// 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.

#[doc(hidden)]; // FIXME #3538

use cast::transmute;

pub type Word = uint;

pub struct Frame {
    fp: *Word
}

pub fn Frame(fp: *Word) -> Frame {
    Frame {
        fp: fp
    }
}

pub fn walk_stack(visit: &fn(Frame) -> bool) {

    debug!("beginning stack walk");

    do frame_address |frame_pointer| {
        let mut frame_address: *Word = unsafe {
            transmute(frame_pointer)
        };
        loop {
            let fr = Frame(frame_address);

            debug!("frame: %x", unsafe { transmute(fr.fp) });
            visit(fr);

            unsafe {
                let next_fp: **Word = transmute(frame_address);
                frame_address = *next_fp;
                if *frame_address == 0u {
                    debug!("encountered task_start_wrapper. ending walk");
                    // This is the task_start_wrapper_frame. There is
                    // no stack beneath it and it is a foreign frame.
                    break;
                }
            }
        }
    }
}

#[test]
fn test_simple() {
    for walk_stack |_frame| {
    }
}

#[test]
fn test_simple_deep() {
    fn run(i: int) {
        if i == 0 { return }

        for walk_stack |_frame| {
            // Would be nice to test something here...
        }
        run(i - 1);
    }

    run(10);
}

fn frame_address(f: &fn(x: *u8)) {
    unsafe {
        rusti::frame_address(f)
    }
}

pub mod rusti {
    #[abi = "rust-intrinsic"]
    pub extern "rust-intrinsic" {
        pub fn frame_address(f: &once fn(x: *u8));
    }
}