/*
 unireadline.c, add readline powers to Unicon
 tectonics: gcc -o unireadline.so -shared -fpic unireadline.c

 Unicon usage: readline := loadfunc("./unireadline", "unirl")

 Dedicated to the public domain

 Date: September 2016
 Modified: 2016-09-07/04:53-0400
*/

#include <stdio.h>
#include <stdlib.h>
#include <readline/readline.h>
#include <readline/history.h>
#include "icall.h"

int
unirl(int argc, descriptor *argv)
{
    static char *line;

    /* need the string prompt */
    if (argc < 1) Error(500);
    ArgString(1);

    /* if line already allocated, free it */
    if (line) {
        free(line);
        line = (char *)NULL;
    }

    /* call readline with prompt */
    line = readline(StringVal(argv[1]));

    /* fail when no line read (EOF for instance) or save and return */
    if (!line) Fail;
    if (*line) add_history(line);
    RetString(line);
}