SQLite

  JsonNode *aNode;   /* Array of nodes containing the parse */
  const char *zJson; /* Original JSON string */
  u32 *aUp;          /* Index of parent of each node */
  u8 oom;            /* Set to true if out of memory */
  u8 nErr;           /* Number of errors seen */
  u16 iDepth;        /* Nesting depth */
  int nJson;         /* Length of the zJson string in bytes */
  u32 iHold;         /* Replace cache line with the lowest iHold value */
};

/*
** Maximum nesting depth of JSON for this implementation.
**
** This limit is needed to avoid a stack overflow in the recursive
** descent parser.  A depth of 2000 is far deeper than any sane JSON

  jsonParseFillInParentage(pParse, 0, 0);
  return SQLITE_OK;
}

/*
** Magic number used for the JSON parse cache in sqlite3_get_auxdata()
*/
#define JSON_CACHE_ID  (-429938)  /* First cache entry */
#define JSON_CACHE_SZ  4          /* Max number of cache entries */

/*
** Obtain a complete parse of the JSON found in the first argument
** of the argv array.  Use the sqlite3_get_auxdata() cache for this
** parse if it is available.  If the cache is not available or if it
** is no longer valid, parse the JSON again and return the new parse,
** and also register the new parse so that it will be available for
** future sqlite3_get_auxdata() calls.
*/
static JsonParse *jsonParseCached(
  sqlite3_context *pCtx,
  sqlite3_value **argv,
  sqlite3_context *pErrCtx
){
  const char *zJson = (const char*)sqlite3_value_text(argv[0]);
  int nJson = sqlite3_value_bytes(argv[0]);
  JsonParse *p;
  JsonParse *pMatch = 0;
  int iKey;
  int iMinKey = 0;
  u32 iMinHold = 0xffffffff;
  u32 iMaxHold = 0;
  if( zJson==0 ) return 0;
  for(iKey=0; iKey<JSON_CACHE_SZ; iKey++){
    p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iKey);
    if( p==0 ){
      iMinKey = iKey;
      break;
    }
    if( pMatch==0
     && p->nJson==nJson
     && memcmp(p->zJson,zJson,nJson)==0
    ){
      p->nErr = 0;
      pMatch = p;
    }else if( p->iHold<iMinHold ){
      iMinHold = p->iHold;
      iMinKey = iKey;
    }
    if( p->iHold>iMaxHold ){
      iMaxHold = p->iHold;
    }
  }
  if( pMatch ){
    pMatch->nErr = 0;
    pMatch->iHold = iMaxHold+1;
    return pMatch;
  }
  p = sqlite3_malloc( sizeof(*p) + nJson + 1 );
  if( p==0 ){
    sqlite3_result_error_nomem(pCtx);
    return 0;
  }
  memset(p, 0, sizeof(*p));
  p->zJson = (char*)&p[1];
  memcpy((char*)p->zJson, zJson, nJson+1);
  if( jsonParse(p, pErrCtx, p->zJson) ){
    sqlite3_free(p);
    return 0;
  }
  p->nJson = nJson;
  p->iHold = iMaxHold+1;
  sqlite3_set_auxdata(pCtx, JSON_CACHE_ID+iMinKey, p,
                      (void(*)(void*))jsonParseFree);
  return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iMinKey);
}

/*
** Compare the OBJECT label at pNode against zKey,nKey.  Return true on
** a match.
*/
static int jsonLabelCompare(JsonNode *pNode, const char *zKey, u32 nKey){

  sqlite3_value **argv
){
  JsonParse *p;          /* The parse */
  sqlite3_int64 n = 0;
  u32 i;
  JsonNode *pNode;

  p = jsonParseCached(ctx, argv, ctx);
  if( p==0 ) return;
  assert( p->nNode );
  if( argc==2 ){
    const char *zPath = (const char*)sqlite3_value_text(argv[1]);
    pNode = jsonLookup(p, zPath, 0, ctx);
  }else{
    pNode = p->aNode;

  JsonParse *p;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  JsonString jx;
  int i;

  if( argc<2 ) return;
  p = jsonParseCached(ctx, argv, ctx);
  if( p==0 ) return;
  jsonInit(&jx, ctx);
  jsonAppendChar(&jx, '[');
  for(i=1; i<argc; i++){
    zPath = (const char*)sqlite3_value_text(argv[i]);
    pNode = jsonLookup(p, zPath, 0, ctx);
    if( p->nErr ) break;

** either the JSON or PATH inputs are not well-formed.
*/
static void jsonTypeFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse *p;          /* The parse */
  const char *zPath;
  JsonNode *pNode;

  p = jsonParseCached(ctx, argv, ctx);
  if( p==0 ) return;
  if( argc==2 ){
    zPath = (const char*)sqlite3_value_text(argv[1]);
    pNode = jsonLookup(p, zPath, 0, ctx);
  }else{
    pNode = p->aNode;
  }
  if( pNode ){
    sqlite3_result_text(ctx, jsonType[pNode->eType], -1, SQLITE_STATIC);
  }

}

/*
** json_valid(JSON)
**
** Return 1 if JSON is a well-formed JSON string according to RFC-7159.
** Return 0 otherwise.
*/
static void jsonValidFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse *p;          /* The parse */


  UNUSED_PARAM(argc);



  p = jsonParseCached(ctx, argv, 0);
  sqlite3_result_int(ctx, p!=0);
}


/****************************************************************************
** Aggregate SQL function implementations
****************************************************************************/
/*