Boost C++ Libraries

doc_info =
        space
    >>  '['
    >>  (   str_p("book")
        |   "article"
        |   "library"
        |   "chapter"
        |   "part"
        )
    >> hard_space
    >>  (  *(anychar_p -
            (ch_p('[') | ']' | eol_p)
            )
        )
    >> *( doc_version
        | doc_id
        | doc_dirname
        | doc_copyright
        | doc_purpose
        | doc_category
        | doc_authors
        | doc_license
        | doc_last_revision
        )
    >> ']' >> +eol_p
    ;

doc_version =
        space
    >> "[version" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_id =
        space
    >> "[id" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_dirname =
        space
    >> "[dirname" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_copyright =
        space
    >> "[copyright" >> hard_space
    >> +( repeat_p(4)[digit_p]
          >> space
        )
    >> space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_purpose =
        space
    >> "[purpose" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_category =
        space
    >> "[category" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_author =
        space
    >>  '[' >> space
    >>  (*(anychar_p - ','))
    >>  ',' >> space
    >>  (*(anychar_p - ']'))
    >>  ']'
    ;

doc_authors =
        space
    >> "[authors" >> hard_space
    >> doc_author
    >> *(   ','
            >>  doc_author
        )
    >> ']' >> +eol_p
    ;

doc_license =
        space
    >> "[license" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_last_revision =
        space
    >> "[last-revision" >> hard_space
    >> (*(anychar_p - ']'))
    >> ']' >> +eol_p
    ;

doc_source_mode =
    space
    >> "[source-mode" >> hard_space
    >> (
          str_p("c++") 
       |  "python"
       )
    >> space >> ']' >> +eol_p
    ;

comment =
    "[/" >> *(anychar_p - ']') >> ']'
    ;

space =
    *(space_p | comment)
    ;

hard_space =
    (eps_p - (alnum_p | '_')) >> space  // must not be followed by
    ;                                   // alpha-numeric or underscore