正则表达式匹配空行 [英] Regex match empty lines

问题描述

目前我有一个正则表达式，它将采用一组给定的换行符并将它们压缩.我需要解决的一个挑战是修改这个正则表达式(\n{2,}) 以便在搜索多个换行符时仍然会忽略空格和制表符.

https://regex101.com/r/dEhyN3/2 显示效果很好我所指的例子.有一行只包含一个空格，导致最终结果中有太多新行.

解决方案

Brief

此答案可确保保留行首的空格(如果它包含除空格字符以外的其他内容).

<小时>

代码

查看此处使用的正则表达式

(?:\h*\n){2,}

注意:某些正则表达式引擎不允许使用 \h，因此必须将其替换为 [\t\p{Zs}]，如果不支持 Unicode 字符类，则为每个字符的简单列表，例如 [\t ] 或 [^\S\n].

其他方法:

(?:\n(?:[^\S\n]*(?=\n))?){2,}(?:\n(?:\s*(?=\n))?){2,}\h*\n(?:\h*\n)+

<小时>

结果

输入

**语言**- 添加了四种语言:意大利语、葡萄牙语(巴西)、西班牙语(墨西哥)和中文(繁体)**Bug修复**- 修正了坐在带边车的摩托车后面的乘客的相机抖动- 修正了坐在带边车的摩托车后面的乘客的相机抖动

输出

**语言**- 添加了四种语言:意大利语、葡萄牙语(巴西)、西班牙语(墨西哥)和中文(繁体)**Bug修复**- 修正了坐在带边车的摩托车后面的乘客的相机抖动- 修正了坐在带边车的摩托车后面的乘客的相机抖动

<小时>

说明

• (?:\h*\n){2,} 匹配任意数量的水平空白字符后跟换行符，两次或多次

其他方法

只是为了解释至少一种其他方法(并保留我原来的答案)

• (?:\n(?:[^\S\n]*(?=\n))?){2,} 匹配以下两次或多次
  • \n 匹配换行符
  • (?:[^\S\n]*(?=\n))? 匹配以下零次或一次
    • [^\S\n]* 匹配除 \n 之外的任何空白字符任意次数
    • (?=\n) 正向前瞻确保后面是换行 \n

Currently I have a regex that will take a given set of newlines and condense them. A challenge I need to solve for is to modify this regex (\n{2,}) so that it still will ignore spaces and tabs when searching for multiple newline characters.

https://regex101.com/r/dEhyN3/2 shows a good working example of what I'm referring to. There's a line that only contains a space which leads to too many new lines in the end result.

解决方案

Brief

This answer ensures whitespace at the start of a line is kept (if it contains something other than a whitespace character).

---

Code

See regex in use here

(?:\h*\n){2,}

Note: Some regex engines don't allow \h, so this will have to be replaced with [\t\p{Zs}], and if Unicode character classes are not supported, a simple list of each character such as [\t ] or [^\S\n].

Other methods:

(?:\n(?:[^\S\n]*(?=\n))?){2,}
(?:\n(?:\s*(?=\n))?){2,}
\h*\n(?:\h*\n)+

---

Results

Input

**Language**

 - Added four languages: Italian, Portuguese (Brazil), Spanish (Mexico) and Chinese (Traditional)





**Bug fixes**


 - Fixed camera jittering for passenger sitting on the back of a motorcycle with sidecar
 - Fixed camera jittering for passenger sitting on the back of a motorcycle with sidecar

Output

**Language**

 - Added four languages: Italian, Portuguese (Brazil), Spanish (Mexico) and Chinese (Traditional)

**Bug fixes**

 - Fixed camera jittering for passenger sitting on the back of a motorcycle with sidecar
 - Fixed camera jittering for passenger sitting on the back of a motorcycle with sidecar

---

Explanation

• (?:\h*\n){2,} Match any number of horizontal whitespace character followed by a line-feed, two or more times

Other methods

Just to explain at least one of the other methods (and keep my original answer)

• (?:\n(?:[^\S\n]*(?=\n))?){2,} Matches the following two or more times
  • \n Match a line-feed character
  • (?:[^\S\n]*(?=\n))? Match the following zero or one time
    • [^\S\n]* Match any whitespace character except \n any number of times
    • (?=\n) Positive lookahead ensuring what follows is a line-feed \n

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