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// 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 {!Object}
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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 from a format string and arguments.
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 *
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 * The arguments for interpolation into the format string map labels to values.
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 * Values of type `goog.string.Const` are interpolated without modifcation.
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 * Values of other types are cast to string and encoded with
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 * encodeURIComponent.
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 *
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 * `%{<label>}` markers are used in the format string to indicate locations
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 * to be interpolated with the valued mapped to the given label. `<label>`
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 * must contain only alphanumeric and `_` characters.
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 *
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 * The format string must start with one of the following:
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 * - `https://<origin>/`
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 * - `//<origin>/`
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 * - `/<pathStart>`
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 * - `about:blank`
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 *
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 * `<origin>` must contain only alphanumeric or any of the following: `-.:[]`.
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 * `<pathStart>` is any character except `/` and `\`.
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 *
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 * Example usage:
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 *
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 *    var url = goog.html.TrustedResourceUrl.format(goog.string.Const.from(
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 *        'https://www.google.com/search?q=%{query}), {'query': searchTerm});
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 *
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 *    var url = goog.html.TrustedResourceUrl.format(goog.string.Const.from(
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 *        '//www.youtube.com/v/%{videoId}?hl=en&fs=1%{autoplay}'), {
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 *        'videoId': videoId,
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 *        'autoplay': opt_autoplay ?
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 *            goog.string.Const.EMPTY : goog.string.Const.from('autoplay=1')
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 *    });
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 *
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 * While this function can be used to create a TrustedResourceUrl from only
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 * constants, fromConstant() and fromConstants() are generally preferable for
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 * that purpose.
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 *
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 * @param {!goog.string.Const} format The format string.
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 * @param {!Object<string, (string|number|!goog.string.Const)>} args Mapping
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 *     of labels to values to be interpolated into the format string.
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 *     goog.string.Const values are interpolated without encoding.
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 * @return {!goog.html.TrustedResourceUrl}
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 * @throws {!Error} On an invalid format string or if a label used in the
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 *     the format string is not present in args.
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 *
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 */
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goog.html.TrustedResourceUrl.format = function(format, args) {
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  var formatStr = goog.string.Const.unwrap(format);
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  if (!goog.html.TrustedResourceUrl.BASE_URL_.test(formatStr)) {
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    throw new Error('Invalid TrustedResourceUrl format: ' + formatStr);
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  }
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  var result = formatStr.replace(
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      goog.html.TrustedResourceUrl.FORMAT_MARKER_, function(match, id) {
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        if (!Object.prototype.hasOwnProperty.call(args, id)) {
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          throw new Error(
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              'Found marker, "' + id + '", in format string, "' + formatStr +
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              '", but no valid label mapping found ' +
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              'in args: ' + JSON.stringify(args));
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        }
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        var arg = args[id];
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        if (arg instanceof goog.string.Const) {
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          return goog.string.Const.unwrap(arg);
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        } else {
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          return encodeURIComponent(String(arg));
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        }
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      });
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  return goog.html.TrustedResourceUrl
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      .createTrustedResourceUrlSecurityPrivateDoNotAccessOrElse(result);
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};
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/**
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 * @private @const {!RegExp}
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 */
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goog.html.TrustedResourceUrl.FORMAT_MARKER_ = /%{(\w+)}/g;
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/**
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 * The URL must be absolute, scheme-relative or path-absolute. So it must
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 * start with:
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 * - https:// followed by allowed origin characters.
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 * - // followed by allowed origin characters.
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 * - / not followed by / or \. There will only be an absolute path.
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 *
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 * Based on
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 * https://url.spec.whatwg.org/commit-snapshots/56b74ce7cca8883eab62e9a12666e2fac665d03d/#url-parsing
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 * an initial / which is not followed by another / or \ will end up in the "path
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 * state" and from there it can only go to "fragment state" and "query state".
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 *
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 * We don't enforce a well-formed domain name. So '.' or '1.2' are valid.
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 * That's ok because the origin comes from a compile-time constant.
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 *
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 * A regular expression is used instead of goog.uri for several reasons:
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 * - Strictness. E.g. we don't want any userinfo component and we don't
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 *   want '/./, nor \' in the first path component.
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 * - Small trusted base. goog.uri is generic and might need to change,
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 *   reasoning about all the ways it can parse a URL now and in the future
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 *   is error-prone.
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 * - Code size. We expect many calls to .format(), many of which might
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 *   not be using goog.uri.
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 * - Simplicity. Using goog.uri would likely not result in simpler nor shorter
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 *   code.
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 * @private @const {!RegExp}
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 */
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goog.html.TrustedResourceUrl.BASE_URL_ =
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    /^(?:https:)?\/\/[0-9a-z.:[\]-]+\/|^\/[^\/\\]|^about:blank(#|$)/i;
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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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