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Improvements to the accuracy of json_error(). Add the extension SQL
functions random_json(SEED) and random_json5(SEED). FossilOrigin-Name: 8d09dc1c45a8026b94f70273d064e47939f30cadedc17548b5a26ba054a8d3a7
This commit is contained in:
drh
202
ext/misc/randomjson.c
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202
ext/misc/randomjson.c
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/*
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** 2023-04-28
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This SQLite extension implements a the random_json(SEED) and
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** random_json5(SEED) functions. Given a numeric SEED value, these
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** routines generate pseudo-random JSON or JSON5, respectively. The
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** same value is always generated for the same seed.
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**
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** These SQL functions are intended for testing. They do not have any
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** practical real-world use, that we know of.
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**
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** COMPILE:
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**
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** gcc --shared -fPIC -o randomjson.so -I. ext/misc/randomjson.c
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**
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** USING FROM THE CLI:
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**
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** .load ./randomjson
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** SELECT random_json(1);
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*/
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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#include <assert.h>
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#include <string.h>
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#include <stdlib.h>
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/* Pseudo-random number generator */
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typedef struct Prng {
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unsigned int x, y;
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} Prng;
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/* Reseed the PRNG */
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static void prngSeed(Prng *p, unsigned int iSeed){
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p->x = iSeed | 1;
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p->y = iSeed;
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}
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/* Extract a random number */
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static unsigned int prngInt(Prng *p){
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p->x = (p->x>>1) ^ ((1+~(p->x&1)) & 0xd0000001);
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p->y = p->y*1103515245 + 12345;
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return p->x ^ p->y;
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}
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static const char *azJsonAtoms[] = {
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/* JSON /* JSON-5 */
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"0", "0",
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"1", "1",
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"-1", "-1",
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"2", "+2",
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"3", "3",
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"2.5", "2.5",
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"0.75", ".75",
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"-4.0e2", "-4.e2",
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"5.0e-3", "+5e-3",
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"0", "0x0",
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"512", "0x200",
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"256", "+0x100",
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"-2748", "-0xabc",
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"true", "true",
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"false", "false",
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"null", "null",
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"9.0e999", "Infinity",
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"-9.0e999", "-Infinity",
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"9.0e999", "+Infinity",
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"null", "NaN",
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"-0.0005123", "-0.0005123",
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"4.35e-3", "+4.35e-3",
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"\"gem\\\"hay\"", "\"gem\\\"hay\"",
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"\"icy'joy\"", "'icy\\'joy\'",
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"\"keylog\"", "\"key\\\nlog\"",
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"\"mix\\\\\\tnet\"", "\"mix\\\\\\tnet\"",
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"{}", "{}",
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"[]", "[]",
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"[]", "[/*empty*/]",
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"{}", "{//empty\n}",
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"\"ask\"", "\"ask\"",
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"\"bag\"", "\"bag\"",
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"\"can\"", "\"can\"",
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"\"day\"", "\"day\"",
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"\"end\"", "'end'",
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"\"fly\"", "\"fly\"",
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"\"\"", "\"\"",
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};
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static const char *azJsonTemplate[] = {
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/* JSON JSON-5 */
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"{\"a\":%,\"b\":%,\"c\":%}", "{a:%,b:%,c:%}",
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"{\"a\":%,\"b\":%,\"c\":%,\"d\":%,\"e\":%}", "{a:%,b:%,c:%,d:%,e:%}",
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"{\"a\":%,\"b\":%,\"c\":%,\"d\":%,\"\":%}", "{a:%,b:%,c:%,d:%,\"\":%}",
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"{\"d\":%}", "{d:%}",
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"{\"eeee\":%, \"ffff\":%}", "{eeee:% /*and*/, ffff:%}",
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"{\"$g\":%,\"_h_\":%}", "{$g:%,_h_:%,}",
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"{\"x\":%,\n \"y\":%}", "{\"x\":%,\n \"y\":%}",
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"{\"a b c d\":%,\"e\":%,\"f\":%,\"x\":%,\"y\":%}",
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"{\"a b c d\":%,e:%,f:%,x:%,y:%}",
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"{\"Z\":%}", "{Z:%,}",
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"[%]", "[%,]",
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"[%,%]", "[%,%]",
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"[%,%,%]", "[%,%,%,]",
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"[%,%,%,%]", "[%,%,%,%]",
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"[%,%,%,%,%]", "[%,%,%,%,%]",
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};
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#define count(X) (sizeof(X)/sizeof(X[0]))
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#define STRSZ 10000
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static void jsonExpand(
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const char *zSrc,
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char *zDest,
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Prng *p,
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int eType, /* 0 for JSON, 1 for JSON5 */
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unsigned int r /* Growth probability 0..1000. 0 means no growth */
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){
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unsigned int i, j, k;
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const char *z;
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size_t n;
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j = 0;
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if( zSrc==0 ){
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k = prngInt(p)%(count(azJsonTemplate)/2);
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k = k*2 + eType;
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zSrc = azJsonTemplate[k];
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}
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if( strlen(zSrc)>=STRSZ/10 ) r = 0;
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for(i=0; zSrc[i]; i++){
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if( zSrc[i]!='%' ){
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if( j<STRSZ ) zDest[j++] = zSrc[i];
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continue;
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}
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if( r==0 || (r<1000 && (prngInt(p)%1000)<=r) ){
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/* Fill in without values without any new % */
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k = prngInt(p)%(count(azJsonAtoms)/2);
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k = k*2 + eType;
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z = azJsonAtoms[k];
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}else{
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/* Add new % terms */
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k = prngInt(p)%(count(azJsonTemplate)/2);
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k = k*2 + eType;
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z = azJsonTemplate[k];
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}
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n = strlen(z);
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if( j+n<STRSZ ){
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memcpy(&zDest[j], z, n);
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j += n;
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}
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}
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zDest[STRSZ-1] = 0;
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if( j<STRSZ ) zDest[j] = 0;
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}
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static void randJsonFunc(
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sqlite3_context *context,
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int argc,
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sqlite3_value **argv
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){
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unsigned int iSeed;
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int eType = *(int*)sqlite3_user_data(context);
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Prng prng;
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char z1[STRSZ+1], z2[STRSZ+1];
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iSeed = (unsigned int)sqlite3_value_int(argv[0]);
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prngSeed(&prng, iSeed);
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jsonExpand(0, z2, &prng, eType, 1000);
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jsonExpand(z2, z1, &prng, eType, 1000);
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jsonExpand(z1, z2, &prng, eType, 100);
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jsonExpand(z2, z1, &prng, eType, 0);
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sqlite3_result_text(context, z1, -1, SQLITE_TRANSIENT);
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}
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#ifdef _WIN32
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__declspec(dllexport)
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#endif
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int sqlite3_randomjson_init(
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sqlite3 *db,
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char **pzErrMsg,
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const sqlite3_api_routines *pApi
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){
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static int cOne = 1;
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static int cZero = 0;
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int rc = SQLITE_OK;
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SQLITE_EXTENSION_INIT2(pApi);
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(void)pzErrMsg; /* Unused parameter */
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rc = sqlite3_create_function(db, "random_json", 1,
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SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC,
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&cZero, randJsonFunc, 0, 0);
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if( rc==SQLITE_OK ){
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rc = sqlite3_create_function(db, "random_json5", 1,
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SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC,
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&cOne, randJsonFunc, 0, 0);
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}
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return rc;
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}
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