Capturing repeating groups in GO











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2
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I'm trying to create a function that can parse strings which consist of an uppercase word followed by zero or more arguments which are encapsulated in double quotes.



For example, each of the following lines:



COPY "filename one" "filename two"
REMOVE "filename"
LIST "x" "y" "z"
DISCONNECT


The result should be a string (the command) followed by a string (the arguments inside the quotes). I created the following regular expression:



re1, _ := regexp.Compile(`([A-Z]+)(?: "([^"]+)")*`)
results := re1.FindAllStringSubmatch(input, -1)


However, no-matter what I try, only the last argument gets captured.



An example of my problem: https://play.golang.org/p/W1rE1X4SWf5



"arg1" is not captured in this example. What am I missing?










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  • Could a command (without considering args) contain white space?
    – Ehsan.Saradar
    Nov 22 at 15:57















up vote
2
down vote

favorite












I'm trying to create a function that can parse strings which consist of an uppercase word followed by zero or more arguments which are encapsulated in double quotes.



For example, each of the following lines:



COPY "filename one" "filename two"
REMOVE "filename"
LIST "x" "y" "z"
DISCONNECT


The result should be a string (the command) followed by a string (the arguments inside the quotes). I created the following regular expression:



re1, _ := regexp.Compile(`([A-Z]+)(?: "([^"]+)")*`)
results := re1.FindAllStringSubmatch(input, -1)


However, no-matter what I try, only the last argument gets captured.



An example of my problem: https://play.golang.org/p/W1rE1X4SWf5



"arg1" is not captured in this example. What am I missing?










share|improve this question
























  • Could a command (without considering args) contain white space?
    – Ehsan.Saradar
    Nov 22 at 15:57













up vote
2
down vote

favorite









up vote
2
down vote

favorite











I'm trying to create a function that can parse strings which consist of an uppercase word followed by zero or more arguments which are encapsulated in double quotes.



For example, each of the following lines:



COPY "filename one" "filename two"
REMOVE "filename"
LIST "x" "y" "z"
DISCONNECT


The result should be a string (the command) followed by a string (the arguments inside the quotes). I created the following regular expression:



re1, _ := regexp.Compile(`([A-Z]+)(?: "([^"]+)")*`)
results := re1.FindAllStringSubmatch(input, -1)


However, no-matter what I try, only the last argument gets captured.



An example of my problem: https://play.golang.org/p/W1rE1X4SWf5



"arg1" is not captured in this example. What am I missing?










share|improve this question















I'm trying to create a function that can parse strings which consist of an uppercase word followed by zero or more arguments which are encapsulated in double quotes.



For example, each of the following lines:



COPY "filename one" "filename two"
REMOVE "filename"
LIST "x" "y" "z"
DISCONNECT


The result should be a string (the command) followed by a string (the arguments inside the quotes). I created the following regular expression:



re1, _ := regexp.Compile(`([A-Z]+)(?: "([^"]+)")*`)
results := re1.FindAllStringSubmatch(input, -1)


However, no-matter what I try, only the last argument gets captured.



An example of my problem: https://play.golang.org/p/W1rE1X4SWf5



"arg1" is not captured in this example. What am I missing?







regex go






share|improve this question















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edited Nov 22 at 16:21









mrzasa

8,054103778




8,054103778










asked Nov 22 at 15:40









Xatoo

2,2312143




2,2312143












  • Could a command (without considering args) contain white space?
    – Ehsan.Saradar
    Nov 22 at 15:57


















  • Could a command (without considering args) contain white space?
    – Ehsan.Saradar
    Nov 22 at 15:57
















Could a command (without considering args) contain white space?
– Ehsan.Saradar
Nov 22 at 15:57




Could a command (without considering args) contain white space?
– Ehsan.Saradar
Nov 22 at 15:57












4 Answers
4






active

oldest

votes

















up vote
2
down vote



accepted










If your commands are well defined, e.i. command names are always upper-case and arguments are always after the command then a looser regex might just fit your use case:



re1, _ := regexp.Compile(`([A-Z]+)|(?: "([^"]+)")`)
results := re1.FindAllStringSubmatch(`COMMAND "arg1" "arg2" "arg3"`, -1)

fmt.Println("Command:", results[0][1])
for _, arg := range results[1:] {
fmt.Println("Arg:", arg[2])
}


Playground






share|improve this answer























  • Awesome, this implementation works for me!
    – Xatoo
    Nov 22 at 17:00










  • Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
    – Wiktor Stribiżew
    Nov 22 at 17:25




















up vote
1
down vote













When you try to capture repeated match, only the last one is captured.
I'd try to do it in two steps: first split commmand and arguments, then parse the arguments.



