Regex Named Groups in Java

Question

It is my understanding that the java regex package does not have support for named groups  http   www regular-expressions info named html  so can anyone point me towards a third-party library that does   I ve looked at jregex but its last release was in 2002 and it didn t work for me  admittedly I only tried briefly  under java5

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A bit old question but I found myself needing this also and that the suggestions above were inaduquate - and as such - developed a thin wrapper myself  https   github com hofmeister MatchIt

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For those running pre-java7  named groups are supported by joni  Java port of the Oniguruma regexp library    Documentation is sparse  but it has worked well for us  Binaries are available via Maven  http   repository codehaus org org jruby joni joni

User · Answer

A bit old question but I found myself needing this also and that the suggestions above were inaduquate - and as such - developed a thin wrapper myself  https   github com hofmeister MatchIt

User · Answer

Update  August 2011   As geofflane mentions in his answer  Java 7 now support named groups  tchrist points out in the comment that the support is limited  He details the limitations in his great answer  Java Regex Helper     Java 7 regex named group support was presented back in September 2010 in Oracle s blog   In the official release of Java 7  the constructs to support the named capturing group are            lt name gt capturing text  to define a named group  name     k lt name gt  to backreference a named group  name      name  to reference to captured group in Matcher s replacement string   Matcher group String name  to return the captured input subsequence by the given  named group          Other alternatives for pre-Java 7 were    Google named-regex  see John Hardy s answer  G  bor Lipt  k mentions  November 2012  that this project might not be active  with several outstanding bugs   and its GitHub fork could be considered instead  jregex  See Brian Clozel s answer       Original answer  Jan 2009  with the next two links now broken   You can not refer to named group  unless you code your own version of Regex     That is precisely what Gorbush2 did in this thread   Regex2   limited implementation  as pointed out again by tchrist  as it looks only for ASCII identifiers  tchrist details the limitation as      only being able to have one named group per same name  which you don   t always have control over   and not being able to use them for in-regex recursion    Note  You can find true regex recursion examples in Perl and PCRE regexes  as mentioned in Regexp Power  PCRE specs and Matching Strings with Balanced Parentheses slide   Example   String    TEST 123    RegExp       lt login gt   w      lt id gt   d      Access  matcher group 1     gt  TEST matcher group  login      gt  TEST matcher name 1     gt  login   Replace  matcher replaceAll  aaaaa  1 sssss  2          gt  aaaaa TEST sssss 123     matcher replaceAll  aaaaa   login  sssss   id           gt  aaaaa TEST sssss 123           extract from the implementation   public final class Pattern     implements java io Serializable                        Parses a group and returns the head node of a set of nodes that process        the group  Sometimes a double return system is used where the tail is        returned in root              private Node group0             boolean capturingGroup   false          Node head   null          Node tail   null          int save   flags          root   null          int ch   next            if  ch                       ch   skip                switch  ch                 case   lt            lt xxx   look behind or group name                 ch   read                    int start   cursor                           test forGroupName                 int startChar   ch                  while ASCII isWord ch   amp  amp  ch      gt    ch read                    if ch      gt                            valid group name                     int len   cursor-start                      int   newtemp   new int 2  len    2                         System arraycopy temp  start  newtemp  0  len                       StringBuilder name   new StringBuilder                        for int i   start  i lt  cursor  i                             name append  char temp i-1                                                 create Named group                     head   createGroup false                         GroupTail root  name   name toString                         capturingGroup   true                      tail   root                      head next   expr tail                       break

