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/* 
|| This file is part of Pike. For copyright information see COPYRIGHT. 
|| Pike is distributed under GPL, LGPL and MPL. See the file COPYING 
|| for more information. 
*/ 
 
#ifndef MULTISET_H 
#define MULTISET_H 
 
/* Multisets using rbtree. 
 * 
 * Created by Martin Stjernholm 2001-05-07 
 */ 
 
/* #define TEST_MULTISET */ 
 
#include "svalue.h" 
#include "dmalloc.h" 
#include "rbtree.h" 
 
/* Note: Don't access the ind svalue (or at least not its type field) 
 * in the following directly, since the rbtree flags overlay that. Use 
 * assign_multiset_index_no_free() or similar instead. */ 
 
struct msnode_ind 
{ 
  struct msnode_ind *prev, *next; /* Must be first. */ 
  struct svalue ind;                /* Must be second. */ 
}; 
 
union msnode 
{ 
  struct msnode_ind i; 
  struct rb_node_hdr rb_hdr; 
}; 
 
#define MULTISET_FLAG_MARKER  0x1000 
#define MULTISET_FLAG_MASK    (RB_FLAG_MASK | MULTISET_FLAG_MARKER) 
/* The flag marker is used to reliably nail direct uses of the ind 
 * type field. */ 
 
struct multiset_data 
{ 
  GC_MARKER_MEMBERS; 
  INT32 noval_refs; 
  union msnode *root, *free_list; 
  struct svalue cmp_less; 
  INT32 size, allocsize; 
  TYPE_FIELD ind_types; 
  TYPE_FIELD val_types;         /* Always BIT_INT in valueless multisets. */ 
  INT16 flags; 
  union msnode nodes[1]; 
}; 
 
struct multiset 
{ 
  GC_MARKER_MEMBERS; 
  struct multiset_data *msd; 
  struct multiset *next, *prev; 
  INT32 node_refs; 
}; 
 
/* Data structure notes: 
 * 
 * o  The node free list through multiset_data.free_list is singly 
 *    linked by the next pointers. Nodes on the free list are either 
 *    free or deleted (see below). Free nodes have ind.type set to 
 *    PIKE_T_UNKNOWN, and deleted nodes are flagged with T_DELETED. 
 * 
 *    Deleted nodes are always before free nodes on the free list. 
 *    multiset_data.size counts both the allocated and the deleted 
 *    nodes. Note that deleted nodes might still be on the free list 
 *    even when there are no node references (see below). 
 * 
 * o  multiset_data.cmp_less is the integer zero when the internal set 
 *    order is used. It must not have any other integer value. 
 * 
 * o  multset_data.refs counts the number of "independent" references 
 *    to the data block. When it's greater than one, the data block 
 *    must always be copied if anything but a node value is changed. 
 *    Changes of node values might be allowed depending on 
 *    multset_data.noval_refs. 
 * 
 *    A direct pointer to or into the data block can only be kept if 
 *    it's accounted for by this ref counter, otherwise an indirection 
 *    via a multiset struct must be used. 
 * 
 *    When the gc runs, it won't touch a multiset_data block that got 
 *    direct external references, i.e. if multiset_data.refs is 
 *    greater than the number of multiset objects that points to 
 *    it. 
 * 
 * o  multiset_data.noval_refs is the number of the multiset_data.refs 
 *    references that don't lock the value part of the data block. 
 *    Thus, values may be changed without copy if (refs - noval_refs) 
 *    is 1 (if youself have a value lock) or 0 (if you don't). The 
 *    functions below that change only values assume that the caller 
 *    has a value lock. 
 * 
 *    Note that you should not do any operation that might cause a 
 *    copy of the data block (which includes insert and delete) when 
 *    you've increased noval_refs, since it then won't be possible for 
 *    the copying function to know whether one ref in noval_refs 
 *    should be moved to the copy or not. All copy operations let 
 *    noval_refs stay with the original. 
 * 
 * o  multiset.node_refs counts the number of references to nodes in 
 *    the multiset. The references are array offsets in 
 *    multiset.msd->nodes, so the data block may be reallocated but no 
 *    nodes may be moved relatively within it. Values but not indices 
 *    may be changed when there are node references, nodes may be 
 *    added and removed, and the order may be changed. 
 * 
 *    Nodes that are deleted during nonzero node_refs are linked in 
 *    first on the free list as usual, but ind.type is set to 
 *    T_DELETED. They are thereby flagged to not be used again. 
 *    Deleted nodes on the free list are flagged as free as soon as 
 *    possible after all node references are gone. There are however 
 *    some combinations of node references and shared data blocks that 
 *    results in deleted nodes on the free list even after all node 
 *    references are gone. 
 * 
 *    The prev and ind.u.ptr pointers in deleted nodes point to the 
 *    previous and next neighbor, respectively, of the node at the 
 *    time it was deleted. Thus the relative position of the node is 
 *    remembered even after it has been deleted. 
 */ 
 
