Re: need help with a Perl regular expression

perlrequick, perlintro, Re^3: My Favourite Regex Tools (Was: Parsing a Variable Format String)

#~ two digits,
#~ followed by a dash,
#~ followed by an optional digit,
#~ followed by four digits 
use Regexp::English;
my $re = Regexp::English
                -> new
                -> digit
                -> digit
                -> literal('-')
                -> optional
                    -> digit
                -> end
                -> digit
                -> digit
                -> digit
                -> digit;
print $re;
__END__
(?^:\d\d\-(?:\d?)\d\d\d\d)
[download]

rxrx describes the regex

\d             Match a digit

\d             Match a digit

\-             Match a literal '-' character

(?:            The start of a non-capturing group

  \d?            Match a digit, one-or-zero times (as many as possible
+)

)              The end of non-capturing group

\d             Match a digit

\d             Match a digit

\d             Match a digit

\d             Match a digit
[download]

wxPPIxregexplain.pl / ppixregexplain.pl says

# my $regstr = join '', ; # The regular expression (PPI::Token::Regexp::Match): ; #
# /(?^:\d\d\-(?:\d?)\d\d\d\d)/
#
# matches as follows:
#r: PPIx::Regexp / PPI::Token::Regexp::Match
#r= "/(?^:\\d\\d\\-(?:\\d?)\\d\\d\\d\\d)/"
#

"",

# address=/1/C0 ; xRe::Token::Structure ; Represent structural elements.
#"",
# ------------------------------------------------------------------

# # address=/1/C1 ; xRe::Structure::Regexp ; Represent the top-level regular expression
# perl_version_introduced=5.013006
# ------

            "/",

# address=/1/C1/S0 ; xRe::Token::Delimiter ; Represent the delimiters of the regular expression
#"/",
# ------------------------------------------------------------------

# # address=/1/C1/C0 ; xRe::Structure::Modifier ; Represent modifying parentheses
# group but do not capture; Basic clustering
# perl_version_introduced=5.013006
# ------------

                  "(",

# address=/1/C1/C0/S0 ; xRe::Token::Structure ; Represent structural elements.
#"(",
# ------------------------------------------------------------------

                    "?^:",

# # address=/1/C1/C0/T0 ; xRe::Token::GroupType::Modifier ; Represent the modifiers in a modifier group.
# perl_version_introduced=5.013006
# mods( match_semantics = d x = 0 m = 0 s = 0 i = 0 )
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"?^:",
# ------------------------------------------------------------------

                      "\\d",

# # address=/1/C1/C0/C0 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                      "\\d",

# # address=/1/C1/C0/C1 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                      "\\-",

# # address=/1/C1/C0/C2 ; xRe::Token::Literal ; a literal character
# ordinal= ord( chr( 45 ) ) alias \N{U+002D} alias \055 alias HYPHEN-MINUS alias -
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\-",
# ------------------------------------------------------------------

# # address=/1/C1/C0/C3 ; xRe::Structure::Modifier ; Represent modifying parentheses
# group but do not capture; Basic clustering
# ------------------

                        "(",

# address=/1/C1/C0/C3/S0 ; xRe::Token::Structure ; Represent structural elements.
#"(",
# ------------------------------------------------------------------

                          "?:",

# address=/1/C1/C0/C3/T0 ; xRe::Token::GroupType::Modifier ; Represent the modifiers in a modifier group.
#"?:",
# ------------------------------------------------------------------

                            "\\d",

# # address=/1/C1/C0/C3/C0 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
# (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
# (?d) is the old, problematic, pre-5.14 Default character set behavior. Its only use is to force that old behavior.
#"\\d",
# ----------------------

                            "?",

# # address=/1/C1/C0/C3/C1 ; xRe::Token::Quantifier ; Represent an atomic quantifier.
# match preceding pattern 0 or 1 times; is optional
# (matching the most amount possible)
# match the preceding pattern at address=/1/C1/C0/C3/C0
#"?",
# ----------------------

                        ")",

# address=/1/C1/C0/C3/F0 ; xRe::Token::Structure ; Represent structural elements.
#")",
# ------------------------------------------------------------------

                      "\\d",

# # address=/1/C1/C0/C4 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                      "\\d",

# # address=/1/C1/C0/C5 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                      "\\d",

# # address=/1/C1/C0/C6 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                      "\\d",

# # address=/1/C1/C0/C7 ; xRe::Token::CharClass::Simple ; This class represents a simple character class
# \d Match a decimal digit character.
# [0-9]
# L<perldebguts/DIGIT>
# L<perlrecharclass/\d>
# L<perlrebackslash/\d>
# (?^) is (?d) is "Depends" or "Dodgy" or "Default"; L<perlunicode/The "Unicode Bug">;
#"\\d",
# ----------------

                  ")",

# address=/1/C1/C0/F0 ; xRe::Token::Structure ; Represent structural elements.
#")",
# ------------------------------------------------------------------

            "/",

# address=/1/C1/F0 ; xRe::Token::Delimiter ; Represent the delimiters of the regular expression
#"/",
# ------------------------------------------------------------------

"",

# address=/1/C2 ; xRe::Token::Modifier ; Represent 1)embedded pattern-match modifiers or 2)(trailing) modifiers for operators match, substitution, regexp constructor
#"",
# ------------------------------------------------------------------

;;;;;;;;;;

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