function $SanitizeProvider() {
  var hasBeenInstantiated = false;
  var svgEnabled = false;

  this.$get = ['$$sanitizeUri', function($$sanitizeUri) {
    hasBeenInstantiated = true;
    if (svgEnabled) {
      extend(validElements, svgElements);
    }
    return function(html) {
      var buf = [];
      htmlParser(html, htmlSanitizeWriter(buf, function(uri, isImage) {
        return !/^unsafe:/.test($$sanitizeUri(uri, isImage));
      }));
      return buf.join('');
    };
  }];


  /**
   * @ngdoc method
   * @name $sanitizeProvider#enableSvg
   * @kind function
   *
   * @description
   * Enables a subset of svg to be supported by the sanitizer.
   *
   * <div class="alert alert-warning">
   *   <p>By enabling this setting without taking other precautions, you might expose your
   *   application to click-hijacking attacks. In these attacks, sanitized svg elements could be positioned
   *   outside of the containing element and be rendered over other elements on the page (e.g. a login
   *   link). Such behavior can then result in phishing incidents.</p>
   *
   *   <p>To protect against these, explicitly setup `overflow: hidden` css rule for all potential svg
   *   tags within the sanitized content:</p>
   *
   *   <br>
   *
   *   <pre><code>
   *   .rootOfTheIncludedContent svg {
   *     overflow: hidden !important;
   *   }
   *   </code></pre>
   * </div>
   *
   * @param {boolean=} flag Enable or disable SVG support in the sanitizer.
   * @returns {boolean|$sanitizeProvider} Returns the currently configured value if called
   *    without an argument or self for chaining otherwise.
   */
  this.enableSvg = function(enableSvg) {
    if (isDefined(enableSvg)) {
      svgEnabled = enableSvg;
      return this;
    } else {
      return svgEnabled;
    }
  };


  /**
   * @ngdoc method
   * @name $sanitizeProvider#addValidElements
   * @kind function
   *
   * @description
   * Extends the built-in lists of valid HTML/SVG elements, i.e. elements that are considered safe
   * and are not stripped off during sanitization. You can extend the following lists of elements:
   *
   * - `htmlElements`: A list of elements (tag names) to extend the current list of safe HTML
   *   elements. HTML elements considered safe will not be removed during sanitization. All other
   *   elements will be stripped off.
   *
   * - `htmlVoidElements`: This is similar to `htmlElements`, but marks the elements as
   *   "void elements" (similar to HTML
   *   [void elements](https://rawgit.com/w3c/html/html5.1-2/single-page.html#void-elements)). These
   *   elements have no end tag and cannot have content.
   *
   * - `svgElements`: This is similar to `htmlElements`, but for SVG elements. This list is only
   *   taken into account if SVG is {@link ngSanitize.$sanitizeProvider#enableSvg enabled} for
   *   `$sanitize`.
   *
   * <div class="alert alert-info">
   *   This method must be called during the {@link angular.Module#config config} phase. Once the
   *   `$sanitize` service has been instantiated, this method has no effect.
   * </div>
   *
   * <div class="alert alert-warning">
   *   Keep in mind that extending the built-in lists of elements may expose your app to XSS or
   *   other vulnerabilities. Be very mindful of the elements you add.
   * </div>
   *
   * @param {Array<String>|Object} elements - A list of valid HTML elements or an object with one or
   *   more of the following properties:
   *   - **htmlElements** - `{Array<String>}` - A list of elements to extend the current list of
   *     HTML elements.
   *   - **htmlVoidElements** - `{Array<String>}` - A list of elements to extend the current list of
   *     void HTML elements; i.e. elements that do not have an end tag.
   *   - **svgElements** - `{Array<String>}` - A list of elements to extend the current list of SVG
   *     elements. The list of SVG elements is only taken into account if SVG is
   *     {@link ngSanitize.$sanitizeProvider#enableSvg enabled} for `$sanitize`.
   *
   * Passing an array (`[...]`) is equivalent to passing `{htmlElements: [...]}`.
   *
   * @return {$sanitizeProvider} Returns self for chaining.
   */
  this.addValidElements = function(elements) {
    if (!hasBeenInstantiated) {
      if (isArray(elements)) {
        elements = {htmlElements: elements};
      }

      addElementsTo(svgElements, elements.svgElements);
      addElementsTo(voidElements, elements.htmlVoidElements);
      addElementsTo(validElements, elements.htmlVoidElements);
      addElementsTo(validElements, elements.htmlElements);
    }

    return this;
  };


