Scala Swing Date Picker - scala

Looking to convert Java Swing DatePicker into Scala but facing difficulty in one area of the code. How should I probably translate the if (x > 6) part into scala?
Original Java taken from http://www.roseindia.net/tutorial/java/swing/datePicker.html
for (int x = 0; x < button.length; x++) {
final int selection = x;
button[x] = new JButton();
button[x].setFocusPainted(false);
button[x].setBackground(Color.white);
if (x > 6)
button[x].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
day = button[selection].getActionCommand();
d.dispose();
}
});
if (x < 7) {
button[x].setText(header[x]);
button[x].setForeground(Color.red);
}
p1.add(button[x]);
}
Converted Scala
for (x <- 0 until buttons.length) {
val selection = x
buttons(x) = new Button {
focusPainted = false
background = Color.white
}
if (x > 6)
buttons(x).reactions += {
case ButtonClicked(_) => {
day = buttons(selection).action
d.dispose()
}
}
if (x < 7) {
buttons(x).text = header(x)
buttons(x).foreground = Color.red
}
contents += buttons(x)
}

What is wrong with your translation? Is it not working? The only thing I can see at a glance is that you do not listen to the button:
button(x) listenTo button(x)
But I'm not sure how wise a button listening to itself is, or whether there are any nasty consequences. You don't need to add the reactions to the button itself, you could probably add them to the date picker itself.
Also, something like zipWithIndex is possibly preferable to the way you have done it:
buttons.zipWithIndex foreach { case (button, x) =>
//no need to use buttons(x)
}

The if(x < 7) could be replaced by else, that would be clearer.
You could use a match statement as well:
x match {
case xx if xx > 6 => ...
case _ => ...
}

Related

How to generate a random Scala Int in Chisel code?

I am trying to implement the way-prediction technique in the RocketChip core (in-order). For this, I need to access each way separately. So this is how SRAM for tags looks like after modification (separate SRAM for each way)
val tag_arrays = Seq.fill(nWays) { SeqMem(nSets, UInt(width = tECC.width(1 + tagBits)))}
val tag_rdata = Reg(Vec(nWays, UInt(width = tECC.width(1 + tagBits))))
for ((tag_array, i) <- tag_arrays zipWithIndex) {
tag_rdata(i) := tag_array.read(s0_vaddr(untagBits-1,blockOffBits), !refill_done && s0_valid)
}
And I want to access it like
when (refill_done) {
val enc_tag = tECC.encode(Cat(tl_out.d.bits.error, refill_tag))
tag_arrays(repl_way).write(refill_idx, enc_tag)
ccover(tl_out.d.bits.error, "D_ERROR", "I$ D-channel error")
}
Where repl_way is Chisel random UInt generated by LFSR. But Seq element can be accessed only by Scala Int index which causes a compilation error. Then I tried access it like this
when (refill_done) {
val enc_tag = tECC.encode(Cat(tl_out.d.bits.error, refill_tag))
for (i <- 0 until nWays) {
when (repl_way === i.U) {tag_arrays(i).write(refill_idx, enc_tag)}
}
ccover(tl_out.d.bits.error, "D_ERROR", "I$ D-channel error")
}
But assertion arises -
assert(PopCount(s1_tag_hit zip s1_tag_disparity map { case (h, d) => h && !d }) <= 1)
I am trying to modify ICache.scala file. Any ideas on how to do this properly? Thanks!
I think you can just use a Vec here instead of a Seq
val tag_arrays = Vec(nWays, SeqMem(nSets, UInt(width = tECC.width(1 + tagBits))))
The Vec allows indexing with a UInt

How to only emit consistent calculations?

