/*-------------------------------------------------------------------------
 *
 * numutils.c
 *	  utility functions for I/O of built-in numeric types.
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/utils/adt/numutils.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

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

#include "port/pg_bitutils.h"
#include "utils/builtins.h"

/*
 * A table of all two-digit numbers. This is used to speed up decimal digit
 * generation by copying pairs of digits into the final output.
 */
static const char DIGIT_TABLE[200] =
"00" "01" "02" "03" "04" "05" "06" "07" "08" "09"
"10" "11" "12" "13" "14" "15" "16" "17" "18" "19"
"20" "21" "22" "23" "24" "25" "26" "27" "28" "29"
"30" "31" "32" "33" "34" "35" "36" "37" "38" "39"
"40" "41" "42" "43" "44" "45" "46" "47" "48" "49"
"50" "51" "52" "53" "54" "55" "56" "57" "58" "59"
"60" "61" "62" "63" "64" "65" "66" "67" "68" "69"
"70" "71" "72" "73" "74" "75" "76" "77" "78" "79"
"80" "81" "82" "83" "84" "85" "86" "87" "88" "89"
"90" "91" "92" "93" "94" "95" "96" "97" "98" "99";

/*
 * Adapted from http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
 */
static inline int
decimalLength32(const uint32 v)
{
	int			t;
	static const uint32 PowersOfTen[] = {
		1, 10, 100,
		1000, 10000, 100000,
		1000000, 10000000, 100000000,
		1000000000
	};

	/*
	 * Compute base-10 logarithm by dividing the base-2 logarithm by a
	 * good-enough approximation of the base-2 logarithm of 10
	 */
	t = (pg_leftmost_one_pos32(v) + 1) * 1233 / 4096;
	return t + (v >= PowersOfTen[t]);
}

static inline int
decimalLength64(const uint64 v)
{
	int			t;
	static const uint64 PowersOfTen[] = {
		UINT64CONST(1), UINT64CONST(10),
		UINT64CONST(100), UINT64CONST(1000),
		UINT64CONST(10000), UINT64CONST(100000),
		UINT64CONST(1000000), UINT64CONST(10000000),
		UINT64CONST(100000000), UINT64CONST(1000000000),
		UINT64CONST(10000000000), UINT64CONST(100000000000),
		UINT64CONST(1000000000000), UINT64CONST(10000000000000),
		UINT64CONST(100000000000000), UINT64CONST(1000000000000000),
		UINT64CONST(10000000000000000), UINT64CONST(100000000000000000),
		UINT64CONST(1000000000000000000), UINT64CONST(10000000000000000000)
	};

	/*
	 * Compute base-10 logarithm by dividing the base-2 logarithm by a
	 * good-enough approximation of the base-2 logarithm of 10
	 */
	t = (pg_leftmost_one_pos64(v) + 1) * 1233 / 4096;
	return t + (v >= PowersOfTen[t]);
}

static const int8 hexlookup[128] = {
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};

/*
 * Convert input string to a signed 16 bit integer.  Input strings may be
 * expressed in base-10, hexadecimal, octal, or binary format, all of which
 * can be prefixed by an optional sign character, either '+' (the default) or
 * '-' for negative numbers.  Hex strings are recognized by the digits being
 * prefixed by 0x or 0X while octal strings are recognized by the 0o or 0O
 * prefix.  The binary representation is recognized by the 0b or 0B prefix.
 *
 * Allows any number of leading or trailing whitespace characters.  Digits may
 * optionally be separated by a single underscore character.  These can only
 * come between digits and not before or after the digits.  Underscores have
 * no effect on the return value and are supported only to assist in improving
 * the human readability of the input strings.
 *
 * pg_strtoint16() will throw ereport() upon bad input format or overflow;
 * while pg_strtoint16_safe() instead returns such complaints in *escontext,
 * if it's an ErrorSaveContext.
*
 * NB: Accumulate input as an unsigned number, to deal with two's complement
 * representation of the most negative number, which can't be represented as a
 * signed positive number.
 */
int16
pg_strtoint16(const char *s)
{
	return pg_strtoint16_safe(s, NULL);
}

int16
pg_strtoint16_safe(const char *s, Node *escontext)
{
	const char *ptr = s;
	const char *firstdigit;
	uint16		tmp = 0;
	bool		neg = false;
	unsigned char digit;

