rust-crafting-interpreters-.../src/errors.rs

87 lines
2.3 KiB
Rust

use crate::tokens::{Token, TokenType};
/// The type of an error.
#[derive(Clone, Copy, Debug)]
pub enum ErrorType {
/// 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}")
}
}
/// An error that occurred while trying to parse the input once it has been
/// scanned.
#[derive(Debug, Clone)]
pub struct ParserError {
line: usize,
pos: String,
message: String,
}
impl ParserError {
/// Initialize a parser error.
pub fn new(token: &Token, message: &str) -> Self {
Self {
line: token.line,
pos: if token.token_type == TokenType::Eof {
String::from(" at end of input")
} else {
format!(" at '{}'", token.lexeme)
},
message: String::from(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);
}
}
/// An error that occurred while trying to evaluate the code.
#[derive(Debug, Clone)]
pub struct InterpreterError {
line: usize,
message: String,
}
impl InterpreterError {
/// Initialize an interpreter error.
pub fn new(token: &Token, message: &str) -> Self {
Self {
line: token.line,
message: String::from(message),
}
}
/// Report the error to an error handler.
pub fn report(&self, err_hdl: &mut ErrorHandler) {
err_hdl.report(ErrorType::Runtime, self.line, "", &self.message);
}
}