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/*-------------------------------------------------------------------------
*
* char.c
* Functions for the built-in type "char" (not to be confused with
* bpchar, which is the SQL CHAR(n) type).
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/utils/adt/char.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <limits.h>
#include "libpq/pqformat.h"
#include "utils/builtins.h"
/*****************************************************************************
* USER I/O ROUTINES *
*****************************************************************************/
/*
* charin - converts "x" to 'x'
*
* Note that an empty input string will implicitly be converted to \0.
*/
Datum
charin(PG_FUNCTION_ARGS)
{
char *ch = PG_GETARG_CSTRING(0);
PG_RETURN_CHAR(ch[0]);
}
/*
* charout - converts 'x' to "x"
*
* Note that if the char value is \0, the resulting string will appear
* to be empty (null-terminated after zero characters). So this is the
* inverse of the charin() function for such data.
*/
Datum
charout(PG_FUNCTION_ARGS)
{
char ch = PG_GETARG_CHAR(0);
char *result = (char *) palloc(2);
result[0] = ch;
result[1] = '\0';
PG_RETURN_CSTRING(result);
}
/*
* charrecv - converts external binary format to char
*
* The external representation is one byte, with no character set
* conversion. This is somewhat dubious, perhaps, but in many
* cases people use char for a 1-byte binary type.
*/
Datum
charrecv(PG_FUNCTION_ARGS)
{
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
PG_RETURN_CHAR(pq_getmsgbyte(buf));
}
/*
* charsend - converts char to binary format
*/
Datum
charsend(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
StringInfoData buf;
pq_begintypsend(&buf);
pq_sendbyte(&buf, arg1);
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
/*****************************************************************************
* PUBLIC ROUTINES *
*****************************************************************************/
/*
* NOTE: comparisons are done as though char is unsigned (uint8).
* Conversions to and from integer are done as though char is signed (int8).
*
* You wanted consistency?
*/
Datum
chareq(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL(arg1 == arg2);
}
Datum
charne(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL(arg1 != arg2);
}
Datum
charlt(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL((uint8) arg1 < (uint8) arg2);
}
Datum
charle(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL((uint8) arg1 <= (uint8) arg2);
}
Datum
chargt(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL((uint8) arg1 > (uint8) arg2);
}
Datum
charge(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
char arg2 = PG_GETARG_CHAR(1);
PG_RETURN_BOOL((uint8) arg1 >= (uint8) arg2);
}
Datum
chartoi4(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
PG_RETURN_INT32((int32) ((int8) arg1));
}
Datum
i4tochar(PG_FUNCTION_ARGS)
{
int32 arg1 = PG_GETARG_INT32(0);
if (arg1 < SCHAR_MIN || arg1 > SCHAR_MAX)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("\"char\" out of range")));
PG_RETURN_CHAR((int8) arg1);
}
Datum
text_char(PG_FUNCTION_ARGS)
{
text *arg1 = PG_GETARG_TEXT_PP(0);
char result;
/*
* An empty input string is converted to \0 (for consistency with charin).
* If the input is longer than one character, the excess data is silently
* discarded.
*/
if (VARSIZE_ANY_EXHDR(arg1) > 0)
result = *(VARDATA_ANY(arg1));
else
result = '\0';
PG_RETURN_CHAR(result);
}
Datum
char_text(PG_FUNCTION_ARGS)
{
char arg1 = PG_GETARG_CHAR(0);
text *result = palloc(VARHDRSZ + 1);
/*
* Convert \0 to an empty string, for consistency with charout (and
* because the text stuff doesn't like embedded nulls all that well).
*/
if (arg1 != '\0')
{
SET_VARSIZE(result, VARHDRSZ + 1);
*(VARDATA(result)) = arg1;
}
else
SET_VARSIZE(result, VARHDRSZ);
PG_RETURN_TEXT_P(result);
}
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