/*
* Production: Selection Statement
* FIRST set: { KW_T (only IF) }
*/
void selection_statement(void) {
match(KW_T, IF);
match(LPR_T, NO_ATTR);
conditional_expression();
match(RPR_T, NO_ATTR);
match(KW_T, THEN);
opt_statements();
match(KW_T, ELSE);
match(LBR_T, NO_ATTR);
opt_statements();
match(RBR_T, NO_ATTR);
match(EOS_T, NO_ATTR);
gen_incode("PLATY: IF statement parsed");
}
/*
* Production: Program
* FIRST set: { KW_T (only PLATYPUS) }
*/
void program(void) {
match(KW_T, PLATYPUS);
match(LBR_T,NO_ATTR);
opt_statements();
match(RBR_T,NO_ATTR);
gen_incode("PLATY: Program parsed");
}
/* FIRST(selection statement)={IF}
<selection statement> ->
IF (<conditional expression>) THEN <opt_statements>
ELSE { <opt_statements> } ;
Author: Kyle Hinskens */
void selection_statement(void){
if (lookahead_token.attribute.get_int == IF){
match(KW_T,IF);
match(LPR_T,NO_ATTR);
conditional_expression();
match(RPR_T,NO_ATTR);
match(KW_T,THEN);
opt_statements();
match(KW_T,ELSE);
match(LBR_T,NO_ATTR);
opt_statements();
match(RBR_T,NO_ATTR);
match(EOS_T,NO_ATTR);
gen_incode("IF statement parsed");
}
}
/*
* Production: Iteration Statement
* FIRST set: { KW_T (only USING) }
*/
void iteration_statement(void) {
match(KW_T, USING);
match(LPR_T, NO_ATTR);
assignment_expression();
match(COM_T, NO_ATTR);
conditional_expression();
match(COM_T, NO_ATTR);
assignment_expression();
match(RPR_T, NO_ATTR);
match(KW_T, REPEAT);
match(LBR_T, NO_ATTR);
opt_statements();
match(RBR_T, NO_ATTR);
match(EOS_T, NO_ATTR);
gen_incode("PLATY: USING statement parsed");
}
/* FIRST(iteration statement)={USING}
<iteration statement> ->
USING (<assignment expression>, <conditional expression>, <assignment expression>)
REPEAT {
< opt_statements>
};
Author: Kwok Hong Kelvin Chan */
void iteration_statement(void) {
if (lookahead_token.code == KW_T && lookahead_token.attribute.get_int == USING) {
match(KW_T,USING);
match(LPR_T,NO_ATTR);
assignment_expression();
match(COM_T, NO_ATTR);
conditional_expression();
match(COM_T, NO_ATTR);
assignment_expression();
match(RPR_T,NO_ATTR);
match(KW_T,REPEAT);
match(LBR_T,NO_ATTR);
opt_statements();
match(RBR_T,NO_ATTR);
match(EOS_T,NO_ATTR);
gen_incode("USING statement parsed");
}
}
statement()
{
/* statement -> expression SEMI
* | expression SEMI statement
*/
/*
expression();
if( match( SEMI ) )
advance();
else
fprintf( stderr, "%d: Inserting missing semicolon\n", yylineno );
if( !match(EOI) )
statements(); // Do another statement.
*/
if(match(ID)){
char *var1 = current_lexeme(), *var2;
add_to_table(var1);
advance();
if(match(ASSIGN)){
advance();
var2 = expression();
if(!var2){
printf("%d: Expression expected\n", yylineno);
return;
}
//printf("%s = %s \n", var1,var2);
//printf("MOV %s,%s\n", var2,var1);
fprintf(f,"MOVB %s,%s\n", var2,var1);
freename(var2);
free(var1);
}
else
fprintf(stderr, "%d: Not a valid assignment\n",yylineno);
}
else if(match(IF)){
char *var1;
if_count++;
int temp_if_count = if_count;
advance();
var1 = expression();
if(!var1){
fprintf(stderr, "%d: Invalid Expression\n",yylineno);
return;
}
//printf("CMP %s, $0\n",var1 );
//printf("JLE Else%d\n",if_count);
fprintf(f, "MOVB $0, %s \n", ACCUMULATOR);
fprintf(f,"CMP %s, %s \n",ACCUMULATOR,var1);
fprintf(f,"JLE Else%d\n",temp_if_count);
if(match(THEN)){
//printf("if(%s){\n", var1);
freename(var1);
advance();
statement();
//printf("Else%d:\n",if_count);
fprintf(f,"Else%d:\n",temp_if_count);
//printf("}\n");
}
else
fprintf(stderr, "%d: Then expected after if\n", yylineno);
}
else if(match(WHILE)){
char *var;
while_count++;
int temp_while_count = while_count;
advance();
var = expression();
if(!var){
fprintf(stderr, "%d: Invalid Expression\n",yylineno);
return;
}
// printf("While%d:\n",while_count);
// printf("CMP %s, $0\n", var);
// printf("JLE Exit%d\n", while_count);
fprintf(f, "MOVB $0, %s \n", ACCUMULATOR);
fprintf(f,"While%d:\n",temp_while_count);
fprintf(f,"CMP %s, %s\n", ACCUMULATOR,var);
fprintf(f,"JLE Exit%d\n", temp_while_count);
if(match(DO)){
//printf("while\t(%s)\n", var);
//printf("do{\n");
advance();
statement();
//printf("}\n");
freename(var);
// printf("JMP While%d\n",while_count);
// printf("Exit%d:\n",while_count);
fprintf(f,"JMP While%d\n",temp_while_count);
fprintf(f,"Exit%d:\n",temp_while_count);
}
else
fprintf(stderr, "%d: Do expected after while\n", yylineno);
}
else if(match(BEGIN)){
printf("begin\n");
advance();
opt_statements();
if(match(END)){
printf("end\n");
advance();
}
else
fprintf(stderr, "%d End expected begin\n", yylineno);
}
else if(match(EOI)){
// printf("thu\n");
return;
}
else{
fprintf(stderr, "%d: Statement Expected\n", yylineno);
exit(1);
}
}