public Node ExprRel()
{
//‹expr-add› (‹op-rel› ‹expr-add›)*
var n1 = ExprAdd();
while (firstOfExprRel.Contains(CurrentToken))
{
var n2 = new ExprRel();
switch (CurrentToken)
{
case TokenCategory.LESS:
n2.AnchorToken = Expect(TokenCategory.LESS);
break;
case TokenCategory.LESSEQUAL:
n2.AnchorToken = Expect(TokenCategory.LESSEQUAL);
break;
case TokenCategory.GREATER:
n2.AnchorToken = Expect(TokenCategory.GREATER);
break;
case TokenCategory.GREATEREQUAL:
n2.AnchorToken = Expect(TokenCategory.GREATEREQUAL);
break;
default:
throw new SyntaxError(firstOfExprRel, tokenStream.Current);
}
n2.Add(n1);
n2.Add(ExprAdd());
n1 = n2;
}
return(n1);
}
public string Visit(ExprRel node)
{
var lbl = GenerateLabel();
if (node.AnchorToken.Category == TokenCategory.GREATER)
{
return
(Line(Indent() + "ldc.i4.0")
+ VisitChildren(node)
+ Line(Indent() + "ble '" + lbl + "'")
+ Line(Indent() + "pop")
+ Line(Indent() + "ldc.i4 42")
+ Line(Indent() + lbl + ":"));
}
if (node.AnchorToken.Category == TokenCategory.LESSEQUAL)
{
return
(Line(Indent() + "ldc.i4 42")
+ VisitChildren(node)
+ Line(Indent() + "ble '" + lbl + "'")
+ Line(Indent() + "pop")
+ Line(Indent() + "ldc.i4.0")
+ Line(Indent() + lbl + ":"));
}
if (node.AnchorToken.Category == TokenCategory.GREATEREQUAL)
{
return
(Line(Indent() + "ldc.i4 42")
+ VisitChildren(node)
+ Line(Indent() + "bge '" + lbl + "'")
+ Line(Indent() + "pop")
+ Line(Indent() + "ldc.i4.0")
+ Line(Indent() + lbl + ":"));
}
if (node.AnchorToken.Category == TokenCategory.LESS)
{
return
(Line(Indent() + "ldc.i4.0")
+ VisitChildren(node)
+ Line(Indent() + "bge '" + lbl + "'")
+ Line(Indent() + "pop")
+ Line(Indent() + "ldc.i4 42")
+ Line(Indent() + lbl + ":"));
}
return(node.ToString() + "\n" + VisitChildren(node));
}
public void Visit(ExprRel node)
{
VisitChildren(node);
}