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#include <stdio.h>
/* do not include libpq-fe.h for backend-loaded functions*/
/* #include "libpq-fe.h" */
#include "postgres.h"
#include "utils/elog.h"
#include "utils/palloc.h"
#include "utils/mcxt.h"
typedef struct Complex {
double x;
double y;
} Complex;
/*****************************************************************************
* Input/Output functions
*****************************************************************************/
Complex *
complex_in(char *str)
{
double x, y;
Complex *result;
if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2) {
elog(WARN, "complex_in: error in parsing \"%s\"", str);
return NULL;
}
result = (Complex *)palloc(sizeof(Complex));
result->x = x;
result->y = y;
return (result);
}
/*
* You might have noticed a slight inconsistency between the following
* declaration and the SQL definition:
* CREATE FUNCTION complex_out(opaque) RETURNS opaque ...
* The reason is that the argument pass into complex_out is really just a
* pointer. POSTGRES thinks all output functions are:
* char *out_func(char *);
*/
char *
complex_out(Complex *complex)
{
char *result;
if (complex == NULL)
return(NULL);
result = (char *) palloc(60);
sprintf(result, "(%lg,%lg)", complex->x, complex->y);
return(result);
}
/*****************************************************************************
* New Operators
*****************************************************************************/
Complex *
complex_add(Complex *a, Complex *b)
{
Complex *result;
result = (Complex *)palloc(sizeof(Complex));
result->x = a->x + b->x;
result->y = a->y + b->y;
return (result);
}
/*****************************************************************************
* Operator class for defining B-tree index
*****************************************************************************/
#define Mag(c) ((c)->x*(c)->x + (c)->y*(c)->y)
bool
complex_abs_lt(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
return (amag<bmag);
}
bool
complex_abs_le(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
return (amag<=bmag);
}
bool
complex_abs_eq(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
return (amag==bmag);
}
bool
complex_abs_ge(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
return (amag>=bmag);
}
bool
complex_abs_gt(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
return (amag>bmag);
}
int4
complex_abs_cmp(Complex *a, Complex *b)
{
double amag = Mag(a), bmag = Mag(b);
if (a < b)
return -1;
else if (a > b)
return 1;
else
return 0;
}
/*****************************************************************************
* test code
*****************************************************************************/
/*
* You should always test your code separately. Trust me, using POSTGRES to
* debug your C function will be very painful and unproductive. In case of
* POSTGRES crashing, it is impossible to tell whether the bug is in your
* code or POSTGRES's.
*/
void
test_main()
{
Complex *a;
Complex *b;
a = complex_in("(4.01, 3.77 )");
printf("a = %s\n", complex_out(a));
b = complex_in("(1.0,2.0)");
printf("b = %s\n", complex_out(b));
printf("a + b = %s\n", complex_out(complex_add(a,b)));
printf("a < b = %d\n", complex_abs_lt(a,b));
printf("a <= b = %d\n", complex_abs_le(a,b));
printf("a = b = %d\n", complex_abs_eq(a,b));
printf("a >= b = %d\n", complex_abs_ge(a,b));
printf("a > b = %d\n", complex_abs_gt(a,b));
}
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