public Code EvalLiteralWordAtom(ParseTreeNode node, ref CgContext ctx)
{
switch (node.Term.Name)
{
case "identifier":
return new Code(EvalIdentifier(node, ref ctx));
case "character":
return new Code(EvalCharacter(node, ref ctx));
case "number":
return new Code(EvalNumber(node, ref ctx));
case "DifferenceLiteral":
{
var @base = ctx.GetCurrentAddress();
var target = EvalLiteralWordAtom(node.ChildNodes[0].ChildNodes[0], ref ctx);
return ctx.EncodeDifference(new Difference(@base, target));
}
case "DifferenceTo":
return EvalLiteralWordAtom(node.ChildNodes[0], ref ctx);
default:
throw new UnexpectedGrammarException();
}
}
public Code EvalLiteralWord(ParseTreeNode node, ref CgContext ctx)
{
var head = node.ChildNodes[0];
var tail = node.ChildNodes.Count > 1 ? node.ChildNodes[1] : null;
var code = EvalLiteralWordAtom(head, ref ctx);
if (tail != null)
{
var tailC = EvalLiteralWordAtom(tail, ref ctx);
var diff = new Difference(code, tailC);
code = ctx.EncodeDifference(diff);
}
return code;
}