Say I have a certain javascript object:
obj = { f: function(someFunc){ someFunc("hello") } }
And I wanted to pass in a someFunc that simply alerts the string given to it, if I have obj as a JSObject in my Java code. How would I go about this?
Thanks in advance!
Related
I am pretty amateur in LLVM. I am trying to write a loop pass in which I need to know which function I'm in. Is there any way to find that?
I want to do this in the following runOnLoop function:
virtual bool runOnLoop(Loop *L, LPPassManager &LPM) override {
}
You need
StringRef Name = L->getHeader()->getParent()->getName();
I have a list<Components> components; which is sub-class of Bonus, hence Bonus are Components too.
The .toRect() method is defined in the Bonus class but not in the Components class.
I'm making sure I'm only calling .toRect() in Bonus objects, so there should be no problem, but Dart is keeping me from running the code with the following error:
The method 'toRect' isn't defined for the type 'Component'.
Is there a way to go around this problem without the need to define .toRect() on the Components Class?
void checkForCollision() {
controller.components.where((c) => c is Bonus).forEach((bonus) {
if (this.toRect().contains(bonus.toRect().topLeft) ||
this.toRect().contains(bonus.toRect().topCenter) ||
this.toRect().contains(bonus.toRect().topRight)) {
this.remove = true;
}
});
}
Could do:
.forEach((bonus) {
Bonus bonus = bonus;
.....
or
(controller.components.where((c) => c is Bonus) as List<Bonus>).forEach((bonus) {
Use whereType to filter on types. It's like where that just checks for a type, but it also ensures that the resulting iterable has that element type.
controller.components.whereType<Bonus>().forEach((bonus) {
... bonus.toRect ...
});
The Dart style guide recommends not using a function literal with forEach, use a for-loop instead:
for (var bonus in controller.components.whereType<Bonus>()) {
... bonus.toRect ...
}
If you are doing that anyway, you can also just do:
for (var component in controller.compenents) {
if (component is Bonus) {
.. component.toRect ...
}
}
The type promotion from the is check will ensure that you can call toRect.
This very directly specifies what's going on, without creating unnecessary intermediate iterables.
I am very new to Dart so excuse me if I didnt see this part.
I want to make a union type e.g. for a function input. In TS this would be:
let variableInput: string | number
typedef doesnt really define types but functions and enums dont really help too.
On the other side how should it look like when a function return either one or the other of two types? There must be something I dont see here.
There are no union types in Dart.
The way to do this in Dart is returning/accepting dynamic as a type:
dynamic stringOrNumber() { ... }
void main() {
final value = stringOrNumber();
if (value is String) {
// Handle a string value.
} else if (value is num) {
// Handle a number.
} else {
throw ArgumentError.value(value);
}
}
See also: https://dart.dev/guides/language/sound-dart
I would want to be able to do something like this with a Dart class constructor:
class Model {
// ... setting instance variables
Model(Map fields) {
fields.forEach((k,v) => this[k] = v);
}
}
Obviously, this doesn't work, because this doesn't have a []= method.
Is there a way to make it work or is it simply not "the dart way" of doing things? If it's not, could you show me what would be the right way to tackle this?
You can use Mirrors:
InstanceMirror im = reflect(theClassInstance);
im.invoke('methodName', ['param 1', 2, 'foo']).then((InstanceMirror value) {
print(value.reflectee); // This is the return value of the method invocation.
});
So, in your case you could do this (since you have setters):
import 'dart:mirrors';
class Model {
Model(Map fields) {
InstanceMirror im = reflect(this);
fields.forEach((k, v) => im.setField(k, v)); // or just fields.forEach(im.setField);
}
}
The documentation for InstanceMirror might come in handy.
Currently no. You will have to wait for reflection to arrive in Dart before something like this (hopefully) becomes possible. Until then your best bet is probably to do it in a constructor. Alternatively you could try to use something like JsonObject which allows you to directly initialize it from a Map (for an explanation on how this works, check this blog post).
If I generate a parser using FSYacc will it be thread safe?
The only reason I ask is because the functions
Parsing.rhs_start_pos and Parsing.symbol_end_pos
don't appear to have any state passed into them, which would lead me to assume that they are getting the current NonTerminal/Symbols from a shared location, is this correct?
After reflecting the code I see that they are getting the postion from a static property
internal static IParseState parse_information
{
get
{
return parse_information;
}
set
{
parse_information = value;
}
}
Is this correct? If so what can I do about it?
Edit: I also see a static method called set_parse_state
public static void set_parse_state(IParseState x)
{
parse_information = x;
}
But that still wont solve my problem...
I really don't like to answer my own question, however since this could save someone else a world of grief someday I will.
It turns out that the functions provided in the parsing module are NOT thread safe.
What you can do however is access the parseState "variable", which is of type IParseState, in your nonterminal action.
For example (rough but work with me):
If you have a NonTerminal like
%token<string> NAME
%%
Person:
NAME NAME { $1 (* action *) }
The code that gets generated is:
(fun (parseState : Microsoft.FSharp.Text.Parsing.IParseState) ->
let _1 = (let data = parseState.GetInput(1) in
(Microsoft.FSharp.Core.Operators.unbox data : string)
) in
Microsoft.FSharp.Core.Operators.box((_1) : 'Person)
);
So you can interact with that parseState object in the same fashion.
%token<string> NAME
%%
Person:
NAME NAME { parseState.DoStuff(); }
The rhs_start_pos method basically does this:
let startPos,endPos = parseState.InputRange(n)
and the symbol_end_pos does this:
let startSymb,endSymb = parseState.ResultRange
I hope this helps