/* $Id$
 *
 * This is LL(1) grammar for LFC based on the "Introduction to LFC Programming
 * Language" (January 25, 2008) by Zhen Lixiao 
 */

%token SC COLON COMMA
%token DEC VAR DEF
%token ASTERISK TO EQ
%token LPAR RPAR
%token IDENTIFIER STRING UNDEFINED
%token CONCAT
%token IF THEN ELSE WHERE

%%

program : function_dec var_dec_and_func_def program_rest ;

program_rest : /*empty*/
             | program
	     ;

function_dec : DEC funname COLON function_type SC ;

var_dec_and_func_def : variable_dec definition
                     | definition
		     ;

variable_dec : VAR vars_decl variable_dec_rest ;

vars_decl : variable_list COLON concept_name SC ;

variable_dec_rest : /*empty*/
                  | vars_decl variable_dec_rest
		  ;

variable_list : variable variable_list_rest ;

variable_list_rest : /*empty*/
                   | COMMA variable variable_list_rest
		   ;

definition : DEF equation equation_rest ;

equation : funname LPAR pattern_list RPAR EQ exp_with_where_or_undef SC ;

equation_rest : /*empty*/
              | equation equation_rest
	      ;

pattern_list : pattern pattern_list_rest ;

pattern : STRING pat_concat
        | variable pat_concat
	;

pat_concat : /*empty*/
           | CONCAT pattern
	   ;

pattern_list_rest : /*empty*/
                  | COMMA pattern pattern_list_rest
		  ;

function_type : concept_name concept_list_rest TO concept_name ;

concept_list_rest : /*empty*/
                  | ASTERISK concept_name concept_list_rest
		  ;

concept_name : IDENTIFIER ;
funname  : IDENTIFIER ;
variable : IDENTIFIER ;

exp : STRING exp_concat
    | IDENTIFIER exp_var_or_func exp_concat
    | LPAR exp_with_where RPAR exp_concat
    | IF exp THEN exp ELSE exp
    ;

exp_with_where : STRING exp_concat_or_where
               | IDENTIFIER exp_var_or_func exp_concat_or_where
               | LPAR exp_with_where RPAR exp_concat_or_where
               | IF exp_with_where THEN exp_with_where ELSE exp_with_where
               ;

exp_with_where_or_undef : UNDEFINED
                        | exp_with_where
			;

exp_var_or_func : /*empty*/
                | LPAR arg_list RPAR
                ;

arg_list : /*empty*/
         | exp arg_list_rest
         ;

arg_list_rest : /*empty*/
              | COMMA exp arg_list_rest
              ;

exp_concat : /*empty*/
           | CONCAT exp
	   ;

exp_concat_or_where : /*empty*/
                    | CONCAT exp_with_where
		    | WHERE varassign_list
                    ;

varassign_list : variable EQ exp varassign_rest ;

varassign_rest : /*empty*/
               | COMMA varassign_list
               ;