1、A set is an unordered collection of distinct members.
2、The basic operations on a set are testing for membership, adding members, and removing members.
3、Other operations include set union, intersection, difference, and symmetric difference.
set實現類似於table(key-value系統)的實現,採用類似的“哈希表和鏈表”的底層數據結構。可以參看上一章的內容。
=============================set.h==============================
#ifndef SET_INCLUDED
#define SET_INCLUDED
#define T Set_T
typedef struct T *T;
//exported functions
extern T Set_new (int hint,
int cmp(const void *x, const void *y),
unsigned hash(const void *x));
extern void Set_free (T *set);
extern int Set_length(T set);
extern int Set_member(T set, const void *member);
extern void Set_put (T set, const void *member);
extern void *Set_remove(T set, const void *member);
extern void Set_map (T set,
void apply(const void *member, void *cl), void *cl);
extern void **Set_toArray(T set, void *end);
extern T Set_union (T s, T t);
extern T Set_inter (T s, T t);
extern T Set_minus (T s, T t);
extern T Set_diff (T s, T t);
#undef
#endif
=============================set.c============================
#include <limits.h>
#include <stddef.h>
#include "mem.h"
#include "assert.h"
#include "arith.h"
#include "set.h"
#define T Set_T
//types
struct T{
int length;
unsigned timestamp;
int (*cmp)(const void *x, const void *y);
unsigned (*hash)(const void *x);
int size;
struct member{
struct member *link;
const void *member;
} **buckets;
}
//static functions
static int cmpatom(const void *x, const void *y){
return x != y;
}
static unsigned hashatom(const void *x){
return (unsigned long)x>>2;
}
static T copy(T t, int hint){
T set;
assert(t);
set = Set_new(hint, t->cmp, t->hash);
{
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
struct member *p;
const void *member = q->member;
int i = (*set->hash)(member)%set->size;
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}
}
}
return set;
}
//functions
T Set_new(int hint,
int cmp(const void *x, const void *y),
unsigned hash(const void *x)){
T set;
int i;
static int primes[] = { 509, 509, 1021, 2053, 4093,
8191, 16381, 32771, 65521, INT_MAX };
assert(hint >= 0);
for(i = 1; primes[i] < hint; ++i){
;
set = ALLOC(sizeof(*set) +
primes[i-1]*sizeof(set->buckets[0]));
set->size = primes[i-1];
set->cmp = cmp ? cmp : cmpatom;
set->hash = hash ? hash : hashatom;
set->buckets = (struct member **)(set + 1);
for(i = 0; i < set->size; ++i){
set->buckets[i] = NULL;
}
set->length = 0;
set->timestamp = 0;
return set;
}
int Set_member(T set, const void *member){
int i;
struct member *p;
assert(set);
assert(member);
//search set for member
i = (*set->hash)(member)%set->size;
for(p = set->buckets[i]; p; p = p->link){
if((*set->cmp)(member, p->member) == 0)
break;
}
return p != NULL;
}
void Set_put(T set, const void *member){
int i;
struct member *p;
assert(set);
assert(member);
//search set for member
i = (*set->hash)(member)%set->size;
for(p = set->buckets[i]; p; p = p->link){
if((*set->cmp)(member, p->member) == 0)
break;
}
if(p == NULL){
//add member to set
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}else{
p->member = member;
}
set->timestamp++;
}
void *Set_remove(T set, const void *member){
int i;
struct member **pp;
assert(set);
assert(member);
set->timestamp++;
i = (*set->hash)(member)%set->size;
for(pp = &set->buckets[i]; *pp; pp = &(*pp)->link){
if((*set->cmp)(member, (*pp)->member) == 0){
struct member *p = *pp;
*pp = p->link;
member = p->member;
FREE(p);
set->length--;
retunr (void *)member;
}
}
return NULL;
}
int Set_length(T set){
assert(set);
return set->length;
}
void Set_free(T *set){
assert(set && *set);
if((*set)->length > 0){
int i;
struct member *p; *q;
for(i = 0; i < (*set)->size; ++i){
for(p = (*set)->buckets[i]; p; p = q){
q = p->link;
FREE(p);
}
}
}
FREE(*set);
}
void Set_map(T set,
void apply(const void *member, void *cl), void *cl){
int i;
unsigned stamp;
struct member *p;
assert(set);
assert(apply);
stamp = set->timestamp;
for(i = 0; i < set->size; ++i){
for(p = set->buckets[i]; p; p = p->link){
apply(p->member, cl);
assert(set->timestamp == stamp);
}
}
}
void **Set_toArray(T set, void *end){
int i, j = 0;
void **array;
struct member *p;
assert(set);
array = ALLOC((set->length + 1)*sizeof(*array));
for(i = 0; i < set->size; ++i){
for(p = set->buckets[i]; p; p = p->link){
array[j++] = (void *)p->member;
}
}
array[j] = end;
return array;
}
T Set_union(T s, T t){
if(s == NULL){
assert(t);
return copy(t, t->size);
}else if( t == NULL){
return copy(s, s->size);
}else{
T set = copy(s, Arith_max(s->size, t->size));
assert(s->cmp == t->cmp && s->hash == t->hash);
{
//for each member q in t
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
Set_put(set, q->member);
}
}
}
return set;
}
}
T Set_inter(T s, T t){
if(s == NULL){
assert(t);
return Set_new(t->size, t->cmp, t->hash);
}else if( t == NULL){
return Set_new(s->size, s->cmp, s->hash);
}else if(s->length < t->length){
return Set_inter(t, s);
}else{
T set = Set_new(Arith_min(s->size, t->size),
s->cmp, s->hash);
assert(s->cmp == t->cmp && s->hash == t->hash);
{
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
if(Set_member(s, q->member)){
struct member *p
const void *member = q->member;
int i = (*set->hash)(member)%set->size;
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}
}
}
}
return set;
}
}
T Set_minus(T t, T s){
if(t == NULL){
assert(s);
return Set_new(s->size, s->cmp, s->hash);
}else if(s == NULL){
return copy(t, t->size);
}else{
T set = Set_new(Arith_min(s->size, t->size),
s->cmp, s->hash);
assert(s->cmp == t->cmp && s->hash == t->hash);
{
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
if(!Set_member(s, q->member)){
struct member *p;
const void *member = q->member;
int i = (*set->hash)(member)%set->size;
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}
}
}
}
return set;
}
}
T Set_diff(T s, T t){
if(s == NULL){
assert(t);
return copy(t, t->size);
}else if(t == NULL){
return copy(s, s->size);
}else{
T set = Set_new(Arith_min(s->size, t->size),
s->cmp, s->hash);
assert(s->cmp == t->cmp && s->hash == t->hash);
{
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
if(!Set_member(s, q->member)){
struct member *p;
const void *member = q->member;
int i = (*set->hash)(member)%set->size;
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}
}
}
}
{T u = t; t = s; s = u;}
{
int i;
struct member *q;
for(i = 0; i < t->size; ++i){
for(q = t->buckets[i]; q; q = q->link){
if(!Set_member(s, q->member)){
struct member *p;
const void *member = q->member;
int i = (*set->hash)(member)%set->size;
NEW(p);
p->member = member;
p->link = set->buckets[i];
set->buckets[i] = p;
set->length++;
}
}
}
}
return set;
}
}