create2

ResettableSelector<S, R> create2<S, T1, T2, R>(

  1. Selector<S, T1> selector1,

  2. Selector<S, T2> selector2,
  3. R combiner(
    1. T1,
    2. T2
    )
)

Creates a resettable selector with two inputs.

Implementation

static ResettableSelector<S, R> create2<S, T1, T2, R>(
  Selector<S, T1> selector1,
  Selector<S, T2> selector2,
  R Function(T1, T2) combiner,
) {
  T1? lastInput1;
  T2? lastInput2;
  R? lastResult;
  var hasCache = false;

void reset() {
lastInput1 = null;
lastInput2 = null;
lastResult = null;
hasCache = false;
}


R select(S state) {
final input1 = selector1(state);
final input2 = selector2(state);


if (hasCache &&
identical(input1, lastInput1) &&
identical(input2, lastInput2)) {
return lastResult as R;
}


lastInput1 = input1;
lastInput2 = input2;
lastResult = combiner(input1, input2);
hasCache = true;


return lastResult as R;
}


return ResettableSelector._(select, reset);
}