I'm using reactive programming to do a bunch of calculations. Here is a simple example that tracks two numbers and their sum:
static void Main(string[] args) {
BehaviorSubject<int> x = new BehaviorSubject<int>(1);
BehaviorSubject<int> y = new BehaviorSubject<int>(2);
var sum = Observable.CombineLatest(x, y, (num1, num2) => num1 + num2);
Observable
.CombineLatest(x, y, sum, (xx, yy, sumsum) => new { X = xx, Y = yy, Sum = sumsum })
.Subscribe(i => Console.WriteLine($"X:{i.X} Y:{i.Y} Sum:{i.Sum}"));
x.OnNext(3);
Console.ReadLine();
}
This generates the following output:
X:1 Y:2 Sum:3
X:3 Y:2 Sum:3
X:3 Y:2 Sum:5
Notice how second output result is "incorrect" because it is showing that 3+2=3. I understand why this is happening (x is updated before the sum is updated) but I want my output calculations to be atomic/consistent - no value should be emitted until all dependent calculations are complete. My first approach was this...
Observable.When(sum.And(Observable.CombineLatest(x, y)).Then((s, xy) => new { Sum = s, X = xy[0], Y = xy[1] } ));
This seems to work for my simple example. But my actual code has LOTS of calculated values and I couldn't figure out how to scale it. For example, if there was a sum and squaredSum, I don't know how to wait for each of these to emit something before taking action.
One method that should work (in-theory) is to timestamp all the values I care about, as shown below.
Observable
.CombineLatest(x.Timestamp(), y.Timestamp(), sum.Timestamp(), (xx, yy, sumsum) => new { X = xx, Y = yy, Sum = sumsum })
.Where(i=>i.Sum.Timestamp>i.X.Timestamp && i.Sum.Timestamp>i.Y.Timestamp)
// do the calculation and subscribe
This method could work for very complicated models. All I have to do is ensure that no calculated value is emitted that is older than any core data value. I find this to be a bit of a kludge. It didn't actually work in my console app. When I replaced Timestamp with a custom extension that assigned a sequential int64 it did work.
What is a simple, clean way to handle this kind of thing in general?
=======
I'm making some progress here. This waits for a sum and sumSquared to emit a value before grabbing the data values that triggered the calculation.
var all = Observable.When(sum.And(sumSquared).And(Observable.CombineLatest(x, y)).Then((s, q, data)
=> new { Sum = s, SumSquared = q, X = data[0], Y = data[1] }));
This should do what you want:
Observable.CombineLatest(x, y, sum)
.DistinctUntilChanged(list => list[2])
.Subscribe(list => Console.WriteLine("{0}+{1}={2}", list[0], list[1], list[2]));
It waits until the sum has been updated, which means that all its sources must have been updated too.
You problem isn't because x is updated before the sum is updated per se. It's really about the way that you've constructed your query.
You've effectively created two queries: Observable.CombineLatest(x, y, (num1, num2) => num1 + num2) & Observable.CombineLatest(x, y, sum, (xx, yy, sumsum) => new { X = xx, Y = yy, Sum = sumsum }). Since in each you're subscribing to x then you've create two subscriptions. Meaning that when x updates then two lots of updates occur.
You need to avoid creating two subscriptions.
If you write your code like this:
BehaviorSubject<int> x = new BehaviorSubject<int>(1);
BehaviorSubject<int> y = new BehaviorSubject<int>(2);
Observable
.CombineLatest(x, y, (num1, num2) => new
{
X = num1,
Y = num2,
Sum = num1 + num2
})
.Subscribe(i => Console.WriteLine($"X:{i.X} Y:{i.Y} Sum:{i.Sum}"));
x.OnNext(3);
...then you correctly get this output:
X:1 Y:2 Sum:3
X:3 Y:2 Sum:5
