1 /*
2 ** 2020-04-14
3 **
4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
6 **
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
10 **
11 ******************************************************************************
12 **
13 ** This SQLite extension implements the UINT collating sequence.
14 **
15 ** UINT works like BINARY for text, except that embedded strings
16 ** of digits compare in numeric order.
17 **
18 ** * Leading zeros are handled properly, in the sense that
19 ** they do not mess of the maginitude comparison of embedded
20 ** strings of digits. "x00123y" is equal to "x123y".
21 **
22 ** * Only unsigned integers are recognized. Plus and minus
23 ** signs are ignored. Decimal points and exponential notation
24 ** are ignored.
25 **
26 ** * Embedded integers can be of arbitrary length. Comparison
27 ** is *not* limited integers that can be expressed as a
28 ** 64-bit machine integer.
29 */
30 #include "sqlite3ext.h"
31 SQLITE_EXTENSION_INIT1
32 #include <assert.h>
33 #include <string.h>
34 #include <ctype.h>
35
36 /*
37 ** Compare text in lexicographic order, except strings of digits
38 ** compare in numeric order.
39 */
uintCollFunc(void * notUsed,int nKey1,const void * pKey1,int nKey2,const void * pKey2)40 static int uintCollFunc(
41 void *notUsed,
42 int nKey1, const void *pKey1,
43 int nKey2, const void *pKey2
44 ){
45 const unsigned char *zA = (const unsigned char*)pKey1;
46 const unsigned char *zB = (const unsigned char*)pKey2;
47 int i=0, j=0, x;
48 (void)notUsed;
49 while( i<nKey1 && j<nKey2 ){
50 x = zA[i] - zB[j];
51 if( isdigit(zA[i]) ){
52 int k;
53 if( !isdigit(zB[j]) ) return x;
54 while( i<nKey1 && zA[i]=='0' ){ i++; }
55 while( j<nKey2 && zB[j]=='0' ){ j++; }
56 k = 0;
57 while( i+k<nKey1 && isdigit(zA[i+k])
58 && j+k<nKey2 && isdigit(zB[j+k]) ){
59 k++;
60 }
61 if( i+k<nKey1 && isdigit(zA[i+k]) ){
62 return +1;
63 }else if( j+k<nKey2 && isdigit(zB[j+k]) ){
64 return -1;
65 }else{
66 x = memcmp(zA+i, zB+j, k);
67 if( x ) return x;
68 i += k;
69 j += k;
70 }
71 }else if( x ){
72 return x;
73 }else{
74 i++;
75 j++;
76 }
77 }
78 return (nKey1 - i) - (nKey2 - j);
79 }
80
81 #ifdef _WIN32
82 __declspec(dllexport)
83 #endif
sqlite3_uint_init(sqlite3 * db,char ** pzErrMsg,const sqlite3_api_routines * pApi)84 int sqlite3_uint_init(
85 sqlite3 *db,
86 char **pzErrMsg,
87 const sqlite3_api_routines *pApi
88 ){
89 SQLITE_EXTENSION_INIT2(pApi);
90 (void)pzErrMsg; /* Unused parameter */
91 return sqlite3_create_collation(db, "uint", SQLITE_UTF8, 0, uintCollFunc);
92 }
93