numeric.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	 * nothing to a zero.
	 */
	if (num->varlen != NUMERIC_HDRSZ)
	{
		/* Else, flip the sign */
		if (NUMERIC_SIGN(num) == NUMERIC_POS)
			res->n_sign_dscale = NUMERIC_NEG | NUMERIC_DSCALE(num);
		else
			res->n_sign_dscale = NUMERIC_POS | NUMERIC_DSCALE(num);
	}

	PG_RETURN_NUMERIC(res);
}


Datum
numeric_uplus(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	Numeric		res;

	res = (Numeric) palloc(num->varlen);
	memcpy(res, num, num->varlen);

	PG_RETURN_NUMERIC(res);
}

/*
 * numeric_sign() -
 *
 * returns -1 if the argument is less than 0, 0 if the argument is equal
 * to 0, and 1 if the argument is greater than zero.
 */
Datum
numeric_sign(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	Numeric		res;
	NumericVar	result;

	/*
	 * Handle NaN
	 */
	if (NUMERIC_IS_NAN(num))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	init_var(&result);

	/*
	 * The packed format is known to be totally zero digit trimmed always. So
	 * we can identify a ZERO by the fact that there are no digits at all.
	 */
	if (num->varlen == NUMERIC_HDRSZ)
		set_var_from_var(&const_zero, &result);
	else
	{
		/*
		 * And if there are some, we return a copy of ONE with the sign of our
		 * argument
		 */
		set_var_from_var(&const_one, &result);
		result.sign = NUMERIC_SIGN(num);
	}

	res = make_result(&result);
	free_var(&result);

	PG_RETURN_NUMERIC(res);
}


/*
 * numeric_round() -
 *
 *	Round a value to have 'scale' digits after the decimal point.
 *	We allow negative 'scale', implying rounding before the decimal
 *	point --- Oracle interprets rounding that way.
 */
Datum
numeric_round(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	int32		scale = PG_GETARG_INT32(1);
	Numeric		res;
	NumericVar	arg;

	/*
	 * Handle NaN
	 */
	if (NUMERIC_IS_NAN(num))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	/*
	 * Limit the scale value to avoid possible overflow in calculations
	 */
	scale = Max(scale, -NUMERIC_MAX_RESULT_SCALE);
	scale = Min(scale, NUMERIC_MAX_RESULT_SCALE);

	/*
	 * Unpack the argument and round it at the proper digit position
	 */
	init_var(&arg);
	set_var_from_num(num, &arg);

	round_var(&arg, scale);

	/* We don't allow negative output dscale */
	if (scale < 0)
		arg.dscale = 0;

	/*
	 * Return the rounded result
	 */
	res = make_result(&arg);

	free_var(&arg);
	PG_RETURN_NUMERIC(res);
}


/*
 * numeric_trunc() -
 *
 *	Truncate a value to have 'scale' digits after the decimal point.
 *	We allow negative 'scale', implying a truncation before the decimal
 *	point --- Oracle interprets truncation that way.
 */
Datum
numeric_trunc(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	int32		scale = PG_GETARG_INT32(1);
	Numeric		res;
	NumericVar	arg;

	/*
	 * Handle NaN
	 */
	if (NUMERIC_IS_NAN(num))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	/*
	 * Limit the scale value to avoid possible overflow in calculations
	 */
	scale = Max(scale, -NUMERIC_MAX_RESULT_SCALE);
	scale = Min(scale, NUMERIC_MAX_RESULT_SCALE);

	/*
	 * Unpack the argument and truncate it at the proper digit position
	 */
	init_var(&arg);
	set_var_from_num(num, &arg);

	trunc_var(&arg, scale);

	/* We don't allow negative output dscale */
	if (scale < 0)
		arg.dscale = 0;

