class.h

FastDb是高效的内存数据库系统

    nat4 size; // number of elements in the array
    int4 offs; // offset from the beginning of the record
};

/**
 * Database record for storing field descriptor
 */
struct dbField { 
    enum FieldTypes { 
        tpBool,
        tpInt1,
        tpInt2,
        tpInt4,
        tpInt8,
        tpReal4, 
        tpReal8, 
        tpString,
        tpReference,
        tpArray,
        tpMethodBool,
        tpMethodInt1,
        tpMethodInt2,
        tpMethodInt4,
        tpMethodInt8,
        tpMethodReal4,
        tpMethodReal8,
        tpMethodString,
        tpMethodReference,
        tpStructure,
        tpRawBinary, 
        tpStdString,
        tpRectangle,
        tpUnknown
    };
        
    /**
     * Full name of the field (for example "x.y.z")
     */
    dbVarying name;    

    /**
     * Name of referenced table( only for references)
     */
    dbVarying tableName; 

    /**
     * Name of inverse reference field (only for refereces)
     */
    dbVarying inverse; 
    
    /**
     * Field type: one of <code>dbField::FieldTypes</code> constants
     */
#ifdef OLD_FIELD_DESCRIPTOR_FORMAT
    int4      type;
#else 
#if BYTE_ORDER == BIG_ENDIAN
    int4      flags : 24;
    int4      type  : 8;
#else
    int4      type  : 8;
    int4      flags : 24;
#endif
#endif

    /**
     *  Offset of the field in the record
     */
    int4      offset; 

    /**
     * Size of the field
     */
    nat4      size;

    /**
     * Hash table for hashed field
     */
    oid_t     hashTable;

    /**
     * T-Tree for field indexed by means of T-Ttree
     */
    oid_t     tTree;
};     


/**
 * Header of any database record
 */
class dbRecord { 
  public:
    /**
     * Size of the record (including header
     */
    nat4   size;

    /**
     * Next record in the table (0 if it is last record)
     */
    oid_t  next;

    /**
     * Previous record in the table (0 if it is first record)
     */
    oid_t  prev;
};


/**
 * Database recod for storing table descriptor
 */
class dbTable : public dbRecord { 
  public:
    /**
     * Name of the table
     */
    dbVarying name;
    
    /**
     * Array with field descriptors
     */
    dbVarying fields;

    /**
     * Size of fixed part of the record (without string and arrays bodies)
     */
    nat4      fixedSize;

    /**
     * Number of rows in the table
     */
    nat4      nRows;

    /**
     * Number of columns in the table
     */
    nat4      nColumns;
    
    /**
     * Identifier of first row in the table
     */
    oid_t     firstRow;

    /**
     * Identifier of last row in the table
     */
    oid_t     lastRow;
#ifdef AUTOINCREMENT_SUPPORT
    /**
     * Autoincremented counter
     */
    nat4      count;
#endif
};

inline dbFieldDescriptor* dbDescribeRawField(dbFieldDescriptor* fd, dbUDTComparator comparator)
{
    fd->type = fd->appType = dbField::tpRawBinary;
    fd->alignment = 1;
    fd->comparator = comparator;
    return fd;
}


template<class T>
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, T& x) 
{ 
    fd->type = fd->appType = dbField::tpStructure;
    fd->components = x.dbDescribeComponents(fd);
    return fd;
}

inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, int1&) 
{ 
    fd->type = fd->appType = dbField::tpInt1; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, int2&) 
{ 
    fd->type = fd->appType = dbField::tpInt2; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, int4&) 
{ 
    fd->type = fd->appType = dbField::tpInt4; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, db_int8&) 
{ 
    fd->type = fd->appType = dbField::tpInt8; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, nat1&) 
{ 
    fd->type = fd->appType = dbField::tpInt1; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, nat2&) 
{ 
    fd->type = fd->appType = dbField::tpInt2; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, nat4&) 
{ 
    fd->type = fd->appType = dbField::tpInt4; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, nat8&) 
{ 
    fd->type = fd->appType = dbField::tpInt8; 
    return fd;
}
#if SIZEOF_LONG != 8
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, long&)
{
    fd->type = fd->appType = dbField::tpInt4;
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, unsigned long&)
{
    fd->type = fd->appType = dbField::tpInt4;
    return fd;
}
#endif
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, bool&) 
{ 
    fd->type = fd->appType = dbField::tpBool; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, real4&) 
{ 
    fd->type = fd->appType = dbField::tpReal4; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, real8&) 
{ 
    fd->type = fd->appType = dbField::tpReal8; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, rectangle&)
{
    fd->type = fd->appType = dbField::tpRectangle;
    fd->alignment = sizeof(coord_t);
    return fd;
}
#ifdef USE_STD_STRING
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, std::string&)
{
    fd->type = dbField::tpString;
    fd->appType = dbField::tpStdString;
    fd->dbsSize = sizeof(dbVarying);
    fd->alignment = 4;
    fd->components = new dbFieldDescriptor("[]");
    fd->components->type = fd->components->appType = dbField::tpInt1;
    fd->components->dbsSize = fd->components->appSize = fd->components->alignment = 1; 
    return fd;
}
#endif
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, char const*&) 
{ 
    fd->type = fd->appType = dbField::tpString; 
    fd->dbsSize = sizeof(dbVarying); 
    fd->alignment = 4;
    fd->components = new dbFieldDescriptor("[]");
    fd->components->type = fd->components->appType = dbField::tpInt1;
    fd->components->dbsSize = fd->components->appSize = 1;
    fd->components->alignment = 1; 
    return fd;
}
inline dbFieldDescriptor* dbDescribeField(dbFieldDescriptor* fd, char*&) 
{ 
    fd->type = fd->appType = dbField::tpString; 
    fd->dbsSize = sizeof(dbVarying); 
    fd->alignment = 4;
    fd->components = new dbFieldDescriptor("[]");
    fd->components->type = fd->components->appType = dbField::tpInt1;
    fd->components->dbsSize = fd->components->appSize = 1;
    fd->components->alignment = 1; 
    return fd;
}


