Chapter 7

src/error.rs

@@ -0,0 +1,57 @@
+use thiserror::Error;
+
+use crate::lexer::Token;
+use crate::misc::CodePos;
+
+#[derive(Error, Debug)]
+pub enum LexerError {
+    #[error("Unexpected character '{c}' at {code_pos}.")]
+    UnexpectedCharacter { c: char, code_pos: CodePos },
+    #[error("Unterminated string literal starting at {code_pos}.")]
+    UnterminatedStringLiteral { code_pos: CodePos },
+    #[error("Unterminated block comment starting at {code_pos}.")]
+    UnterminatedBlockComment { code_pos: CodePos },
+    #[error("Invalid number literal {lexeme} at {code_pos}: {msg}")]
+    InvalidNumberLiteral {
+        lexeme: String,
+        msg: String,
+        code_pos: CodePos,
+    },
+}
+
+#[derive(Error, Debug)]
+pub enum ParserError {
+    #[error("Token stream ended unexpectedly.")]
+    TokenStreamEnded,
+    #[error("Unexpected token {token} at {0}.", token.code_pos())]
+    UnexpectedToken { token: Token },
+}
+
+#[derive(Error, Debug)]
+pub enum LoxError {
+    #[error("{msg}")]
+    LexerError { msg: String },
+    #[error("{msg}")]
+    ParserError { msg: String },
+}
+
+impl From<Vec<LexerError>> for LoxError {
+    fn from(lexer_errs: Vec<LexerError>) -> Self {
+        let msg = if lexer_errs.len() == 1 {
+            format!("{}", lexer_errs[0])
+        } else {
+            let msgs: Vec<String> = lexer_errs.iter().map(|err| format!("{}", err)).collect();
+            msgs.join("\n")
+        };
+
+        LoxError::LexerError { msg }
+    }
+}
+
+impl From<ParserError> for LoxError {
+    fn from(parser_error: ParserError) -> Self {
+        LoxError::ParserError {
+            msg: format!("{parser_error}"),
+        }
+    }
+}