	/*
	 * The majority of cases are likely to be base-10 digits without any
	 * underscore separator characters.  We'll first try to parse the string
	 * with the assumption that's the case and only fallback on a slower
	 * implementation which handles hex, octal and binary strings and
	 * underscores if the fastpath version cannot parse the string.
	 */

	/* leave it up to the slow path to look for leading spaces */

	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}

	/* a leading '+' is uncommon so leave that for the slow path */

	/* process the first digit */
	digit = (*ptr - '0');

	/*
	 * Exploit unsigned arithmetic to save having to check both the upper and
	 * lower bounds of the digit.
	 */
	if (likely(digit < 10))
	{
		ptr++;
		tmp = digit;
	}
	else
	{
		/* we need at least one digit */
		goto slow;
	}

	/* process remaining digits */
	for (;;)
	{
		digit = (*ptr - '0');

		if (digit >= 10)
			break;

		ptr++;

		if (unlikely(tmp > -(PG_INT16_MIN / 10)))
			goto out_of_range;

		tmp = tmp * 10 + digit;
	}

	/* when the string does not end in a digit, let the slow path handle it */
	if (unlikely(*ptr != '\0'))
		goto slow;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (unlikely(tmp > (uint16) (-(PG_INT16_MIN + 1)) + 1))
			goto out_of_range;
		return -((int16) tmp);
	}

	if (unlikely(tmp > PG_INT16_MAX))
		goto out_of_range;

	return (int16) tmp;

slow:
	tmp = 0;
	ptr = s;
	/* no need to reset neg */

	/* skip leading spaces */
	while (isspace((unsigned char) *ptr))
		ptr++;

	/* handle sign */
	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}
	else if (*ptr == '+')
		ptr++;

	/* process digits */
	if (ptr[0] == '0' && (ptr[1] == 'x' || ptr[1] == 'X'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (isxdigit((unsigned char) *ptr))
			{
				if (unlikely(tmp > -(PG_INT16_MIN / 16)))
					goto out_of_range;

				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isxdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'o' || ptr[1] == 'O'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '7')
			{
				if (unlikely(tmp > -(PG_INT16_MIN / 8)))
					goto out_of_range;

				tmp = tmp * 8 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '7')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'b' || ptr[1] == 'B'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '1')
			{
				if (unlikely(tmp > -(PG_INT16_MIN / 2)))
					goto out_of_range;

				tmp = tmp * 2 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '1')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else
	{
		firstdigit = ptr;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '9')
			{
				if (unlikely(tmp > -(PG_INT16_MIN / 10)))
					goto out_of_range;

				tmp = tmp * 10 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore may not be first */
				if (unlikely(ptr == firstdigit))
					goto invalid_syntax;
				/* and it must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}

	/* require at least one digit */
	if (unlikely(ptr == firstdigit))
		goto invalid_syntax;

	/* allow trailing whitespace, but not other trailing chars */
	while (isspace((unsigned char) *ptr))
		ptr++;

	if (unlikely(*ptr != '\0'))
		goto invalid_syntax;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (tmp > (uint16) (-(PG_INT16_MIN + 1)) + 1)
			goto out_of_range;
		return -((int16) tmp);
	}

	if (tmp > PG_INT16_MAX)
		goto out_of_range;

	return (int16) tmp;

out_of_range:
	ereturn(escontext, 0,
			(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
			 errmsg("value \"%s\" is out of range for type %s",
					s, "smallint")));

invalid_syntax:
	ereturn(escontext, 0,
			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type %s: \"%s\"",
					"smallint", s)));
}

/*
 * Convert input string to a signed 32 bit integer.  Input strings may be
 * expressed in base-10, hexadecimal, octal, or binary format, all of which
 * can be prefixed by an optional sign character, either '+' (the default) or
 * '-' for negative numbers.  Hex strings are recognized by the digits being
 * prefixed by 0x or 0X while octal strings are recognized by the 0o or 0O
 * prefix.  The binary representation is recognized by the 0b or 0B prefix.
 *
 * Allows any number of leading or trailing whitespace characters.  Digits may
 * optionally be separated by a single underscore character.  These can only
 * come between digits and not before or after the digits.  Underscores have
 * no effect on the return value and are supported only to assist in improving
 * the human readability of the input strings.
 *
 * pg_strtoint32() will throw ereport() upon bad input format or overflow;
 * while pg_strtoint32_safe() instead returns such complaints in *escontext,
 * if it's an ErrorSaveContext.
 *
 * NB: Accumulate input as an unsigned number, to deal with two's complement
 * representation of the most negative number, which can't be represented as a
 * signed positive number.
 */
int32
pg_strtoint32(const char *s)
{
	return pg_strtoint32_safe(s, NULL);
}

int32
pg_strtoint32_safe(const char *s, Node *escontext)
{
	const char *ptr = s;
	const char *firstdigit;
	uint32		tmp = 0;
	bool		neg = false;
	unsigned char digit;

