/* ** 2020-04-14 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ****************************************************************************** ** ** This SQLite extension implements the UINT collating sequence. ** ** UINT works like BINARY for text, except that embedded strings ** of digits compare in numeric order. ** ** * Leading zeros are handled properly, in the sense that ** they do not mess of the maginitude comparison of embedded ** strings of digits. "x00123y" is equal to "x123y". ** ** * Only unsigned integers are recognized. Plus and minus ** signs are ignored. Decimal points and exponential notation ** are ignored. ** ** * Embedded integers can be of arbitrary length. Comparison ** is *not* limited integers that can be expressed as a ** 64-bit machine integer. */ #include "sqlite3ext.h" SQLITE_EXTENSION_INIT1 #include <assert.h> #include <string.h> #include <ctype.h> /* ** Compare text in lexicographic order, except strings of digits ** compare in numeric order. */ static int uintCollFunc( void *notUsed, int nKey1, const void *pKey1, int nKey2, const void *pKey2 ){ const unsigned char *zA = (const unsigned char*)pKey1; const unsigned char *zB = (const unsigned char*)pKey2; int i=0, j=0, x; (void)notUsed; while( i<nKey1 && j<nKey2 ){ x = zA[i] - zB[j]; if( isdigit(zA[i]) ){ int k; if( !isdigit(zB[j]) ) return x; while( i<nKey1 && zA[i]=='0' ){ i++; } while( j<nKey2 && zB[j]=='0' ){ j++; } k = 0; while( i+k<nKey1 && isdigit(zA[i+k]) && j+k<nKey2 && isdigit(zB[j+k]) ){ k++; } if( i+k<nKey1 && isdigit(zA[i+k]) ){ return +1; }else if( j+k<nKey2 && isdigit(zB[j+k]) ){ return -1; }else{ x = memcmp(zA+i, zB+j, k); if( x ) return x; i += k; j += k; } }else if( x ){ return x; }else{ i++; j++; } } return (nKey1 - i) - (nKey2 - j); } #ifdef _WIN32 __declspec(dllexport) #endif int sqlite3_uint_init( sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi ){ SQLITE_EXTENSION_INIT2(pApi); (void)pzErrMsg; /* Unused parameter */ return sqlite3_create_collation(db, "uint", SQLITE_UTF8, 0, uintCollFunc); }