angular-cn/modules/angular2/src/compiler/template_preparser.ts

import {HtmlElementAst} from './html_ast';
import {isBlank, isPresent} from 'angular2/src/facade/lang';

const NG_CONTENT_SELECT_ATTR = 'select';
const NG_CONTENT_ELEMENT = 'ng-content';
const LINK_ELEMENT = 'link';
const LINK_STYLE_REL_ATTR = 'rel';
const LINK_STYLE_HREF_ATTR = 'href';
const LINK_STYLE_REL_VALUE = 'stylesheet';
const STYLE_ELEMENT = 'style';
const SCRIPT_ELEMENT = 'script';
const NG_NON_BINDABLE_ATTR = 'ng-non-bindable';

export function preparseElement(ast: HtmlElementAst): PreparsedElement {
  var selectAttr = null;
  var hrefAttr = null;
  var relAttr = null;
  var nonBindable = false;
  ast.attrs.forEach(attr => {
    let attrName = attr.name.toLowerCase();
    if (attrName == NG_CONTENT_SELECT_ATTR) {
      selectAttr = attr.value;
    } else if (attrName == LINK_STYLE_HREF_ATTR) {
      hrefAttr = attr.value;
    } else if (attrName == LINK_STYLE_REL_ATTR) {
      relAttr = attr.value;
    } else if (attrName == NG_NON_BINDABLE_ATTR) {
      nonBindable = true;
    }
  });
  selectAttr = normalizeNgContentSelect(selectAttr);
  var nodeName = ast.name.toLowerCase();
  var type = PreparsedElementType.OTHER;
  if (nodeName == NG_CONTENT_ELEMENT) {
    type = PreparsedElementType.NG_CONTENT;
  } else if (nodeName == STYLE_ELEMENT) {
    type = PreparsedElementType.STYLE;
  } else if (nodeName == SCRIPT_ELEMENT) {
    type = PreparsedElementType.SCRIPT;
  } else if (nodeName == LINK_ELEMENT && relAttr == LINK_STYLE_REL_VALUE) {
    type = PreparsedElementType.STYLESHEET;
  }
  return new PreparsedElement(type, selectAttr, hrefAttr, nonBindable);
}

export enum PreparsedElementType {
  NG_CONTENT,
  STYLE,
  STYLESHEET,
  SCRIPT,
  OTHER
}

export class PreparsedElement {
  constructor(public type: PreparsedElementType, public selectAttr: string, public hrefAttr: string,
              public nonBindable: boolean) {}
}


function normalizeNgContentSelect(selectAttr: string): string {
  if (isBlank(selectAttr) || selectAttr.length === 0) {
    return '*';
  }
  return selectAttr;
}