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Update the complex-datatype example to V1 function calling conventions,

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and add binary send/receive functions.  Fix some other grottiness such
as failure to mark the C functions STRICT.
This commit is contained in:
Tom Lane
2003-10-21 22:51:14 +00:00
parent 6c7c493a09
commit 6fbb14a174
4 changed files with 329 additions and 154 deletions
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251
src/tutorial/complex.c
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@ -6,33 +6,44 @@
#include "postgres.h"
#include "fmgr.h"
#include "libpq/pqformat.h" /* needed for send/recv functions */
typedef struct Complex
{
double x;
double y;
} Complex;
/* These prototypes declare the requirements that Postgres places on these
user written functions.
*/
Complex *complex_in(char *str);
char *complex_out(Complex * complex);
Complex *complex_add(Complex * a, Complex * b);
bool complex_abs_lt(Complex * a, Complex * b);
bool complex_abs_le(Complex * a, Complex * b);
bool complex_abs_eq(Complex * a, Complex * b);
bool complex_abs_ge(Complex * a, Complex * b);
bool complex_abs_gt(Complex * a, Complex * b);
int4 complex_abs_cmp(Complex * a, Complex * b);
/*
* 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
*****************************************************************************/
Complex *
complex_in(char *str)
PG_FUNCTION_INFO_V1(complex_in);
Datum
complex_in(PG_FUNCTION_ARGS)
{
char *str = PG_GETARG_CSTRING(0);
double x,
y;
Complex *result;
@ -40,133 +51,173 @@ complex_in(char *str)
if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for complex: \"%s\"", str)));
errmsg("invalid input syntax for complex: \"%s\"",
str)));
result = (Complex *) palloc(sizeof(Complex));
result->x = x;
result->y = y;
return result;
PG_RETURN_POINTER(result);
}
char *
complex_out(Complex * complex)
{
char *result;
PG_FUNCTION_INFO_V1(complex_out);
if (complex == NULL)
return NULL;
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);
return result;
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.
*****************************************************************************/
Complex *
complex_add(Complex * a, Complex * b)
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;
return result;
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)
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)
static int
complex_abs_cmp_internal(Complex *a, Complex *b)
{
double amag = Mag(a),
bmag = Mag(b);
if (amag < bmag)
return -1;
else if (amag > bmag)
if (amag > bmag)
return 1;
else
return 0;
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(void);
void
test_main()
PG_FUNCTION_INFO_V1(complex_abs_lt);
Datum
complex_abs_lt(PG_FUNCTION_ARGS)
{
Complex *a;
Complex *b;
Complex *a = (Complex *) PG_GETARG_POINTER(0);
Complex *b = (Complex *) PG_GETARG_POINTER(1);
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));
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));
}