68 lines
1.5 KiB
Dart
68 lines
1.5 KiB
Dart
extension IterableExt<T> on Iterable<T> {
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Iterable<T> separated(T separator) sync* {
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final iterator = this.iterator;
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if (!iterator.moveNext()) return;
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yield iterator.current;
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while (iterator.moveNext()) {
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yield separator;
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yield iterator.current;
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}
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}
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Iterable<List<T>> chunks(int size) sync* {
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if (length == 0) return;
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var iterator = this.iterator;
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while (iterator.moveNext()) {
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var chunk = [iterator.current];
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for (var i = 1; i < size && iterator.moveNext(); i++) {
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chunk.add(iterator.current);
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}
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yield chunk;
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}
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}
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Iterable<T> fill(
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int length, {
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required T Function(int count) filler,
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}) sync* {
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int count = 0;
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for (var item in this) {
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yield item;
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count++;
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if (count >= length) return;
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}
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while (count < length) {
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yield filler(count);
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count++;
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}
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}
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}
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extension DoubleListExt on List<double> {
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int findInterval(num target) {
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if (isEmpty) return -1;
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if (target < first) return -1;
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if (target >= last) return length - 1;
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int left = 0;
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int right = length - 1;
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while (left <= right) {
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int mid = left + (right - left) ~/ 2;
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if (mid == length - 1 ||
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(this[mid] <= target && target < this[mid + 1])) {
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return mid;
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} else if (target < this[mid]) {
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right = mid - 1;
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} else {
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left = mid + 1;
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}
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}
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return -1; // 这行理论上不会执行到，但为了完整性保留
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}
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}
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