Vue Parse函数定义

/**
 * Convert HTML string to AST.
 */
export function parse(template: string, options: CompilerOptions): ASTElement {
  warn = options.warn || baseWarn
  platformIsPreTag = options.isPreTag || no
  platformMustUseProp = options.mustUseProp || no
  platformGetTagNamespace = options.getTagNamespace || no
  const isReservedTag = options.isReservedTag || no
  maybeComponent = (el: ASTElement) =>
    !!(
      el.component ||
      el.attrsMap[':is'] ||
      el.attrsMap['v-bind:is'] ||
      !(el.attrsMap.is ? isReservedTag(el.attrsMap.is) : isReservedTag(el.tag))
    )
  transforms = pluckModuleFunction(options.modules, 'transformNode')
  preTransforms = pluckModuleFunction(options.modules, 'preTransformNode')
  postTransforms = pluckModuleFunction(options.modules, 'postTransformNode')

  delimiters = options.delimiters

  const stack: any[] = []
  const preserveWhitespace = options.preserveWhitespace !== false
  const whitespaceOption = options.whitespace
  let root
  let currentParent
  let inVPre = false
  let inPre = false
  let warned = false

  function warnOnce(msg, range) {
  }

  function closeElement(element) {
  }

  function trimEndingWhitespace(el) {
  }

  function checkRootConstraints(el) {
  }

  parseHTML(template, {
    warn,
    expectHTML: options.expectHTML,
    isUnaryTag: options.isUnaryTag,
    canBeLeftOpenTag: options.canBeLeftOpenTag,
    shouldDecodeNewlines: options.shouldDecodeNewlines,
    shouldDecodeNewlinesForHref: options.shouldDecodeNewlinesForHref,
    shouldKeepComment: options.comments,
    outputSourceRange: options.outputSourceRange,
    
    start(tag, attrs, unary, start, end) {
    },

    end(tag, start, end) {},

    chars(text: string, start?: number, end?: number) {
    },
    
    comment(text: string, start, end) {
    }
  })
  return root
}