ftb/hashmap.hpp

#pragma once
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "types.hpp"


// inline void print_hm(StringHashMap* hm) {
    // for_str_hash_map(hm) {
        // printf("index: %d desired-index: %llu key: %s hash: %llu value: %llu\n", i, (hm->data[i].hash % hm->current_capacity), (char*)key, hm->data[i].hash, (unsigned long long)value);
    // }
// }

#define __for_hm_generator(key_type, value_type, hm)                \
    if (key_type   key   = 0); else                                 \
    if (value_type value = 0); else                                 \
    for(int        index = 0; index < hm.current_capacity; ++index) \
        if (!((!hm.data[index].deleted) &&                          \
              (key   = hm.data[index].original) &&                  \
              (value = hm.data[index].object))); else


template <typename key_type, typename value_type>
struct Hash_Map {
    int current_capacity;
    int cell_count;
    struct HM_Cell {
        key_type original;
        u64  hash;
        bool deleted;
        value_type object;
    }* data;

    Hash_Map(int initial_capacity = 8) {
        current_capacity = initial_capacity;
        cell_count = 0;
        data = (HM_Cell*)calloc(initial_capacity, sizeof(HM_Cell));
    }

    int get_index_of_living_cell_if_it_exists(key_type key, u64 hash_val) {
        // int index = hash_val & (current_capacity - 1);
        int index = hash_val % current_capacity;
        HM_Cell cell = data[index];
        /* test if cell exists at that index */
        if (cell.original) {
            /* check if strings match */
            if (hm_objects_match(key, cell.original)) {
                /* we found it, now check it it is deleted: */
                if (cell.deleted) {
                    /* we found it but it was deleted, we     */
                    /* dont have to check for collisions then */
                    return -1;
                } else {
                    /* we found it and it is not deleted */
                    return index;
                }
            } else {
                /* strings dont match, this means we have */
                /* a collision. We just search forward */
                for (int i = 0; i < current_capacity; ++i) {
                    int new_idx = (i + index) % current_capacity;
                    cell = data[new_idx];
                    if (!cell.original)
                        return -1;
                    if (!hm_objects_match(key, cell.original))
                        continue;
                    if (cell.deleted)
                        continue;
                    return new_idx;
                }
                /* not or only deleted cells found */
                return -1;
            }
        } else {
            /* no cell exists at this index so the item was never in the  */
            /* hashmap. Either it would be there or be ther and 'deleted' */
            /* or another item would be there and therefore a collistion  */
            /* would exist */
            return -1;
        }
    }

    bool key_exists(key_type key) {
        return get_index_of_living_cell_if_it_exists(key, hm_hash(key)) != -1;
    }

    value_type get_object(key_type key) {
        int index = get_index_of_living_cell_if_it_exists(key, hm_hash(key));
        if (index != -1) {
            return data[index].object;
        }
        return 0;
    }

    void delete_object(key_type key) {
        int index = get_index_of_living_cell_if_it_exists(key, hm_hash(key));
        if (index != -1) {
            data[index].deleted = true;
        }
    }

    void set_object(key_type key, value_type obj) {
        u64 hash_val = hm_hash(key);
        int index = hash_val % current_capacity;

        /* if we the desired cell is just empty, write to it and done :) */
        if (!data[index].original) {
            /* insert new cell into desired slot */
            ++cell_count;
        } else {
            if (hm_objects_match(key, data[index].original)) {
                /* overwrite object with same key, dont increment cell */
                /* count                                               */
            } else {
                /* collision, check resize */
                ++cell_count;
                if ((cell_count*1.0f / current_capacity) > 0.666f) {
                    auto old_data = data;
                    data = (HM_Cell*)calloc(current_capacity*4, sizeof(HM_Cell));
                    cell_count = 0;
                    current_capacity *= 4;

                    /* insert all old items again */
                    for (int i = 0; i < current_capacity/4; ++i) {
                        auto cell = old_data[i];
                        if (cell.original) {
                            set_object(cell.original, cell.object);
                        }
                    }
                    free(old_data);
                    index = hash_val % current_capacity;
                }
                /* search for empty slot for new cell starting at desired index; */
                /* preventing gotos using lambdas!                               */
                [&](){
                    for (int i = index; i < current_capacity; ++i) {
                        if (!data[i].original ||
                            hm_objects_match(data[i].original, key))
                        {
                            index = i;
                            return;
                        }
                    }
                    for (int i = 0; i < index; ++i) {
                        if (!data[i].original ||
                            hm_objects_match(data[i].original, key))
                        {
                            index = i;
                            return;
                        }
                    }
                }();
            }
        }

        data[index].deleted = false;
        data[index].original = key;
        data[index].hash = hash_val;
        data[index].object = obj;
    }

};