I've started to get my head around this some more. Here is a more detailed example of what I'm trying to accomplish. This is some code that validates a first and last name, and should only generate a whole name when both parts are valid. As you can see I'm trying to use a bunch of small independently defined functions, like "firstIsValid", and then compose them together to calculate something more complex.
It seems like the challenge I'm facing here is trying to correlate inputs and outputs in my functions. For example, "firstIsValid" generates an output that says some first name was valid, but doesn't tell you which one. In option 2 below, I'm able to correlate them using Zip.
This strategy won't work if a validation function does not generate one output for each input. For example, if the user is typing web addresses and we're trying to validate them on the web, maybe we'd do a Throttle and/or Switch. There might be 10 web addresses for a single "webAddressIsValid". In that situation, I think I have to include the output with the input. Maybe have an IObservable> where the string is the web address and the bool is whether it is valid or not.
static void Main(string[] args) {
var first = new BehaviorSubject<string>(null);
var last = new BehaviorSubject<string>(null);
var firstIsValid = first.Select(i => string.IsNullOrEmpty(i) || i.Length < 3 ? false : true);
var lastIsValid = last.Select(i => string.IsNullOrEmpty(i) || i.Length < 3 ? false : true);
// OPTION 1 : Does not work
// Output: bob smith, bob, bob roberts, roberts
// firstIsValid and lastIsValid are not in sync with first and last
//var whole = Observable
// .CombineLatest(first, firstIsValid, last, lastIsValid, (f, fv, l, lv) => new {
// First = f,
// Last = l,
// FirstIsValid = fv,
// LastIsValid = lv
// })
// .Where(i => i.FirstIsValid && i.LastIsValid)
// .Select(i => $"{i.First} {i.Last}");
// OPTION 2 : Works as long as every change in a core data value generates one calculated value
// Output: bob smith, bob robert
var firstValidity = Observable.Zip(first, firstIsValid, (f, fv) => new { Name = f, IsValid = fv });
var lastValidity = Observable.Zip(last, lastIsValid, (l, lv) => new { Name = l, IsValid = lv });
var whole =
Observable.CombineLatest(firstValidity, lastValidity, (f, l) => new { First = f, Last = l })
.Where(i => i.First.IsValid && i.Last.IsValid)
.Select(i => $"{i.First.Name} {i.Last.Name}");
whole.Subscribe(i => Console.WriteLine(i));
first.OnNext("bob");
last.OnNext("smith");
last.OnNext(null);
last.OnNext("roberts");
first.OnNext(null);
Console.ReadLine();
}
Another approach here. Each value gets a version number (like a timestamp). Any time a calculated value is older than the data (or other calculated values it relies upon) we can ignore it.
public class VersionedValue {
static long _version;
public VersionedValue() { Version = Interlocked.Increment(ref _version); }
public long Version { get; }
}
public class VersionedValue<T> : VersionedValue {
public VersionedValue(T value) { Value = value; }
public T Value { get; }
public override string ToString() => $"{Value} {Version}";
}
public static class ExtensionMethods {
public static IObservable<VersionedValue<T>> Versioned<T>(this IObservable<T> values) => values.Select(i => new VersionedValue<T>(i));
public static VersionedValue<T> AsVersionedValue<T>(this T obj) => new VersionedValue<T>(obj);
}
static void Main(string[] args) {
// same as before
//
var whole = Observable
.CombineLatest(first.Versioned(), firstIsValid.Versioned(), last.Versioned(), lastIsValid.Versioned(), (f, fv, l, lv) => new {
First = f,
Last = l,
FirstIsValid = fv,
LastIsValid = lv
})
.Where(i => i.FirstIsValid.Version > i.First.Version && i.LastIsValid.Version > i.Last.Version)
.Where(i => i.FirstIsValid.Value && i.LastIsValid.Value)
.Select(i => $"{i.First.Value} {i.Last.Value}");

