void evaluatePostfix(Expression postfix, std::string& evaluation)
{
stack< std::string > evaluationStack;
Token currentToken;
std::string temp1;
std::string temp2;
std::string temp3;
while(!postfix.isEmpty())
{
currentToken = postfix.front();
postfix.pop();
if(currentToken.getTokenType() == OPERAND)
{
evaluationStack.push(currentToken.getSymbol());
}
else
{
temp1 = evaluationStack.pop();
temp2 = evaluationStack.pop();
temp3 = "(" + temp2 + currentToken.getSymbol() + temp1 + ")";
evaluationStack.push(temp3);
}
}
evaluation = evaluationStack.pop();
}
void convertToPostfix(Expression infix, Expression& postfix)
{
stack<Token> conversionStack;
Token currentToken;
//infix.print(std::cout);
Token noopToken;
noopToken.setTokenType(OPERATOR);
noopToken.setOperatorType(NOOP);
noopToken.setSymbol("");
conversionStack.push(noopToken);
while(!infix.isEmpty())
{
// postfix.print(std::cout);
currentToken = infix.front();
infix.pop();
// currentToken.print(std::cout);
if(currentToken.getTokenType() == OPERAND)
{
postfix.push(currentToken);
}
else
{
while(currentToken.getOperatorType() <= conversionStack.top().getOperatorType())
{
postfix.push(conversionStack.pop());
}
conversionStack.push(currentToken);
}
}
while(!conversionStack.isEmpty())
{
if(conversionStack.top().getOperatorType() != NOOP)
{
postfix.push(conversionStack.top());
}
conversionStack.pop();
}
}
//Evaluate an equation in post fix
Cell* ExpParser::PostEval(Expression &post, bool bSymLoad)
{
static TexAnchor constAncs[4];
static bool ancsSet;
if (!ancsSet)
{
constAncs[0] = TexAnchor(0,0); constAncs[1] = TexAnchor(1,0);
constAncs[2] = TexAnchor(1,1); constAncs[3] = TexAnchor(0,1);
}
Expression temp;//a stack for operands
while (!post.empty())
{//there are more terms to evaluate
Cell *cell = post.front();
post.pop_front();
char Operator = cell->op();
if (Operator == 0)//if not operator
temp.push_front(cell);//push it to the stack
else if (Operator == 'C')
{
Vec c;
for (int i = 2; i >= 0; --i) // they come in reverse order
{
if (temp.empty())
return NULL; // not enough arguments
Cell *pc = temp.front();
if (pc->cval() != NULL)
return NULL; // Coord in Coord
c[i] = pc->val();
temp.pop_front();
}
temp.push_front(new CoordCell(c));
}
else if ((Operator == 'A') || (Operator == 'T'))
{
int n = (Operator == 'A')?4:3;
SymCell *v[4] = {0}; // init to NULLs
for (int i = n-1; i >= 0; --i) // they come in reverse order
{
if (temp.empty())
return NULL; // not enough arguments
Cell *pc = temp.front();
if (pc->cval() == NULL)
return NULL; // Coord in Coord
temp.pop_front();
v[i] = static_cast<SymCell*>(pc);
}
MyPolygon *poly = m_obj->AddPoly(v[0]->point(), v[1]->point(), v[2]->point(), (v[3] != NULL)?(v[3]->point()):NULL, constAncs);
*m_decompile += (n == 4)?QString("add4("):QString("add3(");
for(int i = 0; i < n; ++i)
{
DefPoint &def = (*g_symbols)[v[i]->clval()];
def.used = true; // mark symbol as used
poly->vtx[i]->col = def.color;
*m_decompile += + v[i]->clval().c_str();
if (i < n - 1) *m_decompile += ",";
}
*m_decompile += ")\n";
temp.push_front(new NumCell(0));
}
else if (Operator == 'U') // color
{
// get paramtete
if (temp.empty())
return NULL; // not enough arguments
Cell *pc = temp.front();
// don't pop it
if (pc->clval().size() == 0)
return NULL; // not L-value (color ref)
static_cast<SymCell*>(pc)->setColorRef(true);
}
else
{//evaluate the last two operands at the stack
if (temp.empty())
return NULL;
Cell *n2 = temp.front();
temp.pop_front();
if (temp.empty())
return NULL;
Cell *n1 = temp.front();
temp.pop_front();
Cell *res;
if ((cell->op() == '=') && (!bSymLoad)) // do not load symbol
res = n2; // short circuit
else
res = Eval2(n1, cell, n2);
if (res == NULL)
return NULL;
temp.push_front(res);
}
}
if (temp.size() > 1)
return NULL;
return temp.front();
}
//next step is to change it into post fix
bool ExpParser::In2Post(Expression &in, Expression &post)
{
Expression temp;// a temp stack for operators
while (!in.empty())
{//there are more terms
Cell *cell = in.front();
in.pop_front();
char Operator = cell->op();
if (Operator == 0)//this is number
{
post.push_back(cell);//add as is
}
else if (isFunc(Operator))
{
temp.push_front(cell);
}
else if (Operator == ',')
{
while (!temp.empty() && (temp.front()->op() != '('))
{//pops to the open bracket
post.push_back(temp.front());
temp.pop_front();
}
if (temp.empty())
return false; // missing parens
}
else if (Operator == ')')
{
while (temp.front()->op() != '(')
{//pops to the open bracket
post.push_back(temp.front());
temp.pop_front();
}
temp.pop_front(); // pop '('
if (!temp.empty() && (isFunc(temp.front()->op())))
{
post.push_back(temp.front());
temp.pop_front();
}
// we already checked that there are enough parens.
}
else if (Operator == '(')
{
temp.push_front(cell);
}
else
{//need to pop some operaotrs before putting my one
while ((!temp.empty()) &&
( (isLeftAss(Operator) && (opPriority(Operator) <= stackPriority(temp))) ||
(!isLeftAss(Operator) && (opPriority(Operator) < stackPriority(temp))) ))
{
post.push_back(temp.front());
temp.pop_front();
}
temp.push_front(cell);
}
}
while (!temp.empty())
{//pops the rest of operators
post.push_back(temp.front());
temp.pop_front();
}
return true;
}
int stackPriority(Expression &s)
{//returns the priority of the element on the top 0 for an empty stack
return s.empty()?0:opPriority(s.front()->op());
}
