Use gperf - not faster yet

src/json_tokens.hpp

@@ -0,0 +1,12 @@
+#pragma once
+#include <cstring>
+
+struct JsonToken {
+  const char *name;
+  int token_id;
+};
+
+class Perfect_Hash {
+public:
+  static const struct JsonToken *lookup_json_token(const char *str, size_t len);
+};