numeric.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	free_var(&vN);
	free_var(&vNminus1);
	free_var(&vsumX);
	free_var(&vsumX2);

	PG_RETURN_NUMERIC(res);
}


/*
 * SUM transition functions for integer datatypes.
 *
 * To avoid overflow, we use accumulators wider than the input datatype.
 * A Numeric accumulator is needed for int8 input; for int4 and int2
 * inputs, we use int8 accumulators which should be sufficient for practical
 * purposes.  (The latter two therefore don't really belong in this file,
 * but we keep them here anyway.)
 *
 * Because SQL92 defines the SUM() of no values to be NULL, not zero,
 * the initial condition of the transition data value needs to be NULL. This
 * means we can't rely on ExecAgg to automatically insert the first non-null
 * data value into the transition data: it doesn't know how to do the type
 * conversion.	The upshot is that these routines have to be marked non-strict
 * and handle substitution of the first non-null input themselves.
 */

Datum
int2_sum(PG_FUNCTION_ARGS)
{
	int64		newval;

	if (PG_ARGISNULL(0))
	{
		/* No non-null input seen so far... */
		if (PG_ARGISNULL(1))
			PG_RETURN_NULL();	/* still no non-null */
		/* This is the first non-null input. */
		newval = (int64) PG_GETARG_INT16(1);
		PG_RETURN_INT64(newval);
	}

	/*
	 * If we're invoked by nodeAgg, we can cheat and modify out first
	 * parameter in-place to avoid palloc overhead. If not, we need to return
	 * the new value of the transition variable.
	 */
	if (fcinfo->context && IsA(fcinfo->context, AggState))
	{
		int64	   *oldsum = (int64 *) PG_GETARG_POINTER(0);

		/* Leave the running sum unchanged in the new input is null */
		if (!PG_ARGISNULL(1))
			*oldsum = *oldsum + (int64) PG_GETARG_INT16(1);

		PG_RETURN_POINTER(oldsum);
	}
	else
	{
		int64		oldsum = PG_GETARG_INT64(0);

		/* Leave sum unchanged if new input is null. */
		if (PG_ARGISNULL(1))
			PG_RETURN_INT64(oldsum);

		/* OK to do the addition. */
		newval = oldsum + (int64) PG_GETARG_INT16(1);

		PG_RETURN_INT64(newval);
	}
}

Datum
int4_sum(PG_FUNCTION_ARGS)
{
	int64		newval;

	if (PG_ARGISNULL(0))
	{
		/* No non-null input seen so far... */
		if (PG_ARGISNULL(1))
			PG_RETURN_NULL();	/* still no non-null */
		/* This is the first non-null input. */
		newval = (int64) PG_GETARG_INT32(1);
		PG_RETURN_INT64(newval);
	}

	/*
	 * If we're invoked by nodeAgg, we can cheat and modify out first
	 * parameter in-place to avoid palloc overhead. If not, we need to return
	 * the new value of the transition variable.
	 */
	if (fcinfo->context && IsA(fcinfo->context, AggState))
	{
		int64	   *oldsum = (int64 *) PG_GETARG_POINTER(0);

		/* Leave the running sum unchanged in the new input is null */
		if (!PG_ARGISNULL(1))
			*oldsum = *oldsum + (int64) PG_GETARG_INT32(1);

		PG_RETURN_POINTER(oldsum);
	}
	else
	{
		int64		oldsum = PG_GETARG_INT64(0);

		/* Leave sum unchanged if new input is null. */
		if (PG_ARGISNULL(1))
			PG_RETURN_INT64(oldsum);

		/* OK to do the addition. */
		newval = oldsum + (int64) PG_GETARG_INT32(1);

		PG_RETURN_INT64(newval);
	}
}

Datum
int8_sum(PG_FUNCTION_ARGS)
{
	Numeric		oldsum;
	Datum		newval;

	if (PG_ARGISNULL(0))
	{
		/* No non-null input seen so far... */
		if (PG_ARGISNULL(1))
			PG_RETURN_NULL();	/* still no non-null */
		/* This is the first non-null input. */
		newval = DirectFunctionCall1(int8_numeric, PG_GETARG_DATUM(1));
		PG_RETURN_DATUM(newval);
	}