  /**
   * @ngdoc method
   * @name $sanitizeProvider#addValidAttrs
   * @kind function
   *
   * @description
   * Extends the built-in list of valid attributes, i.e. attributes that are considered safe and are
   * not stripped off during sanitization.
   *
   * **Note**:
   * The new attributes will not be treated as URI attributes, which means their values will not be
   * sanitized as URIs using `$compileProvider`'s
   * {@link ng.$compileProvider#aHrefSanitizationTrustedUrlList aHrefSanitizationTrustedUrlList} and
   * {@link ng.$compileProvider#imgSrcSanitizationTrustedUrlList imgSrcSanitizationTrustedUrlList}.
   *
   * <div class="alert alert-info">
   *   This method must be called during the {@link angular.Module#config config} phase. Once the
   *   `$sanitize` service has been instantiated, this method has no effect.
   * </div>
   *
   * <div class="alert alert-warning">
   *   Keep in mind that extending the built-in list of attributes may expose your app to XSS or
   *   other vulnerabilities. Be very mindful of the attributes you add.
   * </div>
   *
   * @param {Array<String>} attrs - A list of valid attributes.
   *
   * @returns {$sanitizeProvider} Returns self for chaining.
   */
  this.addValidAttrs = function(attrs) {
    if (!hasBeenInstantiated) {
      extend(validAttrs, arrayToMap(attrs, true));
    }
    return this;
  };

  //////////////////////////////////////////////////////////////////////////////////////////////////
  // Private stuff
  //////////////////////////////////////////////////////////////////////////////////////////////////

  bind = angular.bind;
  extend = angular.extend;
  forEach = angular.forEach;
  isArray = angular.isArray;
  isDefined = angular.isDefined;
  lowercase = angular.$$lowercase;
  noop = angular.noop;

  htmlParser = htmlParserImpl;
  htmlSanitizeWriter = htmlSanitizeWriterImpl;

  nodeContains = window.Node.prototype.contains || /** @this */ function(arg) {
    // eslint-disable-next-line no-bitwise
    return !!(this.compareDocumentPosition(arg) & 16);
  };

  // Regular Expressions for parsing tags and attributes
  var SURROGATE_PAIR_REGEXP = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g,
    // Match everything outside of normal chars and " (quote character)
    NON_ALPHANUMERIC_REGEXP = /([^#-~ |!])/g;


  // Good source of info about elements and attributes
  // http://dev.w3.org/html5/spec/Overview.html#semantics
  // http://simon.html5.org/html-elements

  // Safe Void Elements - HTML5
  // http://dev.w3.org/html5/spec/Overview.html#void-elements
  var voidElements = stringToMap('area,br,col,hr,img,wbr');

  // Elements that you can, intentionally, leave open (and which close themselves)
  // http://dev.w3.org/html5/spec/Overview.html#optional-tags
  var optionalEndTagBlockElements = stringToMap('colgroup,dd,dt,li,p,tbody,td,tfoot,th,thead,tr'),
      optionalEndTagInlineElements = stringToMap('rp,rt'),
      optionalEndTagElements = extend({},
                                              optionalEndTagInlineElements,
                                              optionalEndTagBlockElements);

  // Safe Block Elements - HTML5
  var blockElements = extend({}, optionalEndTagBlockElements, stringToMap('address,article,' +
          'aside,blockquote,caption,center,del,dir,div,dl,figure,figcaption,footer,h1,h2,h3,h4,h5,' +
          'h6,header,hgroup,hr,ins,map,menu,nav,ol,pre,section,table,ul'));