#define MULTISET_WEAK_INDICES 2 
#define MULTISET_WEAK         2 
 
extern struct multiset *first_multiset; 
extern struct multiset *gc_internal_multiset; 
 
PMOD_EXPORT void multiset_clear_node_refs (struct multiset *l); 
 
#ifdef PIKE_DEBUG 
/* To get good type checking. */ 
static inline union msnode PIKE_UNUSED_ATTRIBUTE *msnode_check (union msnode *x) 
  {return x;} 
PMOD_EXPORT extern const char msg_no_multiset_flag_marker[]; 
#else 
#define msnode_check(X) ((union msnode *) (X)) 
#endif 
 
#define MULTISET_STEP_FUNC(FUNC, NODE)                                        \ 
  ((union msnode *) FUNC (&(msnode_check(NODE)->rb_hdr))) 
#define low_multiset_first(MSD) MULTISET_STEP_FUNC (rb_first, (MSD)->root) 
#define low_multiset_last(MSD) MULTISET_STEP_FUNC (rb_last, (MSD)->root) 
#define low_multiset_prev(NODE) MULTISET_STEP_FUNC (rb_prev, NODE) 
#define low_multiset_next(NODE) MULTISET_STEP_FUNC (rb_next, NODE) 
#define low_multiset_get_nth(MSD, N)                                  \ 
  ((union msnode *) rb_get_nth (&((MSD)->root->rb_hdr), (N))) 
 
#define low_assign_multiset_index_no_free(TO, NODE) do {              \ 
    struct svalue *_ms_index_to_ = (TO);                                \ 
    *_ms_index_to_ = msnode_check (NODE)->i.ind;                        \ 
    DO_IF_DEBUG (                                                       \ 
      if (!(TYPEOF(*_ms_index_to_) & MULTISET_FLAG_MARKER))             \ 
        Pike_fatal (msg_no_multiset_flag_marker);                       \ 
    );                                                                  \ 
    SET_SVAL_TYPE(*_ms_index_to_,                                       \ 
                  TYPEOF(*_ms_index_to_) & ~MULTISET_FLAG_MASK);        \ 
    add_ref_svalue (_ms_index_to_);                                     \ 
  } while (0) 
#define low_assign_multiset_index(TO, NODE) do {                      \ 
    struct svalue *_ms_index_to2_ = (TO);                               \ 
    free_svalue (_ms_index_to2_);                                       \ 
    low_assign_multiset_index_no_free (_ms_index_to2_, (NODE));         \ 
  } while (0) 
#define low_push_multiset_index(NODE)                                 \ 
  low_assign_multiset_index_no_free (Pike_sp++, (NODE)) 
#define low_use_multiset_index(NODE, VAR)                             \ 
  ((VAR) = msnode_check (NODE)->i.ind,                                  \ 
    DO_IF_DEBUG (TYPEOF(VAR) & MULTISET_FLAG_MARKER ? 0 :               \ 
                (Pike_fatal (msg_no_multiset_flag_marker), 0) COMMA)    \ 
   SET_SVAL_TYPE((VAR), TYPEOF(VAR) & ~MULTISET_FLAG_MASK),             \ 
   &(VAR)) 
 
#define low_get_multiset_value(MSD, NODE)                             \ 
  (/* Caller better not try to change this. */                          \ 
   (struct svalue *) &svalue_int_one) 
 
#define OFF2MSNODE(MSD, OFFSET)                                               \ 
  ((MSD)->nodes + (OFFSET)) 
#define MSNODE2OFF(MSD, NODE)                                         \ 
  ((NODE) - (MSD)->nodes) 
 
PMOD_EXPORT INT32 multiset_sizeof (struct multiset *l); 
#define l_sizeof(L) multiset_sizeof (L) 
#define multiset_ind_types(L) ((L)->msd->ind_types) 
#define multiset_val_types(L) ((L)->msd->val_types) 
#define multiset_get_flags(L) ((L)->msd->flags) 
#define multiset_get_cmp_less(L) (&(L)->msd->cmp_less) 
 
/* This is somewhat faster than using multiset_sizeof just to 
 * check whether or not the multiset has no elements at all. */ 
#define multiset_is_empty(L) (!(L)->msd->root) 
 
#if defined(USE_DLL) && defined(DYNAMIC_MODULE) 
/* Use the function in modules so we don't have to export the block 
 * alloc stuff. */ 
#define free_multiset(M) do_free_multiset (M) 
#else 
 
PMOD_EXPORT void really_free_multiset (struct multiset *l); 
PMOD_EXPORT void count_memory_in_multisets (size_t * n, size_t * s); 
 
#define free_multiset(L) do {                                         \ 
    struct multiset *_ms_ = (L);                                        \ 
    debug_malloc_touch (_ms_);                                          \ 
    DO_IF_DEBUG (                                                       \ 
      DO_IF_PIKE_CLEANUP (                                              \ 
        if (gc_external_refs_zapped)                                    \ 
          gc_check_zapped (_ms_, PIKE_T_MULTISET, __FILE__, __LINE__))); \ 
    if (!sub_ref (_ms_)) really_free_multiset (_ms_);                   \ 
  } while (0) 
 
#endif        /* !(USE_DLL && DYNAMIC_MODULE) */ 
 
#ifdef PIKE_DEBUG 
 
PMOD_EXPORT union msnode *debug_check_msnode ( 
  struct multiset *l, ptrdiff_t nodepos, int allow_deleted, 
  char *file, int line); 
#define check_msnode(L, NODEPOS, ALLOW_DELETED)                               \ 
  debug_check_msnode ((L), (NODEPOS), (ALLOW_DELETED), __FILE__, __LINE__) 
#define access_msnode(L, NODEPOS)                                     \ 
  check_msnode ((L), (NODEPOS), 0) 
 
#else 
 
#define check_msnode(L, NODEPOS, ALLOW_DELETED) 
#define access_msnode(L, NODEPOS) OFF2MSNODE ((L)->msd, (NODEPOS)) 
 
#endif 
 
/* See rbtree.h for a description of the operations. 
 * 
 * If cmp_less is used, it's a function pointer used as `< to compare 
 * the entries, otherwise the internal set order is used. `< need not 
 * define a total order for the possible indices; if neither a < b nor 
 * b < a is true then a and b are considered equal orderwise. The 
 * order between such indices is arbitrary and stable. The orderwise 
 * equality doesn't affect searches on equality, however; if several 
 * orderwise equal values are found, then they are searched linearly 
 * backwards until one is found which is equal to the key according to 
 * `==. 
 * 
 * It's possible to keep references to individual nodes. The node 
 * offset within the multiset data block is used then, which together 
 * with the multiset struct can access the node. Use add_msnode_ref 
 * when you store a node reference and sub_msnode_ref when you throw 
 * it away. The multiset_find_*, multiset_first, multiset_last and 
 * multiset_get_nth functions do add_msnode_ref for you (if they 
 * return a match). Other functions, like multiset_insert_2, doesn't, 
 * even though they might return a node offset. 
 * 
 * msnode_is_deleted tells whether the referenced node has been 
 * deleted. The relative position of a deleted node is remembered by 
 * keeping pointers to the neighbors it had when it was deleted. A 
 * "defensive" strategy is employed when a deleted node is used in a 
 * function: If going forward then the previous neighbor links are 
 * followed until a nondeleted neighbor is found, which is then used 
 * as the base for the forward movement. Vice versa in the backward 
 * direction. This has the effect that if nodes are added and removed 
 * in a multiset that is being traversed in some direction, then no 
 * newly added nodes in the vicinity of the current one are missed. It 
 * also has the effect that the node returned by multiset_next for a 
 * deleted node might be before the one returned by multiset_prev. 
 * 
 * Since the functions might run pike code when comparing entries 
 * (even when cmp_less isn't used), the multiset may change during the 
 * search in it. If that happens for a destructive operation, it's 
 * remade in one way or the other to ensure that the change has been 
 * made in the multiset that is current upon return. This normally has 
 * no caller visible effects, except for multiset_add_after, which 
 * might fail to add the requested entry (it returns less than zero in 
 * that case). 
 */ 
 
/* Returns the node offset, or -1 if no match was found. */ 
PMOD_EXPORT ptrdiff_t multiset_first (struct multiset *l); 
PMOD_EXPORT ptrdiff_t multiset_last (struct multiset *l); 
PMOD_EXPORT ptrdiff_t multiset_prev (struct multiset *l, ptrdiff_t nodepos); 
PMOD_EXPORT ptrdiff_t multiset_next (struct multiset *l, ptrdiff_t nodepos); 
 
#ifdef PIKE_DEBUG 
PMOD_EXPORT extern const char msg_multiset_no_node_refs[]; 
#endif 
 
#define add_msnode_ref(L) do {(L)->node_refs++;} while (0) 
#define sub_msnode_ref(L) do {                                                \ 
    struct multiset *_ms_ = (L);                                        \ 
    DO_IF_DEBUG (                                                       \ 
      if (!_ms_->node_refs) Pike_fatal (msg_multiset_no_node_refs);     \ 
    );                                                                  \ 
    if (!--_ms_->node_refs && _ms_->msd->refs == 1)                     \ 
      multiset_clear_node_refs (_ms_);                                  \ 
  } while (0) 
 
PMOD_EXPORT void do_sub_msnode_ref (struct multiset *l); 
PMOD_EXPORT int msnode_is_deleted (struct multiset *l, ptrdiff_t nodepos); 
 
#define assign_multiset_index_no_free(TO, L, NODEPOS) do {            \ 
    struct multiset *_ms_ = (L);                                        \ 
    union msnode *_ms_node_ = access_msnode (_ms_, (NODEPOS));          \ 
    low_assign_multiset_index_no_free (TO, _ms_node_);                  \ 
  } while (0) 
#define assign_multiset_index(TO, L, NODEPOS) do {                    \ 
    struct multiset *_ms_ = (L);                                        \ 
    union msnode *_ms_node_ = access_msnode (_ms_, (NODEPOS));          \ 
    low_assign_multiset_index (TO, _ms_node_);                          \ 
  } while (0) 
#define push_multiset_index(L, NODEPOS)                                       \ 
  assign_multiset_index_no_free (Pike_sp++, (L), (NODEPOS)) 
#define use_multiset_index(L, NODEPOS, VAR)                           \ 
  ((VAR) = access_msnode ((L), (NODEPOS))->i.ind,                       \ 
   SET_SVAL_TYPE((VAR), TYPEOF(VAR) & ~MULTISET_FLAG_MASK),             \ 
   &(VAR)) 
 
#define get_multiset_value(L, NODEPOS)                                        \ 
  (/* Caller better not try to change this. */                          \ 
   (struct svalue *) &svalue_int_one) 
/* Note: It's intentional that the value is silently ignored for 
 * index-only multisets. */ 
 
#define assign_multiset_value_no_free(TO, L, NODEPOS)                 \ 
  assign_svalue_no_free (TO, get_multiset_value (L, NODEPOS)) 
#define assign_multiset_value(TO, L, NODEPOS)                         \ 
  assign_svalue (TO, get_multiset_value (L, NODEPOS)) 
#define push_multiset_value(L, NODEPOS)                                       \ 
  push_svalue (get_multiset_value (L, NODEPOS)) 
 
#define allocate_multiset(allocsize, flags, cmp_less)                 \ 
  dmalloc_touch (struct multiset *,                                     \ 
                 real_allocate_multiset ((allocsize), (flags), (cmp_less))) 
 
PMOD_EXPORT struct multiset *real_allocate_multiset (int allocsize, 
                                                     int flags, 
                                                     struct svalue *cmp_less); 
PMOD_EXPORT void do_free_multiset (struct multiset *l); 
PMOD_EXPORT void multiset_fix_type_field (struct multiset *l); 
PMOD_EXPORT void multiset_set_flags (struct multiset *l, int flags); 
PMOD_EXPORT struct multiset *mkmultiset (struct array *indices); 
PMOD_EXPORT void multiset_insert (struct multiset *l, 
                                  struct svalue *ind); 
PMOD_EXPORT int multiset_delete (struct multiset *l, 
                                 struct svalue *ind); 
PMOD_EXPORT int multiset_delete_2 (struct multiset *l, 
                                   struct svalue *ind, 
                                   struct svalue *removed_val); 
PMOD_EXPORT struct svalue *multiset_lookup (struct multiset *l, 
                                            struct svalue *key); 
PMOD_EXPORT int multiset_member (struct multiset *l, 
                                 struct svalue *key); 
struct array *multiset_indices (struct multiset *l); 
struct array *multiset_values (struct multiset *l); 
PMOD_EXPORT void check_multiset_for_destruct (struct multiset *l); 
PMOD_EXPORT struct multiset *copy_multiset (struct multiset *l); 
PMOD_EXPORT struct multiset *merge_multisets (struct multiset *a, 
                                              struct multiset *b, 
                                              int operation); 
PMOD_EXPORT struct multiset *add_multisets (struct svalue *argp, int count); 
PMOD_EXPORT int multiset_equal_p (struct multiset *a, struct multiset *b, 
                                  struct processing *p); 
void describe_multiset (struct byte_buffer *buf, struct multiset *l, struct processing *p, int indent); 
int multiset_is_constant (struct multiset *l, struct processing *p); 
node *make_node_from_multiset (struct multiset *l); 
PMOD_EXPORT void f_aggregate_multiset (int args); 
struct multiset *copy_multiset_recursively (struct multiset *l, 
                                            struct mapping *p); 
PMOD_EXPORT ptrdiff_t multiset_get_nth (struct multiset *l, size_t n); 
 
PMOD_EXPORT void visit_multiset (struct multiset *l, int action, void *extra); 
unsigned gc_touch_all_multisets (void); 
void gc_check_all_multisets (void); 
void gc_mark_multiset_as_referenced (struct multiset *l); 
void gc_mark_all_multisets (void); 
void gc_zap_ext_weak_refs_in_multisets (void); 
void real_gc_cycle_check_multiset (struct multiset *l, int weak); 
void gc_cycle_check_all_multisets (void); 
size_t gc_free_all_unreferenced_multisets (void); 
 
#define visit_multiset_ref(L, REF_TYPE, EXTRA)                        \ 
  visit_ref (pass_multiset (L), (REF_TYPE),                     \ 
             (visit_thing_fn *) &visit_multiset, (EXTRA)) 
#define gc_cycle_check_multiset(X, WEAK) \ 
  gc_cycle_enqueue ((gc_cycle_check_cb *) real_gc_cycle_check_multiset, (X), (WEAK)) 
 
#ifdef PIKE_DEBUG 
void check_multiset (struct multiset *l, int safe); 
void check_all_multisets (int safe); 
void debug_dump_multiset (struct multiset *l); 
#endif 
 
void count_memory_in_multisets (size_t *num, size_t *size); 
void init_multiset (void); 
void exit_multiset (void); 
void test_multiset (void); 
 
#endif /* MULTISET_H */