Class InsertChange

packages/schematics/angular/utility/change.ts:46–73

 * Will add text to the source code.
 */
export class InsertChange implements Change {
  order: number;
  description: string;

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

  /**
   * This method does not insert spaces if there is none in the original string.
   */
  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);

      return host.write(this.path, `${prefix}${this.toAdd}${suffix}`);
    });
  }
}

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