BRSet.c

//
//  BRSet.c
//
//  Created by Aaron Voisine on 9/11/15.
//  Copyright (c) 2015 breadwallet LLC
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.

#include "BRSet.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

// linear probed hashtable for good cache performance, maximum load factor is 2/3

static const size_t tableSizes[] = { // starting with 1, multiply by 3/2, round up, then find next largest prime
    1, 3, 7, 13, 23, 37, 59, 97, 149, 227, 347, 523, 787, 1187, 1783, 2677, 4019, 6037, 9059, 13591,
    20389, 30593, 45887, 68863, 103307, 154981, 232487, 348739, 523129, 784697, 1177067, 1765609,
    2648419, 3972643, 5958971, 8938469, 13407707, 20111563, 30167359, 45251077, 67876637, 101814991,
    152722489, 229083739, 343625629, 515438447, 773157683, 1159736527, 1739604799, 2609407319, 3914111041
};

#define TABLE_SIZES_LEN (sizeof(tableSizes)/sizeof(*tableSizes))

struct BRSetStruct {
    void **table; // hashtable
    size_t size; // number of buckets in table
    size_t itemCount; // number of items in set
    size_t (*hash)(const void *); // hash function
    int (*eq)(const void *, const void *); // equality function
};

static void _BRSetInit(BRSet *set, size_t (*hash)(const void *), int (*eq)(const void *, const void *), size_t capacity)
{
    assert(set != NULL);
    assert(hash != NULL);
    assert(eq != NULL);
    assert(capacity >= 0);

    size_t i = 0;
    
    while (i < TABLE_SIZES_LEN && tableSizes[i] < capacity) i++;

    if (i + 1 < TABLE_SIZES_LEN) { // use next larger table size to keep load factor below 2/3 at capacity
        set->table = calloc(tableSizes[i + 1], sizeof(void *));
        assert(set->table != NULL);
        set->size = tableSizes[i + 1];
    }
    
    set->itemCount = 0;
    set->hash = hash;
    set->eq = eq;
}

// retruns a newly allocated empty set that must be freed by calling BRSetFree()
// size_t hash(const void *) is a function that returns a hash value for a given set item
// int eq(const void *, const void *) is a function that returns true if two set items are equal
// any two items that are equal must also have identical hash values
// capacity is the maximum estimated number of items the set will need to hold
BRSet *BRSetNew(size_t (*hash)(const void *), int (*eq)(const void *, const void *), size_t capacity)
{
    BRSet *set = calloc(1, sizeof(*set));
    
    assert(set != NULL);
    _BRSetInit(set, hash, eq, capacity);
    return set;
}

// rebuilds hashtable to hold up to capacity items
static void _BRSetGrow(BRSet *set, size_t capacity)
{
    BRSet newSet;
    
    _BRSetInit(&newSet, set->hash, set->eq, capacity);
    BRSetUnion(&newSet, set);
    free(set->table);
    set->table = newSet.table;
    set->size = newSet.size;
    set->itemCount = newSet.itemCount;
}

// adds given item to set or replaces an equivalent existing item and returns item replaced if any
void *BRSetAdd(BRSet *set, void *item)
{
    assert(set != NULL);
    assert(item != NULL);
    
    size_t size = set->size;
    size_t i = set->hash(item) % size;
    void *t = set->table[i];

    while (t && t != item && ! set->eq(t, item)) { // probe for empty bucket
        i = (i + 1) % size;
        t = set->table[i];
    }

    if (! t) set->itemCount++;
    set->table[i] = item;
    if (set->itemCount > ((size + 2)/3)*2) _BRSetGrow(set, size); // limit load factor to 2/3
    return t;
}

