numeric.c

关系型数据库 Postgresql 6.5.2

	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 == 0);
}


bool
numeric_ne(Numeric num1, Numeric num2)
{
	int			result;
	NumericVar	arg1;
	NumericVar	arg2;

	if (num1 == NULL || num2 == NULL)
		return FALSE;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return FALSE;

	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 != 0);
}


bool
numeric_gt(Numeric num1, Numeric num2)
{
	int			result;
	NumericVar	arg1;
	NumericVar	arg2;

	if (num1 == NULL || num2 == NULL)
		return FALSE;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return FALSE;

	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 > 0);
}


bool
numeric_ge(Numeric num1, Numeric num2)
{
	int			result;
	NumericVar	arg1;
	NumericVar	arg2;

	if (num1 == NULL || num2 == NULL)
		return FALSE;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return FALSE;

	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 >= 0);
}


bool
numeric_lt(Numeric num1, Numeric num2)
{
	int			result;
	NumericVar	arg1;
	NumericVar	arg2;

	if (num1 == NULL || num2 == NULL)
		return FALSE;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return FALSE;

	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 < 0);
}


bool
numeric_le(Numeric num1, Numeric num2)
{
	int			result;
	NumericVar	arg1;
	NumericVar	arg2;

	if (num1 == NULL || num2 == NULL)
		return FALSE;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return FALSE;

	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 <= 0);
}


/* ----------------------------------------------------------------------
 *
 * Arithmetic base functions
 *
 * ----------------------------------------------------------------------
 */


/* ----------
 * numeric_add() -
 *
 *	Add two numerics
 * ----------
 */
Numeric
numeric_add(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the values, let add_var() compute the result
	 * and return it. The internals of add_var() will automatically
	 * set the correct result and display scales in the result.
	 * ----------
	 */
	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);

	return res;
}


/* ----------
 * numeric_sub() -
 *
 *	Subtract one numeric from another
 * ----------
 */
Numeric
numeric_sub(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the two arguments, let sub_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);

	sub_var(&arg1, &arg2, &result);
	res = make_result(&result);

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

	return res;
}


/* ----------
 * numeric_mul() -
 *
 *	Calculate the product of two numerics
 * ----------
 */
Numeric
numeric_mul(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the arguments, let mul_var() compute the result
	 * and return it. Unlike add_var() and sub_var(), mul_var()
	 * will round the result to the scale stored in global_rscale.
	 * In the case of numeric_mul(), which is invoked for the *
	 * operator on numerics, we set it to the exact representation
	 * for the product (rscale = sum(rscale of arg1, rscale of arg2)
	 * and the same for the dscale).
	 * ----------
	 */
	init_var(&arg1);
	init_var(&arg2);
	init_var(&result);

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

	global_rscale = arg1.rscale + arg2.rscale;

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

	result.dscale = arg1.dscale + arg2.dscale;

	res = make_result(&result);

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

	return res;
}


/* ----------
 * numeric_div() -
 *
 *	Divide one numeric into another
 * ----------
 */
Numeric
numeric_div(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;
	Numeric		res;
	int			res_dscale;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the arguments
	 * ----------
	 */
	init_var(&arg1);
	init_var(&arg2);
	init_var(&result);

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

	/* ----------
	 * The result scale of a division isn't specified in any
	 * SQL standard. For Postgres it is the following (where
	 * SR, DR are the result- and display-scales of the returned
	 * value, S1, D1, S2 and D2 are the scales of the two arguments,
	 * The minimum and maximum scales are compile time options from
	 * numeric.h):
	 *
	 *	DR = MIN(MAX(D1 + D2, MIN_DISPLAY_SCALE))
	 *	SR = MIN(MAX(MAX(S1 + S2, MIN_RESULT_SCALE), DR + 4), MAX_RESULT_SCALE)
	 *
	 * By default, any result is computed with a minimum of 34 digits
	 * after the decimal point or at least with 4 digits more than
	 * displayed.
	 * ----------
	 */
	res_dscale = MAX(arg1.dscale + arg2.dscale, NUMERIC_MIN_DISPLAY_SCALE);
	res_dscale = MIN(res_dscale, NUMERIC_MAX_DISPLAY_SCALE);
	global_rscale = MAX(arg1.rscale + arg2.rscale,
						NUMERIC_MIN_RESULT_SCALE);
	global_rscale = MAX(global_rscale, res_dscale + 4);
	global_rscale = MIN(global_rscale, NUMERIC_MAX_RESULT_SCALE);