	/*
	 * The majority of cases are likely to be base-10 digits without any
	 * underscore separator characters.  We'll first try to parse the string
	 * with the assumption that's the case and only fallback on a slower
	 * implementation which handles hex, octal and binary strings and
	 * underscores if the fastpath version cannot parse the string.
	 */

	/* leave it up to the slow path to look for leading spaces */

	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}

	/* a leading '+' is uncommon so leave that for the slow path */

	/* process the first digit */
	digit = (*ptr - '0');

	/*
	 * Exploit unsigned arithmetic to save having to check both the upper and
	 * lower bounds of the digit.
	 */
	if (likely(digit < 10))
	{
		ptr++;
		tmp = digit;
	}
	else
	{
		/* we need at least one digit */
		goto slow;
	}

	/* process remaining digits */
	for (;;)
	{
		digit = (*ptr - '0');

		if (digit >= 10)
			break;

		ptr++;

		if (unlikely(tmp > -(PG_INT32_MIN / 10)))
			goto out_of_range;

		tmp = tmp * 10 + digit;
	}

	/* when the string does not end in a digit, let the slow path handle it */
	if (unlikely(*ptr != '\0'))
		goto slow;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (unlikely(tmp > (uint32) (-(PG_INT32_MIN + 1)) + 1))
			goto out_of_range;
		return -((int32) tmp);
	}

	if (unlikely(tmp > PG_INT32_MAX))
		goto out_of_range;

	return (int32) tmp;

slow:
	tmp = 0;
	ptr = s;
	/* no need to reset neg */

	/* skip leading spaces */
	while (isspace((unsigned char) *ptr))
		ptr++;

	/* handle sign */
	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}
	else if (*ptr == '+')
		ptr++;

	/* process digits */
	if (ptr[0] == '0' && (ptr[1] == 'x' || ptr[1] == 'X'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (isxdigit((unsigned char) *ptr))
			{
				if (unlikely(tmp > -(PG_INT32_MIN / 16)))
					goto out_of_range;

				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isxdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'o' || ptr[1] == 'O'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '7')
			{
				if (unlikely(tmp > -(PG_INT32_MIN / 8)))
					goto out_of_range;

				tmp = tmp * 8 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '7')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'b' || ptr[1] == 'B'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '1')
			{
				if (unlikely(tmp > -(PG_INT32_MIN / 2)))
					goto out_of_range;

				tmp = tmp * 2 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '1')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else
	{
		firstdigit = ptr;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '9')
			{
				if (unlikely(tmp > -(PG_INT32_MIN / 10)))
					goto out_of_range;

				tmp = tmp * 10 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore may not be first */
				if (unlikely(ptr == firstdigit))
					goto invalid_syntax;
				/* and it must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}

	/* require at least one digit */
	if (unlikely(ptr == firstdigit))
		goto invalid_syntax;

	/* allow trailing whitespace, but not other trailing chars */
	while (isspace((unsigned char) *ptr))
		ptr++;

	if (unlikely(*ptr != '\0'))
		goto invalid_syntax;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (tmp > (uint32) (-(PG_INT32_MIN + 1)) + 1)
			goto out_of_range;
		return -((int32) tmp);
	}

	if (tmp > PG_INT32_MAX)
		goto out_of_range;

	return (int32) tmp;

out_of_range:
	ereturn(escontext, 0,
			(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
			 errmsg("value \"%s\" is out of range for type %s",
					s, "integer")));

invalid_syntax:
	ereturn(escontext, 0,
			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type %s: \"%s\"",
					"integer", s)));
}

