/**
 *  payloads/string.c
 *
 *  A string cell.
 *
 *  (c) 2026 Simon Brooke <simon@journeyman.cc>
 *  Licensed under GPL version 2.0, or, at your option, any later version.
 */



 /*
  * wide characters
  */

#include "memory/node.h"
#include "memory/pointer.h"
#include "memory/pso.h"
#include "memory/pso2.h"
#include "memory/pso4.h"
#include "memory/tags.h"

#include "ops/string_ops.h"
#include "payloads/cons.h"

#include "ops/stack_ops.h"


/**
 * Construct a string from the character `c` and this `tail`. A string is
 * implemented as a flat list of cells each of which has one character and a
 * pointer to the next; in the last cell the pointer to next is NIL.
 *
 * @param c the character to add (prepend);
 * @param tail the string which is being built.
 */
struct pso_pointer make_string( struct pso_pointer frame_pointer, wint_t c,
                                struct pso_pointer tail ) {
    return make_string_like_thing( frame_pointer, c, tail, STRINGTAG );
}

/**
 * @brief When an string is freed, its cdr pointer must be decremented.
 *
 * Lisp calling conventions; one expected arg, the pointer to the object to
 * be destroyed.
 */
struct pso_pointer destroy_string( struct pso_pointer frame_pointer ) {
    if ( stackp( frame_pointer ) ) {
        dec_ref( c_cdr( fetch_arg( pointer_to_pso4( frame_pointer ), 0 ) ) );
    }

    return nil;
}