Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | 1x 46x 46x 46x 46x 40x 113x 101x 40x 4x 2x 2x 2x 2x 4x 40x 46x | /**
* Options for {@link lookAhead} operations.
* @typeParam T - The type of the items in the sequence.
* @group Array
* @category Iteration
*/
export type LookAheadOptions<T> =
| {
/**
* Specifies the last item in the sequence.
*/
last: T;
}
| {
/**
* Determines whether the look-ahead should wrap around to the beginning when reaching the end.
*/
wrapAround: boolean;
};
/**
* Generates pairs of consecutive elements from the input array, with optional handling for the last
* element.
* @typeParam T - The type of elements in the input array.
* @param array - The array to iterate over.
* @param options - Optional configuration for handling the last element.
* @returns A generator yielding a tuple containing each element, the next element in the sequence,
* and the index of the element within the sequence. Optionally, a tuple is generated for the last
* element as specified by options.
* @example
* ```typescript
* // Basic usage
* const arr = [1, 2, 3];
* for (const [current, next] of lookAhead(arr)) {
* console.log(current, next);
* }
* // [1, 2], [2, 3]
*
* // With wrapAround
* for (const [current, next] of lookAhead(arr, { wrapAround: true })) {
* console.log(current, next);
* }
* // [1, 2], [2, 3], [3, 1]
* ```
*
* With last
* ```typescript
* for (const [current, next] of lookAhead(arr, { last: 0 })) {
* console.log(current, next);
* }
* // [1, 2], [2, 3], [3, 0]
* ```
* @group Array
* @category Iteration
*/
export function* lookAhead<T>(
array: T[],
options?: LookAheadOptions<T>,
): Generator<[T, T, number]> {
if (array.length > 0) {
for (let i = 0; i < array.length - 1; ++i) {
yield [array[i], array[i + 1], i];
}
if (options) {
if ('last' in options) {
yield [array.at(-1)!, options.last, array.length - 1];
} else if (options.wrapAround) {
yield [array.at(-1)!, array.at(0)!, array.length - 1];
}
}
}
}
|