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Indexing.swift
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Indexing.swift
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public protocol NDArrayIndexElementProtocol {
func getNDArrayIndexElement() -> NDArrayIndexElement
}
public struct NDArrayIndexElement: NDArrayIndexElementProtocol {
var start: Int?
var end: Int?
var stride: Int?
// strided range index
init(start: Int?, end: Int?, stride: Int = 1) {
precondition(stride != 0)
if let start = start, let end = end {
precondition((end < 0 && start >= 0) || start <= end, "Invalid range: \(start)..<\(end)")
}
self.start = start
self.end = end
self.stride = stride
}
// Single index
init(single: Int) {
self.start = single
self.end = nil
self.stride = nil
}
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return self
}
}
extension Int: NDArrayIndexElementProtocol {
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return NDArrayIndexElement(single: self)
}
}
public protocol RangeIndexElement: NDArrayIndexElementProtocol {}
extension PartialRangeFrom: NDArrayIndexElementProtocol, RangeIndexElement where Bound == Int {
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return NDArrayIndexElement(start: self.lowerBound, end: nil)
}
}
extension PartialRangeUpTo: NDArrayIndexElementProtocol, RangeIndexElement where Bound == Int {
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return NDArrayIndexElement(start: nil, end: upperBound)
}
}
extension PartialRangeThrough: NDArrayIndexElementProtocol, RangeIndexElement where Bound == Int {
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return NDArrayIndexElement(start: nil, end: upperBound+1)
}
}
extension Range: NDArrayIndexElementProtocol, RangeIndexElement where Bound == Int {
public func getNDArrayIndexElement() -> NDArrayIndexElement {
return NDArrayIndexElement(start: startIndex, end: endIndex)
}
}
precedencegroup StridePrecedence {
associativity: left
lowerThan: RangeFormationPrecedence
}
infix operator ~> : StridePrecedence
prefix operator ~>
infix operator ~>- : StridePrecedence
prefix operator ~>-
public func ~><I: RangeIndexElement>(range: I, stride: Int) -> NDArrayIndexElement {
var index = range.getNDArrayIndexElement()
index.stride = stride
return index
}
public func ~>-<I: RangeIndexElement>(range: I, stride: Int) -> NDArrayIndexElement {
return range ~> (-stride)
}
public prefix func ~>(stride: Int) -> NDArrayIndexElement {
return NDArrayIndexElement(start: nil, end: nil, stride: stride)
}
public prefix func ~>-(stride: Int) -> NDArrayIndexElement {
return ~>(-stride)
}
infix operator ...~>
infix operator ...~>-
public func ...~>(lhs: Int, rhs: Int) -> NDArrayIndexElement {
return NDArrayIndexElement(start: lhs, end: nil, stride: rhs)
}
public func ...~>-(lhs: Int, rhs: Int) -> NDArrayIndexElement {
return lhs ...~> -rhs
}