I have a simple program in Go to aid in learning regular expressions. It runs in an infinite loop and has 2 channels, one which is used to provide input (input contains regex pattern and subject), and the second one, which provides the output.
usage: main.exe (cat)+ catcatdog
However there is propably something wrong in the code, as i can't seem to get any results with the $ modifier.
For example, i expect "cat" output from
main.exe cat$ cat
dog
yet receive zero results.
Code:
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('
')
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
}
