handleOpBeforeCalculate method Null safety

  1. @override
void handleOpBeforeCalculate(
  1. Model<ProgramOperation> m,
  2. void opBeforeCalculate(
      )
    )
    override

    For many of the RCL operations on matrices, we need to take over stack lift, so we do the deferral on beforeCalculate rather than calc.

    Implementation

    @override
void handleOpBeforeCalculate(Model m, void Function() opBeforeCalculate) {
  final Value iv = m.memory.registers.index;
  final int? miv = iv.asMatrix;
  if (miv == null) {
    opBeforeCalculate(); // noStackLift only relevant if I is a matrix
    final int reg = iv.asDouble.floor().abs();
    m.resultX = m.memory.registers[reg]; // Index exception becomes Error 3
  } else {
    final matrix = (m as Model15).matrices[miv];
    matPressed(m, matrix);
    m.deferToButtonUp = DeferredFunction(m, () {
      if (!noStackLift) {
        opBeforeCalculate();
      }
      matReleased(m, matrix);
    }).run;
  }
}