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7ccdcc5cef
* refactor(events): Use "export ... from" where applicable
* refactor(events): Introduce EventType enum
Introduce an enum for the event .type values. We can't actually
use it as the type of the .type property on Abstract events,
because we want to allow developers to add their own custom
event types inheriting from this type, but at least this way we
can be reasonably sure that all of our own event subclasses have
distinct .type values—plus consistent use of enum syntax
(EventType.TYPE_NAME) is probably good for readability overall.
Put it in a separate module from the rest of events/utils.ts
because it would be helpful if event utils could use
event instanceof SomeEventType
for type narrowing but but at the moment most events are in
modules that depend on events/utils.ts for their .type
constant, and although circular ESM dependencies should work
in principle there are various restrictions and this
particular circularity causes issues at the moment.
A few of the event classes also depend on utils.ts for fire()
or other functions, which will be harder to deal with, but at
least this commit is win in terms of reducing the complexity
of our dependencies, making most of the Abstract event subclass
module dependent on type.ts, which has no imports, rather than
on utils.ts which has multiple imports.
130 lines
2.9 KiB
TypeScript
130 lines
2.9 KiB
TypeScript
/**
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* @license
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* Copyright 2018 Google LLC
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* Abstract class for events fired as a result of actions in
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* Blockly's editor.
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*
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* @class
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*/
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// Former goog.module ID: Blockly.Events.Abstract
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import * as common from '../common.js';
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import type {Workspace} from '../workspace.js';
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import {getGroup, getRecordUndo} from './utils.js';
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/**
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* Abstract class for an event.
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*/
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export abstract class Abstract {
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/**
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* Whether or not the event was constructed without necessary parameters
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* (to be populated by fromJson).
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*/
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abstract isBlank: boolean;
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/** The workspace identifier for this event. */
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workspaceId?: string = undefined;
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/**
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* An ID for the group of events this block is associated with.
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*
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* Groups define events that should be treated as an single action from the
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* user's perspective, and should be undone together.
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*/
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group: string;
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/** Whether this event is undoable or not. */
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recordUndo: boolean;
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/** Whether or not the event is a UI event. */
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isUiEvent = false;
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/** Type of this event. */
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type = '';
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constructor() {
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this.group = getGroup();
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this.recordUndo = getRecordUndo();
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}
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/**
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* Encode the event as JSON.
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*
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* @returns JSON representation.
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*/
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toJson(): AbstractEventJson {
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return {
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'type': this.type,
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'group': this.group,
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};
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}
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/**
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* Deserializes the JSON event.
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*
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* @param event The event to append new properties to. Should be a subclass
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* of Abstract (like all events), but we can't specify that due to the
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* fact that parameters to static methods in subclasses must be
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* supertypes of parameters to static methods in superclasses.
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* @internal
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*/
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static fromJson(
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json: AbstractEventJson,
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workspace: Workspace,
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event: any,
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): Abstract {
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event.isBlank = false;
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event.group = json['group'] || '';
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event.workspaceId = workspace.id;
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return event;
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}
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/**
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* Does this event record any change of state?
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*
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* @returns True if null, false if something changed.
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*/
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isNull(): boolean {
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return false;
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}
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/**
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* Run an event.
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*
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* @param _forward True if run forward, false if run backward (undo).
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*/
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run(_forward: boolean) {
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// Defined by subclasses. Cannot be abstract b/c UI events do /not/ define
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// this.
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}
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/**
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* Get workspace the event belongs to.
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*
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* @returns The workspace the event belongs to.
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* @throws {Error} if workspace is null.
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*/
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getEventWorkspace_(): Workspace {
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let workspace;
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if (this.workspaceId) {
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workspace = common.getWorkspaceById(this.workspaceId);
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}
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if (!workspace) {
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throw Error(
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'Workspace is null. Event must have been generated from real' +
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' Blockly events.',
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);
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}
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return workspace;
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}
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}
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export interface AbstractEventJson {
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type: string;
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group: string;
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}
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