// #define define_hash_map(type, name)                                     \
//     bool hm_objects_match(type,type);                                   \
//     u32 hm_hash(type);                                                  \
//                                                                         \
//     struct name##_Hash_Map_Cell {                                       \
//         type original;                                                  \
//         u64  hash;                                                      \
//         bool deleted;                                                   \
//         void* object;                                                   \
//     };                                                                  \
//                                                                         \
//     struct name##_Hash_Map {                                            \
//         int current_capacity;                                           \
//         int cell_count;                                                 \
//         name##_Hash_Map_Cell* data;                                     \
//     };                                                                  \
//                                                                         \
//     name##_Hash_Map* create_##name##_hashmap(int initial_capacity=8)  { \
//         name##_Hash_Map* hm = new name##_Hash_Map;                      \
//         hm->current_capacity = initial_capacity;                        \
//         hm->cell_count = 0;                                             \
//         /* set all data to nullptr */                                   \
//         hm->data = (name##_Hash_Map_Cell*)calloc(initial_capacity, sizeof(name##_Hash_Map_Cell)); \
//         /* printf("check: %s\n", hm->data[6].original_string); */       \
//         return hm;                                                      \
//     }                                                                   \
//                                                                         \
//     int hm_get_index_of_living_cell_if_it_exists(name##_Hash_Map* hm, type key, u64 hash_val) { \
//         int index = hash_val % hm->current_capacity;                    \
//         name##_Hash_Map_Cell cell = hm->data[index];                    \
//         /* test if cell exists at that index */                         \
//         if (cell.original) {                                            \
//             /* check if strings match */                                \
//             if (hm_objects_match(key, cell.original)) {                 \
//                 /* we found it, now check it it is deleted: */          \
//                 if (cell.deleted) {                                     \
//                     /* we found it but it was deleted, we     */        \
//                     /* dont have to check for collisions then */        \
//                     return -1;                                          \
//                 } else {                                                \
//                     /* we found it and it is not deleted */             \
//                     return index;                                       \
//                 }                                                       \
//             } else {                                                    \
//                 /* strings dont match, this means we have */            \
//                 /* a collision. We just search forward */               \
//                 for (int i = 0; i < hm->current_capacity; ++i) {        \
//                     int new_idx = (i + index) % hm->current_capacity;   \
//                     cell = hm->data[new_idx];                           \
//                     if (!cell.original)                                 \
//                         return -1;                                      \
//                     if (!hm_objects_match(key, cell.original))          \
//                         continue;                                       \
//                     if (cell.deleted)                                   \
//                         continue;                                       \
//                     return new_idx;                                     \
//                 }                                                       \
//                 /* not or only deleted cells found */                   \
//                 return -1;                                              \
//             }                                                           \
//         } else {                                                        \
//             /* no cell exists at this index so the item was never in the  */ \
//             /* hashmap. Either it would be there or be ther and 'deleted' */ \
//             /* or another item would be there and therefore a collistion  */ \
//             /* would exist */                                           \
//             return -1;                                                  \
//         }                                                               \
//     }                                                                   \
//                                                                         \
//     inline bool hm_key_exists(name##_Hash_Map* hm, type key) {          \
//         return hm_get_index_of_living_cell_if_it_exists(hm, key, hm_hash(key)) != -1; \
//     }                                                                   \
//                                                                         \
//     inline void* hm_get_object(name##_Hash_Map* hm, type key) {         \
//         int index = hm_get_index_of_living_cell_if_it_exists(hm, key, hm_hash(key)); \
//         if (index != -1) {                                              \
//             return hm->data[index].object;                              \
//         }                                                               \
//         return nullptr;                                                 \
//     }                                                                   \
//                                                                         \
//     inline void hm_delete_object(name##_Hash_Map* hm, type key) {                    \
//         int index = hm_get_index_of_living_cell_if_it_exists(hm, key, hm_hash(key)); \
//         if (index != -1) {                                              \
//             hm->data[index].deleted = true;                             \
//         }                                                               \
//     }                                                                   \
//                                                                         \
//     void hm_set(name##_Hash_Map* hm, type key, void* obj) {             \
//         u64 hash_val = hm_hash(key);                                    \
//         int index = hash_val % hm->current_capacity;                    \
//                                                                         \
//         /* if we the desired cell is just empty, write to it and done :) */ \
//         if (!hm->data[index].original) {                                \
//             /* insert new cell into desired slot */                     \
//             ++hm->cell_count;                                           \
//         } else {                                                        \
//             if (hm_objects_match(key, hm->data[index].original)) {      \
//                 /* overwrite object with same key, dont increment cell */ \
//                 /* count                                               */ \
//             } else {                                                    \
//                 /* collision, check resize */                           \
//                 ++hm->cell_count;                                       \
//                 if ((hm->cell_count*1.0f / hm->current_capacity) > 0.666f) { \
//                     auto old_data = hm->data;                           \
//                     hm->data = (name##_Hash_Map_Cell*)calloc(hm->current_capacity*4, sizeof(name##_Hash_Map_Cell)); \
//                     hm->cell_count = 0;                                 \
//                     hm->current_capacity *= 4;                          \
//                                                                         \
//                     /* insert all old items again */                    \
//                     for (int i = 0; i < hm->current_capacity/4; ++i) {  \
//                         auto cell = old_data[i];                        \
//                         if (cell.original) {                            \
//                             hm_set(hm, cell.original, cell.object);     \
//                         }                                               \
//                     }                                                   \
//                     free(old_data);                                     \
//                     index = hash_val % hm->current_capacity;            \
//                 }                                                       \
//                 /* search for empty slot for new cell starting at desired index; */ \
//                 /* preventing gotos using lambdas!                               */ \
//                 [&](){                                                  \
//                     for (int i = index; i < hm->current_capacity; ++i) { \
//                         if (!hm->data[i].original ||                    \
//                             hm_objects_match(hm->data[i].original, key)) \
//                         {                                               \
//                             index = i;                                  \
//                             return;                                     \
//                         }                                               \
//                     }                                                   \
//                     for (int i = 0; i < index; ++i) {                   \
//                         if (!hm->data[i].original ||                    \
//                             hm_objects_match(hm->data[i].original, key)) \
//                         {                                               \
//                             index = i;                                  \
//                             return;                                     \
//                         }                                               \
//                     }                                                   \
//                 }();                                                    \
//             }                                                           \
//         }                                                               \
//                                                                         \
//         hm->data[index].deleted = false;                                \
//         hm->data[index].original = key;                                 \
//         hm->data[index].hash = hash_val;                                \
//         hm->data[index].object = obj;                                   \
//     }                                                                   \