// Hash tables for making objects unique

#ifndef _CL_HASHUNIQ_H
#define _CL_HASHUNIQ_H

#include "cl_hash.h"
#include "cl_iterator.h"

namespace cln {

// In such a hash table an entry's key is determined by its value
// and not stored explicitly.

// Requirements:
// - function  bool equal (key1_type,key1_type);
// - function  unsigned long hashcode (key1_type);
// - function  key1_type hashkey (value_type);
// - constructor  value_type::value_type (struct hashuniq *, key1_type);

template <class key1_type, class value_type>
struct cl_htuniqentry {
    ALLOCATE_ANYWHERE(cl_htuniqentry)
    value_type val;
    const value_type& htvalue () { return val; }
    cl_htuniqentry (const value_type& v)
        : val (v) {}
#if (defined(__rs6000__) && !defined(__GNUC__))
    cl_htuniqentry () {}
#endif
};

template <class key1_type, class value_type>
struct cl_heap_hashtable_uniq : public cl_heap_hashtable <cl_htuniqentry <key1_type,value_type> > {
    // Allocation.
    void* operator new (size_t size) { return malloc_hook(size); }
    // Deallocation.
    void operator delete (void* ptr) { free_hook(ptr); }
public:
    // Lookup (htref alias gethash).
    // Returns a pointer which you should immediately dereference
    // if it is not NULL.
    value_type * get (const key1_type& key)
    {
        var long index = _slots[hashcode(key) % _modulus] - 1;
        while (index >= 0) {
            if (!(index < _size))
                cl_abort();
            if (equal(key,hashkey(_entries[index].entry.val)))
                return &_entries[index].entry.val;
            index = _entries[index].next - 1;
        }
        return NULL;
    }
    // Store (htset alias puthash).
    void put (const key1_type& key)
    {
        var unsigned long hcode = hashcode(key);
        // Search whether it is already there.
        {
            var long index = _slots[hcode % _modulus] - 1;
            while (index >= 0) {
                if (!(index < _size))
                    cl_abort();
                if (equal(key,hashkey(_entries[index].entry.val)))
                    return;
                index = _entries[index].next - 1;
            }
        }
        // Put it into the table.
        prepare_store();
        var long hindex = hcode % _modulus; // _modulus may have changed!
        var long index = get_free_index();
        new (&_entries[index].entry) cl_htuniqentry<key1_type,value_type> (value_type((struct hashuniq *)0, key));
        _entries[index].next = _slots[hindex];
        _slots[hindex] = 1+index;
        _count++;
    }
    // Remove (htrem alias remhash).
    void remove (const key1_type& key)
    {
        var long* _index = &_slots[hashcode(key) % _modulus];
        while (*_index > 0) {
            var long index = *_index - 1;
            if (!(index < _size))
                cl_abort();
            if (equal(key,hashkey(_entries[index].entry.val))) {
                // Remove _entries[index].entry
                *_index = _entries[index].next;
                _entries[index].~htxentry();
                // The entry is now free.
                put_free_index(index);
                // That's it.
                _count--;
                return;
            }
            _index = &_entries[index].next;
        }
    }
    // Iterate through the table.
    // No stuff should be inserted into the table during the iteration,
    // or you may find yourself iterating over an entry vector which has
    // already been freed!
    // ??
private:
    // Prepare a store operation: make sure that the free list is non-empty.
    // This may change the table's size!
    void prepare_store ()
    {
      #if !(defined(__sparc__) && !defined(__GNUC__))
        if (_freelist < -1)
            return;
        // Can we make room?
        if (_garcol_fun(this))
            if (_freelist < -1)
                return;
        // No! Have to grow the hash table.
        grow();
      #else
        // workaround Sun C++ 4.1 inline function compiler bug
        if (_freelist >= -1) {
            if (!_garcol_fun(this) || (_freelist >= -1))
                grow();
        }
      #endif
    }
    void grow ()
    {
        var long new_size = _size + (_size >> 1) + 1; // _size*1.5
        var long new_modulus = compute_modulus(new_size);
        var void* new_total_vector = malloc_hook(new_modulus*sizeof(long) + new_size*sizeof(htxentry));
        var long* new_slots = (long*) ((char*)new_total_vector + 0);
        var htxentry* new_entries = (htxentry *) ((char*)new_total_vector + new_modulus*sizeof(long));
        for (var long hi = new_modulus-1; hi >= 0; hi--)
            new_slots[hi] = 0;
        var long free_list_head = -1;
        for (var long i = new_size-1; i >= 0; i--) {
            new_entries[i].next = free_list_head;
            free_list_head = -2-i;
        }
        var htxentry* old_entries = _entries;
        for (var long old_index = 0; old_index < _size; old_index++)
            if (old_entries[old_index].next >= 0) {
                var value_type& val = old_entries[old_index].entry.val;
                var long hindex = hashcode(hashkey(val)) % new_modulus;
                var long index = -2-free_list_head;
                free_list_head = new_entries[index].next;
                new (&new_entries[index].entry) cl_htuniqentry<key1_type,value_type> (val);
                new_entries[index].next = new_slots[hindex];
                new_slots[hindex] = 1+index;
                old_entries[old_index].~htxentry();
            }
        free_hook(_total_vector);
        _modulus = new_modulus;
        _size = new_size;
        _freelist = free_list_head;
        _slots = new_slots;
        _entries = new_entries;
        _total_vector = new_total_vector;
    }
};

}  // namespace cln

#endif /* _CL_HASHUNIQ_H */