For Developers targeting macOS 14.4 / iOS 17.4 or later:

This PR For Swift Foundation adds compound functionality to Predicates like so: If you are targeting only those versions and above you should use this instead:

let notTooShort = #Predicate<Book> { $0.pages > 50 }
let notTooLong = #Predicate<Book> { $0.pages <= 350 }
let titleFilter = #Predicate<Book> { $0.title.contains("Swift") }

let filter = #Predicate<Book> {
    (notTooShort.evaluate($0) && notTooLong.evaluate($0)) || titleFilter.evaluate($0)
}

CompoundPredicate

CompoundPredicate aims to improve the Predicate system to enable combining multiple predicates after constructing them:

let notTooShort = #Predicate<Book> {
    $0.pages > 50
}

let notTooLong = #Predicate<Book> {
    $0.pages <= 350
}

let lengthFilter = [notTooShort, notTooShort].conjunction()

// Match Books that are just the right length
let titleFilter = #Predicate<Book> {
    $0.title.contains("Swift")
}

// Match Books that contain "Swift" in the title or
// are just the right length
let filter = [lengthFilter, titleFilter].disjunction()

Documentation

The documentation is available here and as Docc archive you can view using Xcode

Feedback

Please feel free to create an Issue, or even better contribute actively by creating a pull request

Implementation Progress

• Arithmetic (+, -, *, /, %)

  • +, -, * PredicateExpressions.Arithmetic
  • / PredicateExpressions.FloatDivision
  • / PredicateExpressions.IntDivision
  • % PredicateExpressions.IntRemainder

• Unary minus - PredicateExpressions.UnaryMinus

• Range (..., ..<)

  • ... PredicateExpressions.ClosedRange
  • ..< PredicateExpressions.Range
  • x..<z).contains(y) PredicateExpressions.RangeExpressionContains

• Comparison (<, <=, >, >=, ==, !=)

  • <, <=, >, >= PredicateExpressions.Comparison
  • == PredicateExpressions.Equal
  • != PredicateExpressions.NotEqual

• Conditionals & Ternary (?:) PredicateExpressions.Conditional

• Boolean logic (&&, ||, !)

  • && PredicateExpressions.Conjunction
  • || PredicateExpressions.Disjunction
  • ! PredicateExpressions.Negation

• Swift optionals (?, ??, !, flatMap(_:), if-let expressions)

  • ?, flatMap(_:) PredicateExpressions.OptionalFlatMap
  • ??, if-let PredicateExpressions.NilCoalesce

• Types (as, as?, as!, is)

  • as? PredicateExpressions.ConditionalCast
  • as, as! PredicateExpressions.ForceCast

• Sequence operations (allSatisfy(), filter(), contains(), contains(where:), starts(with:), max(), min())

  • allSatisfy() PredicateExpressions.SequenceAllSatisfy
  • filter() PredicateExpressions.Filter [completion:: 2024-03-10]
  • contains() PredicateExpressions.SequenceContains [completion:: 2024-03-10]
  • contains(where:) PredicateExpressions.SequenceContainsWhere
  • starts(with:) PredicateExpressions.SequenceStartsWith
  • min() PredicateExpressions.SequenceMinimum [completion:: 2024-03-10]
  • max() PredicateExpressions.SequenceMaximum

• Subscript and member access ([], .)

  • [0,1][0] PredicateExpressions.CollectionIndexSubscript
  • ["a": "b"]["a"] PredicateExpressions.DictionaryKeySubscript
  • ["a": "b"]["a", defaultValue: "b"] PredicateExpressions.DictionaryKeyDefaultValueSubscript
  • obj.someKey PredicateExpressions.KeyPath

• String comparisons

  • contains(_:) PredicateExpressions.CollectionContainsCollection
  • localizedStandardContains(_:) PredicateExpressions.StringLocalizedStandardContains
  • caseInsensitiveCompare(_:) PredicateExpressions.StringCaseInsensitiveCompare
  • localizedCompare(_:) PredicateExpressions.StringLocalizedCompare