245 lines
8.4 KiB
JavaScript
245 lines
8.4 KiB
JavaScript
// Copyright 2013 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview The TrustedResourceUrl type and its builders.
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*
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* TODO(xtof): Link to document stating type contract.
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*/
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goog.provide('goog.html.TrustedResourceUrl');
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goog.require('goog.asserts');
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goog.require('goog.i18n.bidi.Dir');
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goog.require('goog.i18n.bidi.DirectionalString');
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goog.require('goog.string.Const');
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goog.require('goog.string.TypedString');
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/**
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* A URL which is under application control and from which script, CSS, and
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* other resources that represent executable code, can be fetched.
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*
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* Given that the URL can only be constructed from strings under application
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* control and is used to load resources, bugs resulting in a malformed URL
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* should not have a security impact and are likely to be easily detectable
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* during testing. Given the wide number of non-RFC compliant URLs in use,
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* stricter validation could prevent some applications from being able to use
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* this type.
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*
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* Instances of this type must be created via the factory method,
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* ({@code goog.html.TrustedResourceUrl.fromConstant}), and not by invoking its
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* constructor. The constructor intentionally takes no parameters and the type
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* is immutable; hence only a default instance corresponding to the empty
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* string can be obtained via constructor invocation.
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*
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* @see goog.html.TrustedResourceUrl#fromConstant
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* @constructor
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* @final
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* @struct
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* @implements {goog.i18n.bidi.DirectionalString}
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* @implements {goog.string.TypedString}
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*/
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goog.html.TrustedResourceUrl = function() {
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/**
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* The contained value of this TrustedResourceUrl. The field has a purposely
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* ugly name to make (non-compiled) code that attempts to directly access this
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* field stand out.
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* @private {string}
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*/
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this.privateDoNotAccessOrElseTrustedResourceUrlWrappedValue_ = '';
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/**
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* A type marker used to implement additional run-time type checking.
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* @see goog.html.TrustedResourceUrl#unwrap
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* @const
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* @private
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*/
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this.TRUSTED_RESOURCE_URL_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ =
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goog.html.TrustedResourceUrl.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_;
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};
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/**
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* @override
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* @const
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*/
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goog.html.TrustedResourceUrl.prototype.implementsGoogStringTypedString = true;
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/**
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* Returns this TrustedResourceUrl's value as a string.
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*
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* IMPORTANT: In code where it is security relevant that an object's type is
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* indeed {@code TrustedResourceUrl}, use
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* {@code goog.html.TrustedResourceUrl.unwrap} instead of this method. If in
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* doubt, assume that it's security relevant. In particular, note that
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* goog.html functions which return a goog.html type do not guarantee that
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* the returned instance is of the right type. For example:
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*
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* <pre>
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* var fakeSafeHtml = new String('fake');
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* fakeSafeHtml.__proto__ = goog.html.SafeHtml.prototype;
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* var newSafeHtml = goog.html.SafeHtml.htmlEscape(fakeSafeHtml);
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* // newSafeHtml is just an alias for fakeSafeHtml, it's passed through by
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* // goog.html.SafeHtml.htmlEscape() as fakeSafeHtml instanceof
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* // goog.html.SafeHtml.
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* </pre>
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*
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* @see goog.html.TrustedResourceUrl#unwrap
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* @override
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*/
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goog.html.TrustedResourceUrl.prototype.getTypedStringValue = function() {
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return this.privateDoNotAccessOrElseTrustedResourceUrlWrappedValue_;
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};
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/**
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* @override
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* @const
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*/
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goog.html.TrustedResourceUrl.prototype.implementsGoogI18nBidiDirectionalString =
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true;
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/**
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* Returns this URLs directionality, which is always {@code LTR}.
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* @override
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*/
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goog.html.TrustedResourceUrl.prototype.getDirection = function() {
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return goog.i18n.bidi.Dir.LTR;
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};
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if (goog.DEBUG) {
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/**
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* Returns a debug string-representation of this value.
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*
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* To obtain the actual string value wrapped in a TrustedResourceUrl, use
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* {@code goog.html.TrustedResourceUrl.unwrap}.
