numeric.c

postgresql8.3.4源码,开源数据库

/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/numeric.c,v 1.33 2006/10/04 00:30:12 momjian Exp $ */

#include "postgres_fe.h"
#include <ctype.h>
#include <limits.h>

#include "extern.h"
#include "pgtypes_error.h"

#define Max(x, y)				((x) > (y) ? (x) : (y))
#define Min(x, y)				((x) < (y) ? (x) : (y))

#define init_var(v)				memset(v,0,sizeof(numeric))

#define digitbuf_alloc(size) ((NumericDigit *) pgtypes_alloc(size))
#define digitbuf_free(buf)		\
	   do { \
				 if ((buf) != NULL) \
						  free(buf); \
		  } while (0)

#include "pgtypes_numeric.h"

#if 0
/* ----------
 * apply_typmod() -
 *
 *	Do bounds checking and rounding according to the attributes
 *	typmod field.
 * ----------
 */
static int
apply_typmod(numeric *var, long typmod)
{
	int			precision;
	int			scale;
	int			maxweight;
	int			i;

	/* Do nothing if we have a default typmod (-1) */
	if (typmod < (long) (VARHDRSZ))
		return (0);

	typmod -= VARHDRSZ;
	precision = (typmod >> 16) & 0xffff;
	scale = typmod & 0xffff;
	maxweight = precision - scale;

	/* Round to target scale */
	i = scale + var->weight + 1;
	if (i >= 0 && var->ndigits > i)
	{
		int			carry = (var->digits[i] > 4) ? 1 : 0;

		var->ndigits = i;

		while (carry)
		{
			carry += var->digits[--i];
			var->digits[i] = carry % 10;
			carry /= 10;
		}

		if (i < 0)
		{
			var->digits--;
			var->ndigits++;
			var->weight++;
		}
	}
	else
		var->ndigits = Max(0, Min(i, var->ndigits));

	/*
	 * Check for overflow - note we can't do this before rounding, because
	 * rounding could raise the weight.  Also note that the var's weight could
	 * be inflated by leading zeroes, which will be stripped before storage
	 * but perhaps might not have been yet. In any case, we must recognize a
	 * true zero, whose weight doesn't mean anything.
	 */
	if (var->weight >= maxweight)
	{
		/* Determine true weight; and check for all-zero result */
		int			tweight = var->weight;

		for (i = 0; i < var->ndigits; i++)
		{
			if (var->digits[i])
				break;
			tweight--;
		}

		if (tweight >= maxweight && i < var->ndigits)
		{
			errno = PGTYPES_NUM_OVERFLOW;
			return -1;
		}
	}

	var->rscale = scale;
	var->dscale = scale;
	return (0);
}
#endif

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

numeric *
PGTYPESnumeric_new(void)
{
	numeric    *var;

	if ((var = (numeric *) pgtypes_alloc(sizeof(numeric))) == NULL)
		return NULL;

	if (alloc_var(var, 0) < 0)
	{
		free(var);
		return NULL;
	}

	return var;
}

decimal *
PGTYPESdecimal_new(void)
{
	decimal    *var;

	if ((var = (decimal *) pgtypes_alloc(sizeof(decimal))) == NULL)
		return NULL;

	memset(var, 0, sizeof(decimal));

	return var;
}

/* ----------
 * set_var_from_str()
 *
 *	Parse a string and put the number into a variable
 * ----------
 */
static int
set_var_from_str(char *str, char **ptr, numeric *dest)
{
	bool		have_dp = FALSE;
	int			i = 0;

	errno = 0;
	*ptr = str;
	while (*(*ptr))
	{
		if (!isspace((unsigned char) *(*ptr)))
			break;
		(*ptr)++;
	}

	if (alloc_var(dest, strlen((*ptr))) < 0)
		return -1;
	dest->weight = -1;
	dest->dscale = 0;
	dest->sign = NUMERIC_POS;

	switch (*(*ptr))
	{
		case '+':
			dest->sign = NUMERIC_POS;
			(*ptr)++;
			break;

