/
any.rs
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/
any.rs
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// Copyright 2013 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.
//! Traits for dynamic typing of any type (through runtime reflection)
//!
//! This module implements the `Any` trait, which enables dynamic typing
//! of any type, through runtime reflection.
//!
//! `Any` itself can be used to get a `TypeId`, and has more features when used as a trait object.
//! As `&Any` (a borrowed trait object), it has the `is` and `as_ref` methods, to test if the
//! contained value is of a given type, and to get a reference to the inner value as a type. As
//! `&mut Any`, there is also the `as_mut` method, for getting a mutable reference to the inner
//! value. `~Any` adds the `move` method, which will unwrap a `~T` from the object. See the
//! extension traits (`*Ext`) for the full details.
use cast::transmute;
use option::{Option, Some, None};
use result::{Result, Ok, Err};
use to_str::ToStr;
use unstable::intrinsics::TypeId;
use unstable::intrinsics;
use util::Void;
///////////////////////////////////////////////////////////////////////////////
// Any trait
///////////////////////////////////////////////////////////////////////////////
/// The `Any` trait is implemented by all types, and can be used as a trait object
/// for dynamic typing
pub trait Any {
/// Get the `TypeId` of `self`
fn get_type_id(&self) -> TypeId;
/// Get a void pointer to `self`
fn as_void_ptr(&self) -> *Void;
/// Get a mutable void pointer to `self`
fn as_mut_void_ptr(&mut self) -> *mut Void;
}
impl<T: 'static> Any for T {
/// Get the `TypeId` of `self`
fn get_type_id(&self) -> TypeId {
TypeId::of::<T>()
}
/// Get a void pointer to `self`
fn as_void_ptr(&self) -> *Void {
self as *T as *Void
}
/// Get a mutable void pointer to `self`
fn as_mut_void_ptr(&mut self) -> *mut Void {
self as *mut T as *mut Void
}
}
///////////////////////////////////////////////////////////////////////////////
// Extension methods for Any trait objects.
// Implemented as three extension traits so that generics work.
///////////////////////////////////////////////////////////////////////////////
/// Extension methods for a referenced `Any` trait object
pub trait AnyRefExt<'a> {
/// Returns true if the boxed type is the same as `T`
fn is<T: 'static>(self) -> bool;
/// Returns some reference to the boxed value if it is of type `T`, or
/// `None` if it isn't.
fn as_ref<T: 'static>(self) -> Option<&'a T>;
}
impl<'a> AnyRefExt<'a> for &'a Any {
#[inline]
fn is<T: 'static>(self) -> bool {
// Get TypeId of the type this function is instantiated with
let t = TypeId::of::<T>();
// Get TypeId of the type in the trait object
let boxed = self.get_type_id();
// Compare both TypeIds on equality
t == boxed
}
#[inline]
fn as_ref<T: 'static>(self) -> Option<&'a T> {
if self.is::<T>() {
Some(unsafe { transmute(self.as_void_ptr()) })
} else {
None
}
}
}
/// Extension methods for a mutable referenced `Any` trait object
pub trait AnyMutRefExt<'a> {
/// Returns some mutable reference to the boxed value if it is of type `T`, or
/// `None` if it isn't.
fn as_mut<T: 'static>(self) -> Option<&'a mut T>;
}
impl<'a> AnyMutRefExt<'a> for &'a mut Any {
#[inline]
fn as_mut<T: 'static>(self) -> Option<&'a mut T> {
if self.is::<T>() {
Some(unsafe { transmute(self.as_mut_void_ptr()) })
} else {
None
}
}
}
/// Extension methods for a owning `Any` trait object
pub trait AnyOwnExt {
/// Returns the boxed value if it is of type `T`, or
/// `Err(Self)` if it isn't.