How can I reduce the redundancies of the fields handling of feed handler

I am subscript to a message feed for a number of fields, I need to set the values from the feed to the domain object and have code like below:
if (map.contains(quoteBidPriceAcronym)) {
quote.bid.price = Some(map.get(quoteBidPriceAcronym).get.asInstanceOf[Number].doubleValue());
quote.changed = true;
}
if (map.contains(quoteBidSizeAcronym)) {
quote.bid.size = Some(sizeMultipler() * map.get(quoteBidSizeAcronym).get.asInstanceOf[Number].intValue());
quote.changed = true;
}
if (map.contains(quoteBidNumAcronym)) {
quote.bid.num = Some(map.get(quoteBidNumAcronym).get.asInstanceOf[Number].shortValue());
quote.changed = true;
}
if (map.contains(quoteAskPriceAcronym)) {
quote.ask.price = Some(map.get(quoteAskPriceAcronym).get.asInstanceOf[Number].doubleValue());
quote.changed = true;
}
if (map.contains(quoteAskSizeAcronym)) {
quote.ask.size = Some(sizeMultipler() * map.get(quoteAskSizeAcronym).get.asInstanceOf[Number].intValue());
quote.changed = true;
}
if (map.contains(quoteAskNumAcronym)) {
quote.ask.num = Some(map.get(quoteAskNumAcronym).get.asInstanceOf[Number].shortValue());
quote.changed = true;
}
if (map.contains(quoteExchTimeAcronym)) {
quote.exchtime = getExchTime(String.valueOf(map.get(quoteExchTimeAcronym).get));
}
It look pretty redundant, any suggestion to improve it?
You can do something like:
map.get(quoteBidPriceAcronym).map { item =>
quote.bid.price = item.map(_.asInstanceOf[Number].doubleValue())
quote.changed = true
}
Other issues might be better to fix outside. E.g. why map[quoteBidPriceAcronym] is storing an Option, if your code assumes it's not going to be None?
Something like this perhaps?
val handlers = Map[String, Number => Unit] (
quoteBidPriceAcronym -> { n => quote.bid.price = Some(n.doubleValue) },
quoteBidSizeAcronym -> { n => quote.bid.size = Some(sizeMultipler() * n.intValue },
etc. ...
)
for {
(k,handler) <- handlers
values <- map.get(k).toSeq
quote.chanded = true
_ = handler(n.asInstanceof[Number])
}
Personally, I don't like code changing an object state (quote) but this is a question on Scala, not functional programming.
That said I would reverse the way you are using you map map keys. Instead of checking whether a value exists to perform some action, I'd have a map from your keys to actions and I'd iterate over your map elements.
e.g (assuming map is of the type Map[String, Any]):
val actions: Map[String, PartialFunction[Any, Unit]] = Map(
(quoteBidPriceAcronym, {case n: Number => quote.bid.price = Some(n.doubleValue())}),
(quoteBidSizeAcronym, {case n: Number => quote.bid.size = Some(sizeMultipler() * n.doubleValue())}),
...
...
)
for((k,v) <- map; action <- actions.get(k); _ <- action.lift(v))
quote.changed = true;
The for construct here iterates over map key-values, then (next level of iteration, over the possible action available for the key. If an action is found, which is a partial function, it gets lifted to make it a function from Any to Option[Unit]. That way, you can iterate in an additional inner level so quote.changed = true is only run when the action is defined for v.

removing elements from a sequence using for/yield

Given a Future[Seq[Widget]], where Widget contains a amount : Int property, I'd like to return a Seq[Widget] but for only those Widgets whose amount value is greater than 100. I believe the for { if … } yield { } construct will give me what I want but am unsure how to filter through the Sequence. I have:
val myWidgetFuture : Future[Seq[Widget]] = ...
for {
widgetSeq <- myWidgetFuture
if (??? amount > 100) <— what to put here?
} yield {
widgetSeq
}
If there's a clean non-yield way of doing this that will also work for me.
You don't even need yield. Use map.
val myWidgetFuture: Future[Seq[Widget]] = ???
myWidgetFuture map { ws => ws filter (_.amount > 100) }
If you want to use for … yield with an if filter, you'll need to use two fors:
for {
widgetSeq <- myWidgetFuture
} yield for {
widget <- widgetSeq
if widget.amount > 100
} yield widget

Any Way to Streamline this Logic?

I've written some code that translates an Entity Framework collection to some fixed fields. I ended up with the following snippet but isn't there a slicker way to accomplish this?
var numbers = c.ContactPhoneNumbers.OrderByDescending(n => n.IsPrimary);
int count = 0;
foreach (var number in numbers)
{
if (count == 0)
{
hc.PrimaryPhone = number.PhoneNumber;
hc.PrimaryPhoneType = number.PhoneNumberType;
}
else if (count == 1)
{
hc.SecondaryPhone = number.PhoneNumber;
hc.SecondaryPhoneType = number.PhoneNumberType;
}
else break;
count++;
}
c is an Entity Framework entity and c.ContactPhoneNumbers represents entries in a related table. Seems like this code could be made a little more straight forward and less awkward.
Since you are iterating the phone enumeration right away, might be better to use ToList() so you can use the indexer:
var numbers = c.ContactPhoneNumbers.OrderByDescending(n => n.IsPrimary).ToList();
if(numbers.Count > 0)
{
hc.PrimaryPhone = numbers[0].PhoneNumber;
hc.PrimaryPhoneType = number[0].PhoneNumberType;
}
if(numbers.Count > 1)
{
hc.SecondaryPhone = numbers[1].PhoneNumber;
hc.SecondaryPhoneType = numbers[1].PhoneNumberType;
}