Golang 正则表达式命名组和子匹配

Question

我正在尝试匹配正则表达式并获取匹配的捕获组名称。这在正则表达式只匹配字符串一次时有效，但如果匹配字符串不止一次，SubexpNames则不会返回重复的名称。

下面是一个例子：

package main

import (

    "fmt"

    "regexp"

)

func main() {

    re := regexp.MustCompile("(?P<first>[a-zA-Z]+) ")

    fmt.Printf("%q\n", re.SubexpNames())

    fmt.Printf("%q\n", re.FindAllStringSubmatch("Alan Turing ", -1))

}

输出是：

["" "first"]

[["Alan " "Alan"] ["Turing " "Turing"]]

是否可以获得每个子匹配的捕获组名称？

Answer 1

组名和位置是固定的：re := regexp.MustCompile("(?P<first>[a-zA-Z]+) ")groupNames := re.SubexpNames()for matchNum, match := range re.FindAllStringSubmatch("Alan Turing ", -1) {&nbsp; &nbsp; for groupIdx, group := range match {&nbsp; &nbsp; &nbsp; &nbsp; name := groupNames[groupIdx]&nbsp; &nbsp; &nbsp; &nbsp; if name == "" {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; name = "*"&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; fmt.Printf("#%d text: '%s', group: '%s'\n", matchNum, group, name)&nbsp; &nbsp; }}

Answer 2

这可能包含在 Go 1.14（2020 年第一季度，尚未确认）中。参见“提案：正则表达式：添加(*Regexp).SubexpIndex#32420 ”。更新：它已包含在 Go 1.15（2020 年 8 月）的commit 782fcb4中。// SubexpIndex returns the index of the first subexpression with the given name,// or else -1 if there is no subexpression with that name.//// Note that multiple subexpressions can be written using the same name, as in// (?P<bob>a+)(?P<bob>b+), which declares two subexpressions named "bob".// In this case SubexpIndex returns the index of the leftmost such subexpression// in the regular expression.func (*Regexp) SubexpIndex(name string) int这在CL 187919 中进行了讨论。re := regexp.MustCompile(`(?P<first>[a-zA-Z]+) (?P<last>[a-zA-Z]+)`)fmt.Println(re.MatchString("Alan Turing"))matches := re.FindStringSubmatch("Alan Turing")lastIndex := re.SubexpIndex("last")fmt.Printf("last => %d\n", lastIndex)fmt.Println(matches[lastIndex])// Output:// true// last => 2// Turing