Create NativeCallable trait.

src/fn_native.rs

@@ -0,0 +1,52 @@
+use crate::any::Dynamic;
+use crate::result::EvalAltResult;
+use crate::token::Position;
+
+use crate::stdlib::{boxed::Box, rc::Rc, sync::Arc};
+
+pub type FnCallArgs<'a> = [&'a mut Dynamic];
+
+#[cfg(feature = "sync")]
+pub type FnAny =
+    dyn Fn(&mut FnCallArgs, Position) -> Result<Dynamic, Box<EvalAltResult>> + Send + Sync;
+#[cfg(not(feature = "sync"))]
+pub type FnAny = dyn Fn(&mut FnCallArgs, Position) -> Result<Dynamic, Box<EvalAltResult>>;
+
+#[cfg(feature = "sync")]
+pub type IteratorFn = dyn Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + Send + Sync;
+#[cfg(not(feature = "sync"))]
+pub type IteratorFn = dyn Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>>;
+
+/// A trait implemented by all native Rust functions that are callable by Rhai.
+pub trait NativeCallable {
+    /// Call a native Rust function.
+    fn call(&self, args: &mut FnCallArgs, pos: Position) -> Result<Dynamic, Box<EvalAltResult>>;
+}
+
+/// A type encapsulating a native Rust function callable by Rhai.
+pub struct NativeFunction(Box<FnAny>);
+
+impl NativeCallable for NativeFunction {
+    fn call(&self, args: &mut FnCallArgs, pos: Position) -> Result<Dynamic, Box<EvalAltResult>> {
+        (self.0)(args, pos)
+    }
+}
+
+impl From<Box<FnAny>> for NativeFunction {
+    fn from(func: Box<FnAny>) -> Self {
+        Self::new(func)
+    }
+}
+impl NativeFunction {
+    /// Create a new `NativeFunction`.
+    pub fn new(func: Box<FnAny>) -> Self {
+        Self(func)
+    }
+}
+
+/// An external native Rust function.
+#[cfg(not(feature = "sync"))]
+pub type SharedNativeFunction = Rc<Box<dyn NativeCallable>>;
+/// An external native Rust function.
+#[cfg(feature = "sync")]
+pub type SharedNativeFunction = Arc<Box<dyn NativeCallable>>;