Function appendToEvalState

src/repl.ts:682–698

* Append to the eval instance and return an undo function.

(state: EvalState, input: string)

 * Append to the eval instance and return an undo function.
 */
function appendToEvalState(state: EvalState, input: string) {
  const undoInput = state.input;
  const undoVersion = state.version;
  const undoOutput = state.output;
  const undoLines = state.lines;

  state.input += input;
  state.lines += lineCount(input);
  state.version++;

  return function () {
    state.input = undoInput;
    state.output = undoOutput;
    state.version = undoVersion;
    state.lines = undoLines;
  };
}

/**
 * Count the number of lines.