egui/file_handler: run parsing in file loader thread

- also embed I/O errors with other errors

src/bin/topola-egui/app.rs

@@ -9,8 +9,11 @@ use std::{
 use unic_langid::{langid, LanguageIdentifier};
 
 use topola::{
-    autorouter::{invoker::Invoker, Autorouter},
+    autorouter::{history::History, invoker::Invoker, Autorouter},
-    specctra::{design::SpecctraDesign, mesadata::SpecctraMesadata},
+    specctra::{
+        design::{LoadingError as SpecctraLoadingError, SpecctraDesign},
+        mesadata::SpecctraMesadata,
+    },
     stepper::Step,
 };
 
@@ -38,12 +41,12 @@ pub struct App {
     maybe_activity: Option<ActivityStepperWithStatus>,
 
     content_channel: (
-        Sender<std::io::Result<FileHandlerData>>,
+        Sender<Result<SpecctraDesign, SpecctraLoadingError>>,
-        Receiver<std::io::Result<FileHandlerData>>,
+        Receiver<Result<SpecctraDesign, SpecctraLoadingError>>,
     ),
     history_channel: (
-        Sender<std::io::Result<FileHandlerData>>,
+        Sender<std::io::Result<Result<History, serde_json::Error>>>,
-        Receiver<std::io::Result<FileHandlerData>>,
+        Receiver<std::io::Result<Result<History, serde_json::Error>>>,
     ),
 
     viewport: Viewport,
@@ -109,13 +112,23 @@ impl App {
     fn update_state(&mut self) -> bool {
         if let Ok(data) = self.content_channel.1.try_recv() {
             match data {
-                Ok(data) => match self.load_specctra_dsn(data) {
+                Ok(design) => match self.load_specctra_dsn(design) {
                     Ok(()) => {}
                     Err(err) => {
                         self.error_dialog.push_error("tr-module-specctra-dsn-file-loader", err);
                     }
                 },
-                Err(err) => {
+                Err(SpecctraLoadingError::Parse(err)) => {
+                    self.error_dialog.push_error(
+                        "tr-module-specctra-dsn-file-loader",
+                        format!(
+                            "{}; {}",
+                            self.translator.text("tr-error_failed-to-parse-as-specctra-dsn"),
+                            err
+                        ),
+                    );
+                }
+                Err(SpecctraLoadingError::Io(err)) => {
                     self.error_dialog.push_error(
                         "tr-module-specctra-dsn-file-loader",
                         format!("{}; {}", self.translator.text("tr-error_unable-to-read-file"), err),
@@ -125,18 +138,18 @@ impl App {
         }
 
         if let Some(invoker) = self.arc_mutex_maybe_invoker.lock().unwrap().as_mut() {
-            if let Ok(input) = self.history_channel.1.try_recv() {
+            if let Ok(data) = self.history_channel.1.try_recv() {
                 let tr = &self.translator;
-                match input {
+                match data {
-                    Ok(bufread) => match serde_json::from_reader(bufread) {
+                    Ok(Ok(data)) => {
-                        Ok(res) => invoker.replay(res),
+                        invoker.replay(data);
-                        Err(err) => {
+                    }
+                    Ok(Err(err)) => {
                         self.error_dialog.push_error(
                             "tr-module-history-file-loader",
                             format!("{}; {}", tr.text("tr-error_failed-to-parse-as-history-json"), err),
                         );
                     }
-                    },
                     Err(err) => {
                         self.error_dialog.push_error(
                             "tr-module-history-file-loader",
@@ -161,10 +174,8 @@ impl App {
         false
     }
 
-    fn load_specctra_dsn(&mut self, bufread: FileHandlerData) -> Result<(), String> {
+    fn load_specctra_dsn(&mut self, design: SpecctraDesign) -> Result<(), String> {
         let tr = &self.translator;
-        let design = SpecctraDesign::load(bufread)
-            .map_err(|err| format!("{}; {}", tr.text("tr-error_failed-to-parse-as-specctra-dsn"), err))?;
         let board = design.make_board();
         let overlay = Overlay::new(&board)
             .map_err(|err| format!("{}; {}", tr.text("tr-error_unable-to-initialize-overlay"), err))?;

src/bin/topola-egui/file_handler.rs

@@ -46,19 +46,28 @@ impl io::BufRead for FileHandlerData {
     fhd_forward!(fn consume(&mut self, amt: usize));
 }
 
