streaming/property.js

Transforms and other streaming helpers

"use strict";
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (Object.prototype.hasOwnProperty.call(b, p)) d[p] = b[p]; };
        return extendStatics(d, b);
    };
    return function (d, b) {
        if (typeof b !== "function" && b !== null)
            throw new TypeError("Class extends value " + String(b) + " is not a constructor or null");
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
Object.defineProperty(exports, "__esModule", { value: true });
exports.Omitter = exports.Picker = void 0;
var stream_1 = require("stream");
var Picker = /** @class */ (function (_super) {
    __extends(Picker, _super);
    function Picker(fields) {
        // objects in, objects out
        var _this = _super.call(this, { objectMode: true }) || this;
        _this.fields = fields;
        return _this;
    }
    Picker.prototype._transform = function (chunk, encoding, callback) {
        var filtered = {};
        for (var i = 0; i < this.fields.length; i++) {
            filtered[this.fields[i]] = chunk[this.fields[i]];
        }
        this.push(filtered, encoding);
        callback();
    };
    return Picker;
}(stream_1.Transform));
exports.Picker = Picker;
var Omitter = /** @class */ (function (_super) {
    __extends(Omitter, _super);
    function Omitter(fields) {
        // objects in, objects out
        var _this = _super.call(this, { objectMode: true }) || this;
        _this.fieldsMap = {};
        for (var i = 0, l = fields.length; i < l; i++) {
            _this.fieldsMap[fields[i]] = 1;
        }
        return _this;
    }
    Omitter.prototype._transform = function (chunk, encoding, callback) {
        for (var field in this.fieldsMap) {
            delete chunk[field];
        }
        this.push(chunk, encoding);
        callback();
    };
    return Omitter;
}(stream_1.Transform));
exports.Omitter = Omitter;