/*
\funcref{istrue}{void istrue ()}
    {}
    {0: the last pushed variable yields `false'; otherwise: the last pushed
     variable yields `true'}
    {pop(), discard()}
    {fun\_jmp\_true(), fun\_jmp\_false()}
    {istrue.c}
    {

        This function pops the last pushed variable and determines if that
        variable should yield true. If the variable is of type {\em e\_int},
        then the integer representation is returned. If the variable is of type
        {\em e\_str}, then the first character in the string (this may be a
        zero-byte) is returned. If the variable is of type {\em e\_list}, the
        list size is returned.

        The popped variable is discarded.

    }
*/

#include "icm-exec.h"

int istrue ()
{
    VAR_
        tmp;
    register int
        ret;

    tmp = pop ();
    if (tmp.type & e_int)
        ret = tmp.vu.intval;
    else if (tmp.type & e_str)
        ret = *(tmp.vu.i->ls.str);
    else
        ret = tmp.vu.i->ls.list.size;

    discard (tmp);
    return (ret);
}