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"use strict";
// above is required for Object.freeze to fail correctly.
const isPlainObject = require("./IsPlainObject.js");
const OVERRIDE_PREFIX = "override:";
function cleanKey(key, prefix) {
if (prefix && key.startsWith(prefix)) {
return key.slice(prefix.length);
}
return key;
}
function getMergedItem(target, source, prefixes = {}) {
let { override } = prefixes;
// Shortcut for frozen source (if target does not exist)
if (!target && isPlainObject(source) && Object.isFrozen(source)) {
return source;
}
let sourcePlainObjectShortcut;
if (!target && isPlainObject(source)) {
// deep copy objects to avoid sharing and to effect key renaming
target = {};
sourcePlainObjectShortcut = true;
}
if (Array.isArray(target) && Array.isArray(source)) {
return target.concat(source);
} else if (isPlainObject(target)) {
if (sourcePlainObjectShortcut || isPlainObject(source)) {
for (let key in source) {
let overrideKey = cleanKey(key, override);
// An error happens here if the target is frozen
target[overrideKey] = getMergedItem(target[key], source[key], prefixes);
}
}
return target;
}
// number, string, class instance, etc
return source;
}
// The same as Merge but without override prefixes
function DeepCopy(targetObject, ...sources) {
for (let source of sources) {
if (!source) {
continue;
}
targetObject = getMergedItem(targetObject, source);
}
return targetObject;
}
function Merge(target, ...sources) {
// Remove override prefixes from root target.
if (isPlainObject(target)) {
for (let key in target) {
if (key.indexOf(OVERRIDE_PREFIX) === 0) {
target[key.slice(OVERRIDE_PREFIX.length)] = target[key];
delete target[key];
}
}
}
for (let source of sources) {
if (!source) {
continue;
}
target = getMergedItem(target, source, {
override: OVERRIDE_PREFIX,
});
}
return target;
}
module.exports = Merge;
module.exports.DeepCopy = DeepCopy;
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