float.c

postgresql8.3.4源码,开源数据库

/*-------------------------------------------------------------------------
 *
 * float.c
 *	  Functions for the built-in floating-point types.
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.153 2008/01/01 19:45:52 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <ctype.h>
#include <float.h>
#include <math.h>
#include <limits.h>

#include "catalog/pg_type.h"
#include "libpq/pqformat.h"
#include "utils/array.h"
#include "utils/builtins.h"


#ifndef M_PI
/* from my RH5.2 gcc math.h file - thomas 2000-04-03 */
#define M_PI 3.14159265358979323846
#endif

/* Visual C++ etc lacks NAN, and won't accept 0.0/0.0.  NAN definition from
 * http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclang/html/vclrfNotNumberNANItems.asp
 */
#if defined(WIN32) && !defined(NAN)
static const uint32 nan[2] = {0xffffffff, 0x7fffffff};

#define NAN (*(const double *) nan)
#endif

/* not sure what the following should be, but better to make it over-sufficient */
#define MAXFLOATWIDTH	64
#define MAXDOUBLEWIDTH	128

/*
 * check to see if a float4/8 val has underflowed or overflowed
 */
#define CHECKFLOATVAL(val, inf_is_valid, zero_is_valid)			\
do {															\
	if (isinf(val) && !(inf_is_valid))							\
		ereport(ERROR,											\
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),	\
		  errmsg("value out of range: overflow")));				\
																\
	if ((val) == 0.0 && !(zero_is_valid))						\
		ereport(ERROR,											\
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),	\
		 errmsg("value out of range: underflow")));				\
} while(0)


/* ========== USER I/O ROUTINES ========== */


/* Configurable GUC parameter */
int			extra_float_digits = 0;		/* Added to DBL_DIG or FLT_DIG */


static int	float4_cmp_internal(float4 a, float4 b);
static int	float8_cmp_internal(float8 a, float8 b);

#ifndef HAVE_CBRT
static double cbrt(double x);
#endif   /* HAVE_CBRT */


/*
 * Routines to provide reasonably platform-independent handling of
 * infinity and NaN.  We assume that isinf() and isnan() are available
 * and work per spec.  (On some platforms, we have to supply our own;
 * see src/port.)  However, generating an Infinity or NaN in the first
 * place is less well standardized; pre-C99 systems tend not to have C99's
 * INFINITY and NAN macros.  We centralize our workarounds for this here.
 */

double
get_float8_infinity(void)
{
#ifdef INFINITY
	/* C99 standard way */
	return (double) INFINITY;
#else

	/*
	 * On some platforms, HUGE_VAL is an infinity, elsewhere it's just the
	 * largest normal double.  We assume forcing an overflow will get us a
	 * true infinity.
	 */
	return (double) (HUGE_VAL * HUGE_VAL);
#endif
}

float
get_float4_infinity(void)
{
#ifdef INFINITY
	/* C99 standard way */
	return (float) INFINITY;
#else

	/*
	 * On some platforms, HUGE_VAL is an infinity, elsewhere it's just the
	 * largest normal double.  We assume forcing an overflow will get us a
	 * true infinity.
	 */
	return (float) (HUGE_VAL * HUGE_VAL);
#endif
}

double
get_float8_nan(void)
{
#ifdef NAN
	/* C99 standard way */
	return (double) NAN;
#else
	/* Assume we can get a NAN via zero divide */
	return (double) (0.0 / 0.0);
#endif
}

float
get_float4_nan(void)
{
#ifdef NAN
	/* C99 standard way */
	return (float) NAN;
#else
	/* Assume we can get a NAN via zero divide */
	return (float) (0.0 / 0.0);
#endif
}


/*
 * Returns -1 if 'val' represents negative infinity, 1 if 'val'
 * represents (positive) infinity, and 0 otherwise. On some platforms,
 * this is equivalent to the isinf() macro, but not everywhere: C99
 * does not specify that isinf() needs to distinguish between positive
 * and negative infinity.
 */
int
is_infinite(double val)
{
	int			inf = isinf(val);

	if (inf == 0)
		return 0;
	else if (val > 0)
		return 1;
	else
		return -1;
}


/*
 *		float4in		- converts "num" to float
 *						  restricted syntax:
 *						  {<sp>} [+|-] {digit} [.{digit}] [<exp>]
 *						  where <sp> is a space, digit is 0-9,
 *						  <exp> is "e" or "E" followed by an integer.
 */
Datum
float4in(PG_FUNCTION_ARGS)
{
	char	   *num = PG_GETARG_CSTRING(0);
	char	   *orig_num;
	double		val;
	char	   *endptr;

