rc-js-util
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A collection of TS and C++ utilities to help writing performant and correct applications, achieved through strict typing and (removable) invariant checking.
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JavaScript
import { binaryFindInsertionIndex } from "./binary-find-insertion-index.js";
import { fpIdentity } from "../../fp/impl/fp-identity.js";
/**
* @public
* Performs a bisection search of an 'indexable' object, i.e. can be accessed by index, for example `Array`. Custom data structures are also supported.
* @param indexable - The thing to be searched. This must be sorted ascending.
* @param comparisonValueToSearchFor - The comparison value which is being searched for.
* @param getComparisonValueAtIndex - A function that provides the value for comparison at a given index.
* @param length - The number of elements in the structure `indexable` to search.
* @param start - The start index.
* @returns The index of the searched for item, else -1 if it cannot be found.
*
* @example
* ```typescript
* // searching for the number 3 with start index 1 & length 2
* const index = arrayBinaryIndexOf([1, 2, 3, 4], 3, (a, i) => a[i], 2, 1);
* // index is 2
* ```
*
* @remarks
* The `indexable` parameter must be sorted ascending. Where there are multiple equal values the lowest index will be returned.
*
* See {@link arrayBinaryIndexOf}.
*/
export function arrayBinaryIndexOf(indexable, comparisonValueToSearchFor, getComparisonValueAtIndex, length, start) {
const index = binaryFindInsertionIndex(indexable, comparisonValueToSearchFor, getComparisonValueAtIndex, isLowGetLowest, fpIdentity, length, start);
if (getComparisonValueAtIndex(indexable, index) === comparisonValueToSearchFor) {
return index;
}
else {
return -1;
}
}
function isLowGetLowest(comparisonValueToSearchFor, currentComparisonValue) {
return currentComparisonValue < comparisonValueToSearchFor;
}
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