@signalk/streams/dist/keys-filter.js

Utilities for handling streams of Signal K data

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const stream_1 = require("stream");
class KeysFilter extends stream_1.Transform {
    debug;
    exclude;
    constructor(options) {
        super({ objectMode: true });
        const createDebug = options.createDebug ?? require('debug');
        this.debug = createDebug('signalk:streams:keys-filter');
        this.exclude = options.excludeMatchingPaths;
    }
    _transform(chunk, encoding, done) {
        let delta = null;
        let isString = false;
        if (typeof chunk === 'object' &&
            chunk !== null &&
            !Buffer.isBuffer(chunk)) {
            delta = chunk;
        }
        else if (typeof chunk === 'string') {
            try {
                delta = JSON.parse(chunk);
                isString = true;
            }
            catch (e) {
                const message = e instanceof Error ? e.message : String(e);
                this.debug(`Error parsing chunk: ${message}`);
            }
        }
        if (delta && Array.isArray(delta.updates)) {
            const updates = [];
            for (const update of delta.updates) {
                if (Array.isArray(update.values)) {
                    const values = update.values.filter((value) => !this.exclude.includes(value.path));
                    if (values.length > 0) {
                        const upd = { values };
                        if (update.$source) {
                            upd.$source = update.$source;
                        }
                        if (update.source) {
                            upd.source = update.source;
                        }
                        if (update.timestamp) {
                            upd.timestamp = update.timestamp;
                        }
                        updates.push(upd);
                    }
                }
            }
            if (updates.length > 0) {
                delta.updates = updates;
                this.push(isString ? JSON.stringify(delta) : delta);
            }
        }
        done();
    }
}
exports.default = KeysFilter;