	/*
	 * Note that we cannot special-case the nodeAgg case here, as we do for
	 * int2_sum and int4_sum: numeric is of variable size, so we cannot modify
	 * our first parameter in-place.
	 */

	oldsum = PG_GETARG_NUMERIC(0);

	/* Leave sum unchanged if new input is null. */
	if (PG_ARGISNULL(1))
		PG_RETURN_NUMERIC(oldsum);

	/* OK to do the addition. */
	newval = DirectFunctionCall1(int8_numeric, PG_GETARG_DATUM(1));

	PG_RETURN_DATUM(DirectFunctionCall2(numeric_add,
										NumericGetDatum(oldsum), newval));
}


/*
 * Routines for avg(int2) and avg(int4).  The transition datatype
 * is a two-element int8 array, holding count and sum.
 */

typedef struct Int8TransTypeData
{
#ifndef INT64_IS_BUSTED
	int64		count;
	int64		sum;
#else
	/* "int64" isn't really 64 bits, so fake up properly-aligned fields */
	int32		count;
	int32		pad1;
	int32		sum;
	int32		pad2;
#endif
} Int8TransTypeData;

Datum
int2_avg_accum(PG_FUNCTION_ARGS)
{
	ArrayType  *transarray;
	int16		newval = PG_GETARG_INT16(1);
	Int8TransTypeData *transdata;

	/*
	 * If we're invoked by nodeAgg, we can cheat and modify our first
	 * parameter in-place to reduce palloc overhead. Otherwise we need to make
	 * a copy of it before scribbling on it.
	 */
	if (fcinfo->context && IsA(fcinfo->context, AggState))
		transarray = PG_GETARG_ARRAYTYPE_P(0);
	else
		transarray = PG_GETARG_ARRAYTYPE_P_COPY(0);

	if (ARR_SIZE(transarray) != ARR_OVERHEAD(1) + sizeof(Int8TransTypeData))
		elog(ERROR, "expected 2-element int8 array");

	transdata = (Int8TransTypeData *) ARR_DATA_PTR(transarray);
	transdata->count++;
	transdata->sum += newval;

	PG_RETURN_ARRAYTYPE_P(transarray);
}

Datum
int4_avg_accum(PG_FUNCTION_ARGS)
{
	ArrayType  *transarray;
	int32		newval = PG_GETARG_INT32(1);
	Int8TransTypeData *transdata;

	/*
	 * If we're invoked by nodeAgg, we can cheat and modify our first
	 * parameter in-place to reduce palloc overhead. Otherwise we need to make
	 * a copy of it before scribbling on it.
	 */
	if (fcinfo->context && IsA(fcinfo->context, AggState))
		transarray = PG_GETARG_ARRAYTYPE_P(0);
	else
		transarray = PG_GETARG_ARRAYTYPE_P_COPY(0);

	if (ARR_SIZE(transarray) != ARR_OVERHEAD(1) + sizeof(Int8TransTypeData))
		elog(ERROR, "expected 2-element int8 array");

	transdata = (Int8TransTypeData *) ARR_DATA_PTR(transarray);
	transdata->count++;
	transdata->sum += newval;

	PG_RETURN_ARRAYTYPE_P(transarray);
}

Datum
int8_avg(PG_FUNCTION_ARGS)
{
	ArrayType  *transarray = PG_GETARG_ARRAYTYPE_P(0);
	Int8TransTypeData *transdata;
	Datum		countd,
				sumd;

	if (ARR_SIZE(transarray) != ARR_OVERHEAD(1) + sizeof(Int8TransTypeData))
		elog(ERROR, "expected 2-element int8 array");
	transdata = (Int8TransTypeData *) ARR_DATA_PTR(transarray);

	/* SQL92 defines AVG of no values to be NULL */
	if (transdata->count == 0)
		PG_RETURN_NULL();

	countd = DirectFunctionCall1(int8_numeric,
								 Int64GetDatumFast(transdata->count));
	sumd = DirectFunctionCall1(int8_numeric,
							   Int64GetDatumFast(transdata->sum));

