/**
* Copyright 2017 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Do a deep-copy of basic JavaScript Objects or Arrays.
*/
export function deepCopy<T>(value: T): T {
return deepExtend(undefined, value);
}
/**
* Copy properties from source to target (recursively allows extension
* of Objects and Arrays). Scalar values in the target are over-written.
* If target is undefined, an object of the appropriate type will be created
* (and returned).
*
* We recursively copy all child properties of plain Objects in the source- so
* that namespace- like dictionaries are merged.
*
* Note that the target can be a function, in which case the properties in
* the source Object are copied onto it as static properties of the Function.
*/
export function deepExtend(target: any, source: any): any {
if (!(source instanceof Object)) {
return source;
}
switch (source.constructor) {
case Date:
// Treat Dates like scalars; if the target date object had any child
// properties - they will be lost!
let dateValue = (source as any) as Date;
return new Date(dateValue.getTime());
case Object:
if (target === undefined) {
target = {};
}
break;
case Array:
// Always copy the array source and overwrite the target.
target = [];
break;
default:
// Not a plain Object - treat it as a scalar.
return source;
}
for (let prop in source) {
Iif (!source.hasOwnProperty(prop)) {
continue;
}
target[prop] = deepExtend(target[prop], source[prop]);
}
return target;
}
// TODO: Really needed (for JSCompiler type checking)?
export function patchProperty(obj: any, prop: string, value: any) {
obj[prop] = value;
}
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