[oden] Native Modules

oden-js/src/lib.rs

@@ -1,3 +1,5 @@
+use oden_js_sys as sys;
+use std::ffi::{CString, NulError};
 use thiserror::Error;
 
 mod atom;
@@ -5,6 +7,7 @@ mod callback;
 mod class;
 mod context;
 mod conversion;
+pub mod module;
 mod runtime;
 mod value;
 
@@ -36,8 +39,51 @@ pub enum Error {
     ConversionError(String),
     #[error("an error occurred calling a rust function: {0}")]
     RustFunctionError(String),
-    #[error("an exception was thrown during evaluation")]
-    Exception(Value),
+    #[error("an exception was thrown during evaluation: {1}")]
+    Exception(Value, String),
+    #[error("out of memory")]
+    OutOfMemory,
 }
+
+impl From<NulError> for Error {
+    fn from(_: NulError) -> Self {
+        Error::UnexpectedNul
+    }
+}
+
 pub type Result<T> = core::result::Result<T, Error>;
 pub type ValueResult = core::result::Result<Value, Error>;
+
+pub fn throw_string(context: &ContextRef, message: String) -> sys::JSValue {
+    let ctx = context.ctx;
+    match context.new_string(&message) {
+        Ok(e) => unsafe {
+            // Because context.new_string yields an owned Value, and will
+            // clean it up on the way out, we need to explicitly DupValue a
+            // reference for the `Throw` to own.
+            let err = sys::JS_NewError(ctx);
+            if sys::JS_ValueGetTag(err) == sys::JS_TAG_EXCEPTION {
+                // GIVE UP; this is out of memory anyway things probably went
+                // wrong because of that.
+                return err;
+            }
+
+            sys::JS_DupValue(ctx, e.val); // SetProperty takes ownership.
+            let prop = CString::new("message").unwrap();
+            if sys::JS_SetPropertyStr(ctx, err, prop.as_ptr(), e.val) == -1 {
+                // Also an out of memory but we need to free the error object
+                // on our way out.
+                sys::JS_FreeValue(ctx, err);
+                return sys::JS_MakeException(); // JS_EXCEPTION
+            }
+
+            sys::JS_Throw(ctx, err)
+        },
+        Err(_) => unsafe {
+            sys::JS_Throw(
+                ctx,
+                sys::JS_NewString(ctx, "Errors within errors: embedded nulls in the description of the error that occurred".as_bytes().as_ptr() as *const i8),
+            )
+        },
+    }
+}