feat(parser): report nearby tokens when parse failed (risingwavelabs#…

…8465)

Signed-off-by: TennyZhuang <zty0826@gmail.com>

src/sqlparser/src/parser.rs

@@ -1475,7 +1475,24 @@ impl Parser {
 
     /// Report unexpected token
     pub fn expected<T>(&self, expected: &str, found: Token) -> Result<T, ParserError> {
-        parser_err!(format!("Expected {}, found: {}", expected, found))
+        let start_off = self.index.saturating_sub(10);
+        let end_off = self.index.min(self.tokens.len());
+        let near_tokens = &self.tokens[start_off..end_off];
+        struct TokensDisplay<'a>(&'a [Token]);
+        impl<'a> fmt::Display for TokensDisplay<'a> {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                for token in self.0 {
+                    write!(f, "{}", token)?;
+                }
+                Ok(())
+            }
+        }
+        parser_err!(format!(
+            "Expected {}, found: {}\nNear \"{}\"",
+            expected,
+            found,
+            TokensDisplay(near_tokens),
+        ))
     }
 
     /// Look for an expected keyword and consume it if it exists