Function applyInputEditEvent

packages/core/src/runtime/inputEditor.ts:591–844

(
  event: ZrevEvent,
  ctx: Readonly<{
    id: string;
    value: string;
    cursor: number;
    selectionStart?: number | null;
    selectionEnd?: number | null;
    multiline?: boolean;
  }>,
)

 * @returns Edit result with new value/cursor/selection and optional action, or null if event not applicable
 */
export function applyInputEditEvent(
  event: ZrevEvent,
  ctx: Readonly<{
    id: string;
    value: string;
    cursor: number;
    selectionStart?: number | null;
    selectionEnd?: number | null;
    multiline?: boolean;
  }>,
): InputEditResult | null {
  const id = ctx.id;
  const value = ctx.value;
  const multiline = ctx.multiline === true;
  const selection0 = normalizeInputSelection(value, ctx.selectionStart, ctx.selectionEnd);
  const cursorBase = normalizeInputCursor(value, ctx.cursor);
  const cursor0 = cursorBase;
  const [selectionMin, selectionMax] = selection0
    ? normalizeSelectionRange(selection0)
    : [cursor0, cursor0];

  function result(
    nextValue: string,
    nextCursor: number,
    nextSelectionStart: number | null,
    nextSelectionEnd: number | null,
  ): InputEditResult {
    if (nextValue !== value) {
      const action: InputEditAction = Object.freeze({
        id,
        action: "input",
        value: nextValue,
        cursor: nextCursor,
      });
      return Object.freeze({ nextValue, nextCursor, nextSelectionStart, nextSelectionEnd, action });
    }
    return Object.freeze({ nextValue, nextCursor, nextSelectionStart, nextSelectionEnd });
  }

  if (event.kind === "key") {
    if (event.action !== "down" && event.action !== "repeat") return null;
    const hasShift = (event.mods & ZR_MOD_SHIFT) !== 0;
    const hasCtrl = (event.mods & ZR_MOD_CTRL) !== 0;

    if (event.key === ZR_KEY_A && hasCtrl && !hasShift) {
      if (value.length === 0)
        return Object.freeze({
          nextValue: value,
          nextCursor: 0,
          nextSelectionStart: null,
          nextSelectionEnd: null,
        });
      return Object.freeze({
        nextValue: value,
        nextCursor: value.length,
        nextSelectionStart: 0,
        nextSelectionEnd: value.length,
      });