/// <summary>
/// eval := dynamic | deferred
/// </summary>
protected internal virtual AstEval Eval()
{
AstEval e = Eval(false, false);
if (e == null)
{
e = Eval(false, true);
if (e == null)
{
Fail(Scanner.Symbol.START_EVAL_DEFERRED + "|" + Scanner.Symbol.START_EVAL_DYNAMIC);
}
}
return(e);
}
/// <summary>
/// tree := text? ((dynamic text?)+ | (deferred text?)+)?
/// </summary>
public virtual Tree Tree()
{
ConsumeToken();
AstNode t = Text();
if (token.Symbol == Scanner.Symbol.EOF)
{
if (t == null)
{
t = new AstText("");
}
return(new Tree(t, functions, identifiers, false));
}
AstEval e = Eval();
if (token.Symbol == Scanner.Symbol.EOF && t == null)
{
return(new Tree(e, functions, identifiers, e.Deferred));
}
List <AstNode> list = new List <AstNode>();
if (t != null)
{
list.Add(t);
}
list.Add(e);
t = Text();
if (t != null)
{
list.Add(t);
}
while (token.Symbol != Scanner.Symbol.EOF)
{
if (e.Deferred)
{
list.Add(Eval(true, true));
}
else
{
list.Add(Eval(true, false));
}
t = Text();
if (t != null)
{
list.Add(t);
}
}
return(new Tree(CreateAstComposite(list), functions, identifiers, e.Deferred));
}
/// <summary>
/// dynmamic := <START_EVAL_DYNAMIC> expr <END_EVAL>
/// deferred := <START_EVAL_DEFERRED> expr <END_EVAL>
/// </summary>
protected internal virtual AstEval Eval(bool required, bool deferred)
{
AstEval v = null;
Scanner.Symbol start_eval = deferred ? Scanner.Symbol.START_EVAL_DEFERRED : Scanner.Symbol.START_EVAL_DYNAMIC;
if (token.Symbol == start_eval)
{
ConsumeToken();
v = new AstEval(Expr(true), deferred);
ConsumeToken(Scanner.Symbol.END_EVAL);
}
else if (required)
{
Fail(start_eval);
}
return(v);
}