Splitting to command and arguments can be done with ([A-Z]+)((?: "[^"]+")*) (demo):





  • ([A-Z]+) in first group, you get the command


  • ((?: "[^"]+")*) in the second group, you'll get arguments in quotes, separated by spaces


Then you can use FindAllString with "([^"]+)" to extract arguments (demo).






share|improve this answer




























    up vote
    1
    down vote













    I think this may solve your problem



    re1, _ := regexp.Compile(`([A-Z]+)(?: *)`)
    commandText:=`COPY "filename one" "filename two"`
    if re1.Match(byte(commandText)){
    index:=re1.FindIndex(byte(commandText))[1]
    commandArgs:=commandText[index:]
    commandArgsRegex,_:=regexp.Compile(`"([^"]+)"`)
    fmt.Println("Command= " , commandText[0:index])
    for i,arg:=range commandArgsRegex.FindAllString(commandArgs,-1){
    fmt.Println("args ", i,"= " , arg)
    }
    }else{
    fmt.Println("Failed")
    }





    share|improve this answer




























      up vote
      0
      down vote













      Add an extra capture group. If you make it optional extra data will be empty but the match will work



      re1, _ := regexp.Compile(`^([A-Z]+)(s"[^"]+")(s"[^"]+")?(s"[^"]+")?$`)


      Add more (s"[^"]+")? expressions up to the maximum you need. I put in two as there is an expression with 3 parameters in your examples






      share|improve this answer





















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        4 Answers
        4






        active

        oldest

        votes








        4 Answers
        4






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes








        up vote
        2
        down vote



        accepted










        If your commands are well defined, e.i. command names are always upper-case and arguments are always after the command then a looser regex might just fit your use case:



        re1, _ := regexp.Compile(`([A-Z]+)|(?: "([^"]+)")`)
        results := re1.FindAllStringSubmatch(`COMMAND "arg1" "arg2" "arg3"`, -1)

        fmt.Println("Command:", results[0][1])
        for _, arg := range results[1:] {
        fmt.Println("Arg:", arg[2])
        }


        Playground






        share|improve this answer























        • Awesome, this implementation works for me!
          – Xatoo
          Nov 22 at 17:00










        • Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
          – Wiktor Stribiżew
          Nov 22 at 17:25

















        up vote
        2
        down vote



        accepted










        If your commands are well defined, e.i. command names are always upper-case and arguments are always after the command then a looser regex might just fit your use case:



        re1, _ := regexp.Compile(`([A-Z]+)|(?: "([^"]+)")`)
        results := re1.FindAllStringSubmatch(`COMMAND "arg1" "arg2" "arg3"`, -1)

        fmt.Println("Command:", results[0][1])
        for _, arg := range results[1:] {
        fmt.Println("Arg:", arg[2])
        }


        Playground






        share|improve this answer























        • Awesome, this implementation works for me!
          – Xatoo
          Nov 22 at 17:00










        • Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
          – Wiktor Stribiżew
          Nov 22 at 17:25















        up vote
        2
        down vote



        accepted







        up vote
        2
        down vote



        accepted






        If your commands are well defined, e.i. command names are always upper-case and arguments are always after the command then a looser regex might just fit your use case:



        re1, _ := regexp.Compile(`([A-Z]+)|(?: "([^"]+)")`)
        results := re1.FindAllStringSubmatch(`COMMAND "arg1" "arg2" "arg3"`, -1)

        fmt.Println("Command:", results[0][1])
        for _, arg := range results[1:] {
        fmt.Println("Arg:", arg[2])
        }


