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use std::ffi::{CStr, CString};
use std::os::raw::{c_char, c_int, c_void};
#[link(name = "guile-3.0")]
#[allow(dead_code)]
extern "C" {
fn scm_init_guile();
fn scm_c_define_gsubr(
name: *const c_char,
req: c_int,
opt: c_int,
rst: c_int,
func: extern "C" fn() -> *mut c_void,
);
fn scm_c_eval_string(expr: *const c_char) -> *mut c_void;
fn scm_to_locale_string(scm_obj: *mut c_void) -> *const c_char;
fn scm_c_write(scm_obj: *mut c_void, port: *mut c_void);
fn scm_open_output_string() -> *mut c_void;
fn scm_get_output_string(port: *mut c_void) -> *mut c_void;
fn scm_is_string(scm_obj: *mut c_void) -> c_int;
fn scm_is_number(scm_obj: *mut c_void) -> c_int;
fn scm_object_to_string(scm_obj: *mut c_void, printer: *mut c_void) -> *mut c_void;
}
#[link(name = "guiledefs")]
extern "C" {
pub static scm_undefined: *mut c_void;
}
extern "C" fn my_rust_function() -> *mut c_void {
println!("Hello from Rust!");
unsafe { scm_undefined }
}
/// Convert a scm object into a string using Guile-builtins
fn string_from_scm(scm_obj: *mut c_void) -> Result<String, ()> {
unsafe {
if scm_obj.is_null() {
return Err(());
}
if scm_is_string(scm_obj) != 0 {
let res_str = CStr::from_ptr(scm_to_locale_string(scm_obj))
.to_string_lossy()
.into_owned();
return Ok(res_str);
} else {
let port = scm_open_output_string();
if port.is_null() {
return Err(());
}
let res = scm_object_to_string(scm_obj, scm_undefined);
if res.is_null() {
return Err(());
}
let res_str = CStr::from_ptr(scm_to_locale_string(res))
.to_string_lossy()
.into_owned();
return Ok(res_str);
}
}
}
pub fn smp_guile_init() {}
pub fn testguile() {
unsafe {
scm_init_guile();
let func_name = CString::new("my-rust-function").unwrap();
scm_c_define_gsubr(
func_name.as_ptr(),
0, // required arguments
0, // optional arguments
0, // rest arguments
my_rust_function,
);
let expr = CString::new("(+ 2 3)").unwrap();
let result = scm_c_eval_string(expr.as_ptr());
println!("{:?}", string_from_scm(result));
let expr = CString::new("(my-rust-function)").unwrap();
let result = scm_c_eval_string(expr.as_ptr());
println!("{:?}", string_from_scm(result));
}
}
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