yacc.y

%{
	#include "xu.h"
	#define YYSTYPE node
	#include "yacc.tab.h"
	
	int yyerror();
	int yyerror(char* msg);
	extern int yylex();    
	codelist* list;
%}

%token IF ELSE THEN
%token WHILE DO
%token RELOP
%token NUMBER ID
%token AND
%left AND
%left '+' '-'
%left '*' '/'
%right '='
%right ASSIGN

%%
S	:	IF E THEN M S	
		{ 	
			backpatch(list, $3.truelist, $$.instr); 
			$$.nextlist = merge($2.falselist, $5.nextlist); 
		}

		|IF E THEN M S ELSE N M S	
		{ 	
			backpatch(list, $2.truelist, $4.instr);    
			backpatch(list, $2.falselist, $8.instr);
                  	$5.nextlist = merge($5.nextlist, $7.nextlist);    
                  	$$.nextlist = merge($5.nextlist, $9.nextlist); 
                } 
                  
		|WHILE M E DO M S
		{ 	
			backpatch(list, $6.nextlist, $2.instr);    
			backpatch(list, $3.truelist, $5.instr);
                 	$$.nextlist = $3.falselist;	
                 	gen_goto(list, $2.instr); 
                }
		
		
		|OP ASSIGN E
		{
			copyaddr(&$1, $1.lexeme); 
			gen_assignment(list, $1, $3);
		}
		
		|L
		{
			$$.nextlist = $1.nextlist;
		}
		|	{}
		;
		
L	:	L ';' M S
		{
			backpatch(list, $1.nextlist, $3.instr);
			$$.nextlist = $4.nextlist;
		}
		|S
		{
			$$.nextlist = $1.nextlist;
		}
		;

E	:	E AND M E    
		{ 	
			backpatch(list, $1.truelist, $3.instr);
		  	$$.truelist = $4.truelist; 
		  	$$.falselist = merge($1.falselist, $4.falselist); 
		}
		
		|OP RELOP OP
		{	
			$$.truelist = new_instrlist(nextinstr(list));
                        $$.falselist = new_instrlist(nextinstr(list)+1);
                        gen_if(list, $1, $2.oper, $3);
                        gen_goto_blank(list); 
                }
                
		|OP
		{
			copyaddr_fromnode(&$$, $1);
                }
		;
		
OP	:	OP '+' OP { new_temp(&$$, get_temp_index(list)); gen_3addr(list, $$, $1, "+", $3); }
		|NUMBER {copyaddr(&$$, $1.lexeme);}
		|ID {copyaddr(&$$, $1.lexeme);}
		;
		

M	:	{ $$.instr = nextinstr(list); }
		;

N	:	{
			$$.nextlist = new_instrlist(nextinstr(list));
                 	gen_goto_blank(list);
		}
                ;
                
%%

int yyerror(char* msg)
{
    printf("\nERROR with message: %s\n", msg);
    return 0;
}


int main()
{
    list = newcodelist();

    freopen("test.in", "rt+", stdin);
    freopen("test.out", "wt+", stdout);

    yyparse();
    print(list);
    
    fclose(stdin);

    fclose(stdout);
    return 0;
}