        Playground






        share|improve this answer














        If your commands are well defined, e.i. command names are always upper-case and arguments are always after the command then a looser regex might just fit your use case:



        re1, _ := regexp.Compile(`([A-Z]+)|(?: "([^"]+)")`)
        results := re1.FindAllStringSubmatch(`COMMAND "arg1" "arg2" "arg3"`, -1)

        fmt.Println("Command:", results[0][1])
        for _, arg := range results[1:] {
        fmt.Println("Arg:", arg[2])
        }


        Playground







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 22 at 16:23

























        answered Nov 22 at 16:15









        ssemilla

        3,077424




        3,077424












        • Awesome, this implementation works for me!
          – Xatoo
          Nov 22 at 17:00










        • Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
          – Wiktor Stribiżew
          Nov 22 at 17:25




















        • Awesome, this implementation works for me!
          – Xatoo
          Nov 22 at 17:00










        • Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
          – Wiktor Stribiżew
          Nov 22 at 17:25


















        Awesome, this implementation works for me!
        – Xatoo
        Nov 22 at 17:00




        Awesome, this implementation works for me!
        – Xatoo
        Nov 22 at 17:00












        Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
        – Wiktor Stribiżew
        Nov 22 at 17:25






        Probably, regexp.Compile(`^([A-Z]+)| "([^"]+)"`) will be more precise as it matches the command at the start of string only.
        – Wiktor Stribiżew
        Nov 22 at 17:25














        up vote
        1
        down vote













        When you try to capture repeated match, only the last one is captured.
        I'd try to do it in two steps: first split commmand and arguments, then parse the arguments.



        Splitting to command and arguments can be done with ([A-Z]+)((?: "[^"]+")*) (demo):





        • ([A-Z]+) in first group, you get the command


        • ((?: "[^"]+")*) in the second group, you'll get arguments in quotes, separated by spaces


        Then you can use FindAllString with "([^"]+)" to extract arguments (demo).






        share|improve this answer

























          up vote
          1
          down vote













          When you try to capture repeated match, only the last one is captured.
          I'd try to do it in two steps: first split commmand and arguments, then parse the arguments.



          Splitting to command and arguments can be done with ([A-Z]+)((?: "[^"]+")*) (demo):





          • ([A-Z]+) in first group, you get the command


          • ((?: "[^"]+")*) in the second group, you'll get arguments in quotes, separated by spaces


          Then you can use FindAllString with "([^"]+)" to extract arguments (demo).






          share|improve this answer























            up vote
            1
            down vote










            up vote
            1
            down vote









            When you try to capture repeated match, only the last one is captured.
            I'd try to do it in two steps: first split commmand and arguments, then parse the arguments.



            Splitting to command and arguments can be done with ([A-Z]+)((?: "[^"]+")*) (demo):





            • ([A-Z]+) in first group, you get the command


            • ((?: "[^"]+")*) in the second group, you'll get arguments in quotes, separated by spaces


            Then you can use FindAllString with "([^"]+)" to extract arguments (demo).






            share|improve this answer












            When you try to capture repeated match, only the last one is captured.
            I'd try to do it in two steps: first split commmand and arguments, then parse the arguments.



            Splitting to command and arguments can be done with ([A-Z]+)((?: "[^"]+")*) (demo):





            • ([A-Z]+) in first group, you get the command


            • ((?: "[^"]+")*) in the second group, you'll get arguments in quotes, separated by spaces


            Then you can use FindAllString with "([^"]+)" to extract arguments (demo).







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Nov 22 at 16:05









            mrzasa

            8,054103778




            8,054103778






















                up vote
                1
                down vote













                I think this may solve your problem



                re1, _ := regexp.Compile(`([A-Z]+)(?: *)`)
                commandText:=`COPY "filename one" "filename two"`
                if re1.Match(byte(commandText)){
                index:=re1.FindIndex(byte(commandText))[1]
                commandArgs:=commandText[index:]
                commandArgsRegex,_:=regexp.Compile(`"([^"]+)"`)
                fmt.Println("Command= " , commandText[0:index])
                for i,arg:=range commandArgsRegex.FindAllString(commandArgs,-1){
                fmt.Println("args ", i,"= " , arg)
                }
                }else{
                fmt.Println("Failed")
                }





