Struct GKDecisionTree

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pub struct GKDecisionTree { /* private fields */ }

Available on crate feature GKDecisionTree only.

Expand description

Apple’s documentation

Implementations§

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impl GKDecisionTree

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pub unsafe fn rootNode(&self) -> Option<Retained<GKDecisionNode>>

The node for the decision tree that all other nodes descend from

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pub unsafe fn randomSource(&self) -> Retained<GKRandomSource>

Available on crate feature GKRandomSource only.

The random source used by the decision tree when descending on a random branch This must be set before creating any weighted branches

See: GKDecisionNode

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pub unsafe fn setRandomSource(&self, random_source: &GKRandomSource)

Available on crate feature GKRandomSource only.

Setter for randomSource.

This is copied when set.

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pub unsafe fn initWithAttribute( this: Allocated<Self>, attribute: &ProtocolObject<dyn NSObjectProtocol>, ) -> Retained<Self>

Initializes the decision tree with a root node containing the provided attribute

Parameter attribute: The attribute to be contained at the root of the tree

Returns: GKDecisionTree with the set root

§Safety

attribute should be of the correct type.

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pub unsafe fn initWithExamples_actions_attributes( this: Allocated<Self>, examples: &NSArray<NSArray<ProtocolObject<dyn NSObjectProtocol>>>, actions: &NSArray<ProtocolObject<dyn NSObjectProtocol>>, attributes: &NSArray<ProtocolObject<dyn NSObjectProtocol>>, ) -> Retained<Self>

Initializes and constructs a decision tree by learning from the provided examples & attributes

Parameter examples: Must be an array of examples (with each example being a collection of the various attributes at a given state)

Parameter actions: An array of the corresponding actions for each example. Ordered such that the first action matches with the first example in examples.

Parameter attributes: The list of attributes. Ordered such that the first attribute matches with the first result in each example. So if we have two attributes: [distance, jump height], and two examples: [[20, 8], [15, 14]], and the resulting actions here: [Roll, Jump], we can think of this as a matrix:

distance| height <

Attributes | | | | | 20 | 8 | jump |—––|—––|—–– <
Results | 15 | 14 | roll ||| ^ | Examples

Returns: GKDecisionTree created by learning from the provided examples for the provided attributes

§Safety

examples generic generic should be of the correct type.
actions generic should be of the correct type.
attributes generic should be of the correct type.

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pub unsafe fn initWithURL_error( this: Allocated<Self>, url: &NSURL, error: Option<&NSError>, ) -> Retained<Self>

Initializes a decision tree from the contents of a file

Parameter url: The URL from which the contents will be loaded

Returns: The instance of the decision tree constructed

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pub unsafe fn exportToURL_error( &self, url: &NSURL, error: Option<&NSError>, ) -> bool

Exports a decision tree to the given URL

Parameter url: The URL to which the contents will be exported

Returns: The response indicating the status of the decision tree being successfully exported

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pub unsafe fn findActionForAnswers( &self, answers: &NSDictionary<ProtocolObject<dyn NSObjectProtocol>, ProtocolObject<dyn NSObjectProtocol>>, ) -> Option<Retained<ProtocolObject<dyn NSObjectProtocol>>>

Will branch down from the root node to find the correct action attribute for the given collection of results and their respective attributes

Parameter answers: The dictionary of attributes (keys) and their answers (values)

Returns: The attribute found by traversing the tree given the provided answers

§Safety

answers generic should be of the correct type.
answers generic should be of the correct type.

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impl GKDecisionTree

Methods declared on superclass NSObject.

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pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

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pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = NSObject>§

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pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

§Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

§Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

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pub unsafe fn get_ivar<T>(&self, name: &str) -> &T
where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

§Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

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pub fn downcast_ref<T>(&self) -> Option<&T>
where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

§Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

§Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

§Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

§Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}