什麼 - >（破折號破折號大於）運算斯威夫特

Question

我看看GPUImage2

picture = PictureInput(image:UIImage(named:"WID-small.jpg")!) 
    filter = SaturationAdjustment() 
    picture --> filter --> renderView 
    picture.processImage() 

的源代碼是什麼-->做意味着什麼？

Answer 1

這是一個運算符聲明將目標目標添加到源。

infix operator --> : AdditionPrecedence 
//precedencegroup ProcessingOperationPrecedence { 
// associativity: left 
//// higherThan: Multiplicative 
//} 
@discardableResult public func --><T:ImageConsumer>(source:ImageSource, destination:T) -> T { 
    source.addTarget(destination) 
    return destination 
} 

該功能在pipeline.swift文件

的addTarget函數聲明也是非常強的自我描述。

public func addTarget(_ target:ImageConsumer, atTargetIndex:UInt? = nil) { 
    if let targetIndex = atTargetIndex { 
     target.setSource(self, atIndex:targetIndex) 
     targets.append(target, indexAtTarget:targetIndex) 
     transmitPreviousImage(to:target, atIndex:targetIndex) 
    } else if let indexAtTarget = target.addSource(self) { 
     targets.append(target, indexAtTarget:indexAtTarget) 
     transmitPreviousImage(to:target, atIndex:indexAtTarget) 
    } else { 
     debugPrint("Warning: tried to add target beyond target's input capacity") 
    } 
} 

Answer 2

的-->是特定於項目的自定義操作符，用於功能鏈管道在一起。該項目在framework/Source/Pipeline.swift中由中綴操作員定義。