SQLite

/*
** Names of the various JSON types:
*/
static const char * const jsonType[] = {
  "null", "true", "false", "integer", "real", "text", "array", "object"
};

/* Bit values for the JsonNode.jnFlag field
*/
#define JNODE_RAW     0x01         /* Content is raw, not JSON encoded */
#define JNODE_ESCAPE  0x02         /* Content is text with \ escapes */
#define JNODE_REMOVE  0x04         /* Do not output */


/* A single node of parsed JSON
*/
typedef struct JsonNode JsonNode;
struct JsonNode {
  u8 eType;              /* One of the JSON_ type values */
  u8 jnFlags;            /* JNODE flags */

  u32 n;                 /* Bytes of content, or number of sub-nodes */
  const char *zJContent; /* JSON content */
};

/* A completely parsed JSON string
*/
typedef struct JsonParse JsonParse;
struct JsonParse {
  u32 nNode;         /* Number of slots of aNode[] used */
  u32 nAlloc;        /* Number of slots of aNode[] allocated */
  JsonNode *aNode;   /* Array of nodes containing the parse */
  const char *zJson; /* Original JSON string */
  u8 oom;            /* Set to true if out of memory */
};

/*
** Return the number of consecutive JsonNode slots need to represent
** the parsed JSON at pNode.  The minimum answer is 1.  For ARRAY and
** OBJECT types, the number might be larger.
*/
static u32 jsonSizeof(JsonNode *pNode){
  return pNode->eType>=JSON_ARRAY ? pNode->n+1 : 1;
}

/* Set the Json object to an empty string
*/
static void jsonZero(Json *p){
  p->zBuf = p->zSpace;
  p->nAlloc = sizeof(p->zSpace);
  p->nUsed = 0;

  jsonReset(p);
}

/* Enlarge pJson->zBuf so that it can hold at least N more bytes.
** Return zero on success.  Return non-zero on an OOM error
*/
static int jsonGrow(Json *p, u32 N){
  u64 nTotal = N<p->nAlloc ? p->nAlloc*2 : p->nAlloc+N+10;
  char *zNew;
  if( p->bStatic ){
    if( p->oom ) return SQLITE_NOMEM;
    zNew = sqlite3_malloc64(nTotal);
    if( zNew==0 ){
      jsonOom(p);
      return SQLITE_NOMEM;

/* Append a single character
*/
static void jsonAppendChar(Json *p, char c){
  if( p->nUsed>=p->nAlloc && jsonGrow(p,1)!=0 ) return;
  p->zBuf[p->nUsed++] = c;
}

/* Append a comma separator to the output buffer, if the previous
** character is not '[' or '{'.
*/
static void jsonAppendSeparator(Json *p){
  char c;
  if( p->nUsed==0 ) return;
  c = p->zBuf[p->nUsed-1];
  if( c!='[' && c!='{' ) jsonAppendChar(p, ',');
}

/* Append the N-byte string in zIn to the end of the Json string
** under construction.  Enclose the string in "..." and escape
** any double-quotes or backslash characters contained within the
** string.
*/
static void jsonAppendString(Json *p, const char *zIn, u32 N){

/*
** Convert the JsonNode pNode into a pure JSON string and
** append to pOut.  Subsubstructure is also included.  Return
** the number of JsonNode objects that are encoded.
*/
static int jsonRenderNode(JsonNode *pNode, Json *pOut){
  u32 j = 1;
  switch( pNode->eType ){
    case JSON_NULL: {
      jsonAppendRaw(pOut, "null", 4);
      break;
    }
    case JSON_TRUE: {
      jsonAppendRaw(pOut, "true", 4);
      break;
    }
    case JSON_FALSE: {
      jsonAppendRaw(pOut, "false", 5);
      break;
    }
    case JSON_STRING: {
      if( pNode->jnFlags & JNODE_RAW ){
        jsonAppendString(pOut, pNode->zJContent, pNode->n);
        break;
      }
      /* Fall through into the next case */
    }
    case JSON_REAL:
    case JSON_INT: {
      jsonAppendRaw(pOut, pNode->zJContent, pNode->n);
      break;
    }
    case JSON_ARRAY: {
      jsonAppendChar(pOut, '[');