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*
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* @see goog.html.TrustedResourceUrl#unwrap
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* @override
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*/
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goog.html.TrustedResourceUrl.prototype.toString = function() {
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return 'TrustedResourceUrl{' +
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this.privateDoNotAccessOrElseTrustedResourceUrlWrappedValue_ + '}';
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};
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}
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/**
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* Performs a runtime check that the provided object is indeed a
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* TrustedResourceUrl object, and returns its value.
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*
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* @param {!goog.html.TrustedResourceUrl} trustedResourceUrl The object to
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* extract from.
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* @return {string} The trustedResourceUrl object's contained string, unless
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* the run-time type check fails. In that case, {@code unwrap} returns an
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* innocuous string, or, if assertions are enabled, throws
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* {@code goog.asserts.AssertionError}.
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*/
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goog.html.TrustedResourceUrl.unwrap = function(trustedResourceUrl) {
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// Perform additional Run-time type-checking to ensure that
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// trustedResourceUrl is indeed an instance of the expected type. This
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// provides some additional protection against security bugs due to
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// application code that disables type checks.
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// Specifically, the following checks are performed:
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// 1. The object is an instance of the expected type.
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// 2. The object is not an instance of a subclass.
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// 3. The object carries a type marker for the expected type. "Faking" an
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// object requires a reference to the type marker, which has names intended
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// to stand out in code reviews.
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if (trustedResourceUrl instanceof goog.html.TrustedResourceUrl &&
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trustedResourceUrl.constructor === goog.html.TrustedResourceUrl &&
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trustedResourceUrl
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.TRUSTED_RESOURCE_URL_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ ===
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goog.html.TrustedResourceUrl
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.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_) {
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return trustedResourceUrl
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.privateDoNotAccessOrElseTrustedResourceUrlWrappedValue_;
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} else {
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goog.asserts.fail('expected object of type TrustedResourceUrl, got \'' +
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trustedResourceUrl + '\' of type ' + goog.typeOf(trustedResourceUrl));
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return 'type_error:TrustedResourceUrl';
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}
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};
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/**
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* Creates a TrustedResourceUrl object from a compile-time constant string.
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*
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* Compile-time constant strings are inherently program-controlled and hence
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* trusted.
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*
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* @param {!goog.string.Const} url A compile-time-constant string from which to
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* create a TrustedResourceUrl.
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* @return {!goog.html.TrustedResourceUrl} A TrustedResourceUrl object
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* initialized to {@code url}.
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*/
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goog.html.TrustedResourceUrl.fromConstant = function(url) {
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return goog.html.TrustedResourceUrl
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.createTrustedResourceUrlSecurityPrivateDoNotAccessOrElse(
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goog.string.Const.unwrap(url));
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};
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/**
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* Creates a TrustedResourceUrl object from a compile-time constant strings.
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*
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* Compile-time constant strings are inherently program-controlled and hence
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* trusted.
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*
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* @param {!Array<!goog.string.Const>} parts Compile-time-constant strings from
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* which to create a TrustedResourceUrl.
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* @return {!goog.html.TrustedResourceUrl} A TrustedResourceUrl object
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* initialized to concatenation of {@code parts}.
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*/
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goog.html.TrustedResourceUrl.fromConstants = function(parts) {
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var unwrapped = '';
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for (var i = 0; i < parts.length; i++) {
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unwrapped += goog.string.Const.unwrap(parts[i]);
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}
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return goog.html.TrustedResourceUrl
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.createTrustedResourceUrlSecurityPrivateDoNotAccessOrElse(unwrapped);
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};
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/**
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* Type marker for the TrustedResourceUrl type, used to implement additional
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* run-time type checking.
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* @const {!Object}
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* @private
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*/
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goog.html.TrustedResourceUrl.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ = {};
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/**
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* Package-internal utility method to create TrustedResourceUrl instances.
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*
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* @param {string} url The string to initialize the TrustedResourceUrl object
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* with.
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* @return {!goog.html.TrustedResourceUrl} The initialized TrustedResourceUrl
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* object.
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* @package
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*/
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goog.html.TrustedResourceUrl
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.createTrustedResourceUrlSecurityPrivateDoNotAccessOrElse = function(url) {
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var trustedResourceUrl = new goog.html.TrustedResourceUrl();
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trustedResourceUrl.privateDoNotAccessOrElseTrustedResourceUrlWrappedValue_ =
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url;
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return trustedResourceUrl;
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};
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