// 解析文本
function parseText(context: ParserContext, mode: TextModes): TextNode {
  __TEST__ && assert(context.source.length > 0)

  const endTokens = ['<', context.options.delimiters[0]]
  if (mode === TextModes.CDATA) {
    endTokens.push(']]>')
  }

  let endIndex = context.source.length // 结束位置
  for (let i = 0; i < endTokens.length; i++) {
    const index = context.source.indexOf(endTokens[i], 1)
    if (index !== -1 && endIndex > index) {
      endIndex = index
    }
  }

  __TEST__ && assert(endIndex > 0)

  const start = getCursor(context)
   // 通过对endTokens循环判断就能知道结束的位置
  const content = parseTextData(context, endIndex, mode)

  return {
    type: NodeTypes.TEXT, // 2
    content,
    loc: getSelection(context, start)
  }
}

/**
 * Get text data with a given length from the current location.
 * This translates HTML entities in the text data.
 */
// 获取文本数据
function parseTextData(
  context: ParserContext,
  length: number,
  mode: TextModes
): string {
  const rawText = context.source.slice(0, length) // 获取文本内容
  advanceBy(context, length) // 前进
  if (
    mode === TextModes.RAWTEXT ||
    mode === TextModes.CDATA ||
    rawText.indexOf('&') === -1
  ) {
    return rawText
  } else {
    // DATA or RCDATA containing "&"". Entity decoding required.
    return context.options.decodeEntities(
      rawText,
      mode === TextModes.ATTRIBUTE_VALUE
    )
  }
}

// 解析{{}}

function parseInterpolation(
  context: ParserContext,
  mode: TextModes
): InterpolationNode | undefined {
  const [open, close] = context.options.delimiters
  __TEST__ && assert(startsWith(context.source, open))

  const closeIndex = context.source.indexOf(close, open.length) // 拿到结束位置
  if (closeIndex === -1) { // 如果为 -1就抛出错误
    emitError(context, ErrorCodes.X_MISSING_INTERPOLATION_END)
    return undefined
  }

  const start = getCursor(context) // 获取开始的位置
  advanceBy(context, open.length) // 前进
  const innerStart = getCursor(context) //开始解析的位置
  const innerEnd = getCursor(context) // 结束解析的位置
  const rawContentLength = closeIndex - open.length // 获取文本长度
  const rawContent = context.source.slice(0, rawContentLength) // 获取文本内容
  const preTrimContent = parseTextData(context, rawContentLength, mode)
  const content = preTrimContent.trim() // 去除空格
  const startOffset = preTrimContent.indexOf(content)
  if (startOffset > 0) {
    advancePositionWithMutation(innerStart, rawContent, startOffset)
  }
  const endOffset =
    rawContentLength - (preTrimContent.length - content.length - startOffset) // 结束位置
  advancePositionWithMutation(innerEnd, rawContent, endOffset)
  advanceBy(context, close.length)

  return {
    type: NodeTypes.INTERPOLATION,
    content: {
      type: NodeTypes.SIMPLE_EXPRESSION,
      isStatic: false,
      // Set `isConstant` to false by default and will decide in transformExpression
      constType: ConstantTypes.NOT_CONSTANT,
      content,
      loc: getSelection(context, innerStart, innerEnd)
    },
    loc: getSelection(context, start)
  }
}