Removes _validateIndex(_:file:line:)

Author: philium

Foundation/NSOrderedSet.swift

@@ -132,11 +132,6 @@ open class NSOrderedSet : NSObject, NSCopying, NSMutableCopying, NSSecureCoding,
         return 0..<count
     }
 
-    /// Checks that an index is valid: 0 ≤ `index` ≤ `count`.
-    internal func _validateIndex(_ index: Int, file: StaticString = #file, line: UInt = #line) {
-        precondition(index <= count && index >= 0, "\(self): Index out of bounds", file: file, line: line)
-    }
-    
     /// Checks that an index is valid for subscripting: 0 ≤ `index` < `count`.
     internal func _validateSubscript(_ index: Int, file: StaticString = #file, line: UInt = #line) {
         precondition(_indices.contains(index), "\(self): Index out of bounds", file: file, line: line)
@@ -351,7 +346,7 @@ extension NSOrderedSet {
 open class NSMutableOrderedSet : NSOrderedSet {
 
     open func insert(_ object: Any, at idx: Int) {
-        _validateIndex(idx)
+        precondition(idx <= count && idx >= 0, "\(self): Index out of bounds")
 
         let value = __SwiftValue.store(object)
 
@@ -454,14 +449,18 @@ extension NSMutableOrderedSet {
         }
     }
 
+    /// Sets the object at the specified index of the mutable ordered set.
+    ///
+    /// - Parameters:
+    ///   - obj: The object to be set.
+    ///   - idx: The index. If the index is equal to `count`, then it appends
+    ///   the object. Otherwise it replaces the object at the index with the
+    ///   given object.
     open func setObject(_ obj: Any, at idx: Int) {
-        _validateIndex(idx)
-        let object = __SwiftValue.store(obj)
-        _storage.insert(object)
-        if idx == _orderedStorage.count {
-            _orderedStorage.append(object)
+        if idx == count {
+            insert(obj, at: idx)
         } else {
-            _orderedStorage[idx] = object
+            replaceObject(at: idx, with: obj)
         }
     }