vscroll/dist/esm2015/scroller.js

Virtual scroll engine

import { DatasourceGeneric, makeDatasource } from './classes/datasource';
import { Settings } from './classes/settings';
import { Logger } from './classes/logger';
import { Routines } from './classes/domRoutines';
import { Viewport } from './classes/viewport';
import { Buffer } from './classes/buffer';
import { State } from './classes/state';
import { Adapter } from './classes/adapter';
import { validate, DATASOURCE } from './inputs/index';
import core from './version';
export const INVALID_DATASOURCE_PREFIX = 'Invalid datasource:';
let instanceCount = 0;
export class Scroller {
  constructor({ datasource, consumer, element, workflow, Routines: CustomRoutines, scroller }) {
    const { params: { get } } = validate(datasource, DATASOURCE);
    if (!get.isValid) {
      throw new Error(`${INVALID_DATASOURCE_PREFIX} ${get.errors[0]}`);
    }
    const packageInfo = scroller ? scroller.state.packageInfo : { consumer, core };
    element = scroller ? scroller.routines.element : element;
    workflow = scroller ? scroller.workflow : workflow;
    // In general, custom Routines must extend the original Routines. If not, we provide implicit extending.
    // This is undocumented feature. It should be removed in vscroll v2.
    if (CustomRoutines && !(CustomRoutines.prototype instanceof Routines)) {
      class __Routines extends Routines {
      }
      Object.getOwnPropertyNames(CustomRoutines.prototype)
        .filter(method => method !== 'constructor')
        .forEach(method => __Routines.prototype[method] = CustomRoutines === null || CustomRoutines === void 0 ? void 0 : CustomRoutines.prototype[method]);
      CustomRoutines = __Routines;
    }
    this.workflow = workflow;
    this.settings = new Settings(datasource.settings, datasource.devSettings, ++instanceCount);
    this.logger = new Logger(this, packageInfo, datasource.adapter);
    this.routines = new (CustomRoutines || Routines)(element, this.settings);
    this.state = new State(packageInfo, this.settings, scroller ? scroller.state : void 0);
    this.buffer = new Buffer(this.settings, workflow.onDataChanged, this.logger);
    this.viewport = new Viewport(this.settings, this.routines, this.state, this.logger);
    this.logger.object('vscroll settings object', this.settings, true);
    this.initDatasource(datasource, scroller);
  }
  initDatasource(datasource, scroller) {
    if (scroller) { // scroller re-instantiating case
      this.datasource = datasource;
      this.adapter = scroller.adapter;
      // todo: what about (this.settings.adapter !== scroller.setting.adapter) case?
      return;
    }
    // scroller is being instantiated for the first time
    const constructed = datasource instanceof DatasourceGeneric;
    const mockAdapter = !constructed && !this.settings.adapter;
    if (constructed) { // datasource is already instantiated
      this.datasource = datasource;
    }
    else { // datasource as POJO
      const DS = makeDatasource(() => ({ mock: mockAdapter }));
      this.datasource = new DS(datasource);
      if (this.settings.adapter) {
        datasource.adapter = this.datasource.adapter;
      }
    }
    const publicContext = !mockAdapter ? this.datasource.adapter : null;
    this.adapter = new Adapter(publicContext, () => this.workflow, this.logger);
  }
  init(adapterRun$) {
    this.viewport.reset(this.buffer.startIndex);
    this.logger.stat('initialization');
    this.adapter.initialize({
      buffer: this.buffer,
      state: this.state,
      viewport: this.viewport,
      logger: this.logger, adapterRun$,
      getWorkflow: () => this.workflow
    });
  }
  dispose(forever) {
    this.logger.log(() => 'disposing scroller' + (forever ? ' (forever)' : ''));
    if (forever) { // Adapter is not re-instantiated on reset
      this.adapter.dispose();
    }
    this.buffer.dispose();
    this.state.dispose();
  }
  finalize() {
  }
}
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