	/* ----------
	 * Do the divide, set the display scale and return the result
	 * ----------
	 */
	div_var(&arg1, &arg2, &result);

	result.dscale = res_dscale;

	res = make_result(&result);

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

	return res;
}


/* ----------
 * numeric_mod() -
 *
 *	Calculate the modulo of two numerics
 * ----------
 */
Numeric
numeric_mod(Numeric num1, Numeric num2)
{
	Numeric		res;
	NumericVar	arg1;
	NumericVar	arg2;
	NumericVar	result;

	if (num1 == NULL || num2 == NULL)
		return NULL;

	if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
		return make_result(&const_nan);

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

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

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

	result.dscale = result.rscale;
	res = make_result(&result);

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

	return res;
}


/* ----------
 * numeric_inc() -
 *
 *	Increment a number by one
 * ----------
 */
Numeric
numeric_inc(Numeric num)
{
	NumericVar	arg;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num == NULL)
		return NULL;

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

	/* ----------
	 * Compute the result and return it
	 * ----------
	 */
	init_var(&arg);

	set_var_from_num(num, &arg);

	add_var(&arg, &const_one, &arg);
	res = make_result(&arg);

	free_var(&arg);

	return res;
}


/* ----------
 * numeric_dec() -
 *
 *	Decrement a number by one
 * ----------
 */
Numeric
numeric_dec(Numeric num)
{
	NumericVar	arg;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num == NULL)
		return NULL;

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

	/* ----------
	 * Compute the result and return it
	 * ----------
	 */
	init_var(&arg);

	set_var_from_num(num, &arg);

	sub_var(&arg, &const_one, &arg);
	res = make_result(&arg);

	free_var(&arg);

	return res;
}


/* ----------
 * numeric_smaller() -
 *
 *	Return the smaller of two numbers
 * ----------
 */
Numeric
numeric_smaller(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the values, and decide which is the smaller one
	 * ----------
	 */
	init_var(&arg1);
	init_var(&arg2);

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

	if (cmp_var(&arg1, &arg2) <= 0)
		res = make_result(&arg1);
	else
		res = make_result(&arg2);

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

	return res;
}


/* ----------
 * numeric_larger() -
 *
 *	Return the larger of two numbers
 * ----------
 */
Numeric
numeric_larger(Numeric num1, Numeric num2)
{
	NumericVar	arg1;
	NumericVar	arg2;
	Numeric		res;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num1 == NULL || num2 == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the values, and decide which is the larger one
	 * ----------
	 */
	init_var(&arg1);
	init_var(&arg2);

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

	if (cmp_var(&arg1, &arg2) >= 0)
		res = make_result(&arg1);
	else
		res = make_result(&arg2);

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

	return res;
}


/* ----------------------------------------------------------------------
 *
 * Complex math functions
 *
 * ----------------------------------------------------------------------
 */


/* ----------
 * numeric_sqrt() -
 *
 *	Compute the square root of a numeric.
 * ----------
 */
Numeric
numeric_sqrt(Numeric num)
{
	Numeric		res;
	NumericVar	arg;
	NumericVar	result;
	int			res_dscale;

	/* ----------
	 * Handle NULL
	 * ----------
	 */
	if (num == NULL)
		return NULL;

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

	/* ----------
	 * Unpack the argument, determine the scales like for divide,
	 * let sqrt_var() do the calculation and return the result.
	 * ----------
	 */
	init_var(&arg);
	init_var(&result);

	set_var_from_num(num, &arg);

	res_dscale = MAX(arg.dscale, NUMERIC_MIN_DISPLAY_SCALE);
	res_dscale = MIN(res_dscale, NUMERIC_MAX_DISPLAY_SCALE);
	global_rscale = MAX(arg.rscale, NUMERIC_MIN_RESULT_SCALE);
	global_rscale = MAX(global_rscale, res_dscale + 4);
	global_rscale = MIN(global_rscale, NUMERIC_MAX_RESULT_SCALE);

	sqrt_var(&arg, &result);

	result.dscale = res_dscale;

	res = make_result(&result);

	free_var(&result);
	free_var(&arg);

	return res;
}


/* ----------
 * numeric_exp() -
 *
 *	Raise e to the power of x
 * ----------
 */
Numeric
numeric_exp(Numeric num)