void Expression::PrintTree(std::ostream& os) const
{
if (Empty())
{
throw ExpressionError("Error: Expression is empty!");
}
m_topNode->Print(os);
}
double Expression::Evaluate() const
{
if (Empty())
{
throw ExpressionError("Error: Expression is empty!");
}
return m_topNode->Evaluate();
}
int IsVariableDefinition(const std::string &a_expression)
{
bool found = false;
int index;
for (int i = 0; i < a_expression.length(); i++)
{
if (a_expression[i] == ':')
{
if (!found)
{
found = true;
index = i;
}
else throw ExpressionError("Invalid assignment", new Token);
}
}
if (found)
{
// parse
int name_end = index - 1;
while (a_expression[name_end] == ' ' && name_end >= 0) name_end--;
if (name_end < 0) throw ExpressionError("Invalid variable definition", new Token);
last_variable_name = a_expression.substr(0, name_end + 1);
if (!isvalidname(last_variable_name) || isallupper(last_variable_name, true)) return 0;
int value_start = index + 1;
while (a_expression[value_start] == ' ' && value_start < a_expression.length()) value_start++;
if (value_start == a_expression.length())
{
G::variables.Remove(HashFunc(last_variable_name));
return 2;
}
last_variable_value = a_expression.substr(value_start);
return 1;
}
return 0;
}
void TokenListToRPN(TokenList &a_list, RPNStack &a_rpn)
{
// Shunting yard algorithm
std::vector<Token*> opStack;
Token *c_token = a_list.head;
while (c_token)
{
switch (c_token->type)
{
case Token::Type::Name:
if (isalllower(c_token->name, true) && isvalidname(c_token->name))
{
if (G::functions.Exists(c_token->name))
{
opStack.push_back(c_token);
c_token->type = Token::Type::E_Function;
}
else if (G::variables.Exists(c_token->name))
{
a_rpn.push_back({ ExprNode::Type::Number, G::variables.Get(c_token->name) });
}
else throw ExpressionError("Undefined reference", c_token);
}
else if (isallupper(c_token->name, true) && isvalidname(c_token->name))
{
if (G::constants.Exists(c_token->name))
a_rpn.push_back({ ExprNode::Type::Number, G::constants.Get(c_token->name) });
else throw ExpressionError("Undefined constant", c_token);
}
else throw ExpressionError("Invalid value name", c_token);
break;
case Token::Type::Number:
a_rpn.push_back({ ExprNode::Type::Number, c_token->value });
break;
case Token::Type::Operator:
if (opStack.size() > 0)
{
if (c_token->optype == Token::OpType::RPar)
{
Token *tos = opStack.back();
if (opStack.size() == 0)
throw ExpressionError("#1 Mismatched parenthesis", c_token);
while (tos->optype != Token::OpType::LPar)
{
a_rpn.push_back({ ExprNode::Type::Operator, 0, tos->optype });
opStack.pop_back();
tos = opStack.back();
if (opStack.size() == 0)
throw ExpressionError("#2 Mismatched parenthesis", c_token);
}
opStack.pop_back(); // pop opening parantheses
if (opStack.size() > 0)
{
tos = opStack.back();
if (tos->type == Token::Type::E_Function)
{
a_rpn.push_back({ ExprNode::Type::Function, 0, Token::OpType::None,
HashFunc(tos->name) });
opStack.pop_back();
}
}
}
else if (c_token->optype == Token::OpType::Comma)
{
Token *tos = opStack.back();
if (opStack.size() == 0)
throw ExpressionError("Invalid separator", c_token);
while (tos->optype != Token::OpType::LPar)
{
a_rpn.push_back({ ExprNode::Type::Operator, 0, tos->optype });
opStack.pop_back();
tos = opStack.back();
if (opStack.size() == 0)
throw ExpressionError("Invalid separator", c_token);
}
}
else
{
if (c_token->optype != Token::OpType::LPar)
{
while (opStack.size() > 0 && opStack.back()->optype != Token::OpType::LPar)
{
Token *tos = opStack.back();
if ((is_la(c_token->optype) && precedence(c_token->optype) <= precedence(tos->optype)) ||
(is_ra(c_token->optype) && precedence(c_token->optype) < precedence(tos->optype)))
{
opStack.pop_back();
a_rpn.push_back({ ExprNode::Type::Operator, 0, tos->optype });
}
else break;
}
}
opStack.push_back(c_token);
}
}
else if (c_token->optype != Token::OpType::RPar ||
c_token->optype != Token::OpType::Comma)
opStack.push_back(c_token);
break;
case Token::Type::Special:
a_rpn.push_back({ ExprNode::Type::Special, 0, ExprNode::OpType::None, 0, c_token->sptype });
break;
}
c_token = c_token->next;
}
for (unsigned i = opStack.size(); i-- > 0; )
{
if (opStack[i]->optype == Token::OpType::LPar ||
opStack[i]->optype == Token::OpType::RPar)
throw ExpressionError("#3 Mismatched parenthesis", opStack[i]);
a_rpn.push_back({ ExprNode::Type::Operator, 0, opStack[i]->optype });
}
}
void ExprToValue(const ExprPtrT& e, short unsigned int& val)
{
if (!(e->toTypeQ(typeid(int))))
throw ExpressionError(ExprToValueErrorDescription<int>(e));
val = int(*e);
};
void ExprToValue(const ExprPtrT& e, float& val)
{
if (!(e->toTypeQ(typeid(double))))
throw ExpressionError(ExprToValueErrorDescription<double>(e));
val = double(*e);
};