如何在Golang正则表达式中捕获组功能？ [英] How to get capturing group functionality in Golang regular expressions?

问题描述

我从Ruby to Go移植一个库，刚刚发现Ruby中的正则表达式与Go（google RE2）不兼容。我注意到Ruby& Java（加上其他语言使用PCRE正则表达式（Perl兼容，支持捕获组）），所以我需要重写我的表达式，以便它们在Go中编译成功。

<例如，我有以下正则表达式：

 `（？< Year> \d {4}） - （？< Month> \d {2}） - （？< Day> \d {2}）`
  

这应该接受以下输入：

  2001-01-20 
  

捕获组允许将年，月和日捕获到变量中。为了获得每个组的价值，这很容易;您只需使用组名称将返回的匹配数据编入索引并将值返回。所以，例如为了得到年份，就像这样的伪代码：

  m = expression.Match（2001-01- 20）
 year = m [Year] 
  

这是我使用的模式很多我的表达式，所以我有很多重写要做。

那么，有没有办法在Go regexp中获得这种功能;我应该如何重写这些表达式？

解决方案

我应该如何重写这些表达式？

按照这里：

 （？P   

使用 re.SubexpNames（）。

交叉引用捕获组名称并使用如下：

 <$ c 
 
 
 $ f 
 
 
 
 
 
 
 
 
 
 $ b $ func main（）{$ b $ （？P< Year> \d {4}） - （？P  fmt.Printf（％＃v\\\
，r.FindStringSubmatch（`2015-05-27`））
 fmt.Printf（％＃v\\\
，r。 SubexpNames（））
} 
  

I'm porting a library from Ruby to Go, and have just discovered that regular expressions in Ruby are not compatible with Go (google RE2). It's come to my attention that Ruby & Java (plus other languages use PCRE regular expressions (perl compatible, which supports capturing groups)), so I need to re-write my expressions so that they compile ok in Go.

For example, I have the following regex:

`(?<Year>\d{4})-(?<Month>\d{2})-(?<Day>\d{2})`

This should accept input such as:

2001-01-20

The capturing groups allow the year, month and day to be captured into variables. To get the value of each group, it's very easy; you just index into the returned matched data with the group name and you get the value back. So, for example to get the year, something like this pseudo code:

m=expression.Match("2001-01-20")
year = m["Year"]

This is a pattern I use a lot in my expressions, so I have a lot of re-writing to do.

So, is there a way to get this kind of functionality in Go regexp; how should I re-write these expressions?

解决方案

how should I re-write these expressions?

Add some Ps, as defined here:

(?P<Year>\d{4})-(?P<Month>\d{2})-(?P<Day>\d{2})

Cross reference capture group names with re.SubexpNames().

And use as follows:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    r := regexp.MustCompile(`(?P<Year>\d{4})-(?P<Month>\d{2})-(?P<Day>\d{2})`)
    fmt.Printf("%#v\n", r.FindStringSubmatch(`2015-05-27`))
    fmt.Printf("%#v\n", r.SubexpNames())
}

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