Class RemoveChange

packages/schematics/angular/utility/change.ts:78–103

 * Will remove text from the source code.
 */
export class RemoveChange implements Change {
  order: number;
  description: string;

  constructor(
    public path: string,
    private pos: number,
    public toRemove: string,
  ) {
    if (pos < 0) {
      throw new Error('Negative positions are invalid');
    }
    this.description = `Removed ${toRemove} into position ${pos} of ${path}`;
    this.order = pos;
  }

  apply(host: Host): Promise<void> {
    return host.read(this.path).then((content) => {
      const prefix = content.substring(0, this.pos);
      const suffix = content.substring(this.pos + this.toRemove.length);

      // TODO: throw error if toRemove doesn't match removed string.
      return host.write(this.path, `${prefix}${suffix}`);
    });
  }
}

/**
 * Will replace text from the source code.