Improve const correctness

Author: ChromaticIsobar

json-builder.c

@@ -523,7 +523,7 @@ static size_t serialize_string (json_char * buf,
    return buf - orig_buf;
 }
 
-size_t json_measure (json_value * value)
+size_t json_measure (const json_value * value)
 {
    return json_measure_ex (value, default_opts);
 }
@@ -533,7 +533,7 @@ size_t json_measure (json_value * value)
    indents += depth;                               \
 } while(0);                                        \
 
-size_t json_measure_ex (json_value * value, json_serialize_opts opts)
+size_t json_measure_ex (const json_value * value, json_serialize_opts opts)
 {
    size_t total = 1;  /* null terminator */
    size_t newlines = 0;
@@ -701,7 +701,7 @@ size_t json_measure_ex (json_value * value, json_serialize_opts opts)
    return total;
 }
 
-void json_serialize (json_char * buf, json_value * value)
+void json_serialize (json_char * buf, const json_value * value)
 {
    json_serialize_ex (buf, value, default_opts);
 }
@@ -728,7 +728,7 @@ void json_serialize (json_char * buf, json_value * value)
    *buf ++ = (c);                                     \
 } while(0);                                           \
 
-void json_serialize_ex (json_char * buf, json_value * value, json_serialize_opts opts)
+void json_serialize_ex (json_char * buf, const json_value * value, json_serialize_opts opts)
 {
    json_int_t integer, orig_integer;
    json_object_entry * entry;

json-builder.h

@@ -134,15 +134,15 @@ typedef struct json_serialize_opts
 /* Returns a length in characters that is at least large enough to hold the
  * value in its serialized form, including a null terminator.
  */
-size_t json_measure (json_value *);
-size_t json_measure_ex (json_value *, json_serialize_opts);
+size_t json_measure (const json_value *);
+size_t json_measure_ex (const json_value *, json_serialize_opts);
 
 
 /* Serializes a JSON value into the buffer given (which must already be
  * allocated with a length of at least json_measure(value, opts))
  */
-void json_serialize (json_char * buf, json_value *);
-void json_serialize_ex (json_char * buf, json_value *, json_serialize_opts);
+void json_serialize (json_char * buf, const json_value *);
+void json_serialize_ex (json_char * buf, const json_value *, json_serialize_opts);
 
 
 /*** Cleaning up