export_fn: add "name" parameter

codegen/src/function.rs

@@ -2,12 +2,45 @@
 use quote::{quote, quote_spanned};
 use syn::{parse::Parse, parse::ParseStream, spanned::Spanned};
 
+#[derive(Debug, Default)]
+pub(crate) struct ExportedFnParams {
+    name: Option<String>,
+}
+
+impl Parse for ExportedFnParams {
+    fn parse(args: ParseStream) -> syn::Result<Self> {
+        if args.is_empty() {
+            return Ok(ExportedFnParams::default());
+        }
+        let assignment: syn::ExprAssign = args.parse()?;
+
+        let attr_name: syn::Ident = match assignment.left.as_ref() {
+            syn::Expr::Path(syn::ExprPath { path: attr_path, .. }) => attr_path.get_ident().cloned()
+                .ok_or_else(|| syn::Error::new(attr_path.span(), "expecting attribute name"))?,
+            x => return Err(syn::Error::new(x.span(), "expecting attribute name")),
+        };
+        if &attr_name != "name" {
+            return Err(syn::Error::new(attr_name.span(), format!("unknown attribute '{}'", &attr_name)));
+        }
+
+        let attr_value: String = match assignment.right.as_ref() {
+            syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Str(string), .. }) => string.value(),
+            x => return Err(syn::Error::new(x.span(), "expecting string literal value")),
+        };
+
+        Ok(ExportedFnParams {
+            name: Some(attr_value),
+        })
+    }
+}
+
 #[derive(Debug)]
 pub(crate) struct ExportedFn {
     entire_span: proc_macro2::Span,
     signature: syn::Signature,
     is_public: bool,
     mut_receiver: bool,
+    params: ExportedFnParams,
 }
 
 impl Parse for ExportedFn {
@@ -111,6 +144,7 @@ impl Parse for ExportedFn {
             signature: fn_all.sig,
             is_public,
             mut_receiver,
+            params: ExportedFnParams::default(),
         })
     }
 }
@@ -148,11 +182,20 @@ impl ExportedFn {
         }
     }
 
+    pub fn generate_with_params(mut self,
+                                mut params: ExportedFnParams) -> proc_macro2::TokenStream {
+        self.params = params;
+        self.generate()
+    }
+
     pub fn generate(self) -> proc_macro2::TokenStream {
-        let name: syn::Ident = syn::Ident::new(
-            &format!("rhai_fn_{}", self.name().to_string()),
-            self.name().span(),
-        );
+        let name_str = if let Some(ref name) = self.params.name {
+            name.clone()
+        } else {
+            self.name().to_string()
+        };
+        let name: syn::Ident = syn::Ident::new(&format!("rhai_fn_{}", name_str),
+                                               self.name().span());
         let impl_block = self.generate_impl("Token");
         let callable_block = self.generate_callable("Token");
         let input_types_block = self.generate_input_types("Token");

codegen/src/lib.rs

@@ -76,12 +76,13 @@ mod rhai_module;
 
 #[proc_macro_attribute]
 pub fn export_fn(
-    _args: proc_macro::TokenStream,
+    args: proc_macro::TokenStream,
     input: proc_macro::TokenStream,
 ) -> proc_macro::TokenStream {
     let mut output = proc_macro2::TokenStream::from(input.clone());
+    let parsed_params = parse_macro_input!(args as function::ExportedFnParams);
     let function_def = parse_macro_input!(input as function::ExportedFn);
-    output.extend(function_def.generate());
+    output.extend(function_def.generate_with_params(parsed_params));
     proc_macro::TokenStream::from(output)
 }
 

