davecom/SwiftGraph

//
//  WeightedEdge.swift
//  SwiftGraph
//
//  Copyright (c) 2014-2019 David Kopec
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.


public protocol WeightedEdgeProtocol {
    associatedtype Weight: Equatable

    init(u: Int, v: Int, directed:Bool, weight: Weight)
    var weight: Weight { get }
}

extension WeightedEdge: WeightedEdgeProtocol {
    public typealias Weight = W
}

/// A weighted edge, who's weight subscribes to Comparable.
public struct WeightedEdge<W: Equatable & Codable>: Edge, CustomStringConvertible, Equatable {
    public var u: Int
    public var v: Int
    public var directed: Bool
    public var weight: W
    
    public init(u: Int, v: Int, directed: Bool, weight: W) {
        self.u = u
        self.v = v
        self.directed = directed
        self.weight = weight
    }

    public func reversed() -> WeightedEdge<W> {
        return WeightedEdge(u: v, v: u, directed: directed, weight: weight)
    }

    //Implement Printable protocol
    public var description: String {
        return "\(u) \(weight)> \(v)"
    }
    
    //MARK: Operator Overloads
    static public func == <W>(lhs: WeightedEdge<W>, rhs: WeightedEdge<W>) -> Bool {
        return lhs.u == rhs.u && lhs.v == rhs.v && lhs.weight == rhs.weight
    }

}

extension WeightedEdge: Comparable where W: Comparable {
    static public func < (lhs: WeightedEdge, rhs: WeightedEdge) -> Bool {
        return lhs.weight < rhs.weight
    }
}