	/*
	 * endptr points to the first character _after_ the sequence we recognized
	 * as a valid floating point number. orig_num points to the original input
	 * string.
	 */
	orig_num = num;

	/*
	 * Check for an empty-string input to begin with, to avoid the vagaries of
	 * strtod() on different platforms.
	 */
	if (*num == '\0')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("invalid input syntax for type real: \"%s\"",
						orig_num)));

	/* skip leading whitespace */
	while (*num != '\0' && isspace((unsigned char) *num))
		num++;

	errno = 0;
	val = strtod(num, &endptr);

	/* did we not see anything that looks like a double? */
	if (endptr == num || errno != 0)
	{
		/*
		 * C99 requires that strtod() accept NaN and [-]Infinity, but not all
		 * platforms support that yet (and some accept them but set ERANGE
		 * anyway...)  Therefore, we check for these inputs ourselves.
		 */
		if (pg_strncasecmp(num, "NaN", 3) == 0)
		{
			val = get_float4_nan();
			endptr = num + 3;
		}
		else if (pg_strncasecmp(num, "Infinity", 8) == 0)
		{
			val = get_float4_infinity();
			endptr = num + 8;
		}
		else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
		{
			val = -get_float4_infinity();
			endptr = num + 9;
		}
		else if (errno == ERANGE)
			ereport(ERROR,
					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
					 errmsg("\"%s\" is out of range for type real",
							orig_num)));
		else
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type real: \"%s\"",
							orig_num)));
	}
#ifdef HAVE_BUGGY_SOLARIS_STRTOD
	else
	{
		/*
		 * Many versions of Solaris have a bug wherein strtod sets endptr to
		 * point one byte beyond the end of the string when given "inf" or
		 * "infinity".
		 */
		if (endptr != num && endptr[-1] == '\0')
			endptr--;
	}
#endif   /* HAVE_BUGGY_SOLARIS_STRTOD */

#ifdef HAVE_BUGGY_IRIX_STRTOD

	/*
	 * In some IRIX versions, strtod() recognizes only "inf", so if the input
	 * is "infinity" we have to skip over "inity".	Also, it may return
	 * positive infinity for "-inf".
	 */
	if (isinf(val))
	{
		if (pg_strncasecmp(num, "Infinity", 8) == 0)
		{
			val = get_float4_infinity();
			endptr = num + 8;
		}
		else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
		{
			val = -get_float4_infinity();
			endptr = num + 9;
		}
		else if (pg_strncasecmp(num, "-inf", 4) == 0)
		{
			val = -get_float4_infinity();
			endptr = num + 4;
		}
	}
#endif   /* HAVE_BUGGY_IRIX_STRTOD */

	/* skip trailing whitespace */
	while (*endptr != '\0' && isspace((unsigned char) *endptr))
		endptr++;

	/* if there is any junk left at the end of the string, bail out */
	if (*endptr != '\0')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("invalid input syntax for type real: \"%s\"",
						orig_num)));

	/*
	 * if we get here, we have a legal double, still need to check to see if
	 * it's a legal float4
	 */
	CHECKFLOATVAL((float4) val, isinf(val), val == 0);

	PG_RETURN_FLOAT4((float4) val);
}

/*
 *		float4out		- converts a float4 number to a string
 *						  using a standard output format
 */
Datum
float4out(PG_FUNCTION_ARGS)
{
	float4		num = PG_GETARG_FLOAT4(0);
	char	   *ascii = (char *) palloc(MAXFLOATWIDTH + 1);

	if (isnan(num))
		PG_RETURN_CSTRING(strcpy(ascii, "NaN"));

	switch (is_infinite(num))
	{
		case 1:
			strcpy(ascii, "Infinity");
			break;
		case -1:
			strcpy(ascii, "-Infinity");
			break;
		default:
			{
				int			ndig = FLT_DIG + extra_float_digits;

				if (ndig < 1)
					ndig = 1;

				sprintf(ascii, "%.*g", ndig, num);
			}
	}

	PG_RETURN_CSTRING(ascii);
}

/*
 *		float4recv			- converts external binary format to float4
 */
Datum
float4recv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);

