Add FnPtr to get_literal_value.

src/api/custom_syntax.rs

@@ -131,9 +131,10 @@ impl Expression<'_> {
     /// Returns [`None`] also if the constant is not of the specified type.
     #[inline]
     #[must_use]
-    pub fn get_literal_value<T: Variant>(&self) -> Option<T> {
+    pub fn get_literal_value<T: Variant + Clone>(&self) -> Option<T> {
         // Coded this way in order to maximally leverage potentials for dead-code removal.
         match self.0 {
+            Expr::DynamicConstant(x, ..) => x.clone().try_cast::<T>(),
             Expr::IntegerConstant(x, ..) => reify! { *x => Option<T> },
 
             #[cfg(not(feature = "no_float"))]

tests/custom_syntax.rs

@@ -1,6 +1,6 @@
 #![cfg(not(feature = "no_custom_syntax"))]
 
-use rhai::{Dynamic, Engine, EvalAltResult, ImmutableString, LexError, ParseErrorType, Position, Scope, INT};
+use rhai::{Dynamic, Engine, EvalAltResult, FnPtr, ImmutableString, LexError, ParseErrorType, Position, Scope, INT};
 
 #[test]
 fn test_custom_syntax() {
@@ -278,7 +278,7 @@ fn test_custom_syntax_func() {
     let mut engine = Engine::new();
 
     engine
-        .register_custom_syntax(["hello", "$func$"], false, |context, inputs| context.eval_expression_tree(&inputs[0]))
+        .register_custom_syntax(["hello", "$func$"], false, |_, inputs| Ok(inputs[0].get_literal_value::<FnPtr>().unwrap().into()))
         .unwrap();
 
     assert_eq!(engine.eval::<INT>("call(hello |x| { x + 1 }, 41)").unwrap(), 42);