@sergdudko/objectstream
Version:
Creates a stream to convert json from string or convert json to string.
235 lines (234 loc) • 7.44 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.Parser = void 0;
const stream_1 = require("stream");
const global_js_1 = require("../utils/global.js");
/**
* @class Parser
*
* Сreates an instance of Parser (String to Json conversion stream)
*/
class Parser extends stream_1.Transform {
/**
*
* @param start - first separator
* @param middle - middle separator
* @param end - end separator
*/
constructor(start, middle, end) {
super({ highWaterMark: 64 * 1024, objectMode: true });
if (typeof start !== "undefined" &&
(typeof start !== "string" ||
Buffer.byteLength(start) > 1 ||
start.match(/["{}]/)))
throw new Error("Argument start require one byte String!");
if (typeof middle !== "undefined" &&
(typeof middle !== "string" ||
Buffer.byteLength(middle) > 1 ||
middle.match(/["{}]/)))
throw new Error("Argument separator require one byte String!");
if (typeof end !== "undefined" &&
(typeof end !== "string" ||
Buffer.byteLength(end) > 1 ||
end.match(/["{}]/)))
throw new Error("Argument end require one byte String!");
this.__separators = {
start: Buffer.from(start ? start : "", "utf8")[0],
middle: Buffer.from(middle ? middle : "", "utf8")[0],
end: Buffer.from(end ? end : "", "utf8")[0],
};
this.__clear();
this.__bytesRead = 0;
this.__encoding = "utf8";
this.setDefaultEncoding(this.__encoding);
this.__buffers = [];
this.__leftBrace = 0;
this.__rightBrace = 0;
this.__openQuotes = false;
}
/**
* clear buffer and reset counters
*
* @private
*/
__clear() {
this.__buffers = [];
this.__leftBrace = 0;
this.__rightBrace = 0;
this.__openQuotes = false;
}
/**
* basic stream handler
*/
__handler(buffer, s, errors) {
if (this.__buffers.length > 65536) {
const _nbuffer = Buffer.concat(this.__buffers);
this.__buffers = [];
this.__buffers.push(_nbuffer);
}
if (this.__leftBrace !== 0) {
this.__buffers.push(buffer.slice(s, s + 1));
}
else if (this.__separators.start !== buffer[s] &&
this.__separators.end !== buffer[s] &&
this.__separators.middle !== buffer[s] &&
0x20 !== buffer[s] &&
0x0d !== buffer[s] &&
0x0a !== buffer[s] &&
0x09 !== buffer[s]) {
errors.push(new Error("Unexpected token " +
buffer.slice(s, s + 1).toString(this.__encoding) +
" in JSON at position " +
(this.__bytesRead + s)));
}
}
/**
* Data event handler
*
* @private
* @param string - string or buffer data
* @param encoding - stream encoding
* @param callback - callback function
*/
_transform(string,
// eslint-disable-next-line
encoding = this.__encoding, callback = () => {
return;
}) {
if (typeof string === "undefined") {
callback();
return;
}
if (string === null) {
this._final(() => {
callback();
});
return;
}
const _buffer = typeof string === "string" ? Buffer.from(string, encoding) : string;
if (!(_buffer instanceof Buffer)) {
callback([
new Error("Incoming data type is " +
typeof _buffer +
", require data type is String!"),
]);
return;
}
if (Parser.__empty.equals(_buffer)) {
callback();
return;
}
const errors = [];
for (let s = 0; s < _buffer.length; s++) {
switch (_buffer[s]) {
case 0x7b:
this.__leftBrace += 1;
this.__handler(_buffer, s, errors);
break;
case 0x7d:
this.__rightBrace += 1;
this.__handler(_buffer, s, errors);
break;
case 0x08:
case 0x09:
case 0x0a:
case 0x0c:
case 0x0d:
case 0x00:
case 0x0b:
if (this.__openQuotes && this.__leftBrace !== 0)
this.__buffers.push(Buffer.from("\\u" + ("0000" + _buffer[s].toString(16)).slice(-4), "utf8"));
break;
case 0x22:
if (_buffer[s - 1] !== 0x5c)
if (this.__openQuotes)
this.__openQuotes = false;
else if (this.__leftBrace !== 0)
this.__openQuotes = true;
this.__handler(_buffer, s, errors);
break;
default:
this.__handler(_buffer, s, errors);
break;
}
if (this.__leftBrace !== 0 && this.__leftBrace === this.__rightBrace) {
try {
const _buf = Buffer.concat(this.__buffers);
const _str = _buf.toString("utf8");
const _object = JSON.parse(_str);
if ((0, global_js_1.validator)(_object, false)) {
this.__clear();
this.push(_object);
}
else {
this.__clear();
errors.push(new Error("Validation failed, incoming data type is not pure Object!"));
}
}
catch (err) {
this.__clear();
errors.push(err);
}
}
else if (this.__leftBrace < this.__rightBrace) {
this.__clear();
errors.push(new Error("Parsing error, clear buffer!"));
}
}
if (errors.length > 0)
callback(errors);
else
callback();
this.__bytesRead += _buffer.byteLength;
}
/**
* Flush event handler
*
* @private
* @param callback - callback function
*/
_flush(callback = () => {
return;
}) {
this.__clear();
callback();
}
/**
* End event handler
*
* @private
* @param callback - callback function
*/
_final(callback = () => {
return;
}) {
if (this.__buffers.length === 0) {
callback();
return;
}
try {
const _buf = Buffer.concat(this.__buffers);
const _str = _buf.toString("utf8");
JSON.parse(_str);
callback([new Error("Raw object detected!")]);
}
catch (err) {
callback([err]);
}
}
/**
* set stream encoding
*/
setEncoding(encoding) {
this.__encoding = encoding;
this.setDefaultEncoding(this.__encoding);
return this;
}
}
exports.Parser = Parser;
/**
* empty buffer
*
* @private
*/
Parser.__empty = Buffer.from("");