Tables

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <assert.h>

typedef enum {
    QUERY_UNKNOWN,
    QUERY_SELECT,
    QUERY_WHERE,
    QUERY_ANY,
    QUERY_COUNT,
} Query_Tag;

typedef struct {
    size_t col_count;
    size_t *col_strides;
    size_t row_count;
    size_t row_stride;
    void *data;
} Table_Header;

typedef Table_Header *Table;

typedef struct {
    Query_Tag tag;
    union {
        void *(*select)(void *);
        void *(*where)(void *);
        bool (*any)(void *);
        intptr_t (*count)();
    };
} Query_Cond;

typedef struct {
    size_t count;
    Query_Cond *e;
} Query_Header;

typedef Query_Header *Query;

Table table_init(size_t row_count, size_t col_count)
{
    void *data = calloc(row_count * col_count * 8, 1);
    assert(data);
    size_t *col_strides = (size_t *)calloc(col_count * 8, 1);
    assert(col_strides);
    
    for(size_t i = 0; i < col_count; ++i) {
        col_strides[i] = i * 8;
    }
    
    Table table = (Table)calloc(sizeof(Table_Header), 1);
    
    *table = (Table_Header){
        .col_count = col_count,
        .col_strides = col_strides,
        .row_count = row_count,
        .row_stride = col_count * 8,
        .data = data,
    };
    
    return table;
}

void *get_cell(Table table, size_t r, size_t c) {
    assert(r < table->row_count);
    assert(c < table->col_count);
    
    size_t row_i = r * table->row_stride;
    size_t col_i = table->col_strides[c];
    
    uint8_t *cell = (uint8_t *)table->data + row_i + col_i;
    
    return cell;
}

void *query(Table table, Query query) {
    if (table == 0 || query == 0) {
        return 0;
    }
    
    for(size_t i = 0; i < query->count; ++i) {
        switch(query->e[i].tag) {
            case QUERY_UNKNOWN:break;
            case QUERY_SELECT:break;
            case QUERY_WHERE:break;
            case QUERY_ANY:break;
            case QUERY_COUNT:break;
            default:break;
        }
    }
    
    return 0;
}

int main(int argc, char **argv) {
    Table table = table_init(4, 20);
    size_t *cell0 = (size_t *)get_cell(table, 0, 0);
    assert(table->data == cell0);
    
    size_t *cell1 = (size_t *)get_cell(table, 3, 15);
    *cell1 = 15;
    
    size_t *cell2 = (size_t *)get_cell(table, 3, 15);
    
    printf("%zu\n", *cell2);
    
    void *row = query(table, 0);
    
    return 0;
}