//This is an example of the implementation of the Parse method
public override void Parse(TokensStack sTokens)
{
//We check that the first token is "function"
Token tFunc = sTokens.Pop();
if (!(tFunc is Statement) || ((Statement)tFunc).Name != "function")
{
throw new SyntaxErrorException("Expected function received: " + tFunc, tFunc);
}
//Now there should be the return type. We pop it from the stack, check for errors, and then set the field
Token tType = sTokens.Pop();
if (!(tType is VarType))
{
throw new SyntaxErrorException("Expected var type, received " + tType, tType);
}
ReturnType = VarDeclaration.GetVarType(tType);
//Next is the function name
Token tName = sTokens.Pop();
if (!(tName is Identifier))
{
throw new SyntaxErrorException("Expected function name, received " + tType, tType);
}
Name = ((Identifier)tName).Name;
//After the name there should be opening paranthesis for the arguments
Token t = sTokens.Pop(); //(
//Now we extract the arguments from the stack until we see a closing parathesis
while (sTokens.Count > 0 && !(sTokens.Peek() is Parentheses))//)
{
//For each argument there should be a type, and a name
if (sTokens.Count < 3)
{
throw new SyntaxErrorException("Early termination ", t);
}
Token tArgType = sTokens.Pop();
Token tArgName = sTokens.Pop();
VarDeclaration vc = new VarDeclaration(tArgType, tArgName);
Args.Add(vc);
//If there is a comma, then there is another argument
if (sTokens.Count > 0 && sTokens.Peek() is Separator)//,
{
sTokens.Pop();
}
}
//Now we pop out the ) and the {. Note that you need to check that the stack contains the correct symbols here.
if (sTokens.Count < 1 || !(sTokens.Peek() is Separator))
{
throw new SyntaxErrorException("not the right separator", sTokens.Pop());
}
t = sTokens.Pop();//)
if (sTokens.Count < 1 || !(sTokens.Peek() is Separator))
{
throw new SyntaxErrorException("not the right separator", sTokens.Pop());
}
t = sTokens.Pop();//{
//Now we parse the list of local variable declarations
while (sTokens.Count > 0 && (sTokens.Peek() is Statement) && (((Statement)sTokens.Peek()).Name == "var"))
{
VarDeclaration local = new VarDeclaration();
//We call the Parse method of the VarDeclaration, which is responsible to parsing the elements of the variable declaration
local.Parse(sTokens);
Locals.Add(local);
}
//Now we parse the list of statements
while (sTokens.Count > 0 && !(sTokens.Peek() is Parentheses))
{
//We create the correct Statement type (if, while, return, let) based on the top token in the stack
StatetmentBase s = StatetmentBase.Create(sTokens.Peek());
//And call the Parse method of the statement to parse the different parts of the statement
s.Parse(sTokens);
Body.Add(s);
}
//Need to check here that the last statement is a return statement
//Finally, the function should end with }
Token tEnd = sTokens.Pop();//}
}
