@mtdt.temp/browser-core/esm/tools/mergeInto.js

Datadog browser core utilities.

import { getType } from './utils/typeUtils';
/**
 * Iterate over source and affect its sub values into destination, recursively.
 * If the source and destination can't be merged, return source.
 */
export function mergeInto(destination, source, circularReferenceChecker = createCircularReferenceChecker()) {
    // ignore the source if it is undefined
    if (source === undefined) {
        return destination;
    }
    if (typeof source !== 'object' || source === null) {
        // primitive values - just return source
        return source;
    }
    else if (source instanceof Date) {
        return new Date(source.getTime());
    }
    else if (source instanceof RegExp) {
        const flags = source.flags ||
            // old browsers compatibility
            [
                source.global ? 'g' : '',
                source.ignoreCase ? 'i' : '',
                source.multiline ? 'm' : '',
                source.sticky ? 'y' : '',
                source.unicode ? 'u' : '',
            ].join('');
        return new RegExp(source.source, flags);
    }
    if (circularReferenceChecker.hasAlreadyBeenSeen(source)) {
        // remove circular references
        return undefined;
    }
    else if (Array.isArray(source)) {
        const merged = Array.isArray(destination) ? destination : [];
        for (let i = 0; i < source.length; ++i) {
            merged[i] = mergeInto(merged[i], source[i], circularReferenceChecker);
        }
        return merged;
    }
    const merged = getType(destination) === 'object' ? destination : {};
    for (const key in source) {
        if (Object.prototype.hasOwnProperty.call(source, key)) {
            merged[key] = mergeInto(merged[key], source[key], circularReferenceChecker);
        }
    }
    return merged;
}
/**
 * A simplistic implementation of a deep clone algorithm.
 * Caveats:
 * - It doesn't maintain prototype chains - don't use with instances of custom classes.
 * - It doesn't handle Map and Set
 */
export function deepClone(value) {
    return mergeInto(undefined, value);
}
export function combine(...sources) {
    let destination;
    for (const source of sources) {
        // Ignore any undefined or null sources.
        if (source === undefined || source === null) {
            continue;
        }
        destination = mergeInto(destination, source);
    }
    return destination;
}
function createCircularReferenceChecker() {
    if (typeof WeakSet !== 'undefined') {
        const set = new WeakSet();
        return {
            hasAlreadyBeenSeen(value) {
                const has = set.has(value);
                if (!has) {
                    set.add(value);
                }
                return has;
            },
        };
    }
    const array = [];
    return {
        hasAlreadyBeenSeen(value) {
            const has = array.indexOf(value) >= 0;
            if (!has) {
                array.push(value);
            }
            return has;
        },
    };
}
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