Merge branch 'master' into feature/mutable-leaf-tag-config

Sources/Sugar/Helpers/Date.swift

@@ -1,25 +1,40 @@
 import Foundation
 
 public extension Date {
-    public static func startOfMonth() -> Date {
+    public static func startOfMonth() -> Date? {
         return Date().startOfMonth()
     }
 
-    public static func endOfMonth() -> Date {
+    public static func endOfMonth() -> Date? {
         return Date().endOfMonth()
     }
 
-    public func startOfMonth() -> Date {
+    public func startOfMonth() -> Date? {
         return Calendar.current.date(
             from: Calendar.current.dateComponents([.year, .month],
             from: Calendar.current.startOfDay(for: self))
-        )!
+        )
     }
 
-    public func endOfMonth() -> Date {
+    public func endOfMonth() -> Date? {
+        guard let startOfMonth = self.startOfMonth() else { return nil }
         return Calendar.current.date(
             byAdding: DateComponents(month: 1, day: -1),
-            to: self.startOfMonth()
-        )!
+            to: startOfMonth
+        )
+    }
+
+    public func add(days: Int) -> Date? {
+        return Calendar.current.date(
+            byAdding: DateComponents(day: days),
+            to: self
+        )
+    }
+
+    public func sub(days: Int) -> Date? {
+        return Calendar.current.date(
+            byAdding: DateComponents(day: -days),
+            to: self
+        )
     }
 }