#ifndef MSTRINGS_H_
#define MSTRINGS_H_ 1

#include "driver.h"
#include "typedefs.h"

#include "hash.h"

/* --- Types --- */

/* --- struct string_s : String structure ---
 *
 * This is the data structure referenced by svalues and constitutes 'the'
 * internal string structure. It is used for both tabled (shared) and
 * untabled (free) strings, and allocated to size.
 *
 * Untabled strings are marked by .tabled == MY_FALSE.
 *
 * Tabled strings are the ones managed in the string table and have .tabled
 * = TRUE. The table uses the .next pointer for the table handling.
 * The table reference is not counted.
 *
 * (While the .next pointer is 'ballast' in untabled strings, in practice the
 * majority of strings in a Mud end up being tabled, so not having the
 * overhead of a separate table link structure outweights the overhead
 * for untabled strings.)
 *
 * .refs counts the number of direct references by svalues. A stored refcount of 0 means that the
 * refcounter rolled over and that the string has to be considered a constant.
 * A refcount of 0 after decrementing means that the last reference
 * for this string_t has been removed.
 *
 * .size is the length of the string (excluding the terminating '\0').
 *
 * .hash is the hash code of the string, computed on demand.
 *
 * The string text itself is held at the end of the structure starting
 * at .txt. The structure is allocated large enough to hold the whole
 * string plus an extra terminating '\0' (which is not counted in the size).
 */

struct string_s
{
    struct {
        Bool tabled      :  1;
        unsigned int ref : 31;
    } info;
    string_t * next;    /* Linkpointer in string table. */
    size_t     size;    /* Length of the string */
    whash_t    hash;    /* 0, or the hash of the string */
    char       txt[1];  /* In fact .size characters plus one '\0' */
      /* The string text follows here */
};

/* --- Variables --- */

extern mp_uint mstr_used;
extern mp_uint mstr_used_size;

/* --- Prototypes --- */

extern void mstring_init (void);
extern whash_t    mstring_get_hash (string_t * pStr);
extern string_t * mstring_alloc_string (size_t iSize MTRACE_DECL);
extern string_t * mstring_new_string (const char * const pTxt MTRACE_DECL);
extern string_t * mstring_new_n_string (const char * const pTxt, size_t len MTRACE_DECL);
extern string_t * mstring_new_tabled (const char * const pTxt MTRACE_DECL);
extern string_t * mstring_new_n_tabled (const char * const pTxt, size_t size MTRACE_DECL);
extern string_t * mstring_make_tabled (string_t * pStr, Bool deref_arg MTRACE_DECL);
extern string_t * mstring_dup (string_t * pStr MTRACE_DECL);
extern string_t * mstring_unshare (string_t * pStr MTRACE_DECL);
extern string_t * mstring_resize (string_t * pStr, size_t n MTRACE_DECL);
extern string_t * mstring_find_tabled (string_t * pStr);
extern string_t * mstring_find_tabled_str (const char * const pTxt, size_t size);
extern int        mstring_order( string_t * const pStr1
                               , string_t * const pStr2);
extern int        mstring_compare( string_t * const pStr1
                                 , string_t * const pStr2);
extern Bool       mstring_equal( string_t * const pStr1
                               , string_t * const pStr2);
extern void mstring_free (string_t *s);
extern string_t * mstring_ref ( string_t * str);
extern unsigned long mstring_deref ( string_t * str);
extern const char * mstring_mstr_n_str(const string_t * const pStr, size_t start, const char * const pTxt, size_t len);
extern const char * mstring_mstr_rn_str(const string_t * const pStr, size_t start, const char * const pTxt, size_t len);
extern string_t * mstring_add_slash (const string_t *str MTRACE_DECL);
extern string_t * mstring_del_slash (string_t *str MTRACE_DECL);
extern string_t * mstring_cvt_progname (const string_t *str MTRACE_DECL);
extern string_t * mstring_del_dotc (string_t *str MTRACE_DECL);
extern string_t * mstring_add (const string_t *left, const string_t *right MTRACE_DECL);
extern string_t * mstring_add_txt (const string_t *left, const char *right, size_t len MTRACE_DECL);
extern string_t * mstring_add_to_txt (const char *left, size_t len, const string_t *right MTRACE_DECL);
extern string_t * mstring_append (string_t *left, const string_t *right MTRACE_DECL);
extern string_t * mstring_append_txt (string_t *left, const char *right, size_t len MTRACE_DECL);
extern string_t * mstring_repeat(const string_t *base, size_t num MTRACE_DECL);
extern string_t * mstring_extract (const string_t *str, size_t start, long end MTRACE_DECL);
extern long       mstring_chr (const string_t *p, char c);
extern Bool       mstring_prefixed (const string_t *p, const string_t *s);

