regex101: golang const|func|type declaration matcher

Pro

(?x)applies the following effective flags to the remainder of the pattern: gmx

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Comment: Set intent level

Definition Group(?(DEFINE)(?<indent>[[:space:]]{4}))

Group indent(?<indent>[[:space:]]{4})

Character Class[[:space:]]{4}

{4}matches exactly 4 characters from the set below:

[:space:]a whitespace character, including a line break [ \t\r\n\v\f]

Comment: Must start at new line

^start of line

Comment: Captures following statement's description comment lines if written

Group statementDescComment(?<statementDescComment> (?: # Repeat below until next line not comment (?=(?P>indent)\/)\V*\v )+ )?

?repeats the group contents below at most once:

Non-Capturing Group(?: # Repeat below until next line not comment (?=(?P>indent)\/)\V*\v )+

+repeats the group contents below at least once:

Comment: Repeat below until next line not comment

Positive Lookahead(?=(?P>indent)\/)

(?P>indent)calls group indent as a subroutine

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

\V*any character that's not a vertical whitespace character, repeated any number of times

\vany vertical whitespace character

Comment: Generic Statement Capture

Group statement(?<statement> # Const declaration capture (?<const> (?P>indent)const[[:space:]]*$[[:space:]]* \v (?: (?!(?P>indent)$)\V*\v )* (?P>indent)\) ) | # Full function declaration capture (?<func> # Function declaration initialization (?<funcDecLine> (?P>indent)func\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<funcCloseBracket>(?P>indent)\}) ) | (?<type> # Type Declaration # Check before wasting time (?=(?P>indent)type) # Short Form (?<typeDecShort> (?P>indent)type\V+[^\{]\v ) | # Longer Form (Brackted) (?<typeDecLong> (?P>indent)type\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<typeCloseBracket>(?P>indent)\}) ) )

1st Alternative # Const declaration capture (?<const> (?P>indent)const[[:space:]]*$[[:space:]]* \v (?: (?!(?P>indent)$)\V*\v )* (?P>indent)\) )

Comment: Const declaration capture

Group const(?<const> (?P>indent)const[[:space:]]*$[[:space:]]* \v (?: (?!(?P>indent)$)\V*\v )* (?P>indent)\) )

(?P>indent)calls group indent as a subroutine

constthe literal text const (case sensitive)

Character Class[[:space:]]*

*matches any number of characters from the set below:

[:space:]a whitespace character, including a line break [ \t\r\n\v\f]

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Character Class[[:space:]]*

*matches any number of characters from the set below:

[:space:]a whitespace character, including a line break [ \t\r\n\v\f]

\vany vertical whitespace character

Non-Capturing Group(?: (?!(?P>indent)\))\V*\v )*

*repeats the group contents below any number of times:

Negative Lookahead(?!(?P>indent)\))

(?P>indent)calls group indent as a subroutine

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

\V*any character that's not a vertical whitespace character, repeated any number of times

\vany vertical whitespace character

(?P>indent)calls group indent as a subroutine

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

2nd Alternative # Full function declaration capture (?<func> # Function declaration initialization (?<funcDecLine> (?P>indent)func\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<funcCloseBracket>(?P>indent)\}) )

Comment: Full function declaration capture

Group func(?<func> # Function declaration initialization (?<funcDecLine> (?P>indent)func\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<funcCloseBracket>(?P>indent)\}) )

Comment: Function declaration initialization

Group funcDecLine(?<funcDecLine> (?P>indent)func\V+ )

(?P>indent)calls group indent as a subroutine

functhe literal text func (case sensitive)

\V+any character that's not a vertical whitespace character, repeated at least once

\vany vertical whitespace character

Comment: Repeat subcapture until line starting with close bracket

Non-Capturing Group(?: (?!(?P>indent)\})\V*\v )*

*repeats the group contents below any number of times:

Negative Lookahead(?!(?P>indent)\})

(?P>indent)calls group indent as a subroutine

\}the literal } (125₁₀ / 175₈ / 7D₁₆)

\V*any character that's not a vertical whitespace character, repeated any number of times

\vany vertical whitespace character

Comment: Closing bracket

Group funcCloseBracket(?<funcCloseBracket>(?P>indent)\})

(?P>indent)calls group indent as a subroutine

\}the literal } (125₁₀ / 175₈ / 7D₁₆)

3rd Alternative (?<type> # Type Declaration # Check before wasting time (?=(?P>indent)type) # Short Form (?<typeDecShort> (?P>indent)type\V+[^\{]\v ) | # Longer Form (Brackted) (?<typeDecLong> (?P>indent)type\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<typeCloseBracket>(?P>indent)\}) )

Group type(?<type> # Type Declaration # Check before wasting time (?=(?P>indent)type) # Short Form (?<typeDecShort> (?P>indent)type\V+[^\{]\v ) | # Longer Form (Brackted) (?<typeDecLong> (?P>indent)type\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<typeCloseBracket>(?P>indent)\}) )

1st Alternative # Type Declaration # Check before wasting time (?=(?P>indent)type) # Short Form (?<typeDecShort> (?P>indent)type\V+[^\{]\v )

Comment: Type Declaration

Comment: Check before wasting time

Positive Lookahead(?=(?P>indent)type)

(?P>indent)calls group indent as a subroutine

typethe literal text type (case sensitive)

Comment: Short Form

Group typeDecShort(?<typeDecShort> (?P>indent)type\V+[^\{]\v )

(?P>indent)calls group indent as a subroutine

typethe literal text type (case sensitive)

\V+any character that's not a vertical whitespace character, repeated at least once

Negated Character Class[^\{]

\vany vertical whitespace character

2nd Alternative # Longer Form (Brackted) (?<typeDecLong> (?P>indent)type\V+ )\v # Repeat subcapture until line starting with close bracket (?: (?!(?P>indent)\})\V*\v )* # Closing bracket (?<typeCloseBracket>(?P>indent)\})

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

25 tokens

Regular Expression

(?x)

# Set intent level
(?(DEFINE)(?<indent>[[:space:]]{4}))

# Must start at new line
^
# Captures following statement's description comment lines if written
(?<statementDescComment> 
  (?: 
    # Repeat below until next line not comment
    (?=(?P>indent)\/)\V*\v
  )+
)?
# Generic Statement Capture
(?<statement>
# Const declaration capture
(?<const>
  (?P>indent)const[[:space:]]*\([[:space:]]*
  \v
  (?:
      (?!(?P>indent)\))\V*\v
  )*
  (?P>indent)\)
)
|
# Full function declaration capture
(?<func>
  # Function declaration initialization
  (?<funcDecLine>
    (?P>indent)func\V+
  )\v
  # Repeat subcapture until line starting with close bracket
  (?:
    (?!(?P>indent)\})\V*\v
  )*
  # Closing bracket
  (?<funcCloseBracket>(?P>indent)\})
)
|
(?<type>
  # Type Declaration

  # Check before wasting time
  (?=(?P>indent)type)

    # Short Form
    (?<typeDecShort>
      (?P>indent)type\V+[^\{]\v
    )
  |
    # Longer Form (Brackted)
    (?<typeDecLong>
      (?P>indent)type\V+
    )\v
    # Repeat subcapture until line starting with close bracket
    (?:
      (?!(?P>indent)\})\V*\v
    )*
    # Closing bracket
    (?<typeCloseBracket>(?P>indent)\})
  )
)

Unit Tests

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