正则表达式结束修饰符不在 Go 程序中返回结果

Question

我有一个简单的 Go 程序来帮助学习正则表达式。它在无限循环中运行并有 2 个 channel ，一个用于提供输入(输入包含正则表达式模式和主题)，第二个 channel 提供输出。

usage: main.exe (cat)+ catcatdog

但是代码中可能有问题，因为我似乎无法使用 $ 修饰符获得任何结果。

例如，我希望输出“cat”

main.exe cat$ cat\ndog

但收到零结果。

代码:

package main

import (
    "fmt"
    "regexp"
    "bufio"
    "os"
    "strings"
)

type RegexRequest struct {
    regex string
    subject string
}

func main() {
    regexRequests := make(chan *RegexRequest)
    defer close(regexRequests)

    regexAnswers, err := createResolver(regexRequests)
    defer close(regexAnswers)
    if(err != nil) { // TODO: Panics when exited via ctrl+c
        panic(err)
    }

    interact(regexRequests, regexAnswers)
}

func interact(regexRequests chan *RegexRequest, regexAnswers chan []string) {
    for {
        fmt.Println("Enter regex and subject: ")
        reader := bufio.NewReader(os.Stdin)

        line, err := reader.ReadString('\n')
        if(err != nil) {
            panic(err)
        }

        regAndString := strings.SplitN(line, " ", 2);
        if len(regAndString) != 2 {
            fmt.Println("Invalid input, expected [regex][space][subject]")
            continue
        }

        regexRequests <- &RegexRequest{ regAndString[0], regAndString[1] }
        result := <- regexAnswers
        var filteredResult []string
        for _, element := range result {
            if(element != "") {
                filteredResult = append(filteredResult, element)
            } else {
                filteredResult = append(filteredResult, "EMPTY");
            }
        }

        fmt.Println(strings.Join(filteredResult, " "))
    }
}

func createResolver(inputChan chan *RegexRequest)(outputChan chan []string, err error) {
    if(cap(inputChan) > 0) {
        return nil, fmt.Errorf("Expected an unbuffered channel")
    }

    outputChan = make(chan []string)
    err = nil

    go func() {
        for {
            var regReq *RegexRequest= (<- inputChan);
            var regex *regexp.Regexp = regexp.MustCompile(regReq.regex)
            outputChan <- regex.FindAllString(regReq.subject, -1)
        }
    }()

    return
}

Answer 1

检查您的 regex 模式。例如，

Enter regex and subject: 
cat$ cat\ndog

Enter regex and subject: 
^cat cat\ndog         
cat