Map.h

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/*******************************************************************************************[Map.h]
Copyright (c) 2006-2010, Niklas Sorensson

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substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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**************************************************************************************************/

#ifndef Minisat_Map_h
#define Minisat_Map_h

#include "IntTypes.h"
#include "Vec.h"

namespace Minisat {

//=================================================================================================
// Default hash/equals functions
//

template<class K> struct Hash  { uint32_t operator()(const K& k)               const { return hash(k);  } };
template<class K> struct Equal { bool     operator()(const K& k1, const K& k2) const { return k1 == k2; } };

template<class K> struct DeepHash  { uint32_t operator()(const K* k)               const { return hash(*k);  } };
template<class K> struct DeepEqual { bool     operator()(const K* k1, const K* k2) const { return *k1 == *k2; } };

static inline uint32_t hash(uint32_t x){ return x; }
static inline uint32_t hash(uint64_t x){ return (uint32_t)x; }
static inline uint32_t hash(int32_t x) { return (uint32_t)x; }
static inline uint32_t hash(int64_t x) { return (uint32_t)x; }


//=================================================================================================
// Some primes
//

static const int nprimes          = 25;
static const int primes [nprimes] = { 31, 73, 151, 313, 643, 1291, 2593, 5233, 10501, 21013, 42073, 84181, 168451, 337219, 674701, 1349473, 2699299, 5398891, 10798093, 21596719, 43193641, 86387383, 172775299, 345550609, 691101253 };

//=================================================================================================
// Hash table implementation of Maps
//

template<class K, class D, class H = Hash<K>, class E = Equal<K> >
class Map {
 public:
    struct Pair { K key; D data; };

 private:
    H          hash;
    E          equals;

    vec<Pair>* table;
    int        cap;
    int        size;

    // Don't allow copying (error prone):
    Map<K,D,H,E>&  operator = (Map<K,D,H,E>& other);
                   Map        (Map<K,D,H,E>& other);

    bool    checkCap(int new_size) const { return new_size > cap; }

    int32_t index  (const K& k) const { return hash(k) % cap; }
    void   _insert (const K& k, const D& d) { 
        vec<Pair>& ps = table[index(k)];
        ps.push(); ps.last().key = k; ps.last().data = d; }

    void    rehash () {
        const vec<Pair>* old = table;

        int old_cap = cap;
        int newsize = primes[0];
        for (int i = 1; newsize <= cap && i < nprimes; i++)
           newsize = primes[i];

        table = new vec<Pair>[newsize];
        cap   = newsize;

        for (int i = 0; i < old_cap; i++){
            for (int j = 0; j < old[i].size(); j++){
                _insert(old[i][j].key, old[i][j].data); }}

        delete [] old;

        // printf(" --- rehashing, old-cap=%d, new-cap=%d\n", cap, newsize);
    }

    
 public:

    Map () : table(NULL), cap(0), size(0) {}
    Map (const H& h, const E& e) : hash(h), equals(e), table(NULL), cap(0), size(0){}
    ~Map () { delete [] table; }

    // PRECONDITION: the key must already exist in the map.
    const D& operator [] (const K& k) const
    {
        assert(size != 0);
        const D*         res = NULL;
        const vec<Pair>& ps  = table[index(k)];
        for (int i = 0; i < ps.size(); i++)
            if (equals(ps[i].key, k))
                res = &ps[i].data;
        assert(res != NULL);
        return *res;
    }

    // PRECONDITION: the key must already exist in the map.
    D& operator [] (const K& k)
    {
        assert(size != 0);
        D*         res = NULL;
        vec<Pair>& ps  = table[index(k)];
        for (int i = 0; i < ps.size(); i++)
            if (equals(ps[i].key, k))
                res = &ps[i].data;
        assert(res != NULL);
        return *res;
    }

    // PRECONDITION: the key must *NOT* exist in the map.
    void insert (const K& k, const D& d) { if (checkCap(size+1)) rehash(); _insert(k, d); size++; }
    bool peek   (const K& k, D& d) const {
        if (size == 0) return false;
        const vec<Pair>& ps = table[index(k)];
        for (int i = 0; i < ps.size(); i++)
            if (equals(ps[i].key, k)){
                d = ps[i].data;
                return true; } 
        return false;
    }

    bool has   (const K& k) const {
        if (size == 0) return false;
        const vec<Pair>& ps = table[index(k)];
        for (int i = 0; i < ps.size(); i++)
            if (equals(ps[i].key, k))
                return true;
        return false;
    }

    // PRECONDITION: the key must exist in the map.
    void remove(const K& k) {
        assert(table != NULL);
        vec<Pair>& ps = table[index(k)];
        int j = 0;
        for (; j < ps.size() && !equals(ps[j].key, k); j++);
        assert(j < ps.size());
        ps[j] = ps.last();
        ps.pop();
        size--;
    }

    void clear  () {
        cap = size = 0;
        delete [] table;
        table = NULL;
    }

    int  elems() const { return size; }
    int  bucket_count() const { return cap; }

    // NOTE: the hash and equality objects are not moved by this method:
    void moveTo(Map& other){
        delete [] other.table;

        other.table = table;
        other.cap   = cap;
        other.size  = size;

        table = NULL;
        size = cap = 0;
    }

    // NOTE: given a bit more time, I could make a more C++-style iterator out of this:
    const vec<Pair>& bucket(int i) const { return table[i]; }
};

//=================================================================================================
}

#endif