rust set length checks

Author: samuelcolvin

src/input/return_enums.rs

@@ -176,22 +176,30 @@ fn validate_iter_to_set<'a, 's>(
     recursion_guard: &'s mut RecursionGuard,
 ) -> ValResult<'a, ()> {
     let mut errors: Vec<ValLineError> = Vec::new();
+    let mut spaces_left = max_length.unwrap_or(0);
     for (index, item_result) in iter.enumerate() {
         let item = item_result.map_err(|e| any_next_error!(py, e, input, index))?;
         match validator.validate(py, item, extra, definitions, recursion_guard) {
             Ok(item) => {
                 set.build_add(item)?;
                 if let Some(max_length) = max_length {
-                    let actual_length = set.build_len();
-                    if actual_length > max_length {
-                        return Err(ValError::new(
-                            ErrorType::TooLong {
-                                field_type: field_type.to_string(),
-                                max_length,
-                                actual_length,
-                            },
-                            input,
-                        ));
+                    match spaces_left.checked_sub(1) {
+                        Some(spaces) => spaces_left = spaces,
+                        None => {
+                            let actual_length = set.build_len();
+                            if actual_length > max_length {
+                                return Err(ValError::new(
+                                    ErrorType::TooLong {
+                                        field_type: field_type.to_string(),
+                                        max_length,
+                                        actual_length,
+                                    },
+                                    input,
+                                ));
+                            } else {
+                                spaces_left = max_length - actual_length;
+                            }
+                        }
                     }
                 }
             }