From 4e445322b58f020e73c31ba742dae49fb5c3da1e Mon Sep 17 00:00:00 2001
From: Brian Cully <bjc@spork.org>
Date: Thu, 18 Dec 2025 16:14:25 -0500
Subject: rust: simplify error handling a bit

---
 src/lib.rs | 47 +++++++++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 20 deletions(-)

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
index 7f65a80..9c89c78 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,10 +1,26 @@
 use log::{Level, error, info};
 use wasm_bindgen::prelude::*;
+use web_sys::js_sys;
 
 pub mod forth;
 pub mod robo;
 
-use web_sys::js_sys;
+enum Error {
+    NoVM,
+}
+impl From<Error> for String {
+    fn from(err: Error) -> Self {
+        match err {
+            Error::NoVM => "no vm".to_string().into(),
+        }
+    }
+}
+
+impl From<forth::vm::RuntimeError> for String {
+    fn from(err: forth::vm::RuntimeError) -> Self {
+        format!("runtime error: {}", err)
+    }
+}
 
 fn tr_op(op: &forth::vm::OpCode) -> String {
     use forth::vm::OpCode::*;
@@ -85,20 +101,16 @@ impl ExportedVM {
     }
 
     pub fn tick(&mut self) -> Result<bool, String> {
-        let Some(vm) = &mut self.vm else {
-            return Err("no vm".to_string());
-        };
-        vm.tick().map_err(|err| format!("runtime error: {err:?}"))
+        let vm = (&mut self.vm).as_mut().ok_or(Error::NoVM)?;
+        Ok(vm.tick()?)
     }
 
     pub fn run(&mut self) -> Result<usize, String> {
-        let Some(vm) = &mut self.vm else {
-            return Err("no vm".to_string());
-        };
+        let vm = (&mut self.vm).as_mut().ok_or(Error::NoVM)?;
 
         vm.ip.word = 0;
         vm.ip.offset = 0;
-        vm.run().map_err(|err| format!("runtime error: {err:?}"))
+        Ok(vm.run()?)
     }
 
     pub fn reset_ip(&mut self) {
@@ -109,16 +121,8 @@ impl ExportedVM {
         vm.ip.offset = 0;
     }
 
-    pub fn out(&mut self) -> Vec<String> {
-        let Some(vm) = &mut self.vm else { return vec![] };
-        let mut res = vec![];
-        std::mem::swap(&mut res, &mut vm.out);
-        res
-    }
-
-    pub fn trans(&mut self) -> js_sys::Object {
-        let Some(vm) = &self.vm else { return js_sys::Object::new() };
-
+    pub fn trans(&mut self) -> Result<js_sys::Object, String> {
+        let vm = (&mut self.vm).as_mut().ok_or(Error::NoVM)?;
         let res = js_sys::Map::new();
 
         // wordlist
@@ -167,12 +171,15 @@ impl ExportedVM {
         map_set(&res, "callstack", js_sys::Array::from_iter(cs));
 
         let vars = js_sys::Map::new();
+        let mut out = vec![];
+        std::mem::swap(&mut out, &mut vm.out);
+        map_set(&vars, "out", out);
         map_set::<isize>(&vars, "heading", vm.heading.into());
         map_set::<isize>(&vars, "speed", vm.speed.into());
         map_set::<isize>(&vars, "doppler", vm.doppler.into());
         map_set(&res, "vars", js_sys::Object::from_entries(&vars).expect("can't make object from vars map"));
 
-        js_sys::Object::from_entries(&res).expect("can't make object from results map")
+        Ok(js_sys::Object::from_entries(&res).expect("can't make object from results map"))
     }
 }
 
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