tardis-dev/dist/binarysplit.js

Convenient access to tick-level historical and real-time cryptocurrency market data via Node.js

import { Transform } from 'stream';
// Inspired by https://github.com/maxogden/binary-split/blob/master/index.js
export class BinarySplitStream extends Transform {
    _NEW_LINE_BYTE;
    _buffered;
    constructor() {
        super({
            readableObjectMode: true
        });
        this._NEW_LINE_BYTE = 10;
        this._buffered = undefined;
    }
    _transform(chunk, _, callback) {
        let chunkStart = 0;
        if (this._buffered !== undefined) {
            const firstNewLineIndex = chunk.indexOf(this._NEW_LINE_BYTE);
            if (firstNewLineIndex === -1) {
                this._buffered = Buffer.concat([this._buffered, chunk]);
                callback();
                return;
            }
            this.push(Buffer.concat([this._buffered, chunk.subarray(0, firstNewLineIndex)]));
            this._buffered = undefined;
            chunkStart = firstNewLineIndex + 1;
        }
        let offset = chunkStart;
        let lineStart = chunkStart;
        while (true) {
            const newLineIndex = chunk.indexOf(this._NEW_LINE_BYTE, offset);
            if (newLineIndex === -1) {
                break;
            }
            this.push(chunk.subarray(lineStart, newLineIndex));
            offset = newLineIndex + 1;
            lineStart = offset;
        }
        this._buffered = lineStart < chunk.length ? chunk.subarray(lineStart) : undefined;
        callback();
    }
}
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