Fix error in VaueArraySlice subscripting

Jxrgxn · Dec 9, 2015 · 4a85429 · 4a85429
1 parent 3a07250
commit 4a85429
Show file tree

Hide file tree

Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/Source/Array/ValueArraySlice.swift b/Source/Array/ValueArraySlice.swift
@@ -44,12 +44,12 @@ public struct ValueArraySlice<Element: Value> : ContiguousMutableMemory, Mutable
 
     public subscript(index: Int) -> Element {
         get {
-            let baseIndex = startIndex + index * step
+            let baseIndex = startIndex + (index - startIndex) * step
             precondition(0 <= baseIndex && baseIndex < base.count)
             return pointer[baseIndex]
         }
         set {
-            let baseIndex = startIndex + index * step
+            let baseIndex = startIndex + (index - startIndex) * step
             precondition(0 <= baseIndex && baseIndex < base.count)
             mutablePointer[baseIndex] = newValue
         }

diff --git a/Tests/RealArrayTests.swift b/Tests/RealArrayTests.swift
@@ -76,4 +76,14 @@ class RealArrayTests: XCTestCase {
         XCTAssertEqual(n[0], 1.0)
         XCTAssertEqual(n[1], 2.0)
     }
+
+    func testSlice() {
+        let array = RealArray((0..<10).map({ Double($0) }))
+        let slice = array[5...8]
+
+        XCTAssertEqual(slice.count, 4)
+        XCTAssertEqual(slice.startIndex, 5)
+        XCTAssertEqual(slice.endIndex, 9)
+        XCTAssertEqual([Double](slice), [5.0, 6.0, 7.0, 8.0])
+    }
 }