Merge pull request #131 from dn-m/ordered

Migrate ordered(_:_:) here from Math

Sources/Algorithms/Ordered.swift

@@ -0,0 +1,16 @@
+//
+//  Ordered.swift
+//  Algorithms
+//
+//  Created by James Bean on 8/8/18.
+//
+
+///    let (lower,higher) = ordered(7,3) // => (3,7)
+///
+/// - Note: If both values are equal, they are returned in the order in which they were given
+///
+/// - Returns: 2-tuple of two given values, in order.
+///
+public func ordered <T: Comparable> (_ a: T, _ b: T) -> (T, T) {
+    return a <= b ? (a,b) : (b,a)
+}

Tests/AlgorithmsTests/OrderedTests.swift

@@ -0,0 +1,36 @@
+//
+//  OrderedTests.swift
+//  AlgorithmsTests
+//
+//  Created by James Bean on 8/8/18.
+//
+
+import XCTest
+@testable import Algorithms
+
+class OrderedTests: XCTestCase {
+
+    func testOrderedEqual() {
+        let a = 4
+        let b = 4
+        let (newA, newB) = ordered(a, b)
+        XCTAssertEqual(newA, a)
+        XCTAssertEqual(newB, b)
+    }
+
+    func testOrderInOrder() {
+        let a = 4
+        let b = 5
+        let (newA, newB) = ordered(a, b)
+        XCTAssertEqual(newA, a)
+        XCTAssertEqual(newB, b)
+    }
+
+    func testOrderNeedsOrdering() {
+        let a = 5
+        let b = 4
+        let (newB, newA) = ordered(a, b)
+        XCTAssertEqual(newA, a)
+        XCTAssertEqual(newB, b)
+    }
+}