/** 
 * Trampolinefor invocation of methods from SubSQL
 */
class FASTDB_DLL_ENTRY dbAnyMethodTrampoline { 
  public:
    dbFieldDescriptor* cls;

    /**
     * Invoke method
     * @param data pointer to the record insode database
     * @param result pointer to place result in 
     */
    virtual void invoke(byte* data, void* result) = 0;

    /**
     * Get optimize trampoline. Optimized trampoline can be used for records
     * which format in the database is the same as in application. In this case
     * there is no need to fetch record and pointer insode database can be used intead
     * @return optimized nethod trampoline
     */
    virtual dbAnyMethodTrampoline* optimize() = 0;

    /**
     * Method tramopile constructor
     * @param fd method descriptor
     */
    dbAnyMethodTrampoline(dbFieldDescriptor* fd) { cls = fd; }
    
    void* operator new(size_t size EXTRA_DEBUG_NEW_PARAMS);
    void  operator delete(void* p EXTRA_DEBUG_NEW_PARAMS);

    /**
     * Trampoline desctructor
     */
    virtual~dbAnyMethodTrampoline();
};
    

#if defined(__APPLE__) || defined(__VACPP_MULTI__) || defined(__IBMCPP__) || defined(__HP_aCC) || (defined(__SUNPRO_CC) && __SUNPRO_CC >= 0x520 && __SUNPRO_CC_COMPAT == 5)
/**
 * Template for method trampoline implementation
 */
template<class T, class R>
class dbMethodTrampoline : public dbAnyMethodTrampoline {
  public:
    typedef R (T::*mfunc)();

    mfunc              method;
    dbFieldDescriptor* cls;
    bool               optimized;

    void invoke(byte* data, void* result) {
        if (optimized) { 
            *(R*)result = (((T*)(data + this->cls->dbsOffs))->*method)();
        } else { 
            T rec;
            this->cls->components->fetchRecordFields((byte*)&rec, data);
            *(R*)result = (rec.*method)();
        }
    }
    dbAnyMethodTrampoline* optimize() { 
        optimized = true;
        return this;
    }

    dbMethodTrampoline(dbFieldDescriptor* fd, mfunc f)
    : dbAnyMethodTrampoline(fd)
    {
        this->method = f;
        this->cls = fd;
        this->optimized = false;
    }
};

#else

/**
 * Template for method trampoline implementation
 */
template<class T, class R>
class dbMethodTrampoline : public dbAnyMethodTrampoline { 
  public:
    typedef R (T::*mfunc)();
    mfunc method;
    void invoke(byte* data, void* result) {
        T rec;
        this->cls->components->fetchRecordFields((byte*)&rec, data);
        *(R*)result = (rec.*method)();
    }
    dbAnyMethodTrampoline* optimize();
 
    dbMethodTrampoline(dbFieldDescriptor* fd, mfunc f) 
    : dbAnyMethodTrampoline(fd), method(f) {} 
};


/**
 * Optimized method trampoline which doesn't fetch record from the database
 * and use direct pointer to the record inside database
 */
template<class T, class R>
class dbMethodFastTrampoline : public dbAnyMethodTrampoline { 
    typedef R (T::*mfunc)();
    mfunc method;
  public:
    dbAnyMethodTrampoline* optimize() { 
        return this;
    }
    void invoke(byte* data, void* result) {
        *(R*)result = (((T*)(data + this->cls->dbsOffs))->*method)();
    }
    dbMethodFastTrampoline(dbMethodTrampoline<T,R>* mt) 
    : dbAnyMethodTrampoline(mt->cls), method(mt->method) {
        delete mt;
    }
};

template<class T, class R>
inline dbAnyMethodTrampoline* dbMethodTrampoline<T,R>::optimize() { 
    return new dbMethodFastTrampoline<T,R>(this);
}
    
#endif

template<class T, class R>
inline dbFieldDescriptor* dbDescribeMethod(dbFieldDescriptor* fd, R (T::*p)()) 
{ 
    R ret;
    dbDescribeField(fd, ret);
    assert(fd->type <= dbField::tpReference);
    fd->appType = fd->type += dbField::tpMethodBool;
    fd->method = new dbMethodTrampoline<T,R>(fd, p);
    return fd;
}

END_FASTDB_NAMESPACE

#endif