/*
 * Convert input string to a signed 64 bit integer.  Input strings may be
 * expressed in base-10, hexadecimal, octal, or binary format, all of which
 * can be prefixed by an optional sign character, either '+' (the default) or
 * '-' for negative numbers.  Hex strings are recognized by the digits being
 * prefixed by 0x or 0X while octal strings are recognized by the 0o or 0O
 * prefix.  The binary representation is recognized by the 0b or 0B prefix.
 *
 * Allows any number of leading or trailing whitespace characters.  Digits may
 * optionally be separated by a single underscore character.  These can only
 * come between digits and not before or after the digits.  Underscores have
 * no effect on the return value and are supported only to assist in improving
 * the human readability of the input strings.
 *
 * pg_strtoint64() will throw ereport() upon bad input format or overflow;
 * while pg_strtoint64_safe() instead returns such complaints in *escontext,
 * if it's an ErrorSaveContext.
 *
 * NB: Accumulate input as an unsigned number, to deal with two's complement
 * representation of the most negative number, which can't be represented as a
 * signed positive number.
 */
int64
pg_strtoint64(const char *s)
{
	return pg_strtoint64_safe(s, NULL);
}

int64
pg_strtoint64_safe(const char *s, Node *escontext)
{
	const char *ptr = s;
	const char *firstdigit;
	uint64		tmp = 0;
	bool		neg = false;
	unsigned char digit;

	/*
	 * The majority of cases are likely to be base-10 digits without any
	 * underscore separator characters.  We'll first try to parse the string
	 * with the assumption that's the case and only fallback on a slower
	 * implementation which handles hex, octal and binary strings and
	 * underscores if the fastpath version cannot parse the string.
	 */

	/* leave it up to the slow path to look for leading spaces */

	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}

	/* a leading '+' is uncommon so leave that for the slow path */

	/* process the first digit */
	digit = (*ptr - '0');

	/*
	 * Exploit unsigned arithmetic to save having to check both the upper and
	 * lower bounds of the digit.
	 */
	if (likely(digit < 10))
	{
		ptr++;
		tmp = digit;
	}
	else
	{
		/* we need at least one digit */
		goto slow;
	}

	/* process remaining digits */
	for (;;)
	{
		digit = (*ptr - '0');

		if (digit >= 10)
			break;

		ptr++;

		if (unlikely(tmp > -(PG_INT64_MIN / 10)))
			goto out_of_range;

		tmp = tmp * 10 + digit;
	}

	/* when the string does not end in a digit, let the slow path handle it */
	if (unlikely(*ptr != '\0'))
		goto slow;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (unlikely(tmp > (uint64) (-(PG_INT64_MIN + 1)) + 1))
			goto out_of_range;
		return -((int64) tmp);
	}

	if (unlikely(tmp > PG_INT64_MAX))
		goto out_of_range;

	return (int64) tmp;

slow:
	tmp = 0;
	ptr = s;
	/* no need to reset neg */

	/* skip leading spaces */
	while (isspace((unsigned char) *ptr))
		ptr++;

	/* handle sign */
	if (*ptr == '-')
	{
		ptr++;
		neg = true;
	}
	else if (*ptr == '+')
		ptr++;

	/* process digits */
	if (ptr[0] == '0' && (ptr[1] == 'x' || ptr[1] == 'X'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (isxdigit((unsigned char) *ptr))
			{
				if (unlikely(tmp > -(PG_INT64_MIN / 16)))
					goto out_of_range;

				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isxdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'o' || ptr[1] == 'O'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '7')
			{
				if (unlikely(tmp > -(PG_INT64_MIN / 8)))
					goto out_of_range;

				tmp = tmp * 8 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '7')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else if (ptr[0] == '0' && (ptr[1] == 'b' || ptr[1] == 'B'))
	{
		firstdigit = ptr += 2;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '1')
			{
				if (unlikely(tmp > -(PG_INT64_MIN / 2)))
					goto out_of_range;

				tmp = tmp * 2 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || *ptr < '0' || *ptr > '1')
					goto invalid_syntax;
			}
			else
				break;
		}
	}
	else
	{
		firstdigit = ptr;

		for (;;)
		{
			if (*ptr >= '0' && *ptr <= '9')
			{
				if (unlikely(tmp > -(PG_INT64_MIN / 10)))
					goto out_of_range;

				tmp = tmp * 10 + (*ptr++ - '0');
			}
			else if (*ptr == '_')
			{
				/* underscore may not be first */
				if (unlikely(ptr == firstdigit))
					goto invalid_syntax;
				/* and it must be followed by more digits */
				ptr++;
				if (*ptr == '\0' || !isdigit((unsigned char) *ptr))
					goto invalid_syntax;
			}
			else
				break;
		}
	}

