VersionSort

Version Sort

Difficulty: medium

Problem Statement

You are given a set of version number strings adhering to the regular expression ^v?\d+(?:\.\d+)*(?:[_-]?[a-zA-Z]*\d*)?$. Write a function that compares two such strings, returning their ordering as a value of type ComparisonResult.

The algorithm should ignore the optional v prefix meaning that v1.1 and 1.1 are considered to be the same version number. The same should apply to trailing .0 components, so that 2.0.0 and 2 are identified as being equal.

func compareVersions(
    _ version1: String,
    _ version2: String) -> ComparisonResult
{
    // ?
}

compareVersions("1.0.1", "1.1.0") // .orderedAscending)
compareVersions("1.9", "1.10") // .orderedAscending)
compareVersions("3.0", "2.1.8") // .orderedDescending)
compareVersions("4.7-alpha11", "4.7-alpha2") // .orderedDescending)
compareVersions("v2.22", "2.22") // .orderedSame)
compareVersions("2", "2.0.0")) // .orderedSame)

Further Instructions

To start working on this challenge open Challenge.swift and uncomment the code skeleton.

To run unit tests that validate your code, uncomment the body of the test method in ChallengeTests.swift and hit CMD + U in Xcode. On Linux you can run the tests by executing swift test in the package directory.

To view selected solutions open Solutions.swift.