Convert to pass-by-reference instead of pass-by-value (#678)

src/lntors/event.rs

@@ -101,7 +101,7 @@ pub fn generate(
                             // If it's a bound function, just call it with the argument, if there
                             // is one
                             let arg_str = match &handler_fn.microstatements[0] {
-                                Microstatement::Arg { name, .. } => name.clone(),
+                                Microstatement::Arg { name, .. } => format!("&{}", name).to_string(),
                                 _ => "".to_string(),
                             };
                             out = format!("{}            super::{}({});\n", out, b, arg_str);

src/lntors/function.rs

@@ -12,7 +12,14 @@ pub fn from_microstatement(
     mut out: OrderedHashMap<String, String>,
 ) -> Result<(String, OrderedHashMap<String, String>), Box<dyn std::error::Error>> {
     match microstatement {
-        Microstatement::Arg { .. } => Ok(("".to_string(), out)), // Skip arg microstatements that are just used for discovery during generation
+        Microstatement::Arg { name, .. } => {
+            // TODO: Update the serialization logic to understand values vs references so we can
+            // eliminate this useless (and harmful for mutable references) clone
+            Ok((
+                format!("let {} = {}.clone()", name, name).to_string(),
+                out,
+            ))
+        }
         Microstatement::Assignment {
             name,
             value,
@@ -24,8 +31,8 @@ pub fn from_microstatement(
             out = o;
             Ok((
                 format!(
-                    "let {} {} = {}",
-                    if *mutable { "mut" } else { "" },
+                    "let {}{} = {}",
+                    if *mutable { "mut " } else { "" },
                     name,
                     val,
                 )
@@ -103,7 +110,15 @@ pub fn from_microstatement(
                         for arg in args {
                             let (a, o) = from_microstatement(arg, scope, program, out)?;
                             out = o;
-                            argstrs.push(a);
+                            // If the argument is itself a function, this is the only place in Rust
+                            // where you can't pass by reference, so we check the type and change
+                            // the argument output accordingly.
+                            let arg_type = arg.get_type(scope, program)?;
+                            if arg_type.as_str() == "function" {
+                                argstrs.push(format!("{}", a));
+                            } else {
+                                argstrs.push(format!("&{}", a));
+                            }
                         }
                         Ok((
                             format!("{}({})", rustname, argstrs.join(", ")).to_string(),
@@ -115,7 +130,15 @@ pub fn from_microstatement(
                         for arg in args {
                             let (a, o) = from_microstatement(arg, scope, program, out)?;
                             out = o;
-                            argstrs.push(a);
+                            // If the argument is itself a function, this is the only place in Rust
+                            // where you can't pass by reference, so we check the type and change
+                            // the argument output accordingly.
+                            let arg_type = arg.get_type(scope, program)?;
+                            if arg_type.as_str() == "function" {
+                                argstrs.push(format!("{}", a));
+                            } else {
+                                argstrs.push(format!("&{}", a));
+                            }
                         }
                         Ok((
                             format!("{}({})", rustname, argstrs.join(", ")).to_string(),
@@ -157,7 +180,7 @@ pub fn generate(
     for arg in &function.args {
         if let Some((t, s)) = program.resolve_type(scope, &arg.1) {
             if let Ok(t_str) = typen::generate(t, s, program) {
-                arg_strs.push(format!("{}: {}", arg.0, t_str).to_string());
+                arg_strs.push(format!("{}: &{}", arg.0, t_str).to_string());
             } else {
                 return Err(format!("Failed to convert Alan type {} to Rust", &arg.1).into());
             }

src/std/root.ln

@@ -6,7 +6,7 @@
 // Integer-related bindings
 export type i8 binds i8;
 export type Result<i8> binds Result_i8;
-export fn ok(i: i8): Result<i8> binds Ok;
+export fn ok(i: i8): Result<i8> binds alan_ok;
 export fn getOr(r: Result<i8>, default: i8): i8 binds get_or_i8;
 export fn i8(i: i64): i8 binds i64toi8;
 export fn add(a: i8, b: i8): Result<i8> binds addi8;
@@ -63,7 +63,7 @@ export fn min(a: i32, b: i32): i32 binds mini32;
 export fn max(a: i32, b: i32): i32 binds maxi32;
 export type i64 binds i64;
 export type Result<i64> binds Result_i64;
-export fn ok(i: i64): Result<i64> binds Ok;
+export fn ok(i: i64): Result<i64> binds alan_ok;
 export fn getOr(r: Result<i64>, default: i64): i64 binds get_or_i64;
 export fn i64(i: i64): i64 = i;
 export fn add(a: i64, b: i64): Result<i64> binds addi64;