	/*
	 * Return the truncated result
	 */
	res = make_result(&arg);

	free_var(&arg);
	PG_RETURN_NUMERIC(res);
}


/*
 * numeric_ceil() -
 *
 *	Return the smallest integer greater than or equal to the argument
 */
Datum
numeric_ceil(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	Numeric		res;
	NumericVar	result;

	if (NUMERIC_IS_NAN(num))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	init_var(&result);

	set_var_from_num(num, &result);
	ceil_var(&result, &result);

	res = make_result(&result);
	free_var(&result);

	PG_RETURN_NUMERIC(res);
}


/*
 * numeric_floor() -
 *
 *	Return the largest integer equal to or less than the argument
 */
Datum
numeric_floor(PG_FUNCTION_ARGS)
{
	Numeric		num = PG_GETARG_NUMERIC(0);
	Numeric		res;
	NumericVar	result;

	if (NUMERIC_IS_NAN(num))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	init_var(&result);

	set_var_from_num(num, &result);
	floor_var(&result, &result);

	res = make_result(&result);
	free_var(&result);

	PG_RETURN_NUMERIC(res);
}

/*
 * width_bucket_numeric() -
 *
 * 'bound1' and 'bound2' are the lower and upper bounds of the
 * histogram's range, respectively. 'count' is the number of buckets
 * in the histogram. width_bucket() returns an integer indicating the
 * bucket number that 'operand' belongs in for an equiwidth histogram
 * with the specified characteristics. An operand smaller than the
 * lower bound is assigned to bucket 0. An operand greater than the
 * upper bound is assigned to an additional bucket (with number
 * count+1).
 */
Datum
width_bucket_numeric(PG_FUNCTION_ARGS)
{
	Numeric		operand = PG_GETARG_NUMERIC(0);
	Numeric		bound1 = PG_GETARG_NUMERIC(1);
	Numeric		bound2 = PG_GETARG_NUMERIC(2);
	int32		count = PG_GETARG_INT32(3);
	NumericVar	count_var;
	NumericVar	result_var;
	int32		result;

	if (count <= 0)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
				 errmsg("count must be greater than zero")));

	init_var(&result_var);
	init_var(&count_var);

	/* Convert 'count' to a numeric, for ease of use later */
	int8_to_numericvar((int64) count, &count_var);

	switch (cmp_numerics(bound1, bound2))
	{
		case 0:
			ereport(ERROR,
				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
				 errmsg("lower bound cannot equal upper bound")));

			/* bound1 < bound2 */
		case -1:
			if (cmp_numerics(operand, bound1) < 0)
				set_var_from_var(&const_zero, &result_var);
			else if (cmp_numerics(operand, bound2) >= 0)
				add_var(&count_var, &const_one, &result_var);
			else
				compute_bucket(operand, bound1, bound2,
							   &count_var, &result_var);
			break;

			/* bound1 > bound2 */
		case 1:
			if (cmp_numerics(operand, bound1) > 0)
				set_var_from_var(&const_zero, &result_var);
			else if (cmp_numerics(operand, bound2) <= 0)
				add_var(&count_var, &const_one, &result_var);
			else
				compute_bucket(operand, bound1, bound2,
							   &count_var, &result_var);
			break;
	}

	result = numericvar_to_int4(&result_var);

	free_var(&count_var);
	free_var(&result_var);

	PG_RETURN_INT32(result);
}

/*
 * compute_bucket() -
 *
 * If 'operand' is not outside the bucket range, determine the correct
 * bucket for it to go. The calculations performed by this function
 * are derived directly from the SQL2003 spec.
 */
static void
compute_bucket(Numeric operand, Numeric bound1, Numeric bound2,
			   NumericVar *count_var, NumericVar *result_var)
{
	NumericVar	bound1_var;
	NumericVar	bound2_var;
	NumericVar	operand_var;

	init_var(&bound1_var);
	init_var(&bound2_var);
	init_var(&operand_var);

	set_var_from_num(bound1, &bound1_var);
	set_var_from_num(bound2, &bound2_var);
	set_var_from_num(operand, &operand_var);

