Swift Operators for Python.slice

NumPySlice.swift

import Python

// Slice Operators
precedencegroup SliceFormationPrecedence {
    associativity: left
    lowerThan: AdditionPrecedence
}

infix operator .~: SliceFormationPrecedence
prefix operator .~
postfix operator .~

infix operator .|: SliceFormationPrecedence
prefix operator .|

func .~ (lhs: Int, rhs: Int) -> Python.PyValue {
    return Python.slice.call(with: lhs, rhs, 1)
}

prefix func .~ (rhs: Int) -> Python.PyValue {
    return Python.slice.call(with: Python.None, rhs, 1)
}

postfix func .~ (lhs: Int) -> Python.PyValue {
    return Python.slice.call(with: lhs, Python.None, 1)
}

func .| (lhs: Python.PyValue, rhs: Int) -> Python.PyValue {
    return Python.slice.call(with: lhs.start, lhs.stop, rhs)
}

prefix func .| (rhs: Int) -> Python.PyValue {
    return Python.slice.call(with: Python.None, Python.None, rhs)
}

// NumPy Example
/*
let np = Python.import("numpy")
let a = np.arange.call(with: 10)

let view1 = a[0.~ .| 2] // or a[.|2]
print(view1) // [0 2 4 6 8]

let view2 = a[.~8 .| 2]
print(view2) // [0 2 4 6]

let view3 = a[(-2).~1 .| -1]
print(view3) // [8 7 6 5 4 3 2]

a[.|2] = np.arange.call(with: 10, 15)
print(a) // [10  1 11  3 12  5 13  7 14  9]
*/