/// <summary>
/// Parse one line expression with ++ -- (postfix), function call, array subscript, slice subscript operators.
/// Enumerator must be given with reversed ordering of arguments. This corresponds to Operator2Expression from Grammar.
/// </summary>
public static ExpressionNode ParseOperator2 <TSymbol>(IEnumerator <IParseTree <TSymbol> > opExpr) where TSymbol : ISymbol <TSymbol>
{
// O2 -> O1 ( "++" | "--"
// | "(" (E ",")* E? ")"
// | "[" E "]"
// | "[" E? ".." E? "]"
// )*
if (opExpr.Current.Symbol.IsTerminal)
{
string curText = ASTBuilder.EatTerminal(opExpr);
switch (curText)
{
case "++":
case "--":
return(OperatorNode.BuildUnaryOperator(2, curText, ParseOperator2(opExpr)));
case ")":
var args = new LinkedList <ExpressionNode>();
while (!ASTBuilder.EatSymbol("(", opExpr))
{
ASTBuilder.EatSymbol(",", opExpr); // eat ',' before arg - f(x,y,z,) is also possible
args.AddFirst(GetExpressionNode(opExpr.Current));
opExpr.MoveNext(); // move to next param with ','
}
var res = new FunctionCallNode();
res.Arguments = new List <ExpressionNode>(args);
// TODO: can something return a 'pointer' to function which we can call to execute?
res.Name = opExpr.Current.Fragment.GetOriginText();
return(res);
case "]":
var toExpr = ASTBuilder.EatNonTerminal(opExpr); // slice to or index
bool isSlice = ASTBuilder.EatSymbol("..", opExpr);
var fromExpr = ASTBuilder.EatNonTerminal(opExpr);
Debug.Assert(ASTBuilder.EatSymbol("[", opExpr));
if (isSlice) // slice subscript
{
return(SliceNode.CreateSliceNode(ParseOperator2(opExpr),
GetExpressionOrNull(fromExpr), GetExpressionOrNull(toExpr)));
}
else // array subscript
{
return(ElementNode.Create(ParseOperator2(opExpr), GetExpressionNode(toExpr)));
}
default:
Debug.Assert(false);
break;
}
}
else // non-terminal -> Operator1Expression
{
var op1 = opExpr.Current;
Debug.Assert(!opExpr.MoveNext()); // it must be final symbol in this enumeration
var node = ASTBuilder.FirstChild(op1); // Operator1Expression -> Operator0Expression
// Operator0Expression -> AtomicExpression | "(" Expression ")";
var childs = ASTBuilder.ChildrenEnumerator(node);
Debug.Assert(childs.MoveNext());
if (ASTBuilder.EatSymbol("(", childs))
{
return(GetExpressionNode(childs.Current)); // Expression
}
else // proceed with AtomicExpression
{
return(ResolveAtomicExpression(childs.Current));
}
}
return(null);
}