cfor 1.1.0

A macro that gives Rust a C-style for loop, with initialisation, condition and step. This correctly handles control-flow like continue and break.
Documentation 
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#![crate_type = "lib"]

extern crate test;

pub macro_rules! cfor {

    // for ($init; $cond; $step) { $body }
    ($init: stmt; $cond: expr; $step: expr $body: block) => {
        {
            $init;
            while $cond {
                let mut _first = true;
                let mut _continue = false;
                // this loop runs once, allowing us to implement
                // `goto` to skip forward to the condition.
                //
                // the booleans above are very transparent to the
                // optimiser, since they are modified exactly once,
                // with nice control flow, and this this optimises to
                // be similar to C for loop.
                loop {
                    // if we *don't* hit this, there was a `break` in
                    // the body (otherwise the loop fell-through or
                    // was `continue`d.)
                    if !_first { _continue = true; break }
                    _first = false;

                    $body
                }
                if !_continue {
                    break
                }

                $step
            }
        }
    };
}

macro_rules! cfor2 {

    // for ($init; $cond; $step) { $body }
    ($init: stmt; $cond: expr; $step: expr $body: block) => {
        {
            let mut _first = true;
            $init;
            while {
                if !_first {
                    $step
                }
                _first = false;
                $cond
            } $body
        }
    };
}


pub fn foo(x: uint) {
    cfor!{let (mut i, mut j) = (0u, 0u); i + j < x; { i += 1; j += 1 } {
        test::black_box(i);
    }}
}
pub fn bar(x: uint) {
    cfor2!{let (mut i, mut j) = (0u, 0u); i + j < x; { i += 1; j += 1 } {
        test::black_box(i);
    }}
}