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b663f3443b
with OPAQUE, as per recent pghackers discussion. I still want to do some more work on the 'cstring' pseudo-type, but I'm going to commit the bulk of the changes now before the tree starts shifting under me ...
173 lines
3.9 KiB
C
173 lines
3.9 KiB
C
/******************************************************************************
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This file contains routines that can be bound to a Postgres backend and
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called by the backend in the process of processing queries. The calling
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format for these routines is dictated by Postgres architecture.
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******************************************************************************/
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#include "postgres.h"
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typedef struct Complex
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{
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double x;
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double y;
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} Complex;
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/* These prototypes declare the requirements that Postgres places on these
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user written functions.
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*/
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Complex *complex_in(char *str);
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char *complex_out(Complex * complex);
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Complex *complex_add(Complex * a, Complex * b);
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bool complex_abs_lt(Complex * a, Complex * b);
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bool complex_abs_le(Complex * a, Complex * b);
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bool complex_abs_eq(Complex * a, Complex * b);
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bool complex_abs_ge(Complex * a, Complex * b);
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bool complex_abs_gt(Complex * a, Complex * b);
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int4 complex_abs_cmp(Complex * a, Complex * b);
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/*****************************************************************************
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* Input/Output functions
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*****************************************************************************/
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Complex *
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complex_in(char *str)
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{
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double x,
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y;
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Complex *result;
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if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2)
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{
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elog(ERROR, "complex_in: error in parsing \"%s\"", str);
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return NULL;
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}
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result = (Complex *) palloc(sizeof(Complex));
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result->x = x;
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result->y = y;
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return result;
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}
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char *
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complex_out(Complex * complex)
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{
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char *result;
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if (complex == NULL)
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return NULL;
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result = (char *) palloc(100);
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snprintf(result, 100, "(%g,%g)", complex->x, complex->y);
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return result;
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}
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/*****************************************************************************
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* New Operators
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*****************************************************************************/
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Complex *
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complex_add(Complex * a, Complex * b)
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{
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Complex *result;
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result = (Complex *) palloc(sizeof(Complex));
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result->x = a->x + b->x;
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result->y = a->y + b->y;
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return result;
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}
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/*****************************************************************************
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* Operator class for defining B-tree index
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*****************************************************************************/
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#define Mag(c) ((c)->x*(c)->x + (c)->y*(c)->y)
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bool
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complex_abs_lt(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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return amag < bmag;
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}
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bool
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complex_abs_le(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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return amag <= bmag;
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}
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bool
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complex_abs_eq(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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return amag == bmag;
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}
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bool
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complex_abs_ge(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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return amag >= bmag;
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}
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bool
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complex_abs_gt(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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return amag > bmag;
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}
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int4
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complex_abs_cmp(Complex * a, Complex * b)
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{
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double amag = Mag(a),
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bmag = Mag(b);
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if (amag < bmag)
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return -1;
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else if (amag > bmag)
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return 1;
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else
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return 0;
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}
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/*****************************************************************************
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* test code
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*****************************************************************************/
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/*
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* You should always test your code separately. Trust me, using POSTGRES to
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* debug your C function will be very painful and unproductive. In case of
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* POSTGRES crashing, it is impossible to tell whether the bug is in your
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* code or POSTGRES's.
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*/
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void test_main(void);
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void
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test_main()
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{
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Complex *a;
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Complex *b;
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a = complex_in("(4.01, 3.77 )");
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printf("a = %s\n", complex_out(a));
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b = complex_in("(1.0,2.0)");
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printf("b = %s\n", complex_out(b));
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printf("a + b = %s\n", complex_out(complex_add(a, b)));
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printf("a < b = %d\n", complex_abs_lt(a, b));
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printf("a <= b = %d\n", complex_abs_le(a, b));
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printf("a = b = %d\n", complex_abs_eq(a, b));
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printf("a >= b = %d\n", complex_abs_ge(a, b));
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printf("a > b = %d\n", complex_abs_gt(a, b));
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}
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