                share|improve this answer

























                  up vote
                  1
                  down vote













                  I think this may solve your problem



                  re1, _ := regexp.Compile(`([A-Z]+)(?: *)`)
                  commandText:=`COPY "filename one" "filename two"`
                  if re1.Match(byte(commandText)){
                  index:=re1.FindIndex(byte(commandText))[1]
                  commandArgs:=commandText[index:]
                  commandArgsRegex,_:=regexp.Compile(`"([^"]+)"`)
                  fmt.Println("Command= " , commandText[0:index])
                  for i,arg:=range commandArgsRegex.FindAllString(commandArgs,-1){
                  fmt.Println("args ", i,"= " , arg)
                  }
                  }else{
                  fmt.Println("Failed")
                  }





                  share|improve this answer























                    up vote
                    1
                    down vote










                    up vote
                    1
                    down vote









                    I think this may solve your problem



                    re1, _ := regexp.Compile(`([A-Z]+)(?: *)`)
                    commandText:=`COPY "filename one" "filename two"`
                    if re1.Match(byte(commandText)){
                    index:=re1.FindIndex(byte(commandText))[1]
                    commandArgs:=commandText[index:]
                    commandArgsRegex,_:=regexp.Compile(`"([^"]+)"`)
                    fmt.Println("Command= " , commandText[0:index])
                    for i,arg:=range commandArgsRegex.FindAllString(commandArgs,-1){
                    fmt.Println("args ", i,"= " , arg)
                    }
                    }else{
                    fmt.Println("Failed")
                    }





                    share|improve this answer












                    I think this may solve your problem



                    re1, _ := regexp.Compile(`([A-Z]+)(?: *)`)
                    commandText:=`COPY "filename one" "filename two"`
                    if re1.Match(byte(commandText)){
                    index:=re1.FindIndex(byte(commandText))[1]
                    commandArgs:=commandText[index:]
                    commandArgsRegex,_:=regexp.Compile(`"([^"]+)"`)
                    fmt.Println("Command= " , commandText[0:index])
                    for i,arg:=range commandArgsRegex.FindAllString(commandArgs,-1){
                    fmt.Println("args ", i,"= " , arg)
                    }
                    }else{
                    fmt.Println("Failed")
                    }






                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered Nov 22 at 16:10









                    Ehsan.Saradar

                    45337




                    45337






















                        up vote
                        0
                        down vote













                        Add an extra capture group. If you make it optional extra data will be empty but the match will work



                        re1, _ := regexp.Compile(`^([A-Z]+)(s"[^"]+")(s"[^"]+")?(s"[^"]+")?$`)


                        Add more (s"[^"]+")? expressions up to the maximum you need. I put in two as there is an expression with 3 parameters in your examples






                        share|improve this answer

























                          up vote
                          0
                          down vote













                          Add an extra capture group. If you make it optional extra data will be empty but the match will work



                          re1, _ := regexp.Compile(`^([A-Z]+)(s"[^"]+")(s"[^"]+")?(s"[^"]+")?$`)


                          Add more (s"[^"]+")? expressions up to the maximum you need. I put in two as there is an expression with 3 parameters in your examples






                          share|improve this answer























                            up vote
                            0
                            down vote










                            up vote
                            0
                            down vote









                            Add an extra capture group. If you make it optional extra data will be empty but the match will work



                            re1, _ := regexp.Compile(`^([A-Z]+)(s"[^"]+")(s"[^"]+")?(s"[^"]+")?$`)


                            Add more (s"[^"]+")? expressions up to the maximum you need. I put in two as there is an expression with 3 parameters in your examples






                            share|improve this answer












                            Add an extra capture group. If you make it optional extra data will be empty but the match will work



                            re1, _ := regexp.Compile(`^([A-Z]+)(s"[^"]+")(s"[^"]+")?(s"[^"]+")?$`)


                            Add more (s"[^"]+")? expressions up to the maximum you need. I put in two as there is an expression with 3 parameters in your examples







                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered Nov 22 at 16:25









                            Vorsprung

                            22.1k31941




                            22.1k31941






























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