Simple PDCurses Window Movement in Rust

main.rs

extern crate libc;

use libc::{c_ulong, c_int, c_char};
use std::ffi::{CString};

#[allow(non_camel_case_types)]
pub type c_bool = ::libc::c_uchar;
pub type Chtype = c_ulong;
pub type Window = *mut i8;
pub type CharP = *const c_char;

trait ToCStr {
    fn to_c_str(&self) -> CString;
}

impl <'a>ToCStr for &'a str {
    fn to_c_str(&self) -> CString {
        CString::new(*self).unwrap()
    }
}

// From: https://github.com/rust-lang/rfcs/issues/1010#issuecomment-169712438
macro_rules! finally {
    ($contents:block) => {
        struct A;
        impl Drop for A {
            fn drop(&mut self) {
                { $contents };
            }
        }
        let a = A;
    };
}

#[link(name = "pdcurses", kind = "static")]
extern {
    fn initscr() -> Window;
    fn endwin() -> c_int;
    fn noecho() -> c_int;
    fn cbreak() -> c_int;
    fn curs_set(_: c_int) -> c_int;
    fn waddstr(_: Window, _: CharP) -> c_int;
    fn wnoutrefresh(_: Window) -> c_int;
    fn getmaxx(_: Window) -> c_int;
    fn getmaxy(_: Window) -> c_int;
    fn newwin(_: c_int, _: c_int, _: c_int, _: c_int) -> Window;
    fn keypad(_: Window, _: c_bool) -> c_int;
    fn werase(_: Window) -> c_int;
    fn mvwin(_: Window, _: c_int, _: c_int) -> c_int;
    #[link_name="box"]
    fn box_(_: Window, _: Chtype, _: Chtype) -> c_int;
    fn doupdate() -> c_int;
    fn wgetch(_: Window) -> c_int;
}

const ERR: i32 = -1;
const VLINE: Chtype = '|' as Chtype;
const HLINE: Chtype = '-' as Chtype;
const KEY_Q: c_int = 'q' as c_int;
const KEY_DOWN: i32 = 0x102;
const KEY_UP: i32 = 0x103;
const KEY_LEFT: i32 = 0x104;
const KEY_RIGHT: i32 = 0x105;

fn main() {
    // From: https://github.com/rthornton128/goncurses/blob/master/examples/window/window.go
    unsafe {
        let stdscr = initscr();
        finally! {{ unsafe { endwin(); } }}
        assert!(!stdscr.is_null());
        noecho();
        cbreak();
        assert!(curs_set(0) != ERR);
        waddstr(stdscr, "Use arrow keys to move the window. Press 'q' to exit".to_c_str().as_ptr());
        wnoutrefresh(stdscr);

        let (rows, cols) = (getmaxy(stdscr), getmaxx(stdscr));
        let (height, width) = (5, 10);
        let (mut y, mut x) = ((rows - height) / 2, (cols - width) / 2);

        let win = newwin(height, width, y, x);
        assert!(!win.is_null());
        assert!(keypad(win, true as c_bool) != ERR);

        loop {
            werase(win);
            wnoutrefresh(win);
            mvwin(win, y, x);
            box_(win, VLINE, HLINE);
            wnoutrefresh(win);
            assert!(doupdate() != ERR);
            match wgetch(win) {
                KEY_Q => break,
                KEY_LEFT if x > 0 => x -= 1,
                KEY_RIGHT if x < cols - width => x += 1,
                KEY_UP if y > 1 => y -= 1,
                KEY_DOWN if y < rows - height => y += 1,
                _ => (),
            }
        }
    }
}