Improved error reports

Cargo.lock

@@ -61,6 +61,15 @@ dependencies = [
  "x11rb",
 ]
 
+[[package]]
+name = "ariadne"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1cb2a2046bea8ce5e875551f5772024882de0b540c7f93dfc5d6cf1ca8b030c"
+dependencies = [
+ "yansi",
+]
+
 [[package]]
 name = "atomic_refcell"
 version = "0.1.8"
@@ -1556,6 +1565,7 @@ dependencies = [
 name = "web-lisp"
 version = "0.1.0"
 dependencies = [
+ "ariadne",
  "chumsky",
  "eframe",
  "logos",
@@ -1745,3 +1755,9 @@ name = "xml-rs"
 version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2d7d3948613f75c98fd9328cfdcc45acc4d360655289d0a7d4ec931392200a3"
+
+[[package]]
+name = "yansi"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09041cd90cf85f7f8b2df60c646f853b7f535ce68f85244eb6731cf89fa498ec"

Cargo.toml

@@ -6,7 +6,8 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-logos = "*"
-eframe = "*"
+ariadne = "0.1"
 chumsky = "0.8"
+eframe = "*"
+logos = "*"
 ordered-float = "3.0"

src/error.rs

@@ -0,0 +1,85 @@
+use crate::lexer::Token;
+use ariadne::{Color, Fmt, Label, Report, ReportKind, Source};
+use chumsky::error::{Simple, SimpleReason};
+use std::fmt::Display;
+
+#[derive(Debug, Clone)]
+pub enum Error<'a> {
+    Parse(Simple<Token<'a>>),
+}
+
+impl<'a> Error<'a> {
+    pub fn report(&self, src: &str) -> std::io::Result<()> {
+        match self {
+            Error::Parse(e) => {
+                let report =
+                    Report::<std::ops::Range<usize>>::build(ReportKind::Error, (), e.span().start);
+                match e.reason() {
+                    SimpleReason::Unexpected => report
+                        .with_message(match e.found() {
+                            Some(Token::Error) => {
+                                format!("Invalid token: {}", &src[e.span()].fg(Color::Yellow))
+                            }
+                            Some(t) => format!("Unexpected token `{t:?}`"),
+                            None => "Unexpected end of input".to_owned(),
+                        })
+                        .with_label(
+                            Label::new(e.span())
+                                .with_message(format!(
+                                    "Expected: {}",
+                                    e.expected()
+                                        .map(|exp| match exp {
+                                            Some(expected) => format!("{expected:?}"),
+                                            None => "end of input".to_owned(),
+                                        })
+                                        .collect::<Vec<_>>()
+                                        .join(", ")
+                                ))
+                                .with_color(Color::Red),
+                        ),
+                    SimpleReason::Unclosed { span, delimiter } => {
+                        let msg = format!(
+                            "Unclosed delimiter: {:?}",
+                            format!("{delimiter:?}").fg(Color::Yellow)
+                        );
+                        report
+                            .with_message(&msg)
+                            .with_label(
+                                Label::new(span.clone())
+                                    .with_message(msg)
+                                    .with_color(Color::Red),
+                            )
+                            .with_label(
+                                Label::new(e.span())
+                                    .with_message(format!(
+                                        "Must be closed before {}",
+                                        match e.found() {
+                                            Some(x) => format!("{x:?}"),
+                                            None => "the end of input".to_owned(),
+                                        }
+                                    ))
+                                    .with_color(Color::Yellow),
+                            )
+                    }
+                    SimpleReason::Custom(msg) => report.with_message(msg).with_label(
+                        Label::new(e.span())
+                            .with_message(msg.fg(Color::Red))
+                            .with_color(Color::Red),
+                    ),
+                }
+                .finish()
+                .print(Source::from(&src))
+            }
+        }
+    }
+}
+
+impl<'a> Display for Error<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::Parse(e) => write!(f, "{e:?}"),
+        }
+    }
+}
+
+impl<'a> std::error::Error for Error<'a> {}

src/lib.rs

@@ -1,3 +1,4 @@
+pub mod error;
 pub mod lexer;
 pub mod list;
 pub mod parser;

src/main.rs

@@ -1,17 +1,21 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
-use web_lisp::parser;
+use web_lisp::{error::Error, parser};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    match parser::read(&std::fs::read_to_string(
-        std::env::args().nth(1).ok_or("no filename provided")?,
-    )?) {
+    let src = std::fs::read_to_string(std::env::args().nth(1).ok_or("no filename provided")?)?;
+
+    match parser::read(&src) {
         Ok(vals) => {
             for val in vals {
                 println!("{val}");
             }
         }
-        Err(e) => eprintln!("Parse error: {e:?}"),
+        Err(errs) => {
+            for err in errs {
+                Error::Parse(err).report(&src)?;
+            }
+        }
     }
 
     Ok(())