Errors - Refactoring

* This will break the whole thing but the error handling was getting
    quite messy.

src/errors.rs

@@ -1,89 +1,82 @@
+use core::fmt;
+use std::{error::Error, fmt::Display};
+
 use crate::tokens::{Token, TokenType};
 
 /// The type of an error.
 #[derive(Clone, Copy, Debug)]
-pub enum ErrorType {
+pub enum ErrorKind {
     /// The error occurred while parsing the source code.
     Parse,
     /// The error occurred while trying to run the program.
     Runtime,
 }
 
-/// Error handler. Can be used to print error messages; will also retain the
-/// current error status.
-#[derive(Default, Debug)]
-pub struct ErrorHandler {
-    had_error: Option<ErrorType>,
-}
-
-impl ErrorHandler {
-    /// Check whether this handler reported an error.
-    pub fn had_error(&self) -> Option<ErrorType> {
-        self.had_error
-    }
-
-    /// Report an error.
-    pub fn error(&mut self, err_type: ErrorType, line: usize, message: &str) {
-        self.report(err_type, line, "", message)
-    }
-
-    fn report(&mut self, err_type: ErrorType, line: usize, pos: &str, message: &str) {
-        if self.had_error.is_none() {
-            self.had_error = Option::Some(err_type);
-        }
-        println!("[line {line}] Error{pos}: {message}")
+impl fmt::Display for ErrorKind {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            ErrorKind::Parse => "Parse",
+            ErrorKind::Runtime => "Runtime",
+        })
     }
 }
 
 /// An error that occurred while trying to parse the input once it has been
 /// scanned.
 #[derive(Debug, Clone)]
-pub struct ParserError {
+pub struct SloxError {
+    kind: ErrorKind,
     line: usize,
     pos: String,
     message: String,
 }
 
-impl ParserError {
-    /// Initialize a parser error.
-    pub fn new(token: &Token, message: &str) -> Self {
+impl SloxError {
+    /// Initialize an error record.
+    pub fn new(kind: ErrorKind, token: &Token, message: String) -> Self {
         Self {
+            kind,
             line: token.line,
             pos: if token.token_type == TokenType::Eof {
-                String::from(" at end of input")
+                "at end of input".to_owned()
             } else {
-                format!(" at '{}'", token.lexeme)
+                format!("near '{}'", token.lexeme)
             },
-            message: String::from(message),
+            message,
+        }
     }
 }
 
-    /// Report the error to an error handler.
-    pub fn report(&self, err_hdl: &mut ErrorHandler) {
-        err_hdl.report(ErrorType::Parse, self.line, &self.pos, &self.message);
+impl Error for SloxError {}
+
+impl Display for SloxError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "[line {}] {} error {}: {}",
+            self.line, self.kind, self.pos, self.message
+        )
     }
 }
 
-/// An error that occurred while trying to evaluate the code.
-#[derive(Debug, Clone)]
-pub struct InterpreterError {
-    line: usize,
-    pos: String,
-    message: String,
+/// Error handler. Can be used to print error messages; will also retain the
+/// current error status.
+#[derive(Default, Debug)]
+pub struct ErrorHandler {
+    had_error: Option<ErrorKind>,
 }
 
-impl InterpreterError {
-    /// Initialize an interpreter error.
-    pub fn new(token: &Token, message: &str) -> Self {
-        Self {
-            line: token.line,
-            pos: format!(" at '{}'", token.lexeme),
-            message: String::from(message),
-        }
+impl ErrorHandler {
+    /// Check whether this handler reported an error.
+    pub fn had_error(&self) -> Option<ErrorKind> {
+        self.had_error
     }
 
-    /// Report the error to an error handler.
-    pub fn report(&self, err_hdl: &mut ErrorHandler) {
-        err_hdl.report(ErrorType::Runtime, self.line, &self.pos, &self.message);
+    /// Report an error.
+    pub fn report(&mut self, error: &SloxError) {
+        if self.had_error.is_none() {
+            self.had_error = Some(error.kind);
+        }
+        println!("{error}");
     }
 }