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|
// Copyright 2012 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.
/*! Condition handling */
use local_data::{local_data_pop, local_data_set};
use local_data;
use prelude::*;
// helper for transmutation, shown below.
type RustClosure = (int, int);
pub struct Handler<T, U> {
handle: RustClosure,
prev: Option<@Handler<T, U>>,
}
pub struct Condition<'self, T, U> {
name: &'static str,
key: local_data::LocalDataKey<'self, Handler<T, U>>
}
pub impl<'self, T, U> Condition<'self, T, U> {
fn trap(&'self self, h: &'self fn(T) -> U) -> Trap<'self, T, U> {
unsafe {
let p : *RustClosure = ::cast::transmute(&h);
let prev = local_data::local_data_get(self.key);
let h = @Handler { handle: *p, prev: prev };
Trap { cond: self, handler: h }
}
}
fn raise(&self, t: T) -> U {
let msg = fmt!("Unhandled condition: %s: %?", self.name, t);
self.raise_default(t, || fail!(copy msg))
}
fn raise_default(&self, t: T, default: &fn() -> U) -> U {
unsafe {
match local_data_pop(self.key) {
None => {
debug!("Condition.raise: found no handler");
default()
}
Some(handler) => {
debug!("Condition.raise: found handler");
match handler.prev {
None => {}
Some(hp) => local_data_set(self.key, hp)
}
let handle : &fn(T) -> U =
::cast::transmute(handler.handle);
let u = handle(t);
local_data_set(self.key, handler);
u
}
}
}
}
}
struct Trap<'self, T, U> {
cond: &'self Condition<'self, T, U>,
handler: @Handler<T, U>
}
pub impl<'self, T, U> Trap<'self, T, U> {
fn in<V>(&self, inner: &'self fn() -> V) -> V {
unsafe {
let _g = Guard { cond: self.cond };
debug!("Trap: pushing handler to TLS");
local_data_set(self.cond.key, self.handler);
inner()
}
}
}
struct Guard<'self, T, U> {
cond: &'self Condition<'self, T, U>
}
#[unsafe_destructor]
impl<'self, T, U> Drop for Guard<'self, T, U> {
fn finalize(&self) {
unsafe {
debug!("Guard: popping handler from TLS");
let curr = local_data_pop(self.cond.key);
match curr {
None => {}
Some(h) => match h.prev {
None => {}
Some(hp) => local_data_set(self.cond.key, hp)
}
}
}
}
}
#[cfg(test)]
mod test {
condition! {
sadness: int -> int;
}
fn trouble(i: int) {
debug!("trouble: raising condition");
let j = sadness::cond.raise(i);
debug!("trouble: handler recovered with %d", j);
}
fn nested_trap_test_inner() {
let mut inner_trapped = false;
do sadness::cond.trap(|_j| {
debug!("nested_trap_test_inner: in handler");
inner_trapped = true;
0
}).in {
debug!("nested_trap_test_inner: in protected block");
trouble(1);
}
assert!(inner_trapped);
}
#[test]
fn nested_trap_test_outer() {
let mut outer_trapped = false;
do sadness::cond.trap(|_j| {
debug!("nested_trap_test_outer: in handler");
outer_trapped = true; 0
}).in {
debug!("nested_guard_test_outer: in protected block");
nested_trap_test_inner();
trouble(1);
}
assert!(outer_trapped);
}
fn nested_reraise_trap_test_inner() {
let mut inner_trapped = false;
do sadness::cond.trap(|_j| {
debug!("nested_reraise_trap_test_inner: in handler");
inner_trapped = true;
let i = 10;
debug!("nested_reraise_trap_test_inner: handler re-raising");
sadness::cond.raise(i)
}).in {
debug!("nested_reraise_trap_test_inner: in protected block");
trouble(1);
}
assert!(inner_trapped);
}
#[test]
fn nested_reraise_trap_test_outer() {
let mut outer_trapped = false;
do sadness::cond.trap(|_j| {
debug!("nested_reraise_trap_test_outer: in handler");
outer_trapped = true; 0
}).in {
debug!("nested_reraise_trap_test_outer: in protected block");
nested_reraise_trap_test_inner();
}
assert!(outer_trapped);
}
#[test]
fn test_default() {
let mut trapped = false;
do sadness::cond.trap(|j| {
debug!("test_default: in handler");
sadness::cond.raise_default(j, || { trapped=true; 5 })
}).in {
debug!("test_default: in protected block");
trouble(1);
}
assert!(trapped);
}
// Issue #6009
mod m {
condition! {
sadness: int -> int;
}
mod n {
use super::sadness;
#[test]
fn test_conditions_are_public() {
let mut trapped = false;
do sadness::cond.trap(|_| {
trapped = true;
0
}).in {
sadness::cond.raise(0);
}
assert!(trapped);
}
}
}
}
|
