void factor(){
int l;
int m;
symTableEntry* symbol;
if(currentToken == identsym){
//First looking for a constant that matches
symbol = findSymbol(symTable, CONST, tokenVal.string, scope);
if(findConst(tokenVal.string, scope, &m)){
genCode(LIT, 0, m);
}else if(findVar(tokenVal.string, scope, &l, &m)){
//If that fails, looking for a variable
genCode(LOD, l, m);
}else{
throwError(UNDEC_ID);
}
readToken();
}else if(currentToken == numbersym){
genCode(LIT, 0, tokenVal.numeric);
readToken();
}else if(currentToken == lparentsym){
readToken();
expression();
if(currentToken != rparentsym)
throwError(RPAREN_MISS);
else
readToken();
}
else
throwError(PREC_FACTOR_CANNOT_BEGIN_SYM);
return;
}
struct in_out scanExpression(const Context &context, struct expression &arg, bool ifContext)
{
struct in_out result;
struct expression *temp = &arg;
//temp = &arg;
while (temp != NULL)
{
//cout<<"Before expr"<<endl;
concat(result, scanAssignmentExpression(context, temp->head, ifContext));
temp = temp->tail;
}
findConst(result. in);
findConst(result. out);
arg. dep = result;
return result;
}
void statement(){
int l;
int m;
symTableEntry* symbol;
int tempLabels[2];
if(currentToken == identsym){
symbol = findSymbol(symTable, VAR, tokenVal.string, scope);
if(!findVar(tokenVal.string, scope, &l, &m)){
if(findConst(tokenVal.string, scope, &m))
throwError(CANNOT_ASSIGN_TO_CONST_OR_PROC);
else
throwError(UNDEC_ID);
}
readToken();
if(currentToken != becomessym)
throwError(ASSIGN_EXPEC);
readToken();
expression();
genCode(STO, l, m);
}
else if(currentToken == syawsym){
readToken();
if(currentToken != identsym)
throwError(ID_FOLLOW_SYAW);
if(!findFunc(tokenVal.string, scope, &l, &m))
throwError(UNDEC_ID);
genCode(CAL, l, m);
readToken();
}
else if(currentToken == sngaisym){ // 'beginsym'
readToken();
statement();
while(currentToken == semicolonsym){
readToken();
statement();
}
if(currentToken != fpesym &&
(currentToken != identsym && currentToken != sngaisym
&& currentToken != txosym && currentToken != tengkrrsym)) // 'endsym'
//throwError(WRONG_SYM_AFTER_STATE);
throwError(SEMICOL_OR_RBRACK_EXPEC);
else if(currentToken == identsym || currentToken == sngaisym
|| currentToken == txosym || currentToken == tengkrrsym)
throwError(SEMICOL_BW_STATE_MISS);
readToken();
}
else if(currentToken == txosym){ // 'ifsym'
tempLabels[1] = 0;
readToken();
condition();
tempLabels[0] = reserveCode(); //Conditional jump will go here
if(currentToken != tsakrrsym) // 'thensym'
throwError(TSAKRR_EXPEC);
readToken();
statement();
if(currentToken == txokefyawsym){
tempLabels[1] = reserveCode();
readToken();
}
backPatch(tempLabels[0], JPC, 0, genLabel());
if(tempLabels[1]){
statement();
backPatch(tempLabels[1], JMP, 0, genLabel());
}
}
else if(currentToken == tengkrrsym){ // 'whilesym'
readToken();
tempLabels[0] = genLabel(); //Jump back up to here at the end of the loop
condition();
tempLabels[1] = reserveCode(); //Stick the conditional jump here
if(currentToken != sisym) // 'dosym'
throwError(SI_EXPEC);
readToken();
statement();
genCode(JMP, 0, tempLabels[0]);
backPatch(tempLabels[1], JPC, 0, genLabel());
}
else if(currentToken == misym){ // Input
genCode(SIO, 0, 2);
readToken();
if(currentToken == identsym){
if(findVar(tokenVal.string, scope, &l, &m))
genCode(STO, l, m);
else if(findConst(tokenVal.string, scope, &m)
|| findFunc(tokenVal.string, scope, &l, &m))
throwError(CANNOT_STORE_IN_CONST_OR_PROC);
else
throwError(UNDEC_ID);
readToken();
}
}
else if(currentToken == wrrpasym){ // Output
readToken();
if(currentToken == identsym){
if(findVar(tokenVal.string, scope, &l, &m))
genCode(LOD, l, m);
else if(findConst(tokenVal.string, scope, &m))
genCode(LIT, 0, m);
else
throwError(UNDEC_ID);
readToken();
}
genCode(SOI, 0, 1);
}
else if(currentToken == fpesym){
return;
}
else{
if(currentToken == periodsym)
throwError(RBRACK_EXPEC_AT_END);
else
throwError(STATEMENT_EXPEC);
}
return;
}