	if (cmp_var(&bound1_var, &bound2_var) < 0)
	{
		sub_var(&operand_var, &bound1_var, &operand_var);
		sub_var(&bound2_var, &bound1_var, &bound2_var);
		div_var(&operand_var, &bound2_var, result_var,
				select_div_scale(&operand_var, &bound2_var), true);
	}
	else
	{
		sub_var(&bound1_var, &operand_var, &operand_var);
		sub_var(&bound1_var, &bound2_var, &bound1_var);
		div_var(&operand_var, &bound1_var, result_var,
				select_div_scale(&operand_var, &bound1_var), true);
	}

	mul_var(result_var, count_var, result_var,
			result_var->dscale + count_var->dscale);
	add_var(result_var, &const_one, result_var);
	floor_var(result_var, result_var);

	free_var(&bound1_var);
	free_var(&bound2_var);
	free_var(&operand_var);
}

/* ----------------------------------------------------------------------
 *
 * Comparison functions
 *
 * Note: btree indexes need these routines not to leak memory; therefore,
 * be careful to free working copies of toasted datums.  Most places don't
 * need to be so careful.
 * ----------------------------------------------------------------------
 */


Datum
numeric_cmp(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	int			result;

	result = cmp_numerics(num1, num2);

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_INT32(result);
}


Datum
numeric_eq(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) == 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

Datum
numeric_ne(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) != 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

Datum
numeric_gt(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) > 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

Datum
numeric_ge(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) >= 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

Datum
numeric_lt(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) < 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

Datum
numeric_le(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	bool		result;

	result = cmp_numerics(num1, num2) <= 0;

	PG_FREE_IF_COPY(num1, 0);
	PG_FREE_IF_COPY(num2, 1);

	PG_RETURN_BOOL(result);
}

static int
cmp_numerics(Numeric num1, Numeric num2)
{
	int			result;

	/*
	 * We consider all NANs to be equal and larger than any non-NAN. This is
	 * somewhat arbitrary; the important thing is to have a consistent sort
	 * order.
	 */
	if (NUMERIC_IS_NAN(num1))
	{
		if (NUMERIC_IS_NAN(num2))
			result = 0;			/* NAN = NAN */
		else
			result = 1;			/* NAN > non-NAN */
	}
	else if (NUMERIC_IS_NAN(num2))
	{
		result = -1;			/* non-NAN < NAN */
	}
	else
	{
		NumericVar	arg1;
		NumericVar	arg2;

		init_var(&arg1);
		init_var(&arg2);

		set_var_from_num(num1, &arg1);
		set_var_from_num(num2, &arg2);

		result = cmp_var(&arg1, &arg2);

		free_var(&arg1);
		free_var(&arg2);
	}

	return result;
}


/* ----------------------------------------------------------------------
 *
 * Basic arithmetic functions
 *
 * ----------------------------------------------------------------------
 */


/*
 * numeric_add() -
 *
 *	Add two numerics
 */
Datum
numeric_add(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;

	/*
	 * Handle NaN
	 */
	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	/*
	 * Unpack the values, let add_var() compute the result and return it.
	 */
	init_var(&arg1);
	init_var(&arg2);
	init_var(&result);

	set_var_from_num(num1, &arg1);
	set_var_from_num(num2, &arg2);

	add_var(&arg1, &arg2, &result);

	res = make_result(&result);

	free_var(&arg1);
	free_var(&arg2);
	free_var(&result);

	PG_RETURN_NUMERIC(res);
}


/*
 * numeric_sub() -
 *
 *	Subtract one numeric from another
 */
Datum
numeric_sub(PG_FUNCTION_ARGS)
{
	Numeric		num1 = PG_GETARG_NUMERIC(0);
	Numeric		num2 = PG_GETARG_NUMERIC(1);
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;

	/*
	 * Handle NaN
	 */
	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		PG_RETURN_NUMERIC(make_result(&const_nan));

	/*
	 * Unpack the values, let sub_var() compute the result and return it.
	 */
	init_var(&arg1);
	init_var(&arg2);
	init_var(&result);

	set_var_from_num(num1, &arg1);