/*      $OpenBSD: expand.h,v 1.15 2018/01/06 16:28:58 millert Exp $     */

/*
 * Expanding strings
 */

#define X_EXTRA         8       /* this many extra bytes in X string */

#if 0                           /* Usage */
        XString xs;
        char *xp;

        Xinit(xs, xp, 128, ATEMP); /* allocate initial string */
        while ((c = generate()) {
                Xcheck(xs, xp); /* expand string if necessary */
                Xput(xs, xp, c); /* add character */
        }
        return Xclose(xs, xp);  /* resize string */
/*
 * NOTE:
 *     The Xcheck and Xinit macros have a magic + X_EXTRA in the lengths.
 *     This is so that you can put up to X_EXTRA characters in a XString
 *     before calling Xcheck. (See yylex in lex.c)
 */
#endif /* 0 */

typedef struct XString {
        char   *end, *beg;      /* end, begin of string */
        size_t  len;            /* length */
        Area    *areap;         /* area to allocate/free from */
} XString;

typedef char * XStringP;

/* initialize expandable string */
#define Xinit(xs, xp, length, area) do { \
                        (xs).len = length; \
                        (xs).areap = (area); \
                        (xs).beg = alloc((xs).len + X_EXTRA, (xs).areap); \
                        (xs).end = (xs).beg + (xs).len; \
                        xp = (xs).beg; \
                } while (0)

/* stuff char into string */
#define Xput(xs, xp, c) (*xp++ = (c))

/* check if there are at least n bytes left */
#define XcheckN(xs, xp, n) do { \
                    ptrdiff_t more = ((xp) + (n)) - (xs).end; \
                    if (more > 0) \
                        xp = Xcheck_grow_(&xs, xp, more); \
                } while (0)

/* check for overflow, expand string */
#define Xcheck(xs, xp)  XcheckN(xs, xp, 1)

/* free string */
#define Xfree(xs, xp)   afree((xs).beg, (xs).areap)

/* close, return string */
#define Xclose(xs, xp)  aresize((xs).beg, ((xp) - (xs).beg), (xs).areap)
/* begin of string */
#define Xstring(xs, xp) ((xs).beg)

#define Xnleft(xs, xp) ((xs).end - (xp))        /* may be less than 0 */
#define Xlength(xs, xp) ((xp) - (xs).beg)
#define Xsize(xs, xp) ((xs).end - (xs).beg)
#define Xsavepos(xs, xp) ((xp) - (xs).beg)
#define Xrestpos(xs, xp, n) ((xs).beg + (n))

char *  Xcheck_grow_(XString *xsp, char *xp, size_t more);

/*
 * expandable vector of generic pointers
 */

typedef struct XPtrV {
        void  **cur;            /* next avail pointer */
        void  **beg, **end;     /* begin, end of vector */
} XPtrV;

#define XPinit(x, n) do { \
                        void **vp__; \
                        vp__ = areallocarray(NULL, n, sizeof(void *), ATEMP); \
                        (x).cur = (x).beg = vp__; \
                        (x).end = vp__ + n; \
                } while (0)

#define XPput(x, p) do { \
                        if ((x).cur >= (x).end) { \
                                int n = XPsize(x); \
                                (x).beg = areallocarray((x).beg, n, \
                                                   2 * sizeof(void *), ATEMP); \
                                (x).cur = (x).beg + n; \
                                (x).end = (x).cur + n; \
                        } \
                        *(x).cur++ = (p); \
                } while (0)

#define XPptrv(x)       ((x).beg)
#define XPsize(x)       ((x).cur - (x).beg)

#define XPclose(x)      areallocarray((x).beg, XPsize(x), \
                                         sizeof(void *), ATEMP)

#define XPfree(x)       afree((x).beg, ATEMP)