From 8171b30adbc4cddd2c51f043c3379d78428666b8 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Thu, 25 Mar 2021 13:08:25 +0530
Subject: use new error kinds; track Environment nesting with stack

---
 src/lisp/lex.rs | 64 +++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 56 insertions(+), 8 deletions(-)

(limited to 'src/lisp/lex.rs')

diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index a7b9586..b307e80 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -1,6 +1,6 @@
 use std::{fmt, str::CharIndices};
 
-use super::error::LispError;
+use crate::lisp::error::{LispError, ParseError, ParseErrorKind};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Token<'a> {
@@ -19,6 +19,26 @@ pub enum Token<'a> {
     End,
 }
 
+impl<'a> Token<'a> {
+    pub fn name(&self) -> &'static str {
+        match self {
+            Token::LeftParen => "(",
+            Token::RightParen => ")",
+            Token::Float(_) => "float",
+            Token::Integer(_) => "integer",
+            // Token::Char(_)    => "char",
+            Token::String(_) => "string",
+            Token::Name(_) => "name",
+            // Token::Keyword(_) => "keyword",
+            Token::BackQuote => "`",
+            Token::Comma => ",",
+            Token::CommaAt => ",@",
+            Token::Quote => "'",
+            Token::End => "EOF",
+        }
+    }
+}
+
 impl<'a> fmt::Display for Token<'a> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -54,6 +74,25 @@ impl Span {
     }
 }
 
+#[derive(Debug, Clone)]
+pub struct SpanDisplay<'src> {
+    pub source: &'src str,
+    pub line: usize,
+    pub col: usize,
+}
+
+impl<'src> SpanDisplay<'src> {
+    pub fn highlight_span(span: Span, source: &'src str) -> Self {
+        let line_start = match source[..span.low as usize].rfind('\n') {
+            Some(pos) => pos + 1,
+            None => 0,
+        };
+        let line = source[..line_start].chars().filter(|&c| c == '\n').count() + 1;
+        let col = source[line_start..span.low as usize].chars().count();
+        Self { source, line, col }
+    }
+}
+
 pub struct Lexer<'input> {
     input: &'input str,
     cur_pos: u32,
@@ -68,6 +107,7 @@ impl<'a> Lexer<'a> {
             offset,
         }
     }
+
     pub fn next_token(&mut self) -> Result<(Span, Token<'a>), LispError> {
         let mut chars = self.input.char_indices();
 
@@ -94,11 +134,19 @@ impl<'a> Lexer<'a> {
                     self.cur_pos += ch.len_utf8() as u32;
                     continue;
                 }
-                _ => Err(LispError::ParseError),
+                ch => Err(ParseErrorKind::InvalidChar(ch)),
             };
             let (size, token) = match res {
                 Ok(v) => v,
-                Err(_) => return Err(LispError::ParseError),
+                Err(kind) => {
+                    return Err(LispError::Parse(ParseError {
+                        span: Span {
+                            low,
+                            high: low + chr.len_utf8() as u32,
+                        },
+                        kind,
+                    }))
+                }
             };
             self.cur_pos += size as u32;
             self.input = &self.input[ind + size..];
@@ -113,7 +161,7 @@ impl<'a> Lexer<'a> {
     }
 }
 
-fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError> {
+fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
     let mut dot = false;
     let mut minus = false;
     let mut size = 0;
@@ -137,12 +185,12 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError>
                 dot = true;
                 size += 1;
             } else {
-                return Err(LispError::ParseError);
+                return Err(ParseErrorKind::InvalidChar(chr));
             }
         } else if !is_ident(chr) {
             break;
         } else {
-            return Err(LispError::ParseError);
+            return Err(ParseErrorKind::InvalidChar(chr));
         }
     }
 
@@ -156,7 +204,7 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError>
     return Ok((size, tok));
 }
 
-fn parse_string<'a>(input: &'a str) -> Result<(usize, Token<'a>), LispError> {
+fn parse_string<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
     // count opening quote
     let mut size = 1;
     let mut chars = input.char_indices().skip(1);
@@ -197,7 +245,7 @@ fn consume_comment(start: usize, chars: &mut CharIndices) -> usize {
     last - start + 1
 }
 
-fn parse_name<'a>(input: &'a str) -> Result<(usize, Token<'a>), LispError> {
+fn parse_name<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
     for (ind, chr) in input.char_indices() {
         if !is_ident(chr) {
             return Ok((ind, Token::Name(&input[..ind])));
-- 
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