	/* require at least one digit */
	if (unlikely(ptr == firstdigit))
		goto invalid_syntax;

	/* allow trailing whitespace, but not other trailing chars */
	while (isspace((unsigned char) *ptr))
		ptr++;

	if (unlikely(*ptr != '\0'))
		goto invalid_syntax;

	if (neg)
	{
		/* check the negative equivalent will fit without overflowing */
		if (tmp > (uint64) (-(PG_INT64_MIN + 1)) + 1)
			goto out_of_range;
		return -((int64) tmp);
	}

	if (tmp > PG_INT64_MAX)
		goto out_of_range;

	return (int64) tmp;

out_of_range:
	ereturn(escontext, 0,
			(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
			 errmsg("value \"%s\" is out of range for type %s",
					s, "bigint")));

invalid_syntax:
	ereturn(escontext, 0,
			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
			 errmsg("invalid input syntax for type %s: \"%s\"",
					"bigint", s)));
}

/*
 * Convert input string to an unsigned 32 bit integer.
 *
 * Allows any number of leading or trailing whitespace characters.
 *
 * If endloc isn't NULL, store a pointer to the rest of the string there,
 * so that caller can parse the rest.  Otherwise, it's an error if anything
 * but whitespace follows.
 *
 * typname is what is reported in error messages.
 *
 * If escontext points to an ErrorSaveContext node, that is filled instead
 * of throwing an error; the caller must check SOFT_ERROR_OCCURRED()
 * to detect errors.
 */
uint32
uint32in_subr(const char *s, char **endloc,
			  const char *typname, Node *escontext)
{
	uint32		result;
	unsigned long cvt;
	char	   *endptr;

	errno = 0;
	cvt = strtoul(s, &endptr, 0);

	/*
	 * strtoul() normally only sets ERANGE.  On some systems it may also set
	 * EINVAL, which simply means it couldn't parse the input string.  Be sure
	 * to report that the same way as the standard error indication (that
	 * endptr == s).
	 */
	if ((errno && errno != ERANGE) || endptr == s)
		ereturn(escontext, 0,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("invalid input syntax for type %s: \"%s\"",
						typname, s)));

	if (errno == ERANGE)
		ereturn(escontext, 0,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("value \"%s\" is out of range for type %s",
						s, typname)));

	if (endloc)
	{
		/* caller wants to deal with rest of string */
		*endloc = endptr;
	}
	else
	{
		/* allow only whitespace after number */
		while (*endptr && isspace((unsigned char) *endptr))
			endptr++;
		if (*endptr)
			ereturn(escontext, 0,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type %s: \"%s\"",
							typname, s)));
	}

	result = (uint32) cvt;

	/*
	 * Cope with possibility that unsigned long is wider than uint32, in which
	 * case strtoul will not raise an error for some values that are out of
	 * the range of uint32.
	 *
	 * For backwards compatibility, we want to accept inputs that are given
	 * with a minus sign, so allow the input value if it matches after either
	 * signed or unsigned extension to long.
	 *
	 * To ensure consistent results on 32-bit and 64-bit platforms, make sure
	 * the error message is the same as if strtoul() had returned ERANGE.
	 */
#if PG_UINT32_MAX != ULONG_MAX
	if (cvt != (unsigned long) result &&
		cvt != (unsigned long) ((int) result))
		ereturn(escontext, 0,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("value \"%s\" is out of range for type %s",
						s, typname)));
#endif

	return result;
}

/*
 * Convert input string to an unsigned 64 bit integer.
 *
 * Allows any number of leading or trailing whitespace characters.
 *
 * If endloc isn't NULL, store a pointer to the rest of the string there,
 * so that caller can parse the rest.  Otherwise, it's an error if anything
 * but whitespace follows.
 *
 * typname is what is reported in error messages.
 *
 * If escontext points to an ErrorSaveContext node, that is filled instead
 * of throwing an error; the caller must check SOFT_ERROR_OCCURRED()
 * to detect errors.
 */
uint64
uint64in_subr(const char *s, char **endloc,
			  const char *typname, Node *escontext)
{
	uint64		result;
	char	   *endptr;

	errno = 0;
	result = strtou64(s, &endptr, 0);

