Feature: Use arena-allocation for memory handling

Arena allocation make deallocation of nested structed MUCH faster, and
improves the spatial locality of allocations. It makes no sense to
deallocate only parts of a JSON structure so arenas are a good fit here.

include/json_value.h

@@ -2,6 +2,7 @@
 #ifndef _JSON_VALUE_H
 #define _JSON_VALUE_H
 
+#include "arena.h"
 #include "config.h"
 #include <stdbool.h> // bool
 
@@ -9,7 +10,7 @@ typedef struct obj_entry {
     char const* key;
     struct json_value* val;
     struct obj_entry* next;
-} * __p_obj_entry;
+}* __p_obj_entry;
 
 typedef __p_obj_entry obj_t[OBJ_SIZE];
 
@@ -32,11 +33,11 @@ struct json_value {
 };
 
 void* obj_at(obj_t m, char* const key);
-bool obj_insert(obj_t m, char* const key, struct json_value* value);
-void obj_delete(obj_t* m);
+bool obj_insert(obj_t m, char* const key, struct json_value* value, arena_t* arena);
+void obj_delete(obj_t* m, arena_t* arena);
 
 void print_json(struct json_value val, int indent);
 
-void json_value_delete(struct json_value val);
+void json_value_delete(struct json_value val, arena_t* arena);
 
 #endif

include/parse.h

@@ -4,8 +4,9 @@
 
 #include "json_value.h"
 
+#include "arena.h"
 #include <stdio.h> // FILE*
 
-struct json_value parse_json_value(FILE* fp);
+struct json_value parse_json_value(FILE* fp, arena_t* arena);
 
 #endif

include/util.h

@@ -10,6 +10,6 @@ __attribute__((__noreturn__)) void err_ctx(int exit_code, FILE* fp, const char*
 void* malloc_or_die(size_t size);
 void* realloc_or_die(void* ptr, size_t size);
 void* calloc_or_die(size_t nmemb, size_t size);
-void print_trace();
+void print_trace(void);
 
 #endif