	PG_RETURN_DATUM(DirectFunctionCall2(numeric_div, sumd, countd));
}


/* ----------------------------------------------------------------------
 *
 * Debug support
 *
 * ----------------------------------------------------------------------
 */

#ifdef NUMERIC_DEBUG

/*
 * dump_numeric() - Dump a value in the db storage format for debugging
 */
static void
dump_numeric(const char *str, Numeric num)
{
	NumericDigit *digits = (NumericDigit *) num->n_data;
	int			ndigits;
	int			i;

	ndigits = (num->varlen - NUMERIC_HDRSZ) / sizeof(NumericDigit);

	printf("%s: NUMERIC w=%d d=%d ", str, num->n_weight, NUMERIC_DSCALE(num));
	switch (NUMERIC_SIGN(num))
	{
		case NUMERIC_POS:
			printf("POS");
			break;
		case NUMERIC_NEG:
			printf("NEG");
			break;
		case NUMERIC_NAN:
			printf("NaN");
			break;
		default:
			printf("SIGN=0x%x", NUMERIC_SIGN(num));
			break;
	}

	for (i = 0; i < ndigits; i++)
		printf(" %0*d", DEC_DIGITS, digits[i]);
	printf("\n");
}


/*
 * dump_var() - Dump a value in the variable format for debugging
 */
static void
dump_var(const char *str, NumericVar *var)
{
	int			i;

	printf("%s: VAR w=%d d=%d ", str, var->weight, var->dscale);
	switch (var->sign)
	{
		case NUMERIC_POS:
			printf("POS");
			break;
		case NUMERIC_NEG:
			printf("NEG");
			break;
		case NUMERIC_NAN:
			printf("NaN");
			break;
		default:
			printf("SIGN=0x%x", var->sign);
			break;
	}

	for (i = 0; i < var->ndigits; i++)
		printf(" %0*d", DEC_DIGITS, var->digits[i]);

	printf("\n");
}
#endif   /* NUMERIC_DEBUG */


/* ----------------------------------------------------------------------
 *
 * Local functions follow
 *
 * In general, these do not support NaNs --- callers must eliminate
 * the possibility of NaN first.  (make_result() is an exception.)
 *
 * ----------------------------------------------------------------------
 */


/*
 * alloc_var() -
 *
 *	Allocate a digit buffer of ndigits digits (plus a spare digit for rounding)
 */
static void
alloc_var(NumericVar *var, int ndigits)
{
	digitbuf_free(var->buf);
	var->buf = digitbuf_alloc(ndigits + 1);
	var->buf[0] = 0;			/* spare digit for rounding */
	var->digits = var->buf + 1;
	var->ndigits = ndigits;
}


/*
 * free_var() -
 *
 *	Return the digit buffer of a variable to the free pool
 */
static void
free_var(NumericVar *var)
{
	digitbuf_free(var->buf);
	var->buf = NULL;
	var->digits = NULL;
	var->sign = NUMERIC_NAN;
}


/*
 * zero_var() -
 *
 *	Set a variable to ZERO.
 *	Note: its dscale is not touched.
 */
static void
zero_var(NumericVar *var)
{
	digitbuf_free(var->buf);
	var->buf = NULL;
	var->digits = NULL;
	var->ndigits = 0;
	var->weight = 0;			/* by convention; doesn't really matter */
	var->sign = NUMERIC_POS;	/* anything but NAN... */
}


/*
 * set_var_from_str()
 *
 *	Parse a string and put the number into a variable
 */
static void
set_var_from_str(const char *str, NumericVar *dest)
{
	const char *cp = str;
	bool		have_dp = FALSE;
	int			i;
	unsigned char *decdigits;
	int			sign = NUMERIC_POS;
	int			dweight = -1;
	int			ddigits;
	int			dscale = 0;
	int			weight;
	int			ndigits;
	int			offset;
	NumericDigit *digits;

	/*
	 * We first parse the string to extract decimal digits and determine the
	 * correct decimal weight.	Then convert to NBASE representation.
	 */

