lib.rs

extern crate libc;
extern crate fst;

use std::ffi::{CStr,CString};
use std::fs::File;
use std::io;
use std::mem;
use fst::{IntoStreamer, Streamer, Levenshtein, Set, SetBuilder};

fn cstr_to_str<'a>(s: *mut libc::c_char) -> &'a str {
    let cstr = unsafe { CStr::from_ptr(s) };
    cstr.to_str().unwrap()
}

#[no_mangle]
pub extern fn cleanup_str(s: *mut libc::c_char) {
    unsafe { CString::from_raw(s) };
}

pub type FileSetBuilder = SetBuilder<&'static mut io::BufWriter<File>>;

#[no_mangle]
pub extern fn bufwriter_new(s: *mut libc::c_char) -> *mut io::BufWriter<File> {
    let path = cstr_to_str(s);
    Box::into_raw(Box::new(io::BufWriter::new(File::create(path).unwrap())))
}

#[no_mangle]
pub extern fn fst_setbuilder_new(wtr_ptr: *mut io::BufWriter<File>) -> *mut FileSetBuilder {
    let wtr = unsafe {
        assert!(!wtr_ptr.is_null());
        &mut *wtr_ptr
    };
    let build = SetBuilder::new(wtr).unwrap();
    Box::into_raw(Box::new(build))
}

#[no_mangle]
pub extern fn fst_setbuilder_insert(ptr: *mut FileSetBuilder, s: *mut libc::c_char) {
    let build = unsafe {
        assert!(!ptr.is_null());
        &mut *ptr
    };
    build.insert(cstr_to_str(s)).unwrap();
}

#[no_mangle]
pub extern fn fst_setbuilder_finish(ptr: *mut FileSetBuilder) {
    let build = unsafe {
        assert!(!ptr.is_null());
        &mut *ptr
    };
    /* This call fails with "cannot move out of borrowed content".
       The problem seems to be that build is a reference, whereas finish() expects
       an actual value. How can I solve this? */
    build.finish().unwrap()
}