Introduction
------------
rulegen is a parser that takes rules written in a nicer language to 
the cryptic one needed by irule and core.irb. The input files for 
rulgen is recommended to be *.r (.r extensions) and the output created
by rulegen is in the form of *.ir (.ir extensions). The grammar for
the language of the input files are given at the end of this note.

How to use the parser
---------------------
There are two steps.

1) Creating the parser. This is done by executing
   gmake
in this directory and the binary file 'rulegen' is created in ../bin
directory. 

2) Parsing a *.r file into the *.ir format. This 
is done by running rulegen as shown in example below:

  ../bin/rulegen -s test1.r > test1.ir

Then, test1.ir can be used as an input file for the irule command.

  irule -F test1.ir


Examples
--------
Example use cases can be found in:

  test1.r
  test2.r
  test3.r


Grammar of the rulegen language
-------------------------------
program				
	: program rule_list inputs outputs    
	;

inputs
        : INPUT inp_expr_list        
        ;
outputs
        : OUTPUT out_expr_list        
        ;

rule_list  
        : rule                      
        | rule rule_list            
        ;
rule    
        : action_def '{' first_statement '}' 
        | action_def '{' first_statement statement_list '}' 
        ;

action_def
        : action_name                  
        | action_name '(' arg_list ')' 
        ;

microserve
        : action_name                  
        | action_name '(' arg_list ')' 
        ;

action_name
        : identifier                    
        ;

arg_list
        : arg_val                      
        | arg_val ',' arg_list         
        ;
arg_val 
        : STR_LIT                      
        | Q_STR_LIT                    
	| NUM_LIT                      
        ;

first_statement 
        :  selection_statement         
        |                              
        ; 
compound_statement		
	: '{' '}'			
	| '{' statement_list '}'	
	;

statement_list
	: statement
	| statement_list statement
			
	;

statement			
	: selection_statement
	| iteration_statement
        | compound_statement
        | action_statement ';' 
        | ass_expr ';' 
        | execution_statement
	;

selection_statement	
	: ON '(' cond_expr ')' statement    
	| ON '(' cond_expr ')' statement or_list_statement_list 
	;

iteration_statement		
	: WHILE '(' cond_expr ')' statement
	| FOR '(' ass_expr_list ';' cond_expr ';'  ass_expr_list ')' statement
	| IF '(' cond_expr ')' THEN statement 
	| IF '(' cond_expr ')' THEN statement ELSE statement
        | 'break' 
	;
or_list_statement_list 
        : ORON '(' cond_expr ')' statement  
	| OR  statement                     
	| ORON '(' cond_expr ')' statement or_list_statement_list 
	| OR statement or_list_statement_list 
	;

action_statement
        : microserve ACRAC_SEP microserve   
        | microserve                        
        ;

execution_statement
        : DELAY '(' cond_expr ')' statement
					
        | REMOTE '(' identifier ',' cond_expr ')' statement
        | PARALLEL '(' cond_expr ')' statement
        | ONEOF    statement
        | SOMEOF  '(' identifier ')'   statement
        | FOREACH  '(' identifier ')'   statement
        ;
 /******************************** Expressions *************************/
inp_expr			
	: identifier  '=' cond_expr    
        ;
inp_expr_list
	: inp_expr
        | inp_expr ',' inp_expr_list
	;

out_expr			
	: arg_val
out_expr_list
	: out_expr
        | out_expr ',' out_expr_list
	;

ass_expr			
	: identifier  '=' cond_expr      

ass_expr_list
	: ass_expr
        | ass_expr ',' ass_expr_list
	;

cond_expr		
	: logical_expr
        | '(' logical_expr ')' 
        | cond_expr AND_OP cond_expr 
        | cond_expr OR_OP cond_expr  
        | cond_expr '+'  cond_expr   
        | cond_expr '-'  cond_expr   
	;

logical_expr
        : TRUE                  
        | FALSE                 
        | relational_expr
	| logical_expr EQ_OP logical_expr
	| logical_expr NE_OP logical_expr
	| logical_expr '<' logical_expr
	| logical_expr '>' logical_expr
	| logical_expr LE_OP logical_expr
	| logical_expr GE_OP logical_expr
        | logical_expr LIKE logical_expr
        | logical_expr NOT LIKE logical_expr
        ;
relational_expr
        :  STR_LIT            
	|  NUM_LIT            
	|  Q_STR_LIT          
        ;
identifier
        :  STR_LIT            
        |  Q_STR_LIT          
	|  NUM_LIT            
        ;


STR_LIT    : string of characters
Q_STR_LIT  : quoted (") string of characters
NUM_LIT    : number-string
AND_OP     : "&&"                    
OR_OP     :"||"      
LE_O     :"<="              
GE_OP     :">="             
EQ_OP     :"=="             
NE_OP     :"!="             
ACRAC_SE     :":::"