varlena.c

关系型数据库 Postgresql 6.5.2

	ps1 = p1 = (pg_wchar *) palloc((len1 + 1) * sizeof(pg_wchar));
	(void) pg_mb2wchar_with_len((unsigned char *) VARDATA(t1), p1, len1);
	len1 = pg_wchar_strlen(p1);
	ps2 = p2 = (pg_wchar *) palloc((len2 + 1) * sizeof(pg_wchar));
	(void) pg_mb2wchar_with_len((unsigned char *) VARDATA(t2), p2, len2);
	len2 = pg_wchar_strlen(p2);
#else
	p1 = VARDATA(t1);
	p2 = VARDATA(t2);
#endif
	pos = 0;
	px = (len1 - len2);
	for (p = 0; p <= px; p++)
	{
#ifdef MULTIBYTE
		if ((*p2 == *p1) && (pg_wchar_strncmp(p1, p2, len2) == 0))
#else
		if ((*p2 == *p1) && (strncmp(p1, p2, len2) == 0))
#endif
		{
			pos = p + 1;
			break;
		};
		p1++;
	};
#ifdef MULTIBYTE
	pfree(ps1);
	pfree(ps2);
#endif
	return pos;
}	/* textpos() */

/*
 *		texteq			- returns 1 iff arguments are equal
 *		textne			- returns 1 iff arguments are not equal
 */
bool
texteq(text *arg1, text *arg2)
{
	int			len;
	char	   *a1p,
			   *a2p;

	if (arg1 == NULL || arg2 == NULL)
		return (bool) NULL;
	if ((len = arg1->vl_len) != arg2->vl_len)
		return (bool) 0;
	a1p = arg1->vl_dat;
	a2p = arg2->vl_dat;

	/*
	 * Varlenas are stored as the total size (data + size variable)
	 * followed by the data. Use VARHDRSZ instead of explicit sizeof() -
	 * thomas 1997-07-10
	 */
	len -= VARHDRSZ;
	while (len-- != 0)
		if (*a1p++ != *a2p++)
			return (bool) 0;
	return (bool) 1;
}	/* texteq() */

bool
textne(text *arg1, text *arg2)
{
	return (bool) !texteq(arg1, arg2);
}

/* varstr_cmp()
 * Comparison function for text strings with given lengths.
 * Includes locale support, but must copy strings to temporary memory
 *	to allow null-termination for inputs to strcoll().
 * Returns -1, 0 or 1
 */
int
varstr_cmp(char *arg1, int len1, char *arg2, int len2)
{
	int			result;
	char	   *a1p,
			   *a2p;

#ifdef USE_LOCALE
	a1p = (unsigned char *) palloc(len1 + 1);
	a2p = (unsigned char *) palloc(len2 + 1);

	memcpy(a1p, arg1, len1);
	*(a1p + len1) = '\0';
	memcpy(a2p, arg2, len2);
	*(a2p + len2) = '\0';

	result = strcoll(a1p, a2p);

	pfree(a1p);
	pfree(a2p);

#else

	a1p = arg1;
	a2p = arg2;

	result = strncmp(a1p, a2p, Min(len1, len2));
	if ((result == 0) && (len1 != len2))
		result = (len1 < len2) ? -1 : 1;
#endif

	return result;
}	/* varstr_cmp() */


/* text_cmp()
 * Comparison function for text strings.
 * Includes locale support, but must copy strings to temporary memory
 *	to allow null-termination for inputs to strcoll().
 * XXX HACK code for textlen() indicates that there can be embedded nulls
 *	but it appears that most routines (incl. this one) assume not! - tgl 97/04/07
 * Returns -1, 0 or 1
 */
static int
text_cmp(text *arg1, text *arg2)
{
	char	   *a1p,
			   *a2p;
	int			len1,
				len2;

	if (arg1 == NULL || arg2 == NULL)
		return (bool) FALSE;

	a1p = VARDATA(arg1);
	a2p = VARDATA(arg2);

	len1 = VARSIZE(arg1) - VARHDRSZ;
	len2 = VARSIZE(arg2) - VARHDRSZ;

	return varstr_cmp(a1p, len1, a2p, len2);
}	/* text_cmp() */

/* text_lt()
 * Comparison function for text strings.
 */
bool
text_lt(text *arg1, text *arg2)
{
	return (bool) (text_cmp(arg1, arg2) < 0);
}	/* text_lt() */

/* text_le()
 * Comparison function for text strings.
 */
bool
text_le(text *arg1, text *arg2)
{
	return (bool) (text_cmp(arg1, arg2) <= 0);
}	/* text_le() */

bool
text_gt(text *arg1, text *arg2)
{
	return (bool) !text_le(arg1, arg2);
}

bool
text_ge(text *arg1, text *arg2)
{
	return (bool) !text_lt(arg1, arg2);
}

text *
text_larger(text *arg1, text *arg2)
{
	text	   *result;
	text	   *temp;

	temp = ((text_cmp(arg1, arg2) <= 0) ? arg2 : arg1);

	/* Make a copy */

	result = (text *) palloc(VARSIZE(temp));
	memmove((char *) result, (char *) temp, VARSIZE(temp));

	return (result);
}

text *
text_smaller(text *arg1, text *arg2)
{
	text	   *result;
	text	   *temp;

	temp = ((text_cmp(arg1, arg2) > 0) ? arg2 : arg1);

