Fixed json strings grammar by blacklisting character control set. Closes #1259

Author: abetlen

llama_cpp/llama_grammar.py

@@ -1337,7 +1337,7 @@ def print_grammar(file: TextIO, state: parse_state) -> None:
 
 string ::=
   "\"" (
-    [^"\\] |
+    [^"\\\x7F\x00-\x1F] |
     "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F]) # escapes
   )* "\"" ws
 
@@ -1366,7 +1366,7 @@ def print_grammar(file: TextIO, state: parse_state) -> None:
 
 string ::=
   "\"" (
-    [^"\\] |
+    [^"\\\x7F\x00-\x1F] |
     "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F]) # escapes
   )* "\"" ws