/
observablestring.ts
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/
observablestring.ts
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// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.
import { IDisposable } from '@lumino/disposable';
import { ISignal, Signal } from '@lumino/signaling';
import { IObservable } from './modeldb';
/**
* A string which can be observed for changes.
*/
export interface IObservableString extends IDisposable, IObservable {
/**
* The type of the Observable.
*/
type: 'String';
/**
* A signal emitted when the string has changed.
*/
readonly changed: ISignal<this, IObservableString.IChangedArgs>;
/**
* The value of the string.
*/
text: string;
/**
* Insert a substring.
*
* @param index - The starting index.
*
* @param text - The substring to insert.
*/
insert(index: number, text: string): void;
/**
* Remove a substring.
*
* @param start - The starting index.
*
* @param end - The ending index.
*/
remove(start: number, end: number): void;
/**
* Set the ObservableString to an empty string.
*/
clear(): void;
/**
* Dispose of the resources held by the string.
*/
dispose(): void;
}
/**
* The namespace for `IObservableString` associate interfaces.
*/
export namespace IObservableString {
/**
* The change types which occur on an observable string.
*/
export type ChangeType =
/**
* Text was inserted.
*/
| 'insert'
/**
* Text was removed.
*/
| 'remove'
/**
* Text was set.
*/
| 'set';
/**
* The changed args object which is emitted by an observable string.
*/
export interface IChangedArgs {
/**
* The type of change undergone by the list.
*/
type: ChangeType;
/**
* The starting index of the change.
*/
start: number;
/**
* The end index of the change.
*/
end: number;
/**
* The value of the change.
*
* ### Notes
* If `ChangeType` is `set`, then
* this is the new value of the string.
*
* If `ChangeType` is `insert` this is
* the value of the inserted string.
*
* If `ChangeType` is remove this is the
* value of the removed substring.
*/
value: string;
}
}
/**
* A concrete implementation of [[IObservableString]]
*/
export class ObservableString implements IObservableString {
/**
* Construct a new observable string.
*/
constructor(initialText: string = '') {
this._text = initialText;
}
/**
* The type of the Observable.
*/
get type(): 'String' {
return 'String';
}
/**
* A signal emitted when the string has changed.
*/
get changed(): ISignal<this, IObservableString.IChangedArgs> {
return this._changed;
}
/**
* Set the value of the string.
*/
set text(value: string) {
if (value.length === this._text.length && value === this._text) {
return;
}
this._text = value;
this._changed.emit({
type: 'set',
start: 0,
end: value.length,
value: value
});
}
/**
* Get the value of the string.
*/
get text(): string {
return this._text;
}
/**
* Insert a substring.
*
* @param index - The starting index.
*
* @param text - The substring to insert.
*/
insert(index: number, text: string): void {
this._text = this._text.slice(0, index) + text + this._text.slice(index);
this._changed.emit({
type: 'insert',
start: index,
end: index + text.length,
value: text
});
}
/**
* Remove a substring.
*
* @param start - The starting index.
*
* @param end - The ending index.
*/
remove(start: number, end: number): void {
const oldValue: string = this._text.slice(start, end);
this._text = this._text.slice(0, start) + this._text.slice(end);
this._changed.emit({
type: 'remove',
start: start,
end: end,
value: oldValue
});
}
/**
* Set the ObservableString to an empty string.
*/
clear(): void {
this.text = '';
}
/**
* Test whether the string has been disposed.
*/
get isDisposed(): boolean {
return this._isDisposed;
}
/**
* Dispose of the resources held by the string.
*/
dispose(): void {
if (this._isDisposed) {
return;
}
this._isDisposed = true;
Signal.clearData(this);
this.clear();
}
private _text = '';
private _isDisposed: boolean = false;
private _changed = new Signal<this, IObservableString.IChangedArgs>(this);
}