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Update  August 2011   As geofflane mentions in his answer  Java 7 now support named groups  tchrist points out in the comment that the support is limited  He details the limitations in his great answer  Java Regex Helper     Java 7 regex named group support was presented back in September 2010 in Oracle s blog   In the official release of Java 7  the constructs to support the named capturing group are            lt name gt capturing text  to define a named group  name     k lt name gt  to backreference a named group  name      name  to reference to captured group in Matcher s replacement string   Matcher group String name  to return the captured input subsequence by the given  named group          Other alternatives for pre-Java 7 were    Google named-regex  see John Hardy s answer  G  bor Lipt  k mentions  November 2012  that this project might not be active  with several outstanding bugs   and its GitHub fork could be considered instead  jregex  See Brian Clozel s answer       Original answer  Jan 2009  with the next two links now broken   You can not refer to named group  unless you code your own version of Regex     That is precisely what Gorbush2 did in this thread   Regex2   limited implementation  as pointed out again by tchrist  as it looks only for ASCII identifiers  tchrist details the limitation as      only being able to have one named group per same name  which you don   t always have control over   and not being able to use them for in-regex recursion    Note  You can find true regex recursion examples in Perl and PCRE regexes  as mentioned in Regexp Power  PCRE specs and Matching Strings with Balanced Parentheses slide   Example   String    TEST 123    RegExp       lt login gt   w      lt id gt   d      Access  matcher group 1     gt  TEST matcher group  login      gt  TEST matcher name 1     gt  login   Replace  matcher replaceAll  aaaaa  1 sssss  2          gt  aaaaa TEST sssss 123     matcher replaceAll  aaaaa   login  sssss   id           gt  aaaaa TEST sssss 123           extract from the implementation   public final class Pattern     implements java io Serializable                        Parses a group and returns the head node of a set of nodes that process        the group  Sometimes a double return system is used where the tail is        returned in root              private Node group0             boolean capturingGroup   false          Node head   null          Node tail   null          int save   flags          root   null          int ch   next            if  ch                       ch   skip                switch  ch                 case   lt            lt xxx   look behind or group name                 ch   read                    int start   cursor                           test forGroupName                 int startChar   ch                  while ASCII isWord ch   amp  amp  ch      gt    ch read                    if ch      gt                            valid group name                     int len   cursor-start                      int   newtemp   new int 2  len    2                         System arraycopy temp  start  newtemp  0  len                       StringBuilder name   new StringBuilder                        for int i   start  i lt  cursor  i                             name append  char temp i-1                                                 create Named group                     head   createGroup false                         GroupTail root  name   name toString                         capturingGroup   true                      tail   root                      head next   expr tail                       break

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Yes but its messy hacking the sun classes  There is a simpler way   http   code google com p named-regexp      named-regexp is a thin wrapper for the   standard JDK regular expressions   implementation  with the single   purpose of handling named capturing   groups in the  net style                  It can be used with Java 5 and 6    generics are used        Java 7 will handle named capturing   groups   so this project is not meant   to last

User · Answer

Update  August 2011   As geofflane mentions in his answer  Java 7 now support named groups  tchrist points out in the comment that the support is limited  He details the limitations in his great answer  Java Regex Helper     Java 7 regex named group support was presented back in September 2010 in Oracle s blog   In the official release of Java 7  the constructs to support the named capturing group are            lt name gt capturing text  to define a named group  name     k lt name gt  to backreference a named group  name      name  to reference to captured group in Matcher s replacement string   Matcher group String name  to return the captured input subsequence by the given  named group          Other alternatives for pre-Java 7 were    Google named-regex  see John Hardy s answer  G  bor Lipt  k mentions  November 2012  that this project might not be active  with several outstanding bugs   and its GitHub fork could be considered instead  jregex  See Brian Clozel s answer       Original answer  Jan 2009  with the next two links now broken   You can not refer to named group  unless you code your own version of Regex     That is precisely what Gorbush2 did in this thread   Regex2   limited implementation  as pointed out again by tchrist  as it looks only for ASCII identifiers  tchrist details the limitation as      only being able to have one named group per same name  which you don   t always have control over   and not being able to use them for in-regex recursion    Note  You can find true regex recursion examples in Perl and PCRE regexes  as mentioned in Regexp Power  PCRE specs and Matching Strings with Balanced Parentheses slide   Example   String    TEST 123    RegExp       lt login gt   w      lt id gt   d      Access  matcher group 1     gt  TEST matcher group  login      gt  TEST matcher name 1     gt  login   Replace  matcher replaceAll  aaaaa  1 sssss  2          gt  aaaaa TEST sssss 123     matcher replaceAll  aaaaa   login  sssss   id           gt  aaaaa TEST sssss 123           extract from the implementation   public final class Pattern     implements java io Serializable                        Parses a group and returns the head node of a set of nodes that process        the group  Sometimes a double return system is used where the tail is        returned in root              private Node group0             boolean capturingGroup   false          Node head   null          Node tail   null          int save   flags          root   null          int ch   next            if  ch                       ch   skip                switch  ch                 case   lt            lt xxx   look behind or group name                 ch   read                    int start   cursor                           test forGroupName                 int startChar   ch                  while ASCII isWord ch   amp  amp  ch      gt    ch read                    if ch      gt                            valid group name                     int len   cursor-start                      int   newtemp   new int 2  len    2                         System arraycopy temp  start  newtemp  0  len                       StringBuilder name   new StringBuilder                        for int i   start  i lt  cursor  i                             name append  char temp i-1                                                 create Named group                     head   createGroup false                         GroupTail root  name   name toString                         capturingGroup   true                      tail   root                      head next   expr tail                       break