		case '-':
			dest->sign = NUMERIC_NEG;
			(*ptr)++;
			break;
	}

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

	if (!isdigit((unsigned char) *(*ptr)))
	{
		errno = PGTYPES_NUM_BAD_NUMERIC;
		return -1;
	}

	while (*(*ptr))
	{
		if (isdigit((unsigned char) *(*ptr)))
		{
			dest->digits[i++] = *(*ptr)++ - '0';
			if (!have_dp)
				dest->weight++;
			else
				dest->dscale++;
		}
		else if (*(*ptr) == '.')
		{
			if (have_dp)
			{
				errno = PGTYPES_NUM_BAD_NUMERIC;
				return -1;
			}
			have_dp = TRUE;
			(*ptr)++;
		}
		else
			break;
	}
	dest->ndigits = i;

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

		(*ptr)++;
		exponent = strtol(*ptr, &endptr, 10);
		if (endptr == (*ptr))
		{
			errno = PGTYPES_NUM_BAD_NUMERIC;
			return -1;
		}
		(*ptr) = endptr;
		if (exponent > NUMERIC_MAX_PRECISION ||
			exponent < -NUMERIC_MAX_PRECISION)
		{
			errno = PGTYPES_NUM_BAD_NUMERIC;
			return -1;
		}
		dest->weight += (int) exponent;
		dest->dscale -= (int) exponent;
		if (dest->dscale < 0)
			dest->dscale = 0;
	}

	/* Should be nothing left but spaces */
	while (*(*ptr))
	{
		if (!isspace((unsigned char) *(*ptr)))
		{
			errno = PGTYPES_NUM_BAD_NUMERIC;
			return -1;
		}
		(*ptr)++;
	}

	/* Strip any leading zeroes */
	while (dest->ndigits > 0 && *(dest->digits) == 0)
	{
		(dest->digits)++;
		(dest->weight)--;
		(dest->ndigits)--;
	}
	if (dest->ndigits == 0)
		dest->weight = 0;

	dest->rscale = dest->dscale;
	return (0);
}


/* ----------
 * get_str_from_var() -
 *
 *	Convert a var to text representation (guts of numeric_out).
 *	CAUTION: var's contents may be modified by rounding!
 * ----------
 */
static char *
get_str_from_var(numeric *var, int dscale)
{
	char	   *str;
	char	   *cp;
	int			i;
	int			d;

	/*
	 * Check if we must round up before printing the value and do so.
	 */
	i = dscale + var->weight + 1;
	if (i >= 0 && var->ndigits > i)
	{
		int			carry = (var->digits[i] > 4) ? 1 : 0;

		var->ndigits = i;

		while (carry)
		{
			carry += var->digits[--i];
			var->digits[i] = carry % 10;
			carry /= 10;
		}

		if (i < 0)
		{
			var->digits--;
			var->ndigits++;
			var->weight++;
		}
	}
	else
		var->ndigits = Max(0, Min(i, var->ndigits));

	/*
	 * Allocate space for the result
	 */
	if ((str = (char *) pgtypes_alloc(Max(0, dscale) + Max(0, var->weight) + 4)) == NULL)
		return NULL;
	cp = str;

	/*
	 * Output a dash for negative values
	 */
	if (var->sign == NUMERIC_NEG)
		*cp++ = '-';

	/*
	 * Output all digits before the decimal point
	 */
	i = Max(var->weight, 0);
	d = 0;

	while (i >= 0)
	{
		if (i <= var->weight && d < var->ndigits)
			*cp++ = var->digits[d++] + '0';
		else
			*cp++ = '0';
		i--;
	}

	/*
	 * If requested, output a decimal point and all the digits that follow it.
	 */
	if (dscale > 0)
	{
		*cp++ = '.';
		while (i >= -dscale)
		{
			if (i <= var->weight && d < var->ndigits)
				*cp++ = var->digits[d++] + '0';
			else
				*cp++ = '0';
			i--;
		}
	}