fn move<T: 'static>(self) -> Result<~T, Self>;
}
impl AnyOwnExt for ~Any {
#[inline]
fn move<T: 'static>(self) -> Result<~T, ~Any> {
if self.is::<T>() {
unsafe {
// Extract the pointer to the boxed value, temporary alias with self
let ptr: ~T = transmute(self.as_void_ptr());
// Prevent destructor on self being run
intrinsics::forget(self);
Ok(ptr)
}
} else {
Err(self)
}
}
}
///////////////////////////////////////////////////////////////////////////////
// Trait implementations
///////////////////////////////////////////////////////////////////////////////
impl ToStr for ~Any {
fn to_str(&self) -> ~str { ~"~Any" }
}
impl<'a> ToStr for &'a Any {
fn to_str(&self) -> ~str { ~"&Any" }
}
#[cfg(test)]
mod tests {
use prelude::*;
use super::*;
#[deriving(Eq)]
struct Test;
static TEST: &'static str = "Test";
#[test]
fn any_as_void_ptr() {
let (a, b, c) = (~5u as ~Any, ~TEST as ~Any, ~Test as ~Any);
let a_r: &Any = a;
let b_r: &Any = b;
let c_r: &Any = c;
assert_eq!(a.as_void_ptr(), a_r.as_void_ptr());
assert_eq!(b.as_void_ptr(), b_r.as_void_ptr());
assert_eq!(c.as_void_ptr(), c_r.as_void_ptr());
let (a, b, c) = (@5u as @Any, @TEST as @Any, @Test as @Any);
let a_r: &Any = a;
let b_r: &Any = b;
let c_r: &Any = c;
assert_eq!(a.as_void_ptr(), a_r.as_void_ptr());
assert_eq!(b.as_void_ptr(), b_r.as_void_ptr());
assert_eq!(c.as_void_ptr(), c_r.as_void_ptr());
let (a, b, c) = (&5u as &Any, &TEST as &Any, &Test as &Any);
let a_r: &Any = a;
let b_r: &Any = b;
let c_r: &Any = c;
assert_eq!(a.as_void_ptr(), a_r.as_void_ptr());
assert_eq!(b.as_void_ptr(), b_r.as_void_ptr());
assert_eq!(c.as_void_ptr(), c_r.as_void_ptr());
let mut x = Test;
let mut y: &'static str = "Test";
let (a, b, c) = (&mut 5u as &mut Any,
&mut y as &mut Any,
&mut x as &mut Any);
let a_r: &Any = a;
let b_r: &Any = b;
let c_r: &Any = c;
assert_eq!(a.as_void_ptr(), a_r.as_void_ptr());
assert_eq!(b.as_void_ptr(), b_r.as_void_ptr());
assert_eq!(c.as_void_ptr(), c_r.as_void_ptr());
let (a, b, c) = (5u, "hello", Test);
let (a_r, b_r, c_r) = (&a as &Any, &b as &Any, &c as &Any);
assert_eq!(a.as_void_ptr(), a_r.as_void_ptr());
assert_eq!(b.as_void_ptr(), b_r.as_void_ptr());
assert_eq!(c.as_void_ptr(), c_r.as_void_ptr());
}
#[test]
fn any_as_mut_void_ptr() {
let y: &'static str = "Test";
let mut a = ~5u as ~Any;
let mut b = ~y as ~Any;
let mut c = ~Test as ~Any;
let a_ptr = a.as_mut_void_ptr();
let b_ptr = b.as_mut_void_ptr();
let c_ptr = c.as_mut_void_ptr();
let a_r: &mut Any = a;
let b_r: &mut Any = b;
let c_r: &mut Any = c;
assert_eq!(a_ptr, a_r.as_mut_void_ptr());
assert_eq!(b_ptr, b_r.as_mut_void_ptr());
assert_eq!(c_ptr, c_r.as_mut_void_ptr());
let mut x = Test;
let mut y: &'static str = "Test";
let a = &mut 5u as &mut Any;
let b = &mut y as &mut Any;
let c = &mut x as &mut Any;
let a_ptr = a.as_mut_void_ptr();
let b_ptr = b.as_mut_void_ptr();
let c_ptr = c.as_mut_void_ptr();
