Method: Object#object_id
- Defined in:
- gc.c
- (Fixnum) hash
Generates a Fixnum hash value for this object.
This function must have the property that a.eql?(b) implies
a.hash == b.hash.
The hash value is used by Hash class.
Any hash value that exceeds the capacity of a Fixnum will be truncated before being used.
1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 |
# File 'gc.c', line 1688
VALUE
rb_obj_id(VALUE obj)
{
/*
* 32-bit VALUE space
* MSB ------------------------ LSB
* false 00000000000000000000000000000000
* true 00000000000000000000000000000010
* nil 00000000000000000000000000000100
* undef 00000000000000000000000000000110
* symbol ssssssssssssssssssssssss00001110
* object oooooooooooooooooooooooooooooo00 = 0 (mod sizeof(RVALUE))
* fixnum fffffffffffffffffffffffffffffff1
*
* object_id space
* LSB
* false 00000000000000000000000000000000
* true 00000000000000000000000000000010
* nil 00000000000000000000000000000100
* undef 00000000000000000000000000000110
* symbol 000SSSSSSSSSSSSSSSSSSSSSSSSSSS0 S...S % A = 4 (S...S = s...s * A + 4)
* object oooooooooooooooooooooooooooooo0 o...o % A = 0
* fixnum fffffffffffffffffffffffffffffff1 bignum if required
*
* where A = sizeof(RVALUE)/4
*
* sizeof(RVALUE) is
* 20 if 32-bit, double is 4-byte aligned
* 24 if 32-bit, double is 8-byte aligned
* 40 if 64-bit
*/
if (SYMBOL_P(obj)) {
return (SYM2ID(obj) * sizeof(RVALUE) + (4 << 2)) | FIXNUM_FLAG;
}
else if (FLONUM_P(obj)) {
#if SIZEOF_LONG == SIZEOF_VOIDP
return LONG2NUM((SIGNED_VALUE)obj);
#else
return LL2NUM((SIGNED_VALUE)obj);
#endif
}
else if (SPECIAL_CONST_P(obj)) {
return LONG2NUM((SIGNED_VALUE)obj);
}
return nonspecial_obj_id(obj);
}
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