  // Inline Elements - HTML5
  var inlineElements = extend({}, optionalEndTagInlineElements, stringToMap('a,abbr,acronym,b,' +
          'bdi,bdo,big,br,cite,code,del,dfn,em,font,i,img,ins,kbd,label,map,mark,q,ruby,rp,rt,s,' +
          'samp,small,span,strike,strong,sub,sup,time,tt,u,var'));

  // SVG Elements
  // https://wiki.whatwg.org/wiki/Sanitization_rules#svg_Elements
  // Note: the elements animate,animateColor,animateMotion,animateTransform,set are intentionally omitted.
  // They can potentially allow for arbitrary javascript to be executed. See #11290
  var svgElements = stringToMap('circle,defs,desc,ellipse,font-face,font-face-name,font-face-src,g,glyph,' +
          'hkern,image,linearGradient,line,marker,metadata,missing-glyph,mpath,path,polygon,polyline,' +
          'radialGradient,rect,stop,svg,switch,text,title,tspan');

  // Blocked Elements (will be stripped)
  var blockedElements = stringToMap('script,style');

  var validElements = extend({},
                                     voidElements,
                                     blockElements,
                                     inlineElements,
                                     optionalEndTagElements);

  //Attributes that have href and hence need to be sanitized
  var uriAttrs = stringToMap('background,cite,href,longdesc,src,xlink:href,xml:base');

  var htmlAttrs = stringToMap('abbr,align,alt,axis,bgcolor,border,cellpadding,cellspacing,class,clear,' +
      'color,cols,colspan,compact,coords,dir,face,headers,height,hreflang,hspace,' +
      'ismap,lang,language,nohref,nowrap,rel,rev,rows,rowspan,rules,' +
      'scope,scrolling,shape,size,span,start,summary,tabindex,target,title,type,' +
      'valign,value,vspace,width');

  // SVG attributes (without "id" and "name" attributes)
  // https://wiki.whatwg.org/wiki/Sanitization_rules#svg_Attributes
  var svgAttrs = stringToMap('accent-height,accumulate,additive,alphabetic,arabic-form,ascent,' +
      'baseProfile,bbox,begin,by,calcMode,cap-height,class,color,color-rendering,content,' +
      'cx,cy,d,dx,dy,descent,display,dur,end,fill,fill-rule,font-family,font-size,font-stretch,' +
      'font-style,font-variant,font-weight,from,fx,fy,g1,g2,glyph-name,gradientUnits,hanging,' +
      'height,horiz-adv-x,horiz-origin-x,ideographic,k,keyPoints,keySplines,keyTimes,lang,' +
      'marker-end,marker-mid,marker-start,markerHeight,markerUnits,markerWidth,mathematical,' +
      'max,min,offset,opacity,orient,origin,overline-position,overline-thickness,panose-1,' +
      'path,pathLength,points,preserveAspectRatio,r,refX,refY,repeatCount,repeatDur,' +
      'requiredExtensions,requiredFeatures,restart,rotate,rx,ry,slope,stemh,stemv,stop-color,' +
      'stop-opacity,strikethrough-position,strikethrough-thickness,stroke,stroke-dasharray,' +
      'stroke-dashoffset,stroke-linecap,stroke-linejoin,stroke-miterlimit,stroke-opacity,' +
      'stroke-width,systemLanguage,target,text-anchor,to,transform,type,u1,u2,underline-position,' +
      'underline-thickness,unicode,unicode-range,units-per-em,values,version,viewBox,visibility,' +
      'width,widths,x,x-height,x1,x2,xlink:actuate,xlink:arcrole,xlink:role,xlink:show,xlink:title,' +
      'xlink:type,xml:base,xml:lang,xml:space,xmlns,xmlns:xlink,y,y1,y2,zoomAndPan', true);

  var validAttrs = extend({},
                                  uriAttrs,
                                  svgAttrs,
                                  htmlAttrs);

  function stringToMap(str, lowercaseKeys) {
    return arrayToMap(str.split(','), lowercaseKeys);
  }

  function arrayToMap(items, lowercaseKeys) {
    var obj = {}, i;
    for (i = 0; i < items.length; i++) {
      obj[lowercaseKeys ? lowercase(items[i]) : items[i]] = true;
    }
    return obj;
  }

  function addElementsTo(elementsMap, newElements) {
    if (newElements && newElements.length) {
      extend(elementsMap, arrayToMap(newElements));
    }
  }

