From 9ad468781dfb125546a94d7cf507fbd142c16188 Mon Sep 17 00:00:00 2001
From: Brent Simmons <brent@ranchero.com>
Date: Wed, 26 Sep 2018 13:23:21 -0700
Subject: [PATCH] =?UTF-8?q?Start=20work=20on=20performance=20optimization?=
 =?UTF-8?q?=20for=20the=20timeline=20view=20=E2=80=94=C2=A0make=20looking?=
 =?UTF-8?q?=20up=20a=20row=20for=20an=20Article=20faster.?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Timeline/TimelineViewController.swift     | 45 ++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift b/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
index 97e7ca65d..a46e97e44 100644
--- a/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
+++ b/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
@@ -30,12 +30,14 @@ class TimelineViewController: NSViewController, UndoableCommandRunner {
 			if articles != oldValue {
 				dataSource.articles = articles
 				updateShowAvatars()
+				articleRowMap = [String: Int]()
 				tableView.reloadData()
 			}
 		}
 	}
 
 	var undoableCommands = [UndoableCommand]()
+	private var articleRowMap = [String: Int]() // articleID: rowIndex
 	private var cellAppearance: TimelineCellAppearance!
 	private var cellAppearanceWithAvatar: TimelineCellAppearance!
 	private var showFeedNames = false {
@@ -695,7 +697,48 @@ private extension TimelineViewController {
 		block()
 		restoreSelection(savedSelection)
 	}
-	
+
+	func row(for articleID: String) -> Int? {
+		updateArticleRowMapIfNeeded()
+		return articleRowMap[articleID]
+	}
+
+	func row(for article: Article) -> Int? {
+		return row(for: article.articleID)
+	}
+
+	func updateArticleRowMap() {
+		var rowMap = [String: Int]()
+		var index = 0
+		articles.forEach { (article) in
+			rowMap[article.articleID] = index
+			index += 1
+		}
+		articleRowMap = rowMap
+	}
+
+	func updateArticleRowMapIfNeeded() {
+		if articleRowMap.isEmpty {
+			updateArticleRowMap()
+		}
+	}
+
+	func indexesForArticleIDs(_ articleIDs: Set<String>) -> IndexSet {
+
+		var indexes = IndexSet()
+
+		articleIDs.forEach { (articleID) in
+			guard let oneIndex = row(for: articleID) else {
+				return
+			}
+			if oneIndex != NSNotFound {
+				indexes.insert(oneIndex)
+			}
+		}
+
+		return indexes
+	}
+
 	// MARK: Fetching Articles
 
 	func fetchArticles() {