simplify error handling code

src/function.rs

@@ -86,20 +86,17 @@ impl Default for FunctionEntry {
 
 impl FunctionEntry {
 	/// Create autocomplete ui and handle user input
-	pub fn auto_complete(&mut self, ui: &mut egui::Ui, i: i32) -> (bool, Option<String>) {
+	pub fn auto_complete(&mut self, ui: &mut egui::Ui, i: i32) {
 		let mut output_string: String = self.raw_func_str.clone();
 		self.autocomplete.ui(ui, &mut output_string, i);
 
-		let changed = output_string != self.raw_func_str;
+		if output_string != self.raw_func_str {
-		if changed {
 			self.update_string(&output_string);
 		}
-
-		(changed, self.get_test_result())
 	}
 
 	/// Get function's cached test result
-	pub fn get_test_result(&self) -> Option<String> { self.test_result.clone() }
+	pub fn get_test_result(&self) -> &Option<String> { &self.test_result }
 
 	/// Update function string and test it
 	fn update_string(&mut self, raw_func_str: &str) {

src/math_app.rs

@@ -286,13 +286,6 @@ pub struct MathApp {
 	/// Stores vector of functions
 	functions: Vec<FunctionEntry>,
 
-	/// Stores last error from parsing functions (used to display the same error
-	/// when side panel is minimized)
-	func_errors: Vec<Option<String>>,
-
-	/// Stores whether or not an error is stored in `self.func_errors`
-	exists_error: bool,
-
 	/// Contains the list of Areas calculated (the vector of f64) and time it
 	/// took for the last frame (the Duration). Stored in a Tuple.
 	last_info: (Vec<Option<f64>>, Duration),
@@ -311,8 +304,6 @@ impl Default for MathApp {
 	fn default() -> Self {
 		Self {
 			functions: vec![DEFAULT_FUNCTION_ENTRY.clone()],
-			func_errors: vec![None],
-			exists_error: false,
 			last_info: (vec![None], Duration::ZERO),
 			dark_mode: true,
 			opened: Opened::default(),
@@ -442,7 +433,6 @@ impl MathApp {
 
 				let functions_len = self.functions.len();
 				let mut remove_i: Option<usize> = None;
-				self.exists_error = false;
 				for (i, function) in self.functions.iter_mut().enumerate() {
 					// Entry for a function
 					ui.horizontal(|ui| {
@@ -479,21 +469,13 @@ impl MathApp {
 						);
 
 						// Contains the function string in a text box that the user can edit
-						let (changed, error) = function.auto_complete(ui, i as i32);
+						function.auto_complete(ui, i as i32)
-
-						if let Some(error_string) = error {
-							self.exists_error = true;
-							if changed {
-								self.func_errors[i] = Some(error_string);
-							}
-						}
 					});
 				}
 
 				// Remove function if the user requests it
 				if let Some(remove_i_unwrap) = remove_i {
 					self.functions.remove(remove_i_unwrap);
-					self.func_errors.remove(remove_i_unwrap);
 				}
 
 				// Hyperlink to project's github
@@ -557,7 +539,6 @@ impl epi::App for MathApp {
 					.clicked()
 				{
 					self.functions.push(DEFAULT_FUNCTION_ENTRY.clone());
-					self.func_errors.push(None);
 				}
 
 				// Toggles opening the Help window
@@ -665,15 +646,19 @@ impl epi::App for MathApp {
 		// parsing)
 		CentralPanel::default().show(ctx, |ui| {
 			// Display an error if it exists
-			if self.exists_error {
+			let errors_formatted: Vec<String> = self
-				ui.centered_and_justified(|ui| {
+				.functions
-					self.func_errors
 				.iter()
+				.map(|func| func.get_test_result())
 				.enumerate()
 				.filter(|(_, error)| error.is_some())
-						.map(|(i, error)| (i, error.as_ref().unwrap()))
+				.map(|(i, error)| format!("(Function #{}) {}\n", i, error.as_ref().unwrap()))
-						.for_each(|(i, error)| {
+				.collect();
-							ui.heading(format!("(Function #{}) {}\n", i, error));
+
+			if errors_formatted.len() > 0 {
+				ui.centered_and_justified(|ui| {
+					errors_formatted.iter().for_each(|string| {
+						ui.heading(string);
 					})
 				});
 				return;