  /**
   * Create an inert document that contains the dirty HTML that needs sanitizing.
   * We use the DOMParser API by default and fall back to createHTMLDocument if DOMParser is not
   * available.
   */
  var getInertBodyElement /* function(html: string): HTMLBodyElement */ = (function(window, document) {
    if (isDOMParserAvailable()) {
      return getInertBodyElement_DOMParser;
    }

    if (!document || !document.implementation) {
      throw $sanitizeMinErr('noinert', 'Can\'t create an inert html document');
    }
    var inertDocument = document.implementation.createHTMLDocument('inert');
    var inertBodyElement = (inertDocument.documentElement || inertDocument.getDocumentElement()).querySelector('body');
    return getInertBodyElement_InertDocument;

    function isDOMParserAvailable() {
      try {
        return !!getInertBodyElement_DOMParser('');
      } catch (e) {
        return false;
      }
    }

    function getInertBodyElement_DOMParser(html) {
      // We add this dummy element to ensure that the rest of the content is parsed as expected
      // e.g. leading whitespace is maintained and tags like `<meta>` do not get hoisted to the `<head>` tag.
      html = '<remove></remove>' + html;
      try {
        var body = new window.DOMParser().parseFromString(html, 'text/html').body;
        body.firstChild.remove();
        return body;
      } catch (e) {
        return undefined;
      }
    }

    function getInertBodyElement_InertDocument(html) {
      inertBodyElement.innerHTML = html;

      // Support: IE 9-11 only
      // strip custom-namespaced attributes on IE<=11
      if (document.documentMode) {
        stripCustomNsAttrs(inertBodyElement);
      }

      return inertBodyElement;
    }
  })(window, window.document);

  /**
   * @example
   * htmlParser(htmlString, {
   *     start: function(tag, attrs) {},
   *     end: function(tag) {},
   *     chars: function(text) {},
   *     comment: function(text) {}
   * });
   *
   * @param {string} html string
   * @param {object} handler
   */
  function htmlParserImpl(html, handler) {
    if (html === null || html === undefined) {
      html = '';
    } else if (typeof html !== 'string') {
      html = '' + html;
    }

    var inertBodyElement = getInertBodyElement(html);
    if (!inertBodyElement) return '';

    //mXSS protection
    var mXSSAttempts = 5;
    do {
      if (mXSSAttempts === 0) {
        throw $sanitizeMinErr('uinput', 'Failed to sanitize html because the input is unstable');
      }
      mXSSAttempts--;

      // trigger mXSS if it is going to happen by reading and writing the innerHTML
      html = inertBodyElement.innerHTML;
      inertBodyElement = getInertBodyElement(html);
    } while (html !== inertBodyElement.innerHTML);

    var node = inertBodyElement.firstChild;
    while (node) {
      switch (node.nodeType) {
        case 1: // ELEMENT_NODE
          handler.start(node.nodeName.toLowerCase(), attrToMap(node.attributes));
          break;
        case 3: // TEXT NODE
          handler.chars(node.textContent);
          break;
      }

      var nextNode;
      if (!(nextNode = node.firstChild)) {
        if (node.nodeType === 1) {
          handler.end(node.nodeName.toLowerCase());
        }
        nextNode = getNonDescendant('nextSibling', node);
        if (!nextNode) {
          while (nextNode == null) {
            node = getNonDescendant('parentNode', node);
            if (node === inertBodyElement) break;
            nextNode = getNonDescendant('nextSibling', node);
            if (node.nodeType === 1) {
              handler.end(node.nodeName.toLowerCase());
            }
          }
        }
      }
      node = nextNode;
    }

    while ((node = inertBodyElement.firstChild)) {
      inertBodyElement.removeChild(node);
    }
  }

  function attrToMap(attrs) {
    var map = {};
    for (var i = 0, ii = attrs.length; i < ii; i++) {
      var attr = attrs[i];
      map[attr.name] = attr.value;
    }
    return map;
  }


