private GExpr.Expr assignment()
{
GExpr.Expr expr = or();
if (Match(tt.EQUAL))
{
Token equals = previous();
GExpr.Expr value = assignment();
if (expr is GExpr.Variable)
{
Token name = ((GExpr.Variable)expr).name;
return(new GExpr.Assign(name, value));
}
else if (expr is GExpr.Get)
{
GExpr.Get get = (GExpr.Get)expr;
return(new GExpr.Set(get.Object, get.name, value));
}
error(equals, "Invalid assignment target.");
}
return(expr);
}
public object visit_Get_Expr(GExpr.Get expr)
{
object obj = evaluate(expr.Object);
if (obj is LoxInstance)
{
return(((LoxInstance)obj).get(expr.name));
}
throw new RuntimeError(expr.name, "Only instances have properties");
}
private GExpr.Expr call()
{
GExpr.Expr expr = primary();
while (true)
{
if (Match(tt.LEFT_PAREN))
{
expr = finishCall(expr);
}
else if (Match(tt.DOT))
{
Token name = consume(tt.IDENTIFIER, "Expect property name after '.'.");
expr = new GExpr.Get(expr, name);
}
else
{
break;
}
}
return(expr);
}
public object visit_Get_Expr(GExpr.Get expr)
{
resolve(expr.Object);
return(null);
}