SymbolTableEntry* Parser::parseExpressionPrime(SymbolTableEntry* prevEntry){
SymbolTableEntry* result = prevEntry;
if(isNext(tc_RELOP)){
OpType t = m_currentToken->getOpType();
match(tc_RELOP);
SymbolTableEntry* exp = parseSimpleExpression();
result = newTemp();
SymbolTableEntry* tr = newLabel();
SymbolTableEntry* end = newLabel();
if(t == op_LT){
m_code->generate(cd_LT, prevEntry, exp, tr);
}
else if(t == op_LE){
m_code->generate(cd_LE, prevEntry, exp, tr);
}
else if(t == op_GT){
m_code->generate(cd_GT, prevEntry, exp, tr);
}
else if(t == op_GE){
m_code->generate(cd_GE, prevEntry, exp, tr);
}
else if(t == op_EQ){
m_code->generate(cd_EQ, prevEntry, exp, tr);
}
else{
m_code->generate(cd_NE, prevEntry, exp, tr);
}
m_code->generate(cd_ASSIGN, m_symbolTable->lookup(CodeFalse), NULL, result);
m_code->generate(cd_GOTO, NULL, NULL, end);
m_code->generate(cd_LABEL, NULL, NULL, tr);
m_code->generate(cd_ASSIGN, m_symbolTable->lookup(CodeTrue), NULL, result);
m_code->generate(cd_LABEL, NULL, NULL, end);
}
return result;
}
void Parser::parseExpression_p(RelOpExpressionPtr expr)
{
Token op = m_curToken;
if (match(TokenType::RelOp)) {
expr->relOp = op.operatorType();
expr->rhs = parseSimpleExpression();
return;
}
// is empty
return;
}
ExpressionPtr Parser::parseExpression()
{
RelOpExpressionPtr expr(new RelOpExpression);
expr->lhs = parseSimpleExpression();
parseExpression_p(expr);
if (expr->rhs) {
return expr;
}
return expr->lhs;
}
SymbolTableEntry* Parser::parseExpression(){
SymbolTableEntry* entry = parseSimpleExpression();
entry = parseExpressionPrime(entry);
return entry;
}
