private ExcelExpression Term()
{
var res = Factor();
var next = Peek();
if (next != null)
{
switch (next.Kind)
{
case TokenKind.Star:
Read();
res = ExcelExpression.Multiply(res, Expr());
break;
case TokenKind.Slash:
Read();
res = ExcelExpression.Divide(res, Expr());
break;
case TokenKind.Percent:
Read();
res = ExcelExpression.Modulo(res, Expr());
break;
}
}
return(res);
}
public static LambdaExpression Compile(ExcelExpression expression)
{
var comp = new Impl();
var res = comp.Visit(expression);
return(Expression.Lambda(res, comp._cellReferences.Values));
}
private ExcelExpression Factor()
{
var token = Read();
if (token == null)
{
throw new InvalidOperationException();
}
switch (token.Kind)
{
case TokenKind.Number:
return(ExcelExpression.Number(double.Parse(token.Value, CultureInfo.CurrentCulture /* UI */)));
case TokenKind.Identifier:
var next = Peek();
if (next != null && next.Kind == TokenKind.OpenParen)
{
return(ExcelExpression.Formula(token.Value, ArgList()));
}
else if (next != null && next.Kind == TokenKind.Colon)
{
Read();
var endRange = Peek();
if (endRange == null || endRange.Kind != TokenKind.Identifier)
{
throw new InvalidOperationException("Incomplete range expression.");
}
endRange = Read();
return(ExcelExpression.Range(token.Value, endRange.Value));
}
else
{
return(ExcelExpression.Cell(token.Value));
}
case TokenKind.OpenParen:
var res = Expr();
var closeParen = Read();
if (closeParen == null || closeParen.Kind != TokenKind.CloseParen)
{
throw new InvalidOperationException();
}
return(res);
default:
throw new InvalidOperationException("Unexpected token: " + token.Kind);
}
}
private ExcelExpression Expr()
{
var res = Term();
var next = Peek();
if (next != null)
{
switch (next.Kind)
{
case TokenKind.Plus:
Read();
res = ExcelExpression.Add(res, Expr());
break;
case TokenKind.Dash:
Read();
res = ExcelExpression.Subtract(res, Expr());
break;
}
}
return(res);
}