      while( j<=pNode->n ){
        if( pNode[j].jnFlags & JNODE_REMOVE ){
          j += jsonSizeof(&pNode[j]);
        }else{
          jsonAppendSeparator(pOut);
          j += jsonRenderNode(&pNode[j], pOut);
        }
      }
      jsonAppendChar(pOut, ']');
      break;
    }
    case JSON_OBJECT: {
      jsonAppendChar(pOut, '{');

      while( j<=pNode->n ){
        if( pNode[j+1].jnFlags & JNODE_REMOVE ){
          j += 1 + jsonSizeof(&pNode[j+1]);
        }else{
          jsonAppendSeparator(pOut);
          jsonRenderNode(&pNode[j], pOut);
          jsonAppendChar(pOut, ':');
          j += 1 + jsonRenderNode(&pNode[j+1], pOut);
        }
      }
      jsonAppendChar(pOut, '}');
      break;
    }
  }
  return j;
}

/*
** Make the JsonNode the return value of the function.
*/
static void jsonReturn(JsonNode *pNode, sqlite3_context *pCtx){
  switch( pNode->eType ){

      if( z[0]=='-' ){ z++; }
      while( z[0]>='0' && z[0]<='9' ){ i = i*10 + *(z++) - '0'; }
      if( pNode->zJContent[0]=='-' ){ i = -i; }
      sqlite3_result_int64(pCtx, i);
      break;
    }
    case JSON_STRING: {
      if( pNode->jnFlags & JNODE_RAW ){
        sqlite3_result_text(pCtx, pNode->zJContent, pNode->n, SQLITE_TRANSIENT);
      }else if( (pNode->jnFlags & JNODE_ESCAPE)==0 ){
        /* JSON formatted without any backslash-escapes */
        sqlite3_result_text(pCtx, pNode->zJContent+1, pNode->n-2,
                            SQLITE_TRANSIENT);
      }else{
        /* Translate JSON formatted string into raw text */
        u32 i;
        u32 n = pNode->n;

      return -1;
    }
    pParse->nAlloc = nNew;
    pParse->aNode = pNew;
  }
  p = &pParse->aNode[pParse->nNode];
  p->eType = (u8)eType;
  p->jnFlags = 0;

  p->n = n;
  p->zJContent = zContent;
  return pParse->nNode++;
}

/*
** Parse a single JSON value which begins at pParse->zJson[i].  Return the

      if( c!=']' ) return -1;
      break;
    }
    pParse->aNode[iThis].n = pParse->nNode - iThis - 1;
    return j+1;
  }else if( c=='"' ){
    /* Parse string */
    u8 jnFlags = 0;
    j = i+1;
    for(;;){
      c = pParse->zJson[j];
      if( c==0 ) return -1;
      if( c=='\\' ){
        c = pParse->zJson[++j];
        if( c==0 ) return -1;
        jnFlags = JNODE_ESCAPE;
      }else if( c=='"' ){
        break;
      }
      j++;
    }
    jsonParseAddNode(pParse, JSON_STRING, j+1-i, &pParse->zJson[i]);
    pParse->aNode[pParse->nNode-1].jnFlags = jnFlags;
    return j+1;
  }else if( c=='n'
         && strncmp(pParse->zJson+i,"null",4)==0
         && !isalnum(pParse->zJson[i+4]) ){
    jsonParseAddNode(pParse, JSON_NULL, 0, 0);
    return i+4;
  }else if( c=='t'

    pParse->aNode = 0;
    pParse->nNode = 0;
    pParse->nAlloc = 0;
    return 1;
  }
  return 0;
}

/*
** Search along zPath to find the node specified.  Return a pointer
** to that node, or NULL if zPath is malformed or if there is no such
** node.
*/
static JsonNode *jsonLookup(JsonNode *pRoot, const char *zPath){
  u32 i, j;

    while( j<=pRoot->n ){
      if( pRoot[j].n==i+2
       && strncmp(&pRoot[j].zJContent[1],zPath,i)==0
      ){
        return jsonLookup(&pRoot[j+1], &zPath[i]);
      }
      j++;

      j += jsonSizeof(&pRoot[j]);


    }
  }else if( zPath[0]=='[' && isdigit(zPath[1]) ){
    if( pRoot->eType!=JSON_ARRAY ) return 0;
    i = 0;
    zPath++;
    while( isdigit(zPath[0]) ){
      i = i + zPath[0] - '0';
      zPath++;
    }
    if( zPath[0]!=']' ) return 0;
    zPath++;
    j = 1;
    while( i>0 && j<=pRoot->n ){

      j += jsonSizeof(&pRoot[j]);


      i--;
    }
    if( j<=pRoot->n ){
      return jsonLookup(&pRoot[j], zPath);
    }
  }
  return 0;
}

