more friendly names for glsl ExpectedError, implement Display

src/front/glsl/error.rs

@@ -8,7 +8,7 @@ use thiserror::Error;
 fn join_with_comma(list: &[ExpectedToken]) -> String {
     let mut string = "".to_string();
     for (i, val) in list.iter().enumerate() {
-        string.push_str(&val.expected_str());
+        string.push_str(&val.to_string());
         match i {
             i if i == list.len() - 1 => {}
             i if i == list.len() - 2 => string.push_str(" or "),
@@ -18,7 +18,7 @@ fn join_with_comma(list: &[ExpectedToken]) -> String {
     string
 }
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 pub enum ExpectedToken {
     Token(TokenValue),
     TypeName,
@@ -32,15 +32,15 @@ impl From<TokenValue> for ExpectedToken {
         ExpectedToken::Token(token)
     }
 }
-impl ExpectedToken {
-    fn expected_str(&self) -> String {
+impl std::fmt::Display for ExpectedToken {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            ExpectedToken::Token(token) => format!("{:?}", token),
-            ExpectedToken::TypeName => "TypeName".to_string(),
-            ExpectedToken::Identifier => "Identifier".to_string(),
-            ExpectedToken::IntLiteral => "IntLiteral".to_string(),
-            ExpectedToken::FloatLiteral => "FloatLiteral".to_string(),
-            ExpectedToken::BoolLiteral => "BoolLiteral".to_string(),
+            ExpectedToken::Token(token) => write!(f, "{:?}", token),
+            ExpectedToken::TypeName => write!(f, "a type"),
+            ExpectedToken::Identifier => write!(f, "identifier"),
+            ExpectedToken::IntLiteral => write!(f, "integer literal"),
+            ExpectedToken::FloatLiteral => write!(f, "float literal"),
+            ExpectedToken::BoolLiteral => write!(f, "bool literal"),
         }
     }
 }