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// RUN: %target-swift-frontend %s -emit-ir
protocol SourceTargetTransformable {
associatedtype Source
associatedtype Target
// FIXME: should really be a typealias once we support that
associatedtype Transformer = (Source) -> Target
}
struct PiecewiseTransformedIteratorOf<
Source,
Target,
SourceIterator: IteratorProtocol,
TransformerIterator: IteratorProtocol,
Transformable: SourceTargetTransformable
>
: IteratorProtocol
where
Transformable.Source == Source,
Transformable.Target == Target,
SourceIterator.Element == Source,
TransformerIterator.Element == Transformable.Transformer {
typealias Element = Target
var sourceIterator: SourceIterator
var transformerIterator: TransformerIterator
mutating func next() -> Element? {
let source: Transformable.Source? = sourceIterator.next()
if let source: Transformable.Source = source {
let transformer: Transformable.Transformer? = transformerIterator.next()
if let transformer: Transformable.Transformer = transformer {
let tfunc: ((Source) -> Target)? = transformer as? ((Source) -> Target)
if let tfunc = tfunc {
return tfunc(source)
}
}
}
return nil
}
}
struct PiecewiseTransformedSequenceOf<
SourceSequence: Sequence,
TransformerSequence: Sequence,
Transformable: SourceTargetTransformable
>: Sequence
where
SourceSequence.Iterator.Element == Transformable.Source,
TransformerSequence.Iterator.Element == Transformable.Transformer {
typealias Source = SourceSequence.Iterator.Element
typealias Target = Transformable.Target
typealias Iterator = PiecewiseTransformedIteratorOf<Source, Target, SourceSequence.Iterator, TransformerSequence.Iterator, Transformable>
let inputs: SourceSequence
let transformers: TransformerSequence
init(inputs: SourceSequence, transformers: TransformerSequence) {
self.inputs = inputs
self.transformers = transformers
}
func makeIterator() -> Iterator {
return PiecewiseTransformedIteratorOf(sourceIterator: inputs.makeIterator(), transformerIterator: transformers.makeIterator())
}
}
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