@stringsync/vexml/dist/esm/util/array.js

MusicXML to Vexflow

/** Returns the first element of an array or null if it doesn't exist. */
export const first = (array) => array[0] ?? null;
/** Returns the last element of an array or null if it doesn't exist. */
export const last = (array) => array[array.length - 1] ?? null;
/** Sorts in-place using the transformation of each array item. */
export const sortBy = (array, transform) => {
    const memo = new Map();
    const value = (item) => {
        if (!memo.has(item)) {
            memo.set(item, transform(item));
        }
        return memo.get(item);
    };
    return array.sort((a, b) => {
        const valueA = value(a);
        const valueB = value(b);
        if (valueA > valueB) {
            return 1;
        }
        if (valueA < valueB) {
            return -1;
        }
        return 0;
    });
};
/** Groups the elements in the array using the transform. */
export const groupBy = (array, transform) => {
    return array.reduce((memo, item) => {
        const key = transform(item);
        memo[key] ??= [];
        memo[key].push(item);
        return memo;
    }, {});
};
/** Iterates over each [previous, current, next] triple. */
export const forEachTriple = (array, callback) => {
    for (let index = 0; index < array.length; index++) {
        const previous = array[index - 1] ?? null;
        const current = array[index];
        const next = array[index + 1] ?? null;
        callback([previous, current, next], { index, isFirst: index === 0, isLast: index === array.length - 1 });
    }
};
/** Returns a new array with unique elements, preserving the order. */
export const unique = (array) => {
    const seen = new Set();
    return array.filter((item) => {
        if (seen.has(item)) {
            return false;
        }
        seen.add(item);
        return true;
    });
};
/** Returns a new array with unique elements based on the transformation, preserving the order. */
export const uniqueBy = (array, transform) => {
    const seen = new Set();
    return array.filter((item) => {
        const key = transform(item);
        if (seen.has(key)) {
            return false;
        }
        seen.add(key);
        return true;
    });
};
/** Combines two arrays into an array of tuples. */
export const zip = (array1, array2) => {
    const length = Math.min(array1.length, array2.length);
    const result = [];
    for (let i = 0; i < length; i++) {
        result.push([array1[i], array2[i]]);
    }
    return result;
};