Some more parse trace improvements

schala-lang/language/src/parsing.rs

@@ -263,12 +263,19 @@ impl Parser {
   pub fn format_parse_trace(&self) -> String {
     let mut buf = String::new();
     buf.push_str("Parse productions:\n");
+    let mut next_token = None;
     for r in self.parse_record.iter() {
       let mut indent = String::new();
       for _ in 0..r.level {
         indent.push('.');
       }
-      buf.push_str(&format!("{}`{}`, next token: {}\n", indent, r.production_name, r.next_token))
+      let effective_token = if next_token == Some(&r.next_token) {
+        "".to_string()
+      } else {
+        next_token = Some(&r.next_token);
+        format!(", next token: {}", r.next_token)
+      };
+      buf.push_str(&format!("{}`{}`{}\n", indent, r.production_name, effective_token));
     }
     buf
   }

schala-lang/language/src/tokenizing.rs

@@ -86,7 +86,7 @@ lazy_static! {
     };
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct Token {
   pub kind: TokenKind,
   pub line_num: usize,