Boost C++ Libraries

program
    =
    *(  macro
    |   comment
    |   keyword
    |   identifier
    |   special
    |   string_
    |   number
    |   space_p
    |   anychar_p
    )
    ;

acro
   =   *space_p >> self.macro
   ;

comment
    =   +(*space_p >> comment_p("#"))
    ;

keyword
    =   *space_p >> keyword_ >> (eps_p - (alnum_p | '_'))
    ;   // make sure we recognize whole words only

keyword_
    =
    "and",       "del",       "for",       "is",        "raise",    
    "assert",    "elif",      "from",      "lambda",    "return",   
    "break",     "else",      "global",    "not",       "try",  
    "class",     "except",    "if",        "or",        "while",    
    "continue",  "exec",      "import",    "pass",      "yield",   
    "def",       "finally",   "in",        "print",

    // Technically "as" and "None" are not yet keywords (at Python
    // 2.4). They are destined to become keywords, and we treat them 
    // as such for syntax highlighting purposes.
               
    "as", "None"
    ;

special
    =   *space_p >> +chset_p("~!%^&*()+={[}]:;,<.>/|\\-")
    ;

string_prefix
    =    as_lower_d[str_p("u") >> ! str_p("r")]
    ;
           
string_
    =   *space_p >> ! string_prefix >> (long_string | short_string)
    ;

short_string
    =   confix_p('"', * c_escape_ch_p, '"') |
        confix_p('\'', * c_escape_ch_p, '\'')    
    ;
       
long_string
    =   confix_p("'''", * lex_escape_ch_p, "'''") |
        confix_p("\"\"\"", * lex_escape_ch_p, "\"\"\"")
    ;
           
number
    =   *space_p >>
        (
            as_lower_d["0x"] >> hex_p
        |   '0' >> oct_p
        |   real_p
        )
        >>  *as_lower_d[chset_p("lj")]
    ;

identifier
    =   *space_p >> ((alpha_p | '_') >> *(alnum_p | '_'))
    ;