cfg(test)]
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mod tests {
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use super::*;
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use mem;
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#[test]
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fn synthesize_closure() {
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unsafe {
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let x = 10;
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let f: |int| -> int = |y| x + y;
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assert_eq!(f(20), 30);
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let original_closure: Closure = mem::transmute(f);
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let actual_function_pointer = original_closure.code;
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let environment = original_closure.env;
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let new_closure = Closure {
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code: actual_function_pointer,
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env: environment
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};
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let new_f: |int| -> int = mem::transmute(new_closure);
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assert_eq!(new_f(20), 30);
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}
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}
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}
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