Nikolas Rimikis
1 year ago
committed by
GitHub
12 changed files with 229 additions and 137 deletions
@ -1,58 +1,81 @@
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// ignore_for_file: public_member_api_docs |
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/// Signature of a function returning a [Comparable]. |
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typedef ComparableGetter<T> = Comparable Function(T); |
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/// Sorting Box to sort [List]s on multiple properties. |
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class SortBox<T extends Enum, R> { |
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/// Constructs a new SortBox. |
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/// |
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/// A *Box* is a record of a property and how to order it. |
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SortBox( |
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this._properties, |
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this._secondaryBoxes, |
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this._boxes, |
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); |
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/// A mapping of all values [T] to their [ComparableGetter]. |
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final Map<T, ComparableGetter<R>> _properties; |
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final Map<T, Box<T>> _secondaryBoxes; |
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List<R> sort(final List<R> input, final Box<T> box) { |
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/// A mapping of values [T] to their *Boxes*. |
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/// |
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/// The Boxes are applied if two elements are considered equal regarding their property [T]. |
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final Map<T, Set<(T property, SortBoxOrder order)>> _boxes; |
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/// Sorts the [input] list according to their [box]. |
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/// |
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/// A box contains the property and [SortBoxOrder] how the list should be sorted. |
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/// In case the property of two elements is considered equal all following boxes specified at `_boxes[property]` are applied. |
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/// If specified [presort] will be applied before [box] and [_boxes]. |
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/// |
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/// This function sorts the input in place and a reference to it mutating the provided list. |
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List<R> sort( |
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final List<R> input, |
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final (T property, SortBoxOrder order) box, [ |
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final Set<(T property, SortBoxOrder order)>? presort, |
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]) { |
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if (input.length <= 1) { |
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return input; |
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} |
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final comparableGetter = _properties[box.property]!; |
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final secondaryBox = _secondaryBoxes[box.property]; |
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final comparableGetter2 = _properties[secondaryBox?.property]; |
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final boxes = { |
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...?presort, |
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box, |
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...?_boxes[box.$1], |
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}; |
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return input |
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..sort( |
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(final item1, final item2) { |
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final first = _compare(item1, item2, box.order, comparableGetter); |
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final sorted = input..sort((final item1, final item2) => _compare(item1, item2, boxes.iterator..moveNext())); |
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if (first == 0 && secondaryBox != null) { |
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return _compare(item1, item2, secondaryBox.order, comparableGetter2!); |
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return sorted; |
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} |
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return first; |
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}, |
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); |
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} |
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int _compare( |
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final R item1, |
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final R item2, |
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final Iterator<(T property, SortBoxOrder order)> iterator, |
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) { |
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final box = iterator.current; |
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final (property, sortBoxOrder) = box; |
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final comparableGetter = _properties[property]!; |
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final comparable1 = comparableGetter(item1); |
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final comparable2 = comparableGetter(item2); |
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final order = switch (sortBoxOrder) { |
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SortBoxOrder.ascending => comparable1.compareTo(comparable2), |
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SortBoxOrder.descending => comparable2.compareTo(comparable1), |
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}; |
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int _compare(final R item1, final R item2, final SortBoxOrder order, final ComparableGetter<R> getter) { |
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final comparable1 = getter(item1); |
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final comparable2 = getter(item2); |
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if (order == 0 && iterator.moveNext()) { |
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return _compare(item1, item2, iterator); |
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} |
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return order == SortBoxOrder.ascending ? comparable1.compareTo(comparable2) : comparable2.compareTo(comparable1); |
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return order; |
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} |
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} |
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/// Sorting order used by [SortBox]. |
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enum SortBoxOrder { |
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/// Ascending sorting order. |
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ascending, |
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descending, |
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} |
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class Box<T extends Enum> { |
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Box( |
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this.property, |
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this.order, |
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); |
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final T property; |
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final SortBoxOrder order; |
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/// Descending sorting order. |
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descending, |
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} |
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