start adding closure subroutines

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
 [[package]]
 name = "pkg-config"
 version = "0.3.19"
@@ -30,6 +36,7 @@ dependencies = [
 name = "rust-guile"
 version = "0.1.6"
 dependencies = [
+ "lazy_static",
  "pkg-config",
  "thiserror",
 ]

Cargo.toml

@@ -12,6 +12,7 @@ readme = "Readme.md"
 
 [dependencies]
 thiserror = "1.0"
+lazy_static = "1.4"
 
 [build-dependencies]
 pkg-config = "0.3"

src/api/mod.rs

@@ -1,4 +1,5 @@
 mod exec;
+pub mod subroutines;
 pub use exec::exec_with_guile;
 
 use std::{ffi::{c_void, CString}, path::PathBuf, os::unix::prelude::OsStrExt, fs::canonicalize};

src/api/subroutines.rs

@@ -0,0 +1,47 @@
+use std::{cell::RefCell, rc::Rc, collections::HashMap, sync::{Mutex, atomic::{AtomicU32, AtomicBool, Ordering}}, ffi::{CString, c_void}};
+
+use lazy_static::lazy_static;
+
+use crate::{bindings::{SCM, scm_c_define_gsubr}, try_scm_decons, data::raw::{SCM_BOOL_F, try_scm_to_unsigned}, scm_car_unchecked};
+
+lazy_static! {
+    static ref SUBROUTINES: Mutex<Vec<Box<dyn Fn(SCM) -> SCM + Send>>> = {
+        Mutex::new(vec![])
+    };
+    static ref SUBROUTINE_INDEX: AtomicU32 = AtomicU32::new(0);
+    static ref SUBROUTINE_TRAMPOLINE_INITIALIZED: AtomicBool = AtomicBool::new(false);
+}
+
+const SUBROUTINE_TRAMPOLINE_NAME: &'static str = "rust-guile-subroutine-trampoline";
+
+pub fn register_subroutine<F>(name: &str, f: F)
+where F: Fn(SCM) -> SCM + Send + 'static {
+    if !SUBROUTINE_TRAMPOLINE_INITIALIZED.load(Ordering::Relaxed){
+        let name_cstr = CString::new(SUBROUTINE_TRAMPOLINE_NAME.as_bytes()).unwrap().into_bytes_with_nul();
+
+        unsafe {
+            scm_c_define_gsubr(name_cstr.as_ptr() as *const i8, 1, 0, 1, subroutine_trampoline as *mut c_void);
+        }
+
+        SUBROUTINE_TRAMPOLINE_INITIALIZED.store(true, Ordering::Relaxed);
+        SUBROUTINE_INDEX.fetch_add(1, Ordering::Relaxed); // this just happens to match the index that gets inserted into the vec
+    }
+
+    SUBROUTINES.lock().unwrap().push(Box::new(f))
+}
+
+extern "C" fn subroutine_trampoline(sub_id: SCM, sub_args: SCM) -> SCM {
+    println!("entered subroutine trampoline");
+    match try_scm_to_unsigned(sub_id) {
+        Some(sub_id) => {
+            if let Some(subroutine) = SUBROUTINES.lock().unwrap().get(sub_id as usize) {
+                println!("subroutine {} found", sub_id);
+                subroutine(sub_args)
+            } else {
+                println!("subroutine {} not found", sub_id);
+                SCM_BOOL_F
+            }
+        },
+        None => SCM_BOOL_F
+    }
+}