feat: support minItems/maxItems in JSON grammar converter (by @nopperl)

Author: abetlen

llama_cpp/llama_grammar.py

@@ -1498,9 +1498,21 @@ def visit(self, schema: Dict[str, Any], name: str) -> str:
             item_rule_name = self.visit(
                 schema["items"], f'{name}{"-" if name else ""}item'
             )
-            rule = (
-                f'"[" space ({item_rule_name} ("," space {item_rule_name})*)? "]" space'
-            )
+            list_item_operator = f'("," space {item_rule_name})'
+            successive_items = ""
+            min_items = schema.get("minItems", 0)
+            if min_items > 0:
+               first_item = f"({item_rule_name})"
+               successive_items = list_item_operator * (min_items - 1)
+               min_items -= 1
+            else:
+               first_item = f"({item_rule_name})?"
+            max_items = schema.get("maxItems")
+            if max_items is not None and max_items > min_items:
+                successive_items += (list_item_operator + "?") * (max_items - min_items - 1)
+            else:
+                successive_items += list_item_operator + "*"
+            rule = f'"[" space {first_item} {successive_items} "]" space'
             return self._add_rule(rule_name, rule)
 
         else: