bitmapset.h

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/*-------------------------------------------------------------------------
 *
 * bitmapset.h
 *    PostgreSQL generic bitmap set package
 *
 * A bitmap set can represent any set of nonnegative integers, although
 * it is mainly intended for sets where the maximum value is not large,
 * say at most a few hundred.  By convention, we always represent the
 * empty set by a NULL pointer.
 *
 *
 * Copyright (c) 2003-2025, PostgreSQL Global Development Group
 *
 * src/include/nodes/bitmapset.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef BITMAPSET_H
#define BITMAPSET_H
 
#include "nodes/nodes.h"
 
/*
 * Forward decl to save including pg_list.h
 */
struct List;
 
/*
 * Data representation
 *
 * Larger bitmap word sizes generally give better performance, so long as
 * they're not wider than the processor can handle efficiently.  We use
 * 64-bit words if pointers are that large, else 32-bit words.
 */
#if SIZEOF_VOID_P >= 8
 
#define BITS_PER_BITMAPWORD 64
typedef uint64 bitmapword;      /* must be an unsigned type */
typedef int64 signedbitmapword; /* must be the matching signed type */
 
#else
 
#define BITS_PER_BITMAPWORD 32
typedef uint32 bitmapword;      /* must be an unsigned type */
typedef int32 signedbitmapword; /* must be the matching signed type */
 
#endif
 
typedef struct Bitmapset
{
    pg_node_attr(custom_copy_equal, special_read_write, no_query_jumble)
 
    NodeTag     type;
    int         nwords;         /* number of words in array */
    bitmapword  words[FLEXIBLE_ARRAY_MEMBER];   /* really [nwords] */
} Bitmapset;
 
 
/* result of bms_subset_compare */
typedef enum
{
    BMS_EQUAL,                  /* sets are equal */
    BMS_SUBSET1,                /* first set is a subset of the second */
    BMS_SUBSET2,                /* second set is a subset of the first */
    BMS_DIFFERENT,              /* neither set is a subset of the other */
} BMS_Comparison;
 
/* result of bms_membership */
typedef enum
{
    BMS_EMPTY_SET,              /* 0 members */
    BMS_SINGLETON,              /* 1 member */
    BMS_MULTIPLE,               /* >1 member */
} BMS_Membership;
 
/* Select appropriate bit-twiddling functions for bitmap word size */
#if BITS_PER_BITMAPWORD == 32
#define bmw_leftmost_one_pos(w)     pg_leftmost_one_pos32(w)
#define bmw_rightmost_one_pos(w)    pg_rightmost_one_pos32(w)
#define bmw_popcount(w)             pg_popcount32(w)
#elif BITS_PER_BITMAPWORD == 64
#define bmw_leftmost_one_pos(w)     pg_leftmost_one_pos64(w)
#define bmw_rightmost_one_pos(w)    pg_rightmost_one_pos64(w)
#define bmw_popcount(w)             pg_popcount64(w)
#else
#error "invalid BITS_PER_BITMAPWORD"
#endif
 
 
/*
 * function prototypes in nodes/bitmapset.c
 */
 
extern Bitmapset *bms_copy(const Bitmapset *a);
extern bool bms_equal(const Bitmapset *a, const Bitmapset *b);
extern int  bms_compare(const Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_make_singleton(int x);
extern void bms_free(Bitmapset *a);
 
extern Bitmapset *bms_union(const Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_intersect(const Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_difference(const Bitmapset *a, const Bitmapset *b);
extern bool bms_is_subset(const Bitmapset *a, const Bitmapset *b);
extern BMS_Comparison bms_subset_compare(const Bitmapset *a, const Bitmapset *b);
extern bool bms_is_member(int x, const Bitmapset *a);
extern int  bms_member_index(Bitmapset *a, int x);
extern bool bms_overlap(const Bitmapset *a, const Bitmapset *b);
extern bool bms_overlap_list(const Bitmapset *a, const struct List *b);
extern bool bms_nonempty_difference(const Bitmapset *a, const Bitmapset *b);
extern int  bms_singleton_member(const Bitmapset *a);
extern bool bms_get_singleton_member(const Bitmapset *a, int *member);
extern int  bms_num_members(const Bitmapset *a);
 
/* optimized tests when we don't need to know exact membership count: */
extern BMS_Membership bms_membership(const Bitmapset *a);
 
/* NULL is now the only allowed representation of an empty bitmapset */
#define bms_is_empty(a)  ((a) == NULL)
 
/* these routines recycle (modify or free) their non-const inputs: */
 
extern Bitmapset *bms_add_member(Bitmapset *a, int x);
extern Bitmapset *bms_del_member(Bitmapset *a, int x);
extern Bitmapset *bms_add_members(Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_replace_members(Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_add_range(Bitmapset *a, int lower, int upper);
extern Bitmapset *bms_int_members(Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_del_members(Bitmapset *a, const Bitmapset *b);
extern Bitmapset *bms_join(Bitmapset *a, Bitmapset *b);
 
/* support for iterating through the integer elements of a set: */
extern int  bms_next_member(const Bitmapset *a, int prevbit);
extern int  bms_prev_member(const Bitmapset *a, int prevbit);
 
/* support for hashtables using Bitmapsets as keys: */
extern uint32 bms_hash_value(const Bitmapset *a);
extern uint32 bitmap_hash(const void *key, Size keysize);
extern int  bitmap_match(const void *key1, const void *key2, Size keysize);
 
#endif                          /* BITMAPSET_H */