	PG_RETURN_FLOAT4(pq_getmsgfloat4(buf));
}

/*
 *		float4send			- converts float4 to binary format
 */
Datum
float4send(PG_FUNCTION_ARGS)
{
	float4		num = PG_GETARG_FLOAT4(0);
	StringInfoData buf;

	pq_begintypsend(&buf);
	pq_sendfloat4(&buf, num);
	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 *		float8in		- converts "num" to float8
 *						  restricted syntax:
 *						  {<sp>} [+|-] {digit} [.{digit}] [<exp>]
 *						  where <sp> is a space, digit is 0-9,
 *						  <exp> is "e" or "E" followed by an integer.
 */
Datum
float8in(PG_FUNCTION_ARGS)
{
	char	   *num = PG_GETARG_CSTRING(0);
	char	   *orig_num;
	double		val;
	char	   *endptr;

	/*
	 * endptr points to the first character _after_ the sequence we recognized
	 * as a valid floating point number. orig_num points to the original input
	 * string.
	 */
	orig_num = num;

	/*
	 * Check for an empty-string input to begin with, to avoid the vagaries of
	 * strtod() on different platforms.
	 */
	if (*num == '\0')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type double precision: \"%s\"",
					orig_num)));

	/* skip leading whitespace */
	while (*num != '\0' && isspace((unsigned char) *num))
		num++;

	errno = 0;
	val = strtod(num, &endptr);

	/* did we not see anything that looks like a double? */
	if (endptr == num || errno != 0)
	{
		/*
		 * C99 requires that strtod() accept NaN and [-]Infinity, but not all
		 * platforms support that yet (and some accept them but set ERANGE
		 * anyway...)  Therefore, we check for these inputs ourselves.
		 */
		if (pg_strncasecmp(num, "NaN", 3) == 0)
		{
			val = get_float8_nan();
			endptr = num + 3;
		}
		else if (pg_strncasecmp(num, "Infinity", 8) == 0)
		{
			val = get_float8_infinity();
			endptr = num + 8;
		}
		else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
		{
			val = -get_float8_infinity();
			endptr = num + 9;
		}
		else if (errno == ERANGE)
			ereport(ERROR,
					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				   errmsg("\"%s\" is out of range for type double precision",
						  orig_num)));
		else
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type double precision: \"%s\"",
					orig_num)));
	}
#ifdef HAVE_BUGGY_SOLARIS_STRTOD
	else
	{
		/*
		 * Many versions of Solaris have a bug wherein strtod sets endptr to
		 * point one byte beyond the end of the string when given "inf" or
		 * "infinity".
		 */
		if (endptr != num && endptr[-1] == '\0')
			endptr--;
	}
#endif   /* HAVE_BUGGY_SOLARIS_STRTOD */

#ifdef HAVE_BUGGY_IRIX_STRTOD

	/*
	 * In some IRIX versions, strtod() recognizes only "inf", so if the input
	 * is "infinity" we have to skip over "inity".	Also, it may return
	 * positive infinity for "-inf".
	 */
	if (isinf(val))
	{
		if (pg_strncasecmp(num, "Infinity", 8) == 0)
		{
			val = get_float8_infinity();
			endptr = num + 8;
		}
		else if (pg_strncasecmp(num, "-Infinity", 9) == 0)
		{
			val = -get_float8_infinity();
			endptr = num + 9;
		}
		else if (pg_strncasecmp(num, "-inf", 4) == 0)
		{
			val = -get_float8_infinity();
			endptr = num + 4;
		}
	}
#endif   /* HAVE_BUGGY_IRIX_STRTOD */

	/* skip trailing whitespace */
	while (*endptr != '\0' && isspace((unsigned char) *endptr))
		endptr++;

	/* if there is any junk left at the end of the string, bail out */
	if (*endptr != '\0')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type double precision: \"%s\"",
					orig_num)));