#ifdef GC_SUPPORT

extern void mstring_clear_refs (void);
extern void mstring_note_refs (void);
extern void mstring_walk_table (void (*func)(string_t *));
extern void mstring_gc_table (void);

#endif /* GC_SUPPORT */

extern mp_int add_string_status (strbuf_t *sbuf, Bool verbose);
extern void   string_dinfo_status(svalue_t *svp, int value);


/* --- Inline functions and macros --- */

#define mstr_mem_size(s) \
    (sizeof(string_t) + (s)->size)

  /* size_t mstr_mem_size(string_t * s)
   *   The amount of memory used to hold all this strings' data.
   *   Used only to keep the statistics up to date.
   */

#define mstr_hash(s) \
    ( (s)->hash )

  /* whash_t mstr_hash(string_t * s)
   *   Return the hash value of string <s>, which is 0 if the
   *   hash hasn't been computed yet.
   */

#define mstr_singular(s) \
    (! ((s)->info.tabled || (s)->info.ref != 1) )
  /* Bool mstr_singular(string_t *s)
   *   Return FALSE if string<s> has multiple users, ie. is tabled
   *   or has more than one reference.
   */

#define mstr_untabled(s) \
    (!(s)->info.tabled)

  /* Bool mstr_untabled (string_t *s)
   *   Return TRUE if string <s> is not tabled.
   *   The argument must not have sideeffects!
   */

#define mstr_tabled(s) \
    ((s)->info.tabled)

  /* Bool mstr_tabled (string_t *s)
   *   Return TRUE if string <s> is tabled - directly or indirectly.
   *   The argument must not have sideeffects!
   */

#define mstrsize(s) \
    ((s)->size)

  /* size_t mstrsize(string_t *s)
   *   Return the size (length) of the string <s>.
   */

#define ref_mstring(s) \
    (mstr_used++, mstr_used_size += mstr_mem_size(s), (s)->info.ref ? ++((s)->info.ref) : 0, (s))

#define ref_mstring_safe(s) mstring_ref(s)

  /* string_t * ref_mstring (string_t *s)
   * string_t * ref_mstring_safe (string_t *s)
   *   Increment the refcount for string <s> and return the ref'ed string.
   *   The argument <s> to ref_mstring() must not have sideeffects!
   */


#define deref_mstring(s) \
    (mstr_used--, mstr_used_size -= mstr_mem_size(s), (s)->info.ref ? --((s)->info.ref) : (s)->info.ref)

#define deref_mstring_safe(s) mstring_deref(s)

  /* int deref_mstring (string_t *s)
   * int deref_mstring_safe (string_t *s)
   *   Decrement the refcount for string <s> and return the new count.
   *   The argument <s> to deref_mstring() must not have sideeffects!
   */


#define free_mstring(s) \
    MACRO(string_t * fmsttmp = s; if (fmsttmp != NULL) { if (fmsttmp->info.ref == 1) { mstring_free(fmsttmp); } else deref_mstring(fmsttmp); } )

  /* void free_mstring(s)
   *
   *   Decrement the refcount for string <s>, and if it reaches 0,
   *   deallocate <s> altogether.
   */

#define get_txt(s) \
    ((s)->txt)

  /* char * get_txt (string_t *s)
   *
   *   Return a pointer to the actual string text of string <s>.
   *   There is at least one '\0' terminating the string text.
   */

