Add some basic bindings for Guile-3.0

1 files changed, 86 insertions, 0 deletions

diff --git a/src/guile/guile.rs b/src/guile/guile.rs
new file mode 100644
index 0000000..4a0e25b
--- /dev/null
+++ b/src/guile/guile.rs
@@ -0,0 +1,86 @@
+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));
+    }
+}