-pub async fn push_file_to_read(
+#[inline]
+pub async fn push_file_to_read<R, E, C>(
     file_handle: &rfd::FileHandle,
-    sender: Sender<std::io::Result<FileHandlerData>>,
+    sender: Sender<Result<R, E>>,
-) {
+    callback: C,
-    let _ = sender.send(handle_text(&file_handle).await);
+) where
+    E: From<std::io::Error>,
+    C: FnOnce(FileHandlerData) -> Result<R, E>,
+{
+    let _ = sender.send(handle_text(&file_handle, callback).await);
 }
 
-async fn handle_text(file_handle: &rfd::FileHandle) -> std::io::Result<FileHandlerData> {
+async fn handle_text<R, E, C>(file_handle: &rfd::FileHandle, callback: C) -> Result<R, E>
+where
+    E: From<std::io::Error>,
+    C: FnOnce(FileHandlerData) -> Result<R, E>,
+{
     #[cfg(not(target_arch = "wasm32"))]
     let res = FileHandlerData::File(io::BufReader::new(std::fs::File::open(file_handle.path())?));
 
     #[cfg(target_arch = "wasm32")]
     let res = FileHandlerData::Contents(io::Cursor::new(file_handle.read().await));
 
-    Ok(res)
+    callback(res)
 }

src/bin/topola-egui/menu_bar.rs

@@ -6,11 +6,15 @@ use std::{
 use topola::{
     autorouter::{
         command::Command,
+        history::History,
         invoker::{Invoker, InvokerError},
         AutorouterOptions,
     },
     router::RouterOptions,
-    specctra::{design::SpecctraDesign, mesadata::SpecctraMesadata},
+    specctra::{
+        design::{LoadingError as SpecctraLoadingError, SpecctraDesign},
+        mesadata::SpecctraMesadata,
+    },
     stepper::Abort,
 };
 
@@ -59,8 +63,8 @@ impl MenuBar {
         &mut self,
         ctx: &egui::Context,
         tr: &Translator,
-        content_sender: Sender<std::io::Result<FileHandlerData>>,
+        content_sender: Sender<Result<SpecctraDesign, SpecctraLoadingError>>,
-        history_sender: Sender<std::io::Result<FileHandlerData>>,
+        history_sender: Sender<std::io::Result<Result<History, serde_json::Error>>>,
         arc_mutex_maybe_invoker: Arc<Mutex<Option<Invoker<SpecctraMesadata>>>>,
         maybe_activity: &mut Option<ActivityStepperWithStatus>,
         viewport: &mut Viewport,
@@ -239,7 +243,10 @@ impl MenuBar {
 
                     execute(async move {
                         if let Some(file_handle) = task.await {
-                            push_file_to_read(&file_handle, content_sender).await;
+                            push_file_to_read(&file_handle, content_sender, |data| {
+                                SpecctraDesign::load(data)
+                            })
+                            .await;
                             ctx.request_repaint();
                         }
                     });
@@ -278,7 +285,14 @@ impl MenuBar {
 
                     execute(async move {
                         if let Some(file_handle) = task.await {
-                            push_file_to_read(&file_handle, history_sender).await;
+                            push_file_to_read(&file_handle, history_sender, |data| {
+                                match serde_json::from_reader(data) {
+                                    Ok(history) => Ok(Ok(history)),
+                                    Err(err) if err.is_io() => Err(err.into()),
+                                    Err(err) => Ok(Err(err)),
+                                }
+                            })
+                            .await;
                             ctx.request_repaint();
                         }
                     });

src/specctra/design.rs

@@ -26,9 +26,10 @@ use crate::{
     },
 };
 
-#[derive(Error, Debug)]
+pub use read::ParseErrorContext;
 
 /// Errors raised by [`SpecctraDesign::load`]
+#[derive(Error, Debug)]
 pub enum LoadingError {
     /// I/O file reading error from [`std::io::Error`]
     #[error(transparent)]