	/* skip leading spaces */
	while (*cp)
	{
		if (!isspace((unsigned char) *cp))
			break;
		cp++;
	}

	switch (*cp)
	{
		case '+':
			sign = NUMERIC_POS;
			cp++;
			break;

		case '-':
			sign = NUMERIC_NEG;
			cp++;
			break;
	}

	if (*cp == '.')
	{
		have_dp = TRUE;
		cp++;
	}

	if (!isdigit((unsigned char) *cp))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			  errmsg("invalid input syntax for type numeric: \"%s\"", str)));

	decdigits = (unsigned char *) palloc(strlen(cp) + DEC_DIGITS * 2);

	/* leading padding for digit alignment later */
	memset(decdigits, 0, DEC_DIGITS);
	i = DEC_DIGITS;

	while (*cp)
	{
		if (isdigit((unsigned char) *cp))
		{
			decdigits[i++] = *cp++ - '0';
			if (!have_dp)
				dweight++;
			else
				dscale++;
		}
		else if (*cp == '.')
		{
			if (have_dp)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					  errmsg("invalid input syntax for type numeric: \"%s\"",
							 str)));
			have_dp = TRUE;
			cp++;
		}
		else
			break;
	}

	ddigits = i - DEC_DIGITS;
	/* trailing padding for digit alignment later */
	memset(decdigits + i, 0, DEC_DIGITS - 1);

	/* Handle exponent, if any */
	if (*cp == 'e' || *cp == 'E')
	{
		long		exponent;
		char	   *endptr;

		cp++;
		exponent = strtol(cp, &endptr, 10);
		if (endptr == cp)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type numeric: \"%s\"",
							str)));
		cp = endptr;
		if (exponent > NUMERIC_MAX_PRECISION ||
			exponent < -NUMERIC_MAX_PRECISION)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type numeric: \"%s\"",
							str)));
		dweight += (int) exponent;
		dscale -= (int) exponent;
		if (dscale < 0)
			dscale = 0;
	}

	/* Should be nothing left but spaces */
	while (*cp)
	{
		if (!isspace((unsigned char) *cp))
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type numeric: \"%s\"",
							str)));
		cp++;
	}

	/*
	 * Okay, convert pure-decimal representation to base NBASE.  First we need
	 * to determine the converted weight and ndigits.  offset is the number of
	 * decimal zeroes to insert before the first given digit to have a
	 * correctly aligned first NBASE digit.
	 */
	if (dweight >= 0)
		weight = (dweight + 1 + DEC_DIGITS - 1) / DEC_DIGITS - 1;
	else
		weight = -((-dweight - 1) / DEC_DIGITS + 1);
	offset = (weight + 1) * DEC_DIGITS - (dweight + 1);
	ndigits = (ddigits + offset + DEC_DIGITS - 1) / DEC_DIGITS;

	alloc_var(dest, ndigits);
	dest->sign = sign;
	dest->weight = weight;
	dest->dscale = dscale;

	i = DEC_DIGITS - offset;
	digits = dest->digits;

	while (ndigits-- > 0)
	{
#if DEC_DIGITS == 4
		*digits++ = ((decdigits[i] * 10 + decdigits[i + 1]) * 10 +
					 decdigits[i + 2]) * 10 + decdigits[i + 3];
#elif DEC_DIGITS == 2
		*digits++ = decdigits[i] * 10 + decdigits[i + 1];
#elif DEC_DIGITS == 1
		*digits++ = decdigits[i];
#else
#error unsupported NBASE
#endif
		i += DEC_DIGITS;
	}

	pfree(decdigits);

	/* Strip any leading/trailing zeroes, and normalize weight if zero */
	strip_var(dest);
}


/*
 * set_var_from_num() -
 *
 *	Convert the packed db format into a variable
 */
static void
set_var_from_num(Numeric num, NumericVar *dest)
{
	int			ndigits;

	ndigits = (num->varlen - NUMERIC_HDRSZ) / sizeof(NumericDigit);

	alloc_var(dest, ndigits);

	dest->weight = num->n_weight;
	dest->sign = NUMERIC_SIGN(num);