SnapKit/Source/ConstraintPriority.swift

//
//  SnapKit
//
//  Copyright (c) 2011-Present SnapKit Team - https://github.com/SnapKit
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.

#if os(iOS) || os(tvOS)
    import UIKit
#else
    import AppKit
#endif

public struct ConstraintPriority : ExpressibleByFloatLiteral, Equatable, Strideable {
    public typealias FloatLiteralType = Float
    
    public let value: Float
    
    public init(floatLiteral value: Float) {
        self.value = value
    }
    
    public init(_ value: Float) {
        self.value = value
    }
    
    public static var required: ConstraintPriority {
        return 1000.0
    }
    
    public static var high: ConstraintPriority {
        return 750.0
    }
    
    public static var medium: ConstraintPriority {
        #if os(OSX)
            return 501.0
        #else
            return 500.0
        #endif
        
    }
    
    public static var low: ConstraintPriority {
        return 250.0
    }
    
    public static func ==(lhs: ConstraintPriority, rhs: ConstraintPriority) -> Bool {
        return lhs.value == rhs.value
    }

    // MARK: Strideable

    public func advanced(by n: FloatLiteralType) -> ConstraintPriority {
        return ConstraintPriority(floatLiteral: value + n)
    }

    public func distance(to other: ConstraintPriority) -> FloatLiteralType {
        return other.value - value
    }
}