163 lines
3.7 KiB
Rust
163 lines
3.7 KiB
Rust
// Copyright 2012 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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/*!
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Module for wrapping freezable data structures in managed boxes.
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Normally freezable data structures require an unaliased reference,
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such as `T` or `~T`, so that the compiler can track when they are
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being mutated. The `managed<T>` type converts these static checks into
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dynamic checks: your program will fail if you attempt to perform
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mutation when the data structure should be immutable.
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*/
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#[forbid(deprecated_mode)];
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#[forbid(deprecated_pattern)];
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use util::with;
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use cast::transmute_immut;
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enum Mode { ReadOnly, Mutable, Immutable }
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struct Data<T> {
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priv mut value: T,
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priv mut mode: Mode
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}
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pub type Mut<T> = Data<T>;
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pub fn Mut<T>(t: T) -> Mut<T> {
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Data {value: move t, mode: ReadOnly}
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}
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pub fn unwrap<T>(m: Mut<T>) -> T {
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// Borrowck should prevent us from calling unwrap while the value
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// is in use, as that would be a move from a borrowed value.
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assert (m.mode as uint) == (ReadOnly as uint);
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let Data {value: move value, mode: _} = move m;
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move value
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}
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impl<T> Data<T> {
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fn borrow_mut<R>(op: &fn(t: &mut T) -> R) -> R {
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match self.mode {
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Immutable => die!(fmt!("%? currently immutable",
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self.value)),
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ReadOnly | Mutable => {}
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}
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do with(&mut self.mode, Mutable) {
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op(&mut self.value)
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}
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}
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pure fn borrow_const<R>(op: &fn(t: &const T) -> R) -> R {
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op(&const self.value)
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}
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fn borrow_imm<R>(op: &fn(t: &T) -> R) -> R {
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match self.mode {
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Mutable => die!(fmt!("%? currently mutable",
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self.value)),
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ReadOnly | Immutable => {}
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}
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do with(&mut self.mode, Immutable) {
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op(unsafe{transmute_immut(&mut self.value)})
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}
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}
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#[inline(always)]
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fn unwrap(self) -> T { unwrap(self) }
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}
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#[test]
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#[ignore(cfg(windows))]
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#[should_fail]
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pub fn test_mut_in_imm() {
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let m = @Mut(1);
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do m.borrow_imm |_p| {
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do m.borrow_mut |_q| {
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// should not be permitted
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}
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}
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}
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#[test]
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#[ignore(cfg(windows))]
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#[should_fail]
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pub fn test_imm_in_mut() {
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let m = @Mut(1);
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do m.borrow_mut |_p| {
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do m.borrow_imm |_q| {
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// should not be permitted
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}
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}
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}
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#[test]
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pub fn test_const_in_mut() {
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let m = @Mut(1);
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do m.borrow_mut |p| {
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do m.borrow_const |q| {
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assert *p == *q;
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*p += 1;
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assert *p == *q;
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}
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}
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}
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#[test]
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pub fn test_mut_in_const() {
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let m = @Mut(1);
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do m.borrow_const |p| {
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do m.borrow_mut |q| {
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assert *p == *q;
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*q += 1;
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assert *p == *q;
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}
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}
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}
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#[test]
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pub fn test_imm_in_const() {
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let m = @Mut(1);
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do m.borrow_const |p| {
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do m.borrow_imm |q| {
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assert *p == *q;
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}
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}
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}
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#[test]
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pub fn test_const_in_imm() {
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let m = @Mut(1);
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do m.borrow_imm |p| {
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do m.borrow_const |q| {
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assert *p == *q;
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}
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}
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}
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#[test]
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#[ignore(cfg(windows))]
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#[should_fail]
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pub fn test_mut_in_imm_in_const() {
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let m = @Mut(1);
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do m.borrow_const |_p| {
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do m.borrow_imm |_q| {
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do m.borrow_mut |_r| {
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}
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}
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}
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}
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