	/*
	 * strtoul[l] normally only sets ERANGE.  On some systems it may also set
	 * EINVAL, which simply means it couldn't parse the input string.  Be sure
	 * to report that the same way as the standard error indication (that
	 * endptr == s).
	 */
	if ((errno && errno != ERANGE) || endptr == s)
		ereturn(escontext, 0,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("invalid input syntax for type %s: \"%s\"",
						typname, s)));

	if (errno == ERANGE)
		ereturn(escontext, 0,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("value \"%s\" is out of range for type %s",
						s, typname)));

	if (endloc)
	{
		/* caller wants to deal with rest of string */
		*endloc = endptr;
	}
	else
	{
		/* allow only whitespace after number */
		while (*endptr && isspace((unsigned char) *endptr))
			endptr++;
		if (*endptr)
			ereturn(escontext, 0,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type %s: \"%s\"",
							typname, s)));
	}

	return result;
}

/*
 * pg_itoa: converts a signed 16-bit integer to its string representation
 * and returns strlen(a).
 *
 * Caller must ensure that 'a' points to enough memory to hold the result
 * (at least 7 bytes, counting a leading sign and trailing NUL).
 *
 * It doesn't seem worth implementing this separately.
 */
int
pg_itoa(int16 i, char *a)
{
	return pg_ltoa((int32) i, a);
}

/*
 * pg_ultoa_n: converts an unsigned 32-bit integer to its string representation,
 * not NUL-terminated, and returns the length of that string representation
 *
 * Caller must ensure that 'a' points to enough memory to hold the result (at
 * least 10 bytes)
 */
int
pg_ultoa_n(uint32 value, char *a)
{
	int			olength,
				i = 0;

	/* Degenerate case */
	if (value == 0)
	{
		*a = '0';
		return 1;
	}

	olength = decimalLength32(value);

	/* Compute the result string. */
	while (value >= 10000)
	{
		const uint32 c = value - 10000 * (value / 10000);
		const uint32 c0 = (c % 100) << 1;
		const uint32 c1 = (c / 100) << 1;

		char	   *pos = a + olength - i;

		value /= 10000;

		memcpy(pos - 2, DIGIT_TABLE + c0, 2);
		memcpy(pos - 4, DIGIT_TABLE + c1, 2);
		i += 4;
	}
	if (value >= 100)
	{
		const uint32 c = (value % 100) << 1;

		char	   *pos = a + olength - i;

		value /= 100;

		memcpy(pos - 2, DIGIT_TABLE + c, 2);
		i += 2;
	}
	if (value >= 10)
	{
		const uint32 c = value << 1;

		char	   *pos = a + olength - i;

		memcpy(pos - 2, DIGIT_TABLE + c, 2);
	}
	else
	{
		*a = (char) ('0' + value);
	}

	return olength;
}

/*
 * pg_ltoa: converts a signed 32-bit integer to its string representation and
 * returns strlen(a).
 *
 * It is the caller's responsibility to ensure that a is at least 12 bytes long,
 * which is enough room to hold a minus sign, a maximally long int32, and the
 * above terminating NUL.
 */
int
pg_ltoa(int32 value, char *a)
{
	uint32		uvalue = (uint32) value;
	int			len = 0;

	if (value < 0)
	{
		uvalue = (uint32) 0 - uvalue;
		a[len++] = '-';
	}
	len += pg_ultoa_n(uvalue, a + len);
	a[len] = '\0';
	return len;
}

/*
 * Get the decimal representation, not NUL-terminated, and return the length of
 * same.  Caller must ensure that a points to at least MAXINT8LEN bytes.
 */
int
pg_ulltoa_n(uint64 value, char *a)
{
	int			olength,
				i = 0;
	uint32		value2;

	/* Degenerate case */
	if (value == 0)
	{
		*a = '0';
		return 1;
	}

	olength = decimalLength64(value);

