JavaScript 使用 Lookahead 匹配多行中的相似模式

Question

我正在尝试提出正则表达式 block ，该 block 将使用 JavaScript 从 cucumber 样本中提取表。 cucumber 样本如下

Feature: Sample Feature File

   Scenario: An international coffee shop must handle currencies
      Given the price list for an international coffee shop
      | product | currency | price |
      | coffee  | EUR      | 1     |
      | donut   | SEK      | 18    |
      When I buy 1 coffee and 1 donut
      Then should I pay 1 EUR and 18 SEK

   Scenario Outline: eating
      Given there are <start> cucumbers
      When I eat <eat> cucumbers
      Then I should have <left> cucumbers

      Examples:
      | start | eat | left |
      |  12   |  5  |  7   |
      |  20   |  5  |  15  |

正则表达式应该在两个匹配中返回以下内容，如下所示

1)

  | product | currency | price |
  | coffee  | EUR      | 1     |
  | donut   | SEK      | 18    |

2)

  | start | eat | left |
  |  12   |  5  |  7   |
  |  20   |  5  |  15  |

一旦获得 block ，我将按行分割以获取表中的行数。无论如何，我尝试了否定查找表达式来尝试解决这个问题。我的努力如下

/(\|)[\s\S]*\|(?!\s+\|)/gm

但是返回

| product | currency | price |
      | coffee  | EUR      | 1     |
      | donut   | SEK      | 18    |
      When I buy 1 coffee and 1 donut
      Then should I pay 1 EUR and 18 SEK

   Scenario Outline: eating
      Given there are <start> cucumbers
      When I eat <eat> cucumbers
      Then I should have <left> cucumbers

      Examples:
      | start | eat | left |
      |  12   |  5  |  7   |
      |  20   |  5  |  15  |

如果我删除第二种情况，正则表达式将按预期工作并仅返回

  | product | currency | price |
  | coffee  | EUR      | 1     |
  | donut   | SEK      | 18    |

关于我的正则表达式出错的地方有什么建议吗？非常感谢。

Answer 1

[\s\S]* 模式匹配任何 0+ 字符，尽可能多，直到字符串中没有 1+ 的最后一个 |紧邻当前位置右侧的空格和 |。由于匹配项是从左到右搜索的，因此您得到单个匹配项是合乎逻辑的。

我建议像这样展开图案

/^[^\S\r\n]*\|.*\|(?:[^\S\r\n]*[\r\n]+[^\S\r\n]*\|.*\|)*/gm

参见its demo here .

请注意，如果动态构建它，您可以使其可读:

var h = "[^\\S\r\n]*";     // horizontal whitespace block
var rx = new RegExp("^" +     // start of a line
      h + "\\|.*\\|" +        // hor. whitespace, |, 0+ chars other than line breaks, |
      "(?:" + h + "[\r\n]+" + // 0+ sequences of hor. whitespace, line breaks, 
      h + "\\|.*\\|)*",       // hor. whitespace, |, 0+ chars other than line breaks, |
      "gm"); // Global (find multiple matches) and multiline (^ matches line start)
var s = "Feature: Sample Feature File\r\n\r\n   Scenario: An international coffee shop must handle currencies\r\n      Given the price list for an international coffee shop\r\n      | product | currency | price |\r\n      | coffee  | EUR      | 1     |\r\n      | donut   | SEK      | 18    |\r\n      When I buy 1 coffee and 1 donut\r\n      Then should I pay 1 EUR and 18 SEK\r\n\r\n   Scenario Outline: eating\r\n      Given there are <start> cucumbers\r\n      When I eat <eat> cucumbers\r\n      Then I should have <left> cucumbers\r\n\r\n      Examples:\r\n      | start | eat | left |\r\n      |  12   |  5  |  7   |\r\n      |  20   |  5  |  15  |";
console.log(s.match(rx));

详细信息

• ^ - 行的开头
• [^\S\r\n]* - 0+ 水平空白
• \| - 一个 |
• .* - 除换行符之外的任何 0+ 个字符，尽可能多
• \| - 一个 |
• (?:[^\S\r\n]*[\r\n]+[^\S\r\n]*\|.*\|)* - 零或多个序列:
  • [^\S\r\n]* - 0+ 水平空白
  • [\r\n]+ - 1 个或多个 CR 或/和 LF 符号(如果您只想匹配 1 个换行符，请使用 (?:\r\n? |\n) 此处)
  • [^\S\r\n]*\|.*\| - 0+ 水平空白、|、除换行符之外的任何 0+ 字符，尽可能多，|