From 6cc1b5013a305771e60781081319a45a96d12019 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Sun, 24 Jul 2022 22:21:34 +0200
Subject: [PATCH] Span everything

---
 src/repl.rs          |  4 ++--
 src/syntax/ast.rs    | 43 +++++++++++++++++++++++++++++++++++++++----
 src/syntax/parser.rs | 22 +++++++++++++++-------
 3 files changed, 56 insertions(+), 13 deletions(-)

diff --git a/src/repl.rs b/src/repl.rs
index b8d2100..3c7423f 100644
--- a/src/repl.rs
+++ b/src/repl.rs
@@ -1,4 +1,4 @@
-use crate::{error::Error, syntax::parser::read};
+use crate::{error::Error, syntax::parser::parse};
 use rustyline::{error::ReadlineError, Editor};
 
 pub fn repl() -> rustyline::Result<()> {
@@ -6,7 +6,7 @@ pub fn repl() -> rustyline::Result<()> {
     let mut rl = Editor::<()>::new()?;
     loop {
         match rl.readline(prompt) {
-            Ok(line) => match read(&line) {
+            Ok(line) => match parse(&line) {
                 Ok(values) => values.iter().for_each(|e| println!("{e}")),
                 Err(e) => e.into_iter().map(Error::Parse).for_each(|e| {
                     if let Err(e) = e.report(&line) {
diff --git a/src/syntax/ast.rs b/src/syntax/ast.rs
index 58a9edb..937b290 100644
--- a/src/syntax/ast.rs
+++ b/src/syntax/ast.rs
@@ -2,14 +2,48 @@ use ordered_float::OrderedFloat;
 use std::{
     borrow::Cow,
     fmt::{Display, Write},
+    hash::Hash,
 };
 
+pub type Span = std::ops::Range<usize>;
+
+/// A spanned item
+#[derive(Clone, Debug)]
+pub struct Spanned<T> {
+    pub item: T,
+    pub span: Span,
+}
+
+impl<T> Spanned<T> {
+    pub fn new(item: T, span: Span) -> Self {
+        Self { item, span }
+    }
+}
+
+impl<T: Display> Display for Spanned<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} \x1B[2m@ {:?}\x1B[22m", self.item, self.span)
+    }
+}
+
+impl<T: PartialEq> PartialEq for Spanned<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.item == other.item
+    }
+}
+impl<T: Hash> Hash for Spanned<T> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.item.hash(state);
+    }
+}
+
 /// A Wisp AST
-#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Debug, Clone, Hash, PartialEq)]
 pub enum Expr<'a> {
-    List(Vec<Self>),
-    Vector(Vec<Self>),
-    Map(Vec<(Self, Self)>),
+    List(Vec<Spanned<Self>>),
+    Vector(Vec<Spanned<Self>>),
+    Map(Vec<(Spanned<Self>, Spanned<Self>)>),
+    Quote(Box<Spanned<Self>>),
     Symbol(Cow<'a, str>),
     Keyword(Cow<'a, str>),
     Number(OrderedFloat<f64>),
@@ -22,6 +56,7 @@ impl<'a> Display for Expr<'a> {
             Self::List(list) => write_seq(f, list, "(", ")"),
             Self::Vector(vec) => write_seq(f, vec, "[", "]"),
             Self::Map(map) => write_seq(f, map.iter().map(|(k, v)| format!("{k} {v}")), "{", "}"),
+            Self::Quote(expr) => write!(f, "'{expr}"),
             Self::Symbol(sym) => write!(f, "{sym}"),
             Self::Keyword(kw) => write!(f, ":{kw}"),
             Self::Number(n) => write!(f, "{n}"),
diff --git a/src/syntax/parser.rs b/src/syntax/parser.rs
index 0cfd7b1..e4dd914 100644
--- a/src/syntax/parser.rs
+++ b/src/syntax/parser.rs
@@ -1,15 +1,18 @@
-use super::{ast::Expr, lexer::Token};
+use super::{
+    ast::{Expr, Spanned},
+    lexer::Token,
+};
 use chumsky::{prelude::*, Stream};
 use logos::Logos;
 
 /// Parse source string into a Expr
-pub fn read(src: &str) -> Result<Vec<Expr>, Vec<Simple<Token<'_>>>> {
+pub fn parse(src: &str) -> Result<Vec<Spanned<Expr>>, Vec<Simple<Token<'_>>>> {
     let lexer = Token::lexer(src);
     let len = lexer.source().len();
     parser().parse(Stream::from_iter(len..len + 1, lexer.spanned()))
 }
 
-fn parser<'a>() -> impl Parser<Token<'a>, Vec<Expr<'a>>, Error = Simple<Token<'a>>> {
+fn parser<'a>() -> impl Parser<Token<'a>, Vec<Spanned<Expr<'a>>>, Error = Simple<Token<'a>>> {
     recursive(|expr| {
         let atom = select! {
             Token::Symbol(s) => Expr::Symbol(s.into()),
@@ -40,9 +43,14 @@ fn parser<'a>() -> impl Parser<Token<'a>, Vec<Expr<'a>>, Error = Simple<Token<'a
 
         let quote = just(Token::Quote)
             .ignore_then(expr)
-            .map(|expr| Expr::List(vec![Expr::Symbol("quote".into()), expr]));
+            .map(Box::new)
+            .map(Expr::Quote);
 
-        atom.or(list).or(vector).or(map).or(quote)
+        atom.or(list)
+            .or(vector)
+            .or(map)
+            .or(quote)
+            .map_with_span(Spanned::new)
     })
     .repeated()
     .then_ignore(end())
@@ -52,7 +60,7 @@ fn parser<'a>() -> impl Parser<Token<'a>, Vec<Expr<'a>>, Error = Simple<Token<'a
 mod tests {
     use super::*;
 
-    fn assert_parse<'a>(src: &'a str, expected: &'a [Expr<'a>]) {
-        assert_eq!(read(src).unwrap(), expected);
+    fn assert_parse<'a>(src: &'a str, expected: &'a [Spanned<Expr<'a>>]) {
+        assert_eq!(parse(src).unwrap(), expected);
     }
 }