From dd812a2b2b391da41b82d533175b00152513d666 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Thu, 12 Nov 2015 15:20:51 -0500
Subject: [PATCH] =?UTF-8?q?Test=20that=20we=20aren=E2=80=99t=20at=20the=20?=
 =?UTF-8?q?`endIndex`=20instead=20of=20testing=20containment.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This should be O(1) for all index types.
---
 prototype/Doubt/Matrix.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/prototype/Doubt/Matrix.swift b/prototype/Doubt/Matrix.swift
index 5537729bd..0f87ac294 100644
--- a/prototype/Doubt/Matrix.swift
+++ b/prototype/Doubt/Matrix.swift
@@ -14,7 +14,7 @@ public struct Matrix<A, I: ForwardIndexType> {
 	private let values: [Memo<A>]
 
 	public subscript (i: I, j: I) -> Memo<A>? {
-		guard across.contains(i) && down.contains(j) else { return nil }
+		guard i != across.endIndex && j != down.endIndex else { return nil }
 		let i = across.startIndex.distanceTo(i)
 		let j = down.startIndex.distanceTo(j)
 		return values[Int((i + j * across.count).toIntMax())]