models.c

#include <string.h>
#include <stdint.h>

#define COLUMN_USERNAME_SIZE 32
#define COLUMN_EMAIL_SIZE 255
#define TABLE_MAX_PAGES 100

#define size_of_attribute(Struct, Attribute) sizeof(((Struct*)0)->Attribute)

typedef struct {
    char *buffer;
    size_t buffer_length;
    ssize_t input_length;
} InputBuffer;

typedef enum {
    META_COMMAND_SUCCESS,
    META_COMMAND_UNRECOGNIZED_COMMAND
} MetaCommandResult;

typedef enum {
    PREPARE_SUCCESS,
    PREPARE_NEGATIVE_ID,
    PREPARE_STRING_TOO_LONG,
    PREPARE_SYNTAX_ERROR,
    PREPARE_UNRECOGNIZED_STATEMENT
} PrepareResult;

typedef enum {
    STATEMENT_INSERT,
    STATEMENT_SELECT
} StatementType;

typedef enum {
    EXECUTE_SUCCESS,
    EXECUTE_TABLE_FULL
} ExecuteResult;

typedef struct {
    uint32_t num_rows;
    void *pages[TABLE_MAX_PAGES];
} Table;

typedef struct {
    uint32_t id;
    char username[COLUMN_USERNAME_SIZE + 1];
    char email[COLUMN_EMAIL_SIZE + 1];
} Row;

typedef struct {
    StatementType type;
    Row row_to_insert;
} Statement;

const uint32_t ID_SIZE = size_of_attribute(Row, id);
const uint32_t USERNAME_SIZE = size_of_attribute(Row, username);
const uint32_t EMAIL_SIZE = size_of_attribute(Row, email);
const uint32_t ID_OFFSET = 0;
const uint32_t USERNAME_OFFSET = ID_OFFSET + ID_SIZE;
const uint32_t EMAIL_OFFSET = USERNAME_OFFSET + USERNAME_SIZE;
const uint32_t ROW_SIZE = ID_SIZE + USERNAME_SIZE + EMAIL_SIZE;

const uint32_t PAGE_SIZE = 4096;
const uint32_t ROWS_PER_PAGE = PAGE_SIZE / ROW_SIZE;
const uint32_t TABLE_MAX_ROWS = ROWS_PER_PAGE * TABLE_MAX_PAGES;