Method getDescDialect3

src/dsql/ExprNodes.cpp:1630–1909

}

void ArithmeticNode::getDescDialect3(thread_db* /*tdbb*/, dsc* desc, dsc& desc1, dsc& desc2)
{
	USHORT dtype;

	switch (blrOp)
	{
		case blr_add:
		case blr_subtract:
		{
			USHORT dtype1 = desc1.dsc_dtype;
			USHORT dtype2 = desc2.dsc_dtype;

			// In Dialect 2 or 3, strings can never participate in addition / sub
			// (use a specific cast instead)
			if (DTYPE_IS_TEXT(dtype1) || DTYPE_IS_TEXT(dtype2))
				ERR_post(Arg::Gds(isc_expression_eval_err));

			// Because dtype_int64 > dtype_double, we cannot just use the MAX macro to set
			// the result dtype. The rule is that two exact numeric operands yield an int64
			// result, while an approximate numeric and anything yield a double result.

			if (DTYPE_IS_EXACT(dtype1) && DTYPE_IS_EXACT(dtype2))
			{
				if (desc1.isInt128() || desc2.isInt128())
					dtype = dtype_int128;
				else
					dtype = dtype_int64;
			}
			else if (DTYPE_IS_NUMERIC(dtype1) && DTYPE_IS_NUMERIC(dtype2))
			{
				if (DTYPE_IS_DECFLOAT(dtype1) || DTYPE_IS_DECFLOAT(dtype2))
				{
					USHORT d1 = DTYPE_IS_DECFLOAT(dtype1) ? dtype1 : 0;
					USHORT d2 = DTYPE_IS_DECFLOAT(dtype2) ? dtype2 : 0;
					dtype = MAX(d1, d2);
				}
				else
				{
					fb_assert(DTYPE_IS_APPROX(dtype1) || DTYPE_IS_APPROX(dtype2));
					dtype = dtype_double;
				}
			}
			else
			{
				// mixed numeric and non-numeric:

				fb_assert(couldBeDate(desc1) || couldBeDate(desc2));

				// the MAX(dtype) rule doesn't apply with dtype_int64

				if (dtype_int64 == dtype1)
					dtype1 = dtype_double;

				if (dtype_int64 == dtype2)
					dtype2 = dtype_double;

				dtype = CVT2_compare_priority[dtype1] > CVT2_compare_priority[dtype2] ? dtype1 : dtype2;
			}