1 /*
2 * src/tutorial/complex.c
3 *
4 ******************************************************************************
5 This file contains routines that can be bound to a Postgres backend and
6 called by the backend in the process of processing queries. The calling
7 format for these routines is dictated by Postgres architecture.
8 ******************************************************************************/
9
10 #include "postgres.h"
11
12 #include "fmgr.h"
13 #include "libpq/pqformat.h" /* needed for send/recv functions */
14
15 PG_MODULE_MAGIC;
16
17 typedef struct Complex
18 {
19 double x;
20 double y;
21 } Complex;
22
23
24 /*****************************************************************************
25 * Input/Output functions
26 *****************************************************************************/
27
28 PG_FUNCTION_INFO_V1(complex_in);
29
30 Datum
complex_in(PG_FUNCTION_ARGS)31 complex_in(PG_FUNCTION_ARGS)
32 {
33 char *str = PG_GETARG_CSTRING(0);
34 double x,
35 y;
36 Complex *result;
37
38 if (sscanf(str, " ( %lf , %lf )", &x, &y) != 2)
39 ereport(ERROR,
40 (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
41 errmsg("invalid input syntax for complex: \"%s\"",
42 str)));
43
44 result = (Complex *) palloc(sizeof(Complex));
45 result->x = x;
46 result->y = y;
47 PG_RETURN_POINTER(result);
48 }
49
50 PG_FUNCTION_INFO_V1(complex_out);
51
52 Datum
complex_out(PG_FUNCTION_ARGS)53 complex_out(PG_FUNCTION_ARGS)
54 {
55 Complex *complex = (Complex *) PG_GETARG_POINTER(0);
56 char *result;
57
58 result = psprintf("(%g,%g)", complex->x, complex->y);
59 PG_RETURN_CSTRING(result);
60 }
61
62 /*****************************************************************************
63 * Binary Input/Output functions
64 *
65 * These are optional.
66 *****************************************************************************/
67
68 PG_FUNCTION_INFO_V1(complex_recv);
69
70 Datum
complex_recv(PG_FUNCTION_ARGS)71 complex_recv(PG_FUNCTION_ARGS)
72 {
73 StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
74 Complex *result;
75
76 result = (Complex *) palloc(sizeof(Complex));
77 result->x = pq_getmsgfloat8(buf);
78 result->y = pq_getmsgfloat8(buf);
79 PG_RETURN_POINTER(result);
80 }
81
82 PG_FUNCTION_INFO_V1(complex_send);
83
84 Datum
complex_send(PG_FUNCTION_ARGS)85 complex_send(PG_FUNCTION_ARGS)
86 {
87 Complex *complex = (Complex *) PG_GETARG_POINTER(0);
88 StringInfoData buf;
89
90 pq_begintypsend(&buf);
91 pq_sendfloat8(&buf, complex->x);
92 pq_sendfloat8(&buf, complex->y);
93 PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
94 }
95
96 /*****************************************************************************
97 * New Operators
98 *
99 * A practical Complex datatype would provide much more than this, of course.
100 *****************************************************************************/
101
102 PG_FUNCTION_INFO_V1(complex_add);
103
104 Datum
complex_add(PG_FUNCTION_ARGS)105 complex_add(PG_FUNCTION_ARGS)
106 {
107 Complex *a = (Complex *) PG_GETARG_POINTER(0);
108 Complex *b = (Complex *) PG_GETARG_POINTER(1);
109 Complex *result;
110
111 result = (Complex *) palloc(sizeof(Complex));
112 result->x = a->x + b->x;
113 result->y = a->y + b->y;
114 PG_RETURN_POINTER(result);
115 }
116
117
118 /*****************************************************************************
119 * Operator class for defining B-tree index
120 *
121 * It's essential that the comparison operators and support function for a
122 * B-tree index opclass always agree on the relative ordering of any two
123 * data values. Experience has shown that it's depressingly easy to write
124 * unintentionally inconsistent functions. One way to reduce the odds of
125 * making a mistake is to make all the functions simple wrappers around
126 * an internal three-way-comparison function, as we do here.
127 *****************************************************************************/
128
129 #define Mag(c) ((c)->x*(c)->x + (c)->y*(c)->y)
130
131 static int
complex_abs_cmp_internal(Complex * a,Complex * b)132 complex_abs_cmp_internal(Complex * a, Complex * b)
133 {
134 double amag = Mag(a),
135 bmag = Mag(b);
136
137 if (amag < bmag)
138 return -1;
139 if (amag > bmag)
140 return 1;
141 return 0;
142 }
143
144
145 PG_FUNCTION_INFO_V1(complex_abs_lt);
146
147 Datum
complex_abs_lt(PG_FUNCTION_ARGS)148 complex_abs_lt(PG_FUNCTION_ARGS)
149 {
150 Complex *a = (Complex *) PG_GETARG_POINTER(0);
151 Complex *b = (Complex *) PG_GETARG_POINTER(1);
152
153 PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) < 0);
154 }
155
156 PG_FUNCTION_INFO_V1(complex_abs_le);
157
158 Datum
complex_abs_le(PG_FUNCTION_ARGS)159 complex_abs_le(PG_FUNCTION_ARGS)
160 {
161 Complex *a = (Complex *) PG_GETARG_POINTER(0);
162 Complex *b = (Complex *) PG_GETARG_POINTER(1);
163
164 PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) <= 0);
165 }
166
167 PG_FUNCTION_INFO_V1(complex_abs_eq);
168
169 Datum
complex_abs_eq(PG_FUNCTION_ARGS)170 complex_abs_eq(PG_FUNCTION_ARGS)
171 {
172 Complex *a = (Complex *) PG_GETARG_POINTER(0);
173 Complex *b = (Complex *) PG_GETARG_POINTER(1);
174
175 PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) == 0);
176 }
177
178 PG_FUNCTION_INFO_V1(complex_abs_ge);
179
180 Datum
complex_abs_ge(PG_FUNCTION_ARGS)181 complex_abs_ge(PG_FUNCTION_ARGS)
182 {
183 Complex *a = (Complex *) PG_GETARG_POINTER(0);
184 Complex *b = (Complex *) PG_GETARG_POINTER(1);
185
186 PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) >= 0);
187 }
188
189 PG_FUNCTION_INFO_V1(complex_abs_gt);
190
191 Datum
complex_abs_gt(PG_FUNCTION_ARGS)192 complex_abs_gt(PG_FUNCTION_ARGS)
193 {
194 Complex *a = (Complex *) PG_GETARG_POINTER(0);
195 Complex *b = (Complex *) PG_GETARG_POINTER(1);
196
197 PG_RETURN_BOOL(complex_abs_cmp_internal(a, b) > 0);
198 }
199
200 PG_FUNCTION_INFO_V1(complex_abs_cmp);
201
202 Datum
complex_abs_cmp(PG_FUNCTION_ARGS)203 complex_abs_cmp(PG_FUNCTION_ARGS)
204 {
205 Complex *a = (Complex *) PG_GETARG_POINTER(0);
206 Complex *b = (Complex *) PG_GETARG_POINTER(1);
207
208 PG_RETURN_INT32(complex_abs_cmp_internal(a, b));
209 }
210