some combinators

src/parser/types.rs

@@ -63,6 +63,30 @@ impl Tokens {
         }
         Ok(None)
     }
+    pub fn sep_by<T1, T2>(
+        &mut self,
+        separator: Token,
+        parser1: Parser<T1>,
+        parser2: Parser<T2>,
+    ) -> ParseResult<(T1, T2)> {
+        if let Some(t1) = parser1(self)? {
+            let _sep = self.next_if(separator).ok_or(Error::UnexpectedEndOfInput)?;
+            if let Some(t2) = parser2(self)? {
+                Ok(Some((t1, t2)))
+            } else {
+                Err(Error::UnexpectedTokenForParser)
+            }
+        } else {
+            Ok(None)
+        }
+    }
+    pub fn many<T>(&mut self, parser: Parser<T>) -> ParseResult<Vec<T>> {
+        let mut results = vec![];
+        while let Some(result) = parser(self)? {
+            results.push(result);
+        }
+        Ok(Some(results))
+    }
 }
 
 pub type Parser<T> = fn(&mut Tokens) -> ParseResult<T>;