xpl_draft.par

//Meta information
#parser             "XPL";
#description        "eXample Programming Language (Draft)";
#copyright          "In the public domain, 2011";
#version            "0.1";
#prefix             "xpl";

//Precedence and associativity
#left               "=";

#left               "=="
                    "!="
                    "<="
                    ">="
                    '>'
                    '<'
                    ;

#left               '+'
                    '-'
                    ;

#left               '*'
                    '/'
                    ;

//Regular expressions
@string             '"' !'"'* '"'
                    ;

@identifier         'A-Za-z_' 'A-Za-z0-9_'*
                    ;

//Lexemes
#lexeme             real
                    ;

real               ->       real_integer '.' real_fraction
                    |       real_integer '.'?
                    |       '.' real_fraction
                    ;

real_integer        ->      real_integer '0-9'
                    |       '0-9'
                    ;
                    
real_fraction       ->      real_fraction '0-9'
                    |       '0-9'
                    ;
                    
//Whitespace grammar construct
#whitespaces        whitespace
                    ;

whitespace          ->      ' \r\n\t'+
                    |       "//" !'\n'* '\n'
                    ;

//Goal symbol
program$            ->      statement*
                    ;

statement           ->      "if" '(' expression ')' statement
                    |       "if" '(' expression ')' statement
                                "else" statement
                    |       "while" '(' expression ')' statement
                    |       '{' statement* '}'
                    |       expression ';'
                    |       ';'
                    ;

expression          ->      variable "=" expression
                    |       expression "==" expression
                    |       expression "!=" expression
                    |       expression '>' expression
                    |       expression '<' expression
                    |       expression "<=" expression
                    |       expression ">=" expression
                    |       expression '+' expression
                    |       expression '-' expression
                    |       expression '*' expression
                    |       expression '/' expression
                    |       '-' expression              #precedence '*'
                    |       '(' expression ')'
                    |       real
                    |       @string
                    |       variable
                    |       function '(' parameter_list? ')'
                    ;

parameter_list      ->      parameter_list ',' expression
                    |       expression
                    ;

variable
function            ->      @identifier
                    ;