//TODO: Be Careful: sin(x) / x => x x / sin. The expected is obtained: (sin x) / x => x sin x /
std::string InfixToPostfix::transform(const std::string& infix) const {
std::string p_infix = preprocess(infix);
std::string postfix;
std::stack<std::string> stack;
std::stringstream ss(p_infix);
std::string token;
while (ss >> token) {
if (token == "(") {
stack.push(token);
} else if (token == ")") {
while (!stack.empty()) {
if (stack.top() == "(") {
stack.pop();
break;
}
postfix += stack.top() + " ";
stack.pop();
}
} else if (isOperand(token)) {
postfix += token + " ";
} else if (isOperator(token)) {
while (!stack.empty() &&
operatorPrecedence(token) <= operatorPrecedence(stack.top())) {
postfix += stack.top() + " ";
stack.pop();
}
stack.push(token);
}
}
while (!stack.empty()) {
postfix += stack.top() + " ";
stack.pop();
}
return postfix;
}
bool InfixToPostfix::isOperator(const std::string& op) const {
return operatorPrecedence(op) != -1;
}
void Expression::buildPostfix(Tokens *tokens, Parser *parser) {
Stack<Token*> stack;
int paranthCnt = 0;
const Token *next = tokens->checkNext();
while (tokens->isMore() && next->aType != Token::SEMICOLON && next->aType != Token::COMMA) {
if (next->aType == Token::VARIABLE_INT || next->aType == Token::VARIABLE_FLOAT) {
postfix.push_back(new ExpressionTerm(tokens->popNext()));
} else if (next->aType == Token::VARIABLE_FUNCTION) {
Token *token = tokens->popNext();
// Function call
if (tokens->checkNext()->aType == Token::PARANTH_BEG) {
FunctionCall *func = new FunctionCall(token);
func->parseFragment(tokens, parser);
postfix.push_back(new ExpressionTerm(func));
} else {
postfix.push_back(new ExpressionTerm(token));
}
} else if (next->aType & Token::OPERATOR) {
Token *token = tokens->popNext();
while (stack.Size() && stack.peek()->aType != Token::PARANTH_BEG) {
if (operatorPrecedence(stack.peek()) > operatorPrecedence(token)) {
postfix.push_back(new ExpressionTerm(stack.pop()));
} else {
break;
}
}
stack.push(token);
} else if (next->aType == Token::PARANTH_BEG) {
paranthCnt++;
stack.push(tokens->popNext());
} else if (next->aType == Token::PARANTH_END) {
paranthCnt--;
if (paranthCnt < 0) break;
while (stack.Size() && stack.peek()->aType != Token::PARANTH_BEG) {
postfix.push_back(new ExpressionTerm(stack.pop()));
}
// Pop the "("
stack.pop();
// Pop the ")"
tokens->popNext();
} else {
throw InvalidTokenException("Unexpected token: " + next->token);
}
next = tokens->checkNext();
}
while (stack.Size()) {
postfix.push_back(new ExpressionTerm(stack.pop()));
}
if (!isParam) {
delete tokens->popExpected(Token::SEMICOLON);
}
}