let a_r: &mut Any = a;
let b_r: &mut Any = b;
let c_r: &mut Any = c;
assert_eq!(a_ptr, a_r.as_mut_void_ptr());
assert_eq!(b_ptr, b_r.as_mut_void_ptr());
assert_eq!(c_ptr, c_r.as_mut_void_ptr());
let y: &'static str = "Test";
let mut a = 5u;
let mut b = y;
let mut c = Test;
let a_ptr = a.as_mut_void_ptr();
let b_ptr = b.as_mut_void_ptr();
let c_ptr = c.as_mut_void_ptr();
let (a_r, b_r, c_r) = (&mut a as &mut Any, &mut b as &mut Any, &mut c as &mut Any);
assert_eq!(a_ptr, a_r.as_mut_void_ptr());
assert_eq!(b_ptr, b_r.as_mut_void_ptr());
assert_eq!(c_ptr, c_r.as_mut_void_ptr());
}
#[test]
fn any_referenced() {
let (a, b, c) = (&5u as &Any, &TEST as &Any, &Test as &Any);
assert!(a.is::<uint>());
assert!(!b.is::<uint>());
assert!(!c.is::<uint>());
assert!(!a.is::<&'static str>());
assert!(b.is::<&'static str>());
assert!(!c.is::<&'static str>());
assert!(!a.is::<Test>());
assert!(!b.is::<Test>());
assert!(c.is::<Test>());
}
#[test]
fn any_owning() {
let (a, b, c) = (~5u as ~Any, ~TEST as ~Any, ~Test as ~Any);
assert!(a.is::<uint>());
assert!(!b.is::<uint>());
assert!(!c.is::<uint>());
assert!(!a.is::<&'static str>());
assert!(b.is::<&'static str>());
assert!(!c.is::<&'static str>());
assert!(!a.is::<Test>());
assert!(!b.is::<Test>());
assert!(c.is::<Test>());
}
#[test]
fn any_managed() {
let (a, b, c) = (@5u as @Any, @TEST as @Any, @Test as @Any);
assert!(a.is::<uint>());
assert!(!b.is::<uint>());
assert!(!c.is::<uint>());
assert!(!a.is::<&'static str>());
assert!(b.is::<&'static str>());
assert!(!c.is::<&'static str>());
assert!(!a.is::<Test>());
assert!(!b.is::<Test>());
assert!(c.is::<Test>());
}
#[test]
fn any_as_ref() {
let a = &5u as &Any;
match a.as_ref::<uint>() {
Some(&5) => {}
x => fail!("Unexpected value {:?}", x)
}
match a.as_ref::<Test>() {
None => {}
x => fail!("Unexpected value {:?}", x)
}
}
#[test]
fn any_as_mut() {
let mut a = 5u;
let mut b = ~7u;
let a_r = &mut a as &mut Any;
let tmp: &mut uint = b;
let b_r = tmp as &mut Any;
match a_r.as_mut::<uint>() {
Some(x) => {
assert_eq!(*x, 5u);
*x = 612;
}
x => fail!("Unexpected value {:?}", x)
}
match b_r.as_mut::<uint>() {
Some(x) => {
assert_eq!(*x, 7u);
*x = 413;
}
x => fail!("Unexpected value {:?}", x)
}
match a_r.as_mut::<Test>() {
None => (),
x => fail!("Unexpected value {:?}", x)
}
match b_r.as_mut::<Test>() {
None => (),
x => fail!("Unexpected value {:?}", x)
}
match a_r.as_mut::<uint>() {
Some(&612) => {}
x => fail!("Unexpected value {:?}", x)
}
match b_r.as_mut::<uint>() {
Some(&413) => {}
x => fail!("Unexpected value {:?}", x)
}
}
#[test]
fn any_move() {
let a = ~8u as ~Any;
let b = ~Test as ~Any;
match a.move::<uint>() {
Ok(a) => { assert_eq!(a, ~8u); }
Err(..) => fail!()
}
match b.move::<Test>() {
Ok(a) => { assert_eq!(a, ~Test); }
Err(..) => fail!()
}
let a = ~8u as ~Any;
let b = ~Test as ~Any;
assert!(a.move::<~Test>().is_err());
assert!(b.move::<~uint>().is_err());
}
}