  /**
   * Escapes all potentially dangerous characters, so that the
   * resulting string can be safely inserted into attribute or
   * element text.
   * @param value
   * @returns {string} escaped text
   */
  function encodeEntities(value) {
    return value.
      replace(/&/g, '&amp;').
      replace(SURROGATE_PAIR_REGEXP, function(value) {
        var hi = value.charCodeAt(0);
        var low = value.charCodeAt(1);
        return '&#' + (((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000) + ';';
      }).
      replace(NON_ALPHANUMERIC_REGEXP, function(value) {
        return '&#' + value.charCodeAt(0) + ';';
      }).
      replace(/</g, '&lt;').
      replace(/>/g, '&gt;');
  }

  /**
   * create an HTML/XML writer which writes to buffer
   * @param {Array} buf use buf.join('') to get out sanitized html string
   * @returns {object} in the form of {
   *     start: function(tag, attrs) {},
   *     end: function(tag) {},
   *     chars: function(text) {},
   *     comment: function(text) {}
   * }
   */
  function htmlSanitizeWriterImpl(buf, uriValidator) {
    var ignoreCurrentElement = false;
    var out = bind(buf, buf.push);
    return {
      start: function(tag, attrs) {
        tag = lowercase(tag);
        if (!ignoreCurrentElement && blockedElements[tag]) {
          ignoreCurrentElement = tag;
        }
        if (!ignoreCurrentElement && validElements[tag] === true) {
          out('<');
          out(tag);
          forEach(attrs, function(value, key) {
            var lkey = lowercase(key);
            var isImage = (tag === 'img' && lkey === 'src') || (lkey === 'background');
            if (validAttrs[lkey] === true &&
              (uriAttrs[lkey] !== true || uriValidator(value, isImage))) {
              out(' ');
              out(key);
              out('="');
              out(encodeEntities(value));
              out('"');
            }
          });
          out('>');
        }
      },
      end: function(tag) {
        tag = lowercase(tag);
        if (!ignoreCurrentElement && validElements[tag] === true && voidElements[tag] !== true) {
          out('</');
          out(tag);
          out('>');
        }
        // eslint-disable-next-line eqeqeq
        if (tag == ignoreCurrentElement) {
          ignoreCurrentElement = false;
        }
      },
      chars: function(chars) {
        if (!ignoreCurrentElement) {
          out(encodeEntities(chars));
        }
      }
    };
  }


  /**
   * When IE9-11 comes across an unknown namespaced attribute e.g. 'xlink:foo' it adds 'xmlns:ns1' attribute to declare
   * ns1 namespace and prefixes the attribute with 'ns1' (e.g. 'ns1:xlink:foo'). This is undesirable since we don't want
   * to allow any of these custom attributes. This method strips them all.
   *
   * @param node Root element to process
   */
  function stripCustomNsAttrs(node) {
    while (node) {
      if (node.nodeType === window.Node.ELEMENT_NODE) {
        var attrs = node.attributes;
        for (var i = 0, l = attrs.length; i < l; i++) {
          var attrNode = attrs[i];
          var attrName = attrNode.name.toLowerCase();
          if (attrName === 'xmlns:ns1' || attrName.lastIndexOf('ns1:', 0) === 0) {
            node.removeAttributeNode(attrNode);
            i--;
            l--;
          }
        }
      }

      var nextNode = node.firstChild;
      if (nextNode) {
        stripCustomNsAttrs(nextNode);
      }

      node = getNonDescendant('nextSibling', node);
    }
  }

  function getNonDescendant(propName, node) {
    // An element is clobbered if its `propName` property points to one of its descendants
    var nextNode = node[propName];
    if (nextNode && nodeContains.call(node, nextNode)) {
      throw $sanitizeMinErr('elclob', 'Failed to sanitize html because the element is clobbered: {0}', node.outerHTML || node.outerText);
    }
    return nextNode;
  }
}
@ngdoc provider
@name $sanitizeProvider
@this

@description
Creates and configures {@link $sanitize} instance.