PureeBenchmark.swift

import Foundation

private let separator: Character = "."
private let allWildcard = "**"
private let wildcard = "*"

func isValidPattern(_ pattern: String) -> Bool {
    let patternElements = pattern.split(separator: separator, omittingEmptySubsequences: false)
    let isValidWildcardCount = patternElements.filter { $0 == allWildcard || $0 == wildcard }.count <= 1
    let containsInvalidElement = patternElements.contains { $0.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }
    return isValidWildcardCount && !containsInvalidElement
}

func isValidPatternWithException(_ pattern: String) -> Bool {
    enum ValidationError: Error {
        case invalidElement
    }

    let elements = pattern.split(separator: separator, omittingEmptySubsequences: false)

    let wildcards = try? elements.filter { element in
        guard !element.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else { throw ValidationError.invalidElement }
        return element == allWildcard || element == wildcard
    }
    return wildcards.map { $0.count <= 1 } ?? false
}

func doBenchmark(execute: () -> Void) {
    let date = Date()
    execute()
    print(Date().timeIntervalSince1970 - date.timeIntervalSince1970)
}

doBenchmark {
    for a in (0..<1000000) {
        isValidPattern("a.b..c")
    }
}

doBenchmark {
    for a in (0..<1000000) {
        isValidPatternWithException("a.b..c")
    }
}

11.2514770030975
7.97567987442017