#define extract_cstr(d,s,l) \
    MACRO(strncpy((d), get_txt(s), (l)-1); \
          if ((l) > mstrsize(s)) \
            d[mstrsize(s)] = '\0'; \
          else \
            d[(l)-1] = '\0'; \
         )

  /* void extract_cstr (char * d, string_t *s, size_t l)
   *
   *   Extract the C string from <s> (that is: all characters up to the
   *   first '\0' resp the end of the string) and copy it into buffer <d>
   *   of size <l>. The macro makes sure that the string is terminated
   *   with a '\0'
   */

/* A handful of shorthands for commonly used functions */

#define alloc_mstring(iSize)     mstring_alloc_string(iSize MTRACE_ARG)
#define new_mstring(pTxt)        mstring_new_string(pTxt MTRACE_ARG)
#define new_n_mstring(pTxt,len)  mstring_new_n_string(pTxt,len MTRACE_ARG)
#define new_tabled(pTxt)         mstring_new_tabled(pTxt MTRACE_ARG)
#define new_n_tabled(pTxt,len)   mstring_new_n_tabled(pTxt,len MTRACE_ARG)
#define make_tabled(pStr)        mstring_make_tabled(pStr, MY_TRUE MTRACE_ARG)
#define make_tabled_from(pStr)   mstring_make_tabled(pStr, MY_FALSE MTRACE_ARG)
#define dup_mstring(pStr)        mstring_dup(pStr MTRACE_ARG)
#define unshare_mstring(pStr)    mstring_unshare(pStr MTRACE_ARG)
#define resize_mstring(pStr,n)   mstring_resize(pStr,n MTRACE_ARG)
#define find_tabled(pStr)          mstring_find_tabled(pStr)
#define find_tabled_str(pTxt)      mstring_find_tabled_str(pTxt, strlen(pTxt))
#define find_tabled_str_n(pTxt,n)  mstring_find_tabled_str(pTxt,n)
#define mstr_get_hash(s)         ((s)->hash ? (s)->hash : mstring_get_hash(s))
#define mstrcmp(pStr1,pStr2)     mstring_compare(pStr1, pStr2)
#define mstr_order(pStr1,pStr2)  mstring_order(pStr1, pStr2)
#define mstreq(pStr1,pStr2)      mstring_equal(pStr1, pStr2)
#define mstrstr(pStr,pTxt)       mstring_mstr_n_str(pStr, 0, pTxt, strlen(pTxt))
#define mstrrstr(pStr,pTxt)      mstring_mstr_rn_str(pStr, mstrsize(pStr)-1, pTxt, strlen(pTxt))
#define mstr_add(pStr1,pStr2)     mstring_add(pStr1,pStr2 MTRACE_ARG)
#define mstr_add_txt(pStr1,pTxt2,len) mstring_add_txt(pStr1,pTxt2,len MTRACE_ARG)
#define mstr_add_to_txt(pTxt1,len,pStr2) mstring_add_to_txt(pTxt1, len, pStr2 MTRACE_ARG)
#define mstr_append(pStr1,pStr2)  mstring_append(pStr1,pStr2 MTRACE_ARG)
#define mstr_append_txt(pStr1,pTxt2,len) mstring_append_txt(pStr1,pTxt2,len MTRACE_ARG)
#define mstr_repeat(pStr,num)    mstring_repeat(pStr,num MTRACE_ARG)
#define mstr_extract(pStr,start,end) mstring_extract (pStr,start,end MTRACE_ARG)
#define add_slash(pStr)          mstring_add_slash(pStr MTRACE_ARG)
#define del_slash(pStr)          mstring_del_slash(pStr MTRACE_ARG)
#define del_dotc(pStr)           mstring_del_dotc(pStr MTRACE_ARG)
#define cvt_progname(pStr)       mstring_cvt_progname(pStr MTRACE_ARG)
#define mstrchr(pStr,c)          mstring_chr(pStr, c)
#define mstrprefixed(pStr1, pStr2) mstring_prefixed(pStr1, pStr2)

#endif /* MSTRINGS_H_ */