// removes item equivalent to given item from set and returns item removed if any
void *BRSetRemove(BRSet *set, const void *item)
{
    assert(set != NULL);
    assert(item != NULL);
    
    size_t size = set->size;
    size_t i = set->hash(item) % size;
    void *r = set->table[i], *t;

    while (r != item && r && ! set->eq(r, item)) { // probe for item
        i = (i + 1) % size;
        r = set->table[i];
    }
    
    if (r) {
        set->itemCount--;
        set->table[i] = NULL;
        i = (i + 1) % size;
        t = set->table[i];
        
        while (t) { // hashtable cleanup
            set->itemCount--;
            set->table[i] = NULL;
            BRSetAdd(set, t);
            i = (i + 1) % size;
            t = set->table[i];
        }
    }
    
    return r;
}

// removes all items from set
void BRSetClear(BRSet *set)
{
    assert(set != NULL);
    
    memset(set->table, 0, set->size*sizeof(*set->table));
    set->itemCount = 0;
}

// returns the number of items in set
size_t BRSetCount(const BRSet *set)
{
    assert(set != NULL);
    
    return set->itemCount;
}

// true if an item equivalant to the given item is contained in set
int BRSetContains(const BRSet *set, const void *item)
{
    return (BRSetGet(set, item) != NULL);
}

// true if any items in otherSet are contained in set
int BRSetIntersects(const BRSet *set, const BRSet *otherSet)
{
    assert(set != NULL);
    assert(otherSet != NULL);
    
    size_t i = 0, size = otherSet->size;
    void *t;
    
    while (i < size) {
        t = otherSet->table[i++];
        if (t && BRSetGet(set, t) != NULL) return 1;
    }
    
    return 0;
}

// returns member item from set equivalent to given item, or NULL if there is none
void *BRSetGet(const BRSet *set, const void *item)
{
    assert(set != NULL);
    assert(item != NULL);
    
    size_t size = set->size;
    size_t i = set->hash(item) % size;
    void *t = set->table[i];

    while (t != item && t && ! set->eq(t, item)) { // probe for item
        i = (i + 1) % size;
        t = set->table[i];
    }
    
    return t;
}

// interates over set and returns the next item after previous, or NULL if no more items are available
// if previous is NULL, an initial item is returned
void *BRSetIterate(const BRSet *set, const void *previous)
{
    assert(set != NULL);
    
    size_t i = 0, size = set->size;
    void *t, *r = NULL;
    
    if (previous != NULL) {
        i = set->hash(previous) % size;
        t = set->table[i];
        
        while (t != previous && t && ! set->eq(t, previous)) { // probe for item
            i = (i + 1) % size;
            t = set->table[i];
        }
    
        i++;
    }
    
    while (! r && i < size) r = set->table[i++];
    return r;
}

// writes up to count items from set to allItems and returns the number of items written
size_t BRSetAll(const BRSet *set, void *allItems[], size_t count)
{
    assert(set != NULL);
    assert(allItems != NULL || count == 0);
    assert(count >= 0);
    
    size_t i = 0, j = 0, size = set->size;
    void *t;
    
    while (i < size && j < count) {
        t = set->table[i++];
        if (t) allItems[j++] = t;
    }
    
    return j;
}

// calls apply() with each item in set
void BRSetApply(const BRSet *set, void *info, void (*apply)(void *info, void *item))
{
    assert(set != NULL);
    assert(apply != NULL);
    
    size_t i = 0, size = set->size;
    void *t;
    
    while (i < size) {
        t = set->table[i++];
        if (t) apply(info, t);
    }
}

// adds or replaces items from otherSet into set
void BRSetUnion(BRSet *set, const BRSet *otherSet)
{
    assert(set != NULL);
    assert(otherSet != NULL);
    
    size_t i = 0, size = otherSet->size;
    void *t;
    
    while (i < size) {
        t = otherSet->table[i++];
        if (t) BRSetAdd(set, t);
    }
}

// removes items contained in otherSet from set
void BRSetMinus(BRSet *set, const BRSet *otherSet)
{
    assert(set != NULL);
    assert(otherSet != NULL);

    size_t i = 0, size = otherSet->size;
    void *t;
    
    while (i < size) {
        t = otherSet->table[i++];
        if (t) BRSetRemove(set, t);
    }
}

// removes items not contained in otherSet from set
void BRSetIntersect(BRSet *set, const BRSet *otherSet)
{
    assert(set != NULL);
    assert(otherSet != NULL);

    size_t i = 0, size = set->size;
    void *t;
    
    while (i < size) {
        t = set->table[i];

        if (t && ! BRSetContains(otherSet, t)) {
            BRSetRemove(set, t);
        }
        else i++;
    }
}

// frees memory allocated for set
void BRSetFree(BRSet *set)
{
    assert(set != NULL);

    free(set->table);
    free(set);
}