createSelector4

Selector<S, R> createSelector4<S, T1, T2, T3, T4, R>(

  1. Selector<S, T1> selector1,

  2. Selector<S, T2> selector2,
  3. Selector<S, T3> selector3,
  4. Selector<S, T4> selector4,
  5. R combiner(
    1. T1,
    2. T2,
    3. T3,
    4. T4,
    ),
)

Creates a memoized selector with four input selectors.

Implementation

Selector<S, R> createSelector4<S, T1, T2, T3, T4, R>(
  Selector<S, T1> selector1,
  Selector<S, T2> selector2,
  Selector<S, T3> selector3,
  Selector<S, T4> selector4,
  R Function(T1, T2, T3, T4) combiner,
) {
  T1? lastInput1;
  T2? lastInput2;
  T3? lastInput3;
  T4? lastInput4;
  R? lastResult;
  var hasCache = false;

return (S state) {
final input1 = selector1(state);
final input2 = selector2(state);
final input3 = selector3(state);
final input4 = selector4(state);


if (hasCache &&
identical(input1, lastInput1) &&
identical(input2, lastInput2) &&
identical(input3, lastInput3) &&
identical(input4, lastInput4)) {
return lastResult as R;
}


lastInput1 = input1;
lastInput2 = input2;
lastInput3 = input3;
lastInput4 = input4;
lastResult = combiner(input1, input2, input3, input4);
hasCache = true;


return lastResult as R;
};
}