	CHECKFLOATVAL(val, true, true);

	PG_RETURN_FLOAT8(val);
}

/*
 *		float8out		- converts float8 number to a string
 *						  using a standard output format
 */
Datum
float8out(PG_FUNCTION_ARGS)
{
	float8		num = PG_GETARG_FLOAT8(0);
	char	   *ascii = (char *) palloc(MAXDOUBLEWIDTH + 1);

	if (isnan(num))
		PG_RETURN_CSTRING(strcpy(ascii, "NaN"));

	switch (is_infinite(num))
	{
		case 1:
			strcpy(ascii, "Infinity");
			break;
		case -1:
			strcpy(ascii, "-Infinity");
			break;
		default:
			{
				int			ndig = DBL_DIG + extra_float_digits;

				if (ndig < 1)
					ndig = 1;

				sprintf(ascii, "%.*g", ndig, num);
			}
	}

	PG_RETURN_CSTRING(ascii);
}

/*
 *		float8recv			- converts external binary format to float8
 */
Datum
float8recv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);

	PG_RETURN_FLOAT8(pq_getmsgfloat8(buf));
}

/*
 *		float8send			- converts float8 to binary format
 */
Datum
float8send(PG_FUNCTION_ARGS)
{
	float8		num = PG_GETARG_FLOAT8(0);
	StringInfoData buf;

	pq_begintypsend(&buf);
	pq_sendfloat8(&buf, num);
	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}


/* ========== PUBLIC ROUTINES ========== */


/*
 *		======================
 *		FLOAT4 BASE OPERATIONS
 *		======================
 */

/*
 *		float4abs		- returns |arg1| (absolute value)
 */
Datum
float4abs(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);

	PG_RETURN_FLOAT4((float4) fabs(arg1));
}

/*
 *		float4um		- returns -arg1 (unary minus)
 */
Datum
float4um(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		result;

	result = ((arg1 != 0) ? -(arg1) : arg1);

	CHECKFLOATVAL(result, isinf(arg1), true);
	PG_RETURN_FLOAT4(result);
}

Datum
float4up(PG_FUNCTION_ARGS)
{
	float4		arg = PG_GETARG_FLOAT4(0);

	PG_RETURN_FLOAT4(arg);
}

Datum
float4larger(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);
	float4		result;

	if (float4_cmp_internal(arg1, arg2) > 0)
		result = arg1;
	else
		result = arg2;
	PG_RETURN_FLOAT4(result);
}

Datum
float4smaller(PG_FUNCTION_ARGS)
{
	float4		arg1 = PG_GETARG_FLOAT4(0);
	float4		arg2 = PG_GETARG_FLOAT4(1);
	float4		result;

	if (float4_cmp_internal(arg1, arg2) < 0)
		result = arg1;
	else
		result = arg2;
	PG_RETURN_FLOAT4(result);
}

/*
 *		======================
 *		FLOAT8 BASE OPERATIONS
 *		======================
 */

/*
 *		float8abs		- returns |arg1| (absolute value)
 */
Datum
float8abs(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);

	PG_RETURN_FLOAT8(fabs(arg1));
}


/*
 *		float8um		- returns -arg1 (unary minus)
 */
Datum
float8um(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		result;

	result = ((arg1 != 0) ? -(arg1) : arg1);

	CHECKFLOATVAL(result, isinf(arg1), true);
	PG_RETURN_FLOAT8(result);
}

Datum
float8up(PG_FUNCTION_ARGS)
{
	float8		arg = PG_GETARG_FLOAT8(0);

	PG_RETURN_FLOAT8(arg);
}

Datum
float8larger(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		arg2 = PG_GETARG_FLOAT8(1);
	float8		result;

	if (float8_cmp_internal(arg1, arg2) > 0)
		result = arg1;
	else
		result = arg2;
	PG_RETURN_FLOAT8(result);
}

Datum
float8smaller(PG_FUNCTION_ARGS)
{
	float8		arg1 = PG_GETARG_FLOAT8(0);
	float8		arg2 = PG_GETARG_FLOAT8(1);
	float8		result;

	if (float8_cmp_internal(arg1, arg2) < 0)
		result = arg1;
	else
		result = arg2;
	PG_RETURN_FLOAT8(result);
}