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/*
* $PostgreSQL: pgsql/src/tutorial/complex.c,v 1.15 2009/06/11 14:49:15 momjian Exp $
*
******************************************************************************
This file contains routines that can be bound to a Postgres backend and
called by the backend in the process of processing queries. The calling
format for these routines is dictated by Postgres architecture.
******************************************************************************/
#include "postgres.h"
#include "fmgr.h"
#include "libpq/pqformat.h" /* needed for send/recv functions */
PG_MODULE_MAGIC;
typedef struct Complex
{
double x;
double y;
} Complex;
/*
* Since we use V1 function calling convention, all these functions have
* the same signature as far as C is concerned. We provide these prototypes
* just to forestall warnings when compiled with gcc -Wmissing-prototypes.
*/
Datum complex_in(PG_FUNCTION_ARGS);
Datum complex_out(PG_FUNCTION_ARGS);
Datum complex_recv(PG_FUNCTION_ARGS);
Datum complex_send(PG_FUNCTION_ARGS);
Datum complex_add(PG_FUNCTION_ARGS);
Datum complex_abs_lt(PG_FUNCTION_ARGS);
Datum complex_abs_le(PG_FUNCTION_ARGS);
Datum complex_abs_eq(PG_FUNCTION_ARGS);
Datum complex_abs_ge(PG_FUNCTION_ARGS);
Datum complex_abs_gt(PG_FUNCTION_ARGS);
Datum complex_abs_cmp(PG_FUNCTION_ARGS);
/*****************************************************************************
* Input/Output functions
*****************************************************************************/
PG_FUNCTION_INFO_V1(complex_in);
Datum
complex_in(PG_FUNCTION_ARGS)
{
char *str = PG_GETARG_CSTRING(0);
double x,
y;
Complex *result;
if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for complex: \"%s\"",
str)));
result = (Complex *) palloc(sizeof(Complex));
result->x = x;
result->y = y;
PG_RETURN_POINTER(result);
}
PG_FUNCTION_INFO_V1(complex_out);
Datum
complex_out(PG_FUNCTION_ARGS)
{
Complex *complex = (Complex *) PG_GETARG_POINTER(0);
char *result;
result = (char *) palloc(100);
snprintf(result, 100, "(%g,%g)", complex->x, complex->y);
PG_RETURN_CSTRING(result);
}
/*****************************************************************************
* Binary Input/Output functions
*
* These are optional.
*****************************************************************************/
PG_FUNCTION_INFO_V1(complex_recv);
Datum
complex_recv(PG_FUNCTION_ARGS)
{
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
Complex *result;
result = (Complex *) palloc(sizeof(Complex));
result->x = pq_getmsgfloat8(buf);
result->y = pq_getmsgfloat8(buf);
PG_RETURN_POINTER(result);
}
PG_FUNCTION_INFO_V1(complex_send);
Datum
complex_send(PG_FUNCTION_ARGS)
{
Complex *complex = (Complex *) PG_GETARG_POINTER(0);
StringInfoData buf;
pq_begintypsend(&buf);
pq_sendfloat8(&buf, complex->x);
pq_sendfloat8(&buf, complex->y);
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
/*****************************************************************************
* New Operators
*
* A practical Complex datatype would provide much more than this, of course.
*****************************************************************************/
PG_FUNCTION_INFO_V1(complex_add);
Datum
complex_add(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
Complex *result;
result = (Complex *) palloc(sizeof(Complex));
result->x = a->x + b->x;
result->y = a->y + b->y;
PG_RETURN_POINTER(result);
}
/*****************************************************************************
* Operator class for defining B-tree index
*
* It's essential that the comparison operators and support function for a
* B-tree index opclass always agree on the relative ordering of any two
* data values. Experience has shown that it's depressingly easy to write
* unintentionally inconsistent functions. One way to reduce the odds of
* making a mistake is to make all the functions simple wrappers around
* an internal three-way-comparison function, as we do here.
*****************************************************************************/
#define Mag(c) ((c)->x*(c)->x + (c)->y*(c)->y)
static int
complex_abs_cmp_internal(Complex * a, Complex * b)
{
double amag = Mag(a),
bmag = Mag(b);
if (amag < bmag)
return -1;
if (amag > bmag)
return 1;
return 0;
}
PG_FUNCTION_INFO_V1(complex_abs_lt);
Datum
complex_abs_lt(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) < 0);
}
PG_FUNCTION_INFO_V1(complex_abs_le);
Datum
complex_abs_le(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) <= 0);
}
PG_FUNCTION_INFO_V1(complex_abs_eq);
Datum
complex_abs_eq(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) == 0);
}
PG_FUNCTION_INFO_V1(complex_abs_ge);
Datum
complex_abs_ge(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) >= 0);
}
PG_FUNCTION_INFO_V1(complex_abs_gt);
Datum
complex_abs_gt(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) > 0);
}
PG_FUNCTION_INFO_V1(complex_abs_cmp);
Datum
complex_abs_cmp(PG_FUNCTION_ARGS)
{
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
PG_RETURN_INT32(complex_abs_cmp_internal(a, b));
}
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