	/* Compute the result string. */
	while (value >= 100000000)
	{
		const uint64 q = value / 100000000;
		uint32		value3 = (uint32) (value - 100000000 * q);

		const uint32 c = value3 % 10000;
		const uint32 d = value3 / 10000;
		const uint32 c0 = (c % 100) << 1;
		const uint32 c1 = (c / 100) << 1;
		const uint32 d0 = (d % 100) << 1;
		const uint32 d1 = (d / 100) << 1;

		char	   *pos = a + olength - i;

		value = q;

		memcpy(pos - 2, DIGIT_TABLE + c0, 2);
		memcpy(pos - 4, DIGIT_TABLE + c1, 2);
		memcpy(pos - 6, DIGIT_TABLE + d0, 2);
		memcpy(pos - 8, DIGIT_TABLE + d1, 2);
		i += 8;
	}

	/* Switch to 32-bit for speed */
	value2 = (uint32) value;

	if (value2 >= 10000)
	{
		const uint32 c = value2 - 10000 * (value2 / 10000);
		const uint32 c0 = (c % 100) << 1;
		const uint32 c1 = (c / 100) << 1;

		char	   *pos = a + olength - i;

		value2 /= 10000;

		memcpy(pos - 2, DIGIT_TABLE + c0, 2);
		memcpy(pos - 4, DIGIT_TABLE + c1, 2);
		i += 4;
	}
	if (value2 >= 100)
	{
		const uint32 c = (value2 % 100) << 1;
		char	   *pos = a + olength - i;

		value2 /= 100;

		memcpy(pos - 2, DIGIT_TABLE + c, 2);
		i += 2;
	}
	if (value2 >= 10)
	{
		const uint32 c = value2 << 1;
		char	   *pos = a + olength - i;

		memcpy(pos - 2, DIGIT_TABLE + c, 2);
	}
	else
		*a = (char) ('0' + value2);

	return olength;
}

/*
 * pg_lltoa: converts a signed 64-bit integer to its string representation and
 * returns strlen(a).
 *
 * Caller must ensure that 'a' points to enough memory to hold the result
 * (at least MAXINT8LEN + 1 bytes, counting a leading sign and trailing NUL).
 */
int
pg_lltoa(int64 value, char *a)
{
	uint64		uvalue = value;
	int			len = 0;

	if (value < 0)
	{
		uvalue = (uint64) 0 - uvalue;
		a[len++] = '-';
	}

	len += pg_ulltoa_n(uvalue, a + len);
	a[len] = '\0';
	return len;
}


/*
 * pg_ultostr_zeropad
 *		Converts 'value' into a decimal string representation stored at 'str'.
 *		'minwidth' specifies the minimum width of the result; any extra space
 *		is filled up by prefixing the number with zeros.
 *
 * Returns the ending address of the string result (the last character written
 * plus 1).  Note that no NUL terminator is written.
 *
 * The intended use-case for this function is to build strings that contain
 * multiple individual numbers, for example:
 *
 *	str = pg_ultostr_zeropad(str, hours, 2);
 *	*str++ = ':';
 *	str = pg_ultostr_zeropad(str, mins, 2);
 *	*str++ = ':';
 *	str = pg_ultostr_zeropad(str, secs, 2);
 *	*str = '\0';
 *
 * Note: Caller must ensure that 'str' points to enough memory to hold the
 * result.
 */
char *
pg_ultostr_zeropad(char *str, uint32 value, int32 minwidth)
{
	int			len;

	Assert(minwidth > 0);

	if (value < 100 && minwidth == 2)	/* Short cut for common case */
	{
		memcpy(str, DIGIT_TABLE + value * 2, 2);
		return str + 2;
	}

	len = pg_ultoa_n(value, str);
	if (len >= minwidth)
		return str + len;

	memmove(str + minwidth - len, str, len);
	memset(str, '0', minwidth - len);
	return str + minwidth;
}

/*
 * pg_ultostr
 *		Converts 'value' into a decimal string representation stored at 'str'.
 *
 * Returns the ending address of the string result (the last character written
 * plus 1).  Note that no NUL terminator is written.
 *
 * The intended use-case for this function is to build strings that contain
 * multiple individual numbers, for example:
 *
 *	str = pg_ultostr(str, a);
 *	*str++ = ' ';
 *	str = pg_ultostr(str, b);
 *	*str = '\0';
 *
 * Note: Caller must ensure that 'str' points to enough memory to hold the
 * result.
 */
char *
pg_ultostr(char *str, uint32 value)
{
	int			len = pg_ultoa_n(value, str);

	return str + len;
}