	/* Make a copy */

	result = (text *) palloc(VARSIZE(temp));
	memmove((char *) result, (char *) temp, VARSIZE(temp));

	return (result);
}

/*-------------------------------------------------------------
 * byteaGetSize
 *
 * get the number of bytes contained in an instance of type 'bytea'
 *-------------------------------------------------------------
 */
int32
byteaGetSize(text *v)
{
	int			len;

	len = v->vl_len - sizeof(v->vl_len);

	return len;
}

/*-------------------------------------------------------------
 * byteaGetByte
 *
 * this routine treats "bytea" as an array of bytes.
 * It returns the Nth byte (a number between 0 and 255) or
 * it dies if the length of this array is less than n.
 *-------------------------------------------------------------
 */
int32
byteaGetByte(text *v, int32 n)
{
	int			len;
	int			byte;

	len = byteaGetSize(v);

	if (n >= len)
	{
		elog(ERROR, "byteaGetByte: index (=%d) out of range [0..%d]",
			 n, len - 1);
	}
#ifdef USE_LOCALE
	byte = (unsigned char) (v->vl_dat[n]);
#else
	byte = v->vl_dat[n];
#endif
	return (int32) byte;
}

/*-------------------------------------------------------------
 * byteaGetBit
 *
 * This routine treats a "bytea" type like an array of bits.
 * It returns the value of the Nth bit (0 or 1).
 * If 'n' is out of range, it dies!
 *
 *-------------------------------------------------------------
 */
int32
byteaGetBit(text *v, int32 n)
{
	int			byteNo,
				bitNo;
	int			byte;

	byteNo = n / 8;
	bitNo = n % 8;

	byte = byteaGetByte(v, byteNo);

	if (byte & (1 << bitNo))
		return (int32) 1;
	else
		return (int32) 0;
}

/*-------------------------------------------------------------
 * byteaSetByte
 *
 * Given an instance of type 'bytea' creates a new one with
 * the Nth byte set to the given value.
 *
 *-------------------------------------------------------------
 */
text *
byteaSetByte(text *v, int32 n, int32 newByte)
{
	int			len;
	text	   *res;

	len = byteaGetSize(v);

	if (n >= len)
	{
		elog(ERROR,
			 "byteaSetByte: index (=%d) out of range [0..%d]",
			 n, len - 1);
	}

	/*
	 * Make a copy of the original varlena.
	 */
	res = (text *) palloc(VARSIZE(v));
	if (res == NULL)
	{
		elog(ERROR, "byteaSetByte: Out of memory (%d bytes requested)",
			 VARSIZE(v));
	}
	memmove((char *) res, (char *) v, VARSIZE(v));

	/*
	 * Now set the byte.
	 */
	res->vl_dat[n] = newByte;

	return res;
}

/*-------------------------------------------------------------
 * byteaSetBit
 *
 * Given an instance of type 'bytea' creates a new one with
 * the Nth bit set to the given value.
 *
 *-------------------------------------------------------------
 */
text *
byteaSetBit(text *v, int32 n, int32 newBit)
{
	text	   *res;
	int			oldByte,
				newByte;
	int			byteNo,
				bitNo;

	/*
	 * sanity check!
	 */
	if (newBit != 0 && newBit != 1)
		elog(ERROR, "byteaSetByte: new bit must be 0 or 1");

	/*
	 * get the byte where the bit we want is stored.
	 */
	byteNo = n / 8;
	bitNo = n % 8;
	oldByte = byteaGetByte(v, byteNo);

	/*
	 * calculate the new value for that byte
	 */
	if (newBit == 0)
		newByte = oldByte & (~(1 << bitNo));
	else
		newByte = oldByte | (1 << bitNo);

	/*
	 * NOTE: 'byteaSetByte' creates a copy of 'v' & sets the byte.
	 */
	res = byteaSetByte(v, byteNo, newByte);

	return res;
}


/* text_name()
 * Converts a text() type to a NameData type.
 */
NameData   *
text_name(text *s)
{
	NameData   *result;
	int			len;

	if (s == NULL)
		return NULL;

	len = VARSIZE(s) - VARHDRSZ;
	if (len > NAMEDATALEN)
		len = NAMEDATALEN;

#ifdef STRINGDEBUG
	printf("text- convert string length %d (%d) ->%d\n",
		   VARSIZE(s) - VARHDRSZ, VARSIZE(s), len);
#endif

	result = palloc(NAMEDATALEN);
	StrNCpy(result->data, VARDATA(s), NAMEDATALEN);

	/* now null pad to full length... */
	while (len < NAMEDATALEN)
	{
		*(result->data + len) = '\0';
		len++;
	}

	return result;
}	/* text_name() */

/* name_text()
 * Converts a NameData type to a text type.
 */
text *
name_text(NameData *s)
{
	text	   *result;
	int			len;

	if (s == NULL)
		return NULL;

	len = strlen(s->data);

#ifdef STRINGDEBUG
	printf("text- convert string length %d (%d) ->%d\n",
		   VARSIZE(s) - VARHDRSZ, VARSIZE(s), len);
#endif

	result = palloc(VARHDRSZ + len);
	strncpy(VARDATA(result), s->data, len);
	VARSIZE(result) = len + VARHDRSZ;

	return result;
}	/* name_text() */