User · Answer

For people coming to this late  Java 7 adds named groups  Matcher group String groupName  documentation

User · Answer

For people coming to this late  Java 7 adds named groups  Matcher group String groupName  documentation

User · Answer

What kind of problem do you get with jregex  It worked well for me under java5 and java6   Jregex does the job well  even if the last version is from 2002   unless you want to wait for javaSE 7

User · Answer

For those running pre-java7  named groups are supported by joni  Java port of the Oniguruma regexp library    Documentation is sparse  but it has worked well for us  Binaries are available via Maven  http   repository codehaus org org jruby joni joni

User · Answer

Update  August 2011   As geofflane mentions in his answer  Java 7 now support named groups  tchrist points out in the comment that the support is limited  He details the limitations in his great answer  Java Regex Helper     Java 7 regex named group support was presented back in September 2010 in Oracle s blog   In the official release of Java 7  the constructs to support the named capturing group are            lt name gt capturing text  to define a named group  name     k lt name gt  to backreference a named group  name      name  to reference to captured group in Matcher s replacement string   Matcher group String name  to return the captured input subsequence by the given  named group          Other alternatives for pre-Java 7 were    Google named-regex  see John Hardy s answer  G  bor Lipt  k mentions  November 2012  that this project might not be active  with several outstanding bugs   and its GitHub fork could be considered instead  jregex  See Brian Clozel s answer       Original answer  Jan 2009  with the next two links now broken   You can not refer to named group  unless you code your own version of Regex     That is precisely what Gorbush2 did in this thread   Regex2   limited implementation  as pointed out again by tchrist  as it looks only for ASCII identifiers  tchrist details the limitation as      only being able to have one named group per same name  which you don   t always have control over   and not being able to use them for in-regex recursion    Note  You can find true regex recursion examples in Perl and PCRE regexes  as mentioned in Regexp Power  PCRE specs and Matching Strings with Balanced Parentheses slide   Example   String    TEST 123    RegExp       lt login gt   w      lt id gt   d      Access  matcher group 1     gt  TEST matcher group  login      gt  TEST matcher name 1     gt  login   Replace  matcher replaceAll  aaaaa  1 sssss  2          gt  aaaaa TEST sssss 123     matcher replaceAll  aaaaa   login  sssss   id           gt  aaaaa TEST sssss 123           extract from the implementation   public final class Pattern     implements java io Serializable                        Parses a group and returns the head node of a set of nodes that process        the group  Sometimes a double return system is used where the tail is        returned in root              private Node group0             boolean capturingGroup   false          Node head   null          Node tail   null          int save   flags          root   null          int ch   next            if  ch                       ch   skip                switch  ch                 case   lt            lt xxx   look behind or group name                 ch   read                    int start   cursor                           test forGroupName                 int startChar   ch                  while ASCII isWord ch   amp  amp  ch      gt    ch read                    if ch      gt                            valid group name                     int len   cursor-start                      int   newtemp   new int 2  len    2                         System arraycopy temp  start  newtemp  0  len                       StringBuilder name   new StringBuilder                        for int i   start  i lt  cursor  i                             name append  char temp i-1                                                 create Named group                     head   createGroup false                         GroupTail root  name   name toString                         capturingGroup   true                      tail   root                      head next   expr tail                       break

User · Answer

Yes but its messy hacking the sun classes  There is a simpler way   http   code google com p named-regexp      named-regexp is a thin wrapper for the   standard JDK regular expressions   implementation  with the single   purpose of handling named capturing   groups in the  net style                  It can be used with Java 5 and 6    generics are used        Java 7 will handle named capturing   groups   so this project is not meant   to last

User · Answer

What kind of problem do you get with jregex  It worked well for me under java5 and java6   Jregex does the job well  even if the last version is from 2002   unless you want to wait for javaSE 7

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