/****************************************************************************
** SQL functions used for testing and debugging
****************************************************************************/

#ifdef SQLITE_DEBUG
/*
** The json_parse(JSON) function returns a string which describes
** a parse of the JSON provided.  Or it returns NULL if JSON is not
** well-formed.
*/
static void jsonParseFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  Json s;       /* Output string - not real JSON */
  JsonParse x;  /* The parse */
  u32 i;
  char zBuf[100];

  assert( argc==1 );
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  jsonInit(&s, context);
  for(i=0; i<x.nNode; i++){
    sqlite3_snprintf(sizeof(zBuf), zBuf, "node %3u: %7s n=%d\n",


                     i, jsonType[x.aNode[i].eType], x.aNode[i].n);
    jsonAppend(&s, zBuf);




    if( x.aNode[i].zJContent!=0 ){



      jsonAppendRaw(&s, "    text: ", 10);
      jsonAppendRaw(&s, x.aNode[i].zJContent, x.aNode[i].n);
      jsonAppendRaw(&s, "\n", 1);
    }
  }
  sqlite3_free(x.aNode);
  jsonResult(&s);
}

  sqlite3_value **argv
){
  JsonParse x;  /* The parse */
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  sqlite3_result_int64(context, x.nNode);
  sqlite3_free(x.aNode);
}
#endif /* SQLITE_DEBUG */

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

/*
** Implementation of the json_array(VALUE,...) function.  Return a JSON

    zPath = 0;
  }
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0]))==0 ){
    if( x.nNode ){
      JsonNode *pNode = x.aNode;
      if( zPath ) pNode = jsonLookup(pNode, zPath);
      if( pNode->eType==JSON_ARRAY ){
        for(i=1; i<=pNode->n; n++){

          i += jsonSizeof(&pNode[i]);

        }
      }
    }
    sqlite3_free(x.aNode);
  }
  sqlite3_result_int64(context, n);
}

      }
    }
  }
  jsonAppendRaw(&jx, "}", 1);
  jsonResult(&jx);
}


/*
** json_remove(JSON, PATH, ...)
**
** Remove the named elements from JSON and return the result.  Ill-formed
** PATH arguments are silently ignored.  If JSON is ill-formed, then NULL
** is returned.
*/
static void jsonRemoveFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  u32 i;

  if( argc<1 ) return;
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<argc; i++){
      zPath = (const char*)sqlite3_value_text(argv[i]);
      if( zPath==0 ) continue;
      if( zPath[0]!='$' ) continue;
      pNode = jsonLookup(x.aNode, &zPath[1]);
      if( pNode ) pNode->jnFlags |= JNODE_REMOVE;
    }
    if( (x.aNode[0].jnFlags & JNODE_REMOVE)==0 ){
      jsonReturn(x.aNode, context);
    }
  }
  sqlite3_free(x.aNode);
}

/*
** json_type(JSON)
** json_type(JSON, PATH)
**
** Return the top-level "type" of a JSON string.  Return NULL if the
** input is not a well-formed JSON string.

     void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  } aFunc[] = {
    { "json_array",          -1,    jsonArrayFunc         },
    { "json_array_length",    1,    jsonArrayLengthFunc   },
    { "json_array_length",    2,    jsonArrayLengthFunc   },
    { "json_extract",         2,    jsonExtractFunc       },
    { "json_object",         -1,    jsonObjectFunc        },
    { "json_remove",         -1,    jsonRemoveFunc        },
    { "json_type",            1,    jsonTypeFunc          },
    { "json_type",            2,    jsonTypeFunc          },

#if SQLITE_DEBUG
    /* DEBUG and TESTING functions */
    { "json_parse",           1,    jsonParseFunc     },
    { "json_test1",           1,    jsonTest1Func     },
    { "json_nodecount",       1,    jsonNodeCountFunc },
#endif
  };
  SQLITE_EXTENSION_INIT2(pApi);
  (void)pzErrMsg;  /* Unused parameter */
  for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){
    rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg,
                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC, 0,
                                 aFunc[i].xFunc, 0, 0);
  }
  return rc;
}