	/*
	 * terminate the string and return it
	 */
	*cp = '\0';
	return str;
}

numeric *
PGTYPESnumeric_from_asc(char *str, char **endptr)
{
	numeric    *value = (numeric *) pgtypes_alloc(sizeof(numeric));
	int			ret;

	char	   *realptr;
	char	  **ptr = (endptr != NULL) ? endptr : &realptr;

	if (!value)
		return (NULL);

	ret = set_var_from_str(str, ptr, value);
	if (ret)
	{
		free(value);
		return (NULL);
	}

	return (value);
}

char *
PGTYPESnumeric_to_asc(numeric *num, int dscale)
{
	numeric    *numcopy = PGTYPESnumeric_new();
	char	   *s;

	if (dscale < 0)
		dscale = num->dscale;

	if (PGTYPESnumeric_copy(num, numcopy) < 0)
	{
		PGTYPESnumeric_free(numcopy);
		return NULL;
	}
	/* get_str_from_var may change its argument */
	s = get_str_from_var(numcopy, dscale);
	PGTYPESnumeric_free(numcopy);
	return (s);
}

/* ----------
 * zero_var() -
 *
 *	Set a variable to ZERO.
 *	Note: rscale and dscale are not touched.
 * ----------
 */
static void
zero_var(numeric *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... */
}

void
PGTYPESnumeric_free(numeric *var)
{
	digitbuf_free(var->buf);
	free(var);
}

void
PGTYPESdecimal_free(decimal *var)
{
	free(var);
}

/* ----------
 * cmp_abs() -
 *
 *	Compare the absolute values of var1 and var2
 *	Returns:	-1 for ABS(var1) < ABS(var2)
 *				0  for ABS(var1) == ABS(var2)
 *				1  for ABS(var1) > ABS(var2)
 * ----------
 */
static int
cmp_abs(numeric *var1, numeric *var2)
{
	int			i1 = 0;
	int			i2 = 0;
	int			w1 = var1->weight;
	int			w2 = var2->weight;
	int			stat;

	while (w1 > w2 && i1 < var1->ndigits)
	{
		if (var1->digits[i1++] != 0)
			return 1;
		w1--;
	}
	while (w2 > w1 && i2 < var2->ndigits)
	{
		if (var2->digits[i2++] != 0)
			return -1;
		w2--;
	}

	if (w1 == w2)
	{
		while (i1 < var1->ndigits && i2 < var2->ndigits)
		{
			stat = var1->digits[i1++] - var2->digits[i2++];
			if (stat)
			{
				if (stat > 0)
					return 1;
				return -1;
			}
		}
	}

	while (i1 < var1->ndigits)
	{
		if (var1->digits[i1++] != 0)
			return 1;
	}
	while (i2 < var2->ndigits)
	{
		if (var2->digits[i2++] != 0)
			return -1;
	}

	return 0;
}


/* ----------
 * add_abs() -
 *
 *	Add the absolute values of two variables into result.
 *	result might point to one of the operands without danger.
 * ----------
 */
static int
add_abs(numeric *var1, numeric *var2, numeric *result)
{
	NumericDigit *res_buf;
	NumericDigit *res_digits;
	int			res_ndigits;
	int			res_weight;
	int			res_rscale;
	int			res_dscale;
	int			i,
				i1,
				i2;
	int			carry = 0;

	/* copy these values into local vars for speed in inner loop */
	int			var1ndigits = var1->ndigits;
	int			var2ndigits = var2->ndigits;
	NumericDigit *var1digits = var1->digits;
	NumericDigit *var2digits = var2->digits;

	res_weight = Max(var1->weight, var2->weight) + 1;
	res_rscale = Max(var1->rscale, var2->rscale);
	res_dscale = Max(var1->dscale, var2->dscale);
	res_ndigits = res_rscale + res_weight + 1;
	if (res_ndigits <= 0)
		res_ndigits = 1;

	if ((res_buf = digitbuf_alloc(res_ndigits)) == NULL)
		return -1;
	res_digits = res_buf;