breaktarget 0.1.0

Implementation of nonlocal breaks in Rust

Crate breaktarget [] [src]

The breaktarget module defines one type: The BreakTarget type. A value of this type may be obtained by invoking BreakTarget::deploy.

BreakTarget::deploy takes a lambda, which is passed a reference to a BreakTarget. This object defines a single method, break_with, which takes a value of type T and returns control flow to the site of the BreakTarget::deploy call, producing the value as the result. If the lambda exits normally, it must also produce a value of type T, which is produced as the result of the BreakTarget::deploy call.

Important Notes

The nonlocal breaking is implemented using a panic to unwind the stack. Any open Mutexes which are closed by this unwinding will be poisoned, among with other unwinding specific effects.

If panic = abort is enabled, calls to break_with will abort the program

Examples

use breaktarget::BreakTarget;

let result = BreakTarget::deploy(|target| {
    // ... Some logic here
    target.break_with(10i32);
    // ... Some logic here
});
assert_eq!(result, 10i32);
use breaktarget::BreakTarget;

fn some_function(target: &BreakTarget<i32>, cond: bool) {
   if cond {
       target.break_with(10);
   }
}

let result1 = BreakTarget::deploy(|target| {
    some_function(target, false);
    20
});
assert_eq!(result1, 20);

let result2 = BreakTarget::deploy(|target| {
    some_function(target, true);
    20
});
assert_eq!(result2, 10);

Structs

BreakTarget

This object represents the target stack frame which we will unwind toward when the break_with method is invoked. The value which we are breaking with will be stored within the BreakTarget to be returned when control flow resumes.