Method spliceText

src/node/db/Pad.ts:475–501

* Splices text into the pad. If the result of the splice does not end with a newline, one will be * automatically appended. * * @param {number} start - Location in pad text to start removing and inserting characters. Must * be a non-negative integer less than or equal to `this.text()

(start:number, ndel:number, ins: string, authorId: string = '')

   * @param {string} [authorId] - Author ID of the user making the change (if applicable).
   */
  async spliceText(start:number, ndel:number, ins: string, authorId: string = '') {
    if (start < 0) throw new RangeError(`start index must be non-negative (is ${start})`);
    if (ndel < 0) throw new RangeError(`characters to delete must be non-negative (is ${ndel})`);
    const orig = this.text();
    assert(orig.endsWith('\n'));
    if (start + ndel > orig.length) throw new RangeError('start/delete past the end of the text');
    ins = exports.cleanText(ins);
    const willEndWithNewline =
        start + ndel < orig.length || // Keeping last char (which is guaranteed to be a newline).
        ins.endsWith('\n') ||
        (!ins && start > 0 && orig[start - 1] === '\n');
    if (!willEndWithNewline) ins += '\n';
    if (ndel === 0 && ins.length === 0) return;
    // An unattributed insert (empty authorId + non-empty ins) would produce
    // an AText where `text` and `attribs` disagree on length — clients fail
    // setDocAText reconciliation on load. Backward-compat fix: if the caller
    // didn't provide an authorId, attribute the insert to a stable system
    // author. ep_post_data and other plugins that want named attribution
    // should still pass an explicit authorId.
    const effectiveAuthorId =
        (ins.length > 0 && !authorId) ? Pad.SYSTEM_AUTHOR_ID : authorId;
    const attribs = effectiveAuthorId
        ? [['author', effectiveAuthorId] as [string, string]]
        : undefined;
    const changeset = makeSplice(orig, start, ndel, ins, attribs, this.pool);
    await this.appendRevision(changeset, effectiveAuthorId);
  }

  /**
   * Replaces the pad's text with new text.