sequency/lib/createComparatorFactory.js

Functional sequences for processing iterable data in JavaScript

Object.defineProperty(exports, "__esModule", { value: true });
function compare(comparison) {
    return Object.assign(comparison, {
        reversed: function () {
            return compare(function (a, b) { return comparison(a, b) * -1; });
        },
        then: function (nextComparison) {
            return compare(function (a, b) {
                var result = comparison(a, b);
                return result !== 0
                    ? result
                    : nextComparison(a, b);
            });
        },
        thenDescending: function (nextComparison) {
            return this.then(compare(nextComparison)
                .reversed());
        },
        thenBy: function (keyOrSelector) {
            var selector = asSelector(keyOrSelector);
            return this.then(function (a, b) { return naturalCompare(selector(a), selector(b)); });
        },
        thenByDescending: function (keyOrSelector) {
            var selector = asSelector(keyOrSelector);
            return this.then(compare(function (a, b) { return naturalCompare(selector(a), selector(b)); }).reversed());
        }
    });
}
function compareBy(keyOrSelector) {
    var selector = asSelector(keyOrSelector);
    return compare(function (a, b) { return naturalCompare(selector(a), selector(b)); });
}
function compareByDescending(keyOrSelector) {
    var selector = asSelector(keyOrSelector);
    return compare(function (a, b) { return naturalCompare(selector(b), selector(a)); });
}
function asSelector(keyOrSelector) {
    return typeof keyOrSelector === "function"
        ? keyOrSelector
        : function (item) { return item[keyOrSelector]; };
}
function naturalCompare(a, b) {
    return a < b ? -1 : a > b ? 1 : 0;
}
function naturalOrder() {
    return compare(naturalCompare);
}
function reverseOrder() {
    return compare(naturalCompare).reversed();
}
function nullsLast() {
    return compare(function (a, b) { return a === null ? 1 : b === null ? -1 : 0; });
}
function nullsFirst() {
    return compare(function (a, b) { return a === null ? -1 : b === null ? 1 : 0; });
}
function createComparatorFactory() {
    return {
        compare: compare,
        compareBy: compareBy,
        compareByDescending: compareByDescending,
        naturalOrder: naturalOrder,
        reverseOrder: reverseOrder,
        nullsFirst: nullsFirst,
        nullsLast: nullsLast
    };
}
exports.default = createComparatorFactory;
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