codegen/tests/test_functions.rs

@@ -158,3 +158,35 @@ fn mut_opaque_ref_test() -> Result<(), Box<EvalAltResult>> {
     );
     Ok(())
 }
+
+mod rename_fn {
+    use rhai::plugin::*;
+    use rhai::FLOAT;
+
+    #[export_fn(name = "add_float")]
+    pub fn add(f1: FLOAT, f2: FLOAT) -> FLOAT {
+        f1 + f2
+    }
+}
+
+#[test]
+fn rename_fn_test() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+    engine.register_fn("get_mystic_number", || 42 as FLOAT);
+    let mut m = Module::new();
+    rhai::register_exported_fn!(m, "add_two_floats", rename_fn::add_float);
+    let mut r = StaticModuleResolver::new();
+    r.insert("Math::Advanced".to_string(), m);
+    engine.set_module_resolver(Some(r));
+
+    assert_eq!(
+        engine.eval::<FLOAT>(
+            r#"import "Math::Advanced" as math;
+           let x = get_mystic_number();
+           let y = math::add_two_floats(x, 1.0);
+           y"#
+        )?,
+        43.0
+    );
+    Ok(())
+}

codegen/ui_tests/export_fn_bad_attr.rs

@@ -0,0 +1,24 @@
+use rhai::plugin::*;
+
+#[derive(Clone)]
+struct Point {
+    x: f32,
+    y: f32,
+}
+
+#[export_fn(unknown = true)]
+pub fn test_fn(input: Point) -> bool {
+    input.x > input.y
+}
+
+fn main() {
+    let n = Point {
+        x: 0.0,
+        y: 10.0,
+    };
+    if test_fn(n) {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}

codegen/ui_tests/export_fn_bad_attr.stderr

@@ -0,0 +1,11 @@
+error: unknown attribute 'unknown'
+ --> $DIR/export_fn_bad_attr.rs:9:13
+  |
+9 | #[export_fn(unknown = true)]
+  |             ^^^^^^^
+
+error[E0425]: cannot find function `test_fn` in this scope
+  --> $DIR/export_fn_bad_attr.rs:19:8
+   |
+19 |     if test_fn(n) {
+   |        ^^^^^^^ not found in this scope

codegen/ui_tests/export_fn_bad_value.rs

@@ -0,0 +1,24 @@
+use rhai::plugin::*;
+
+#[derive(Clone)]
+struct Point {
+    x: f32,
+    y: f32,
+}
+
+#[export_fn(name = true)]
+pub fn test_fn(input: Point) -> bool {
+    input.x > input.y
+}
+
+fn main() {
+    let n = Point {
+        x: 0.0,
+        y: 10.0,
+    };
+    if test_fn(n) {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}

codegen/ui_tests/export_fn_bad_value.stderr

@@ -0,0 +1,11 @@
+error: expecting string literal value
+ --> $DIR/export_fn_bad_value.rs:9:20
+  |
+9 | #[export_fn(name = true)]
+  |                    ^^^^
+
+error[E0425]: cannot find function `test_fn` in this scope
+  --> $DIR/export_fn_bad_value.rs:19:8
+   |
+19 |     if test_fn(n) {
+   |        ^^^^^^^ not found in this scope

codegen/ui_tests/export_fn_junk_arg.rs

@@ -0,0 +1,24 @@
+use rhai::plugin::*;
+
+#[derive(Clone)]
+struct Point {
+    x: f32,
+    y: f32,
+}
+
+#[export_fn("wheeeee")]
+pub fn test_fn(input: Point) -> bool {
+    input.x > input.y
+}
+
+fn main() {
+    let n = Point {
+        x: 0.0,
+        y: 10.0,
+    };
+    if test_fn(n) {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}

codegen/ui_tests/export_fn_junk_arg.stderr

@@ -0,0 +1,11 @@
+error: expected assignment expression
+ --> $DIR/export_fn_junk_arg.rs:9:13
+  |
+9 | #[export_fn("wheeeee")]
+  |             ^^^^^^^^^
+
+error[E0425]: cannot find function `test_fn` in this scope
+  --> $DIR/export_fn_junk_arg.rs:19:8
+   |
+19 |     if test_fn(n) {
+   |        ^^^^^^^ not found in this scope