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ExpressibleByArgument.swift
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ExpressibleByArgument.swift
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//===----------------------------------------------------------*- swift -*-===//
//
// This source file is part of the Swift Argument Parser open source project
//
// Copyright (c) 2020 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
//
//===----------------------------------------------------------------------===//
/// A type that can be expressed as a command-line argument.
public protocol ExpressibleByArgument {
/// Creates a new instance of this type from a command-line-specified
/// argument.
init?(argument: String)
}
extension String: ExpressibleByArgument {
public init?(argument: String) {
self = argument
}
}
extension Optional: ExpressibleByArgument where Wrapped: ExpressibleByArgument {
public init?(argument: String) {
if let value = Wrapped(argument: argument) {
self = value
} else {
return nil
}
}
}
extension RawRepresentable where Self: ExpressibleByArgument, RawValue: ExpressibleByArgument {
public init?(argument: String) {
if let value = RawValue(argument: argument) {
self.init(rawValue: value)
} else {
return nil
}
}
}
// MARK: LosslessStringConvertible
extension LosslessStringConvertible {
public init?(argument: String) {
self.init(argument)
}
}
extension Int: ExpressibleByArgument {}
extension Int8: ExpressibleByArgument {}
extension Int16: ExpressibleByArgument {}
extension Int32: ExpressibleByArgument {}
extension Int64: ExpressibleByArgument {}
extension UInt: ExpressibleByArgument {}
extension UInt8: ExpressibleByArgument {}
extension UInt16: ExpressibleByArgument {}
extension UInt32: ExpressibleByArgument {}
extension UInt64: ExpressibleByArgument {}
extension Float: ExpressibleByArgument {}
extension Double: ExpressibleByArgument {}
extension Bool: ExpressibleByArgument {}