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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2022-2023 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
@available(FoundationPredicate 0.1, *)
public struct Predicate<each Input> : Sendable {
public let expression : any StandardPredicateExpression<Bool>
public let variable: (repeat PredicateExpressions.Variable<each Input>)
public init(_ builder: (repeat PredicateExpressions.Variable<each Input>) -> any StandardPredicateExpression<Bool>) {
self.variable = (repeat PredicateExpressions.Variable<each Input>())
self.expression = builder(repeat each variable)
}
public func evaluate(_ input: repeat each Input) throws -> Bool {
try expression.evaluate(
.init(repeat (each variable, each input))
)
}
}
@freestanding(expression)
@available(FoundationPredicate 0.1, *)
public macro Predicate<each Input>(_ body: (repeat each Input) -> Bool) -> Predicate<repeat each Input> = #externalMacro(module: "FoundationMacros", type: "PredicateMacro")
@available(FoundationPredicate 0.1, *)
extension Predicate {
private init(value: Bool) {
self.variable = (repeat PredicateExpressions.Variable<each Input>())
self.expression = PredicateExpressions.Value(value)
}
public static var `true`: Self {
Self(value: true)
}
public static var `false`: Self {
Self(value: false)
}
}
// Namespace for operator expressions
@available(FoundationPredicate 0.1, *)
@frozen @_nonSendable public enum PredicateExpressions {}
@available(FoundationPredicate 0.1, *)
extension Sequence {
public func filter(_ predicate: Predicate<Element>) throws -> [Element] {
try self.filter {
try predicate.evaluate($0)
}
}
}
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