- Added Swift solution to the "Rotate String" task.

challenge-063/mohammad-anwar/swift/ch-2.swift

@@ -0,0 +1,81 @@
+import Foundation
+
+/*
+Perl Weekly Challenge - 063
+
+Task #2: Rotate String
+
+https://perlweeklychallenge.org/blog/perl-weekly-challenge-063
+*/
+
+enum ParamError: Error {
+    case missingWord
+    case invalidWord
+}
+
+do {
+    let paramCount:Int = Int(CommandLine.argc)
+
+    if paramCount <= 1 {
+        throw ParamError.missingWord
+    }
+
+    let word:String = CommandLine.arguments[1]
+
+    if isValidWord(word) {
+        let size:Int    = word.count;
+        var temp:String = word
+        var i:Int = 1
+        var c:Int = 1
+
+        while i <= size {
+            let partA:String = String(temp.substring(to: i))
+            let partB:String = String(temp.substring(from: i))
+            temp = partB + partA
+            print("[\(c)]: [\(temp)]")
+
+            if temp == word {
+                break
+            }
+
+            i = i + 1
+            c = c + 1
+
+            if i > size {
+                i = 1
+            }
+        }
+
+        print("Rotation: \(c)")
+    }
+    else {
+        throw ParamError.invalidWord
+    }
+}
+catch ParamError.missingWord {
+    print("Missing word.")
+}
+catch ParamError.invalidWord {
+    print("Invalid word.")
+}
+catch let error {
+    print(error)
+}
+
+//
+//
+// Function
+
+func isValidWord(_ word:String) -> Bool {
+
+    let pattern = "^[xy]+$"
+    let regex   = try! NSRegularExpression(pattern: pattern, options: .caseInsensitive)
+    let range   = NSRange(location: 0, length: word.utf16.count)
+
+    if regex.firstMatch(in: word, options: [], range: range) != nil {
+        return true
+    }
+    else {
+        return false
+    }
+}