Prohibit ASCII control characters from showing up in strings.

These must be escaped properly, so we see them naked in a string, we throw.

We shouldn't need explicit checks for these characters outside the strings,
as we chomp specific whitespace and then check for specific characters,
so the presence of such control characters should error out anyway.

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.14)
 
 project(millijson
-    VERSION 1.0.0
+    VERSION 1.0.1
     DESCRIPTION "Lightweight JSON library for C++"
     LANGUAGES CXX)
 

include/millijson/millijson.hpp

@@ -336,6 +336,11 @@ std::string extract_string(Input& input) {
                     }
                 }
                 break;
+            case (char) 0: case (char) 1: case (char) 2: case (char) 3: case (char) 4: case (char) 5: case (char) 6: case (char) 7: case (char) 8: case (char) 9:
+            case (char)10: case (char)11: case (char)12: case (char)13: case (char)14: case (char)15: case (char)16: case (char)17: case (char)18: case (char)19:
+            case (char)20: case (char)21: case (char)22: case (char)23: case (char)24: case (char)25: case (char)26: case (char)27: case (char)28: case (char)29:
+            case (char)30: case (char)31:
+                throw std::runtime_error("string contains ASCII control character at position " + std::to_string(input.position() + 1));
             default:
                 output += next;
                 break;

tests/src/json.cpp

@@ -97,6 +97,8 @@ TEST(JsonParsingTest, StringLoading) {
     parse_raw_json_error(" \"asdasdaasd\\a", "unrecognized escape");
     parse_raw_json_error(" \"asdas\\uasdasd", "invalid unicode");
     parse_raw_json_error(" \"asdas\\u00", "unterminated string");
+    parse_raw_json_error(" \"0sdasd\nasdasd\"", "string contains ASCII control character at position 9");
+    parse_raw_json_error(" \"sdasd\tasdasd\"", "string contains ASCII control character at position 8");
 }
 
 TEST(JsonParsingTest, IntegerLoading) {