Avoid rescanning all builds when closing a build

spec/System/TestBuildListHelpers_spec.lua

@@ -2,6 +2,7 @@ describe("BuildListHelpers", function()
 	local originalBuildPath
 	local originalCloudErrorPopup
 	local originalFileSearch
+	local originalFilterBuildList
 	local originalOpen
 	local buildListHelpers
 	local fileHeaders
@@ -14,6 +15,7 @@ describe("BuildListHelpers", function()
 		originalBuildPath = main.buildPath
 		originalCloudErrorPopup = main.OpenCloudErrorPopup
 		originalFileSearch = _G.NewFileSearch
+		originalFilterBuildList = main.filterBuildList
 		originalOpen = io.open
 		buildListHelpers = LoadModule("Modules/BuildListHelpers")
 		fileHeaders = { }
@@ -22,6 +24,7 @@ describe("BuildListHelpers", function()
 		searchCount = 0
 		cloudErrorPath = nil
 		main.buildPath = "Builds/"
+		main.filterBuildList = ""
 		main.OpenCloudErrorPopup = function(_, path)
 			cloudErrorPath = path
 		end
@@ -53,6 +56,7 @@ describe("BuildListHelpers", function()
 		main.buildPath = originalBuildPath
 		main.OpenCloudErrorPopup = originalCloudErrorPopup
 		_G.NewFileSearch = originalFileSearch
+		main.filterBuildList = originalFilterBuildList
 		io.open = originalOpen
 	end)
 
@@ -77,6 +81,33 @@ describe("BuildListHelpers", function()
 		assert.are.same(opensAfterIndex, fileOpenCount)
 	end)
 
+	it("refreshes only the reopened build when returning to the build list", function()
+		searches["files:Builds/*.xml"] = { { name = "Root.xml", modified = 1 } }
+		searches["folders:Builds/*"] = { { name = "League", modified = 2 } }
+		searches["files:Builds/League/*.xml"] = { { name = "Nested.xml", modified = 3 } }
+		fileHeaders["Builds/Root.xml"] = '<Build level="80" className="Witch" ascendClassName="Occultist">'
+		fileHeaders["Builds/League/Nested.xml"] = '<Build level="90" className="Shadow" ascendClassName="Assassin">'
+		local listMode = require("Modules.BuildList")
+
+		listMode:Init()
+		local scansAfterIndex = searchCount
+		local opensAfterIndex = fileOpenCount
+		searches["files:Builds/Root.xml"] = { { name = "Root.xml", modified = 4 } }
+		fileHeaders["Builds/Root.xml"] = '<Build level="81" className="Shadow" ascendClassName="Assassin">'
+		listMode:Init("Root", "")
+
+		assert.are.same(scansAfterIndex + 1, searchCount)
+		assert.are.same(opensAfterIndex + 1, fileOpenCount)
+		assert.are.same(81, listMode.controls.buildList.selValue.level)
+		assert.are.same("Assassin", listMode.controls.buildList.selValue.ascendClassName)
+		assert.are.same(4, listMode.controls.buildList.selValue.modified)
+
+		local scansBeforeFolderChange = searchCount
+		listMode:Init("Nested", "League/")
+		assert.are.same(scansBeforeFolderChange + 2, searchCount)
+		assert.are.same("Builds/League/Nested.xml", listMode.controls.buildList.selValue.fullFileName)
+	end)
+
 	it("reports cloud read failures", function()
 		searches["files:Builds/*.xml"] = { { name = "Cloud.xml" } }
 		fileHeaders["Builds/Cloud.xml"] = false

src/Modules/BuildList.lua

@@ -14,6 +14,8 @@ local listMode = new("ControlHost"):ControlHost()
 
 function listMode:Init(selBuildName, subPath)
 	if self.initialised then
+		local subPathChanged = subPath and subPath ~= self.subPath
+		local reuseBuildIndex = not subPathChanged and self.indexedBuildPath == main.buildPath
 		self.subPath = subPath or self.subPath
 		self.controls.buildList.controls.path:SetSubPath(self.subPath)
 		--if main.showPublicBuilds then
@@ -22,7 +24,14 @@ function listMode:Init(selBuildName, subPath)
 		else
 			self.controls.ExtBuildList = nil
 		end
-		self:BuildList()
+		if reuseBuildIndex then
+			if selBuildName then
+				buildListHelpers.RefreshBuild(self.buildIndex, self.subPath, selBuildName..".xml")
+			end
+			self:FilterBuildList()
+		elseif not subPathChanged then
+			self:BuildList()
+		end
 		self.controls.buildList:SelByFullFileName(selBuildName and main.buildPath..self.subPath..selBuildName..".xml")
 		self:SelectControl(self.controls.buildList)
 		return
@@ -199,6 +208,7 @@ function listMode:GetDestName(subPath, fileName)
 end
 
 function listMode:BuildList()
+	self.indexedBuildPath = main.buildPath
 	self.buildIndex = buildListHelpers.ScanFolder(self.subPath)
 	self:FilterBuildList()
 end

src/Modules/BuildListHelpers.lua

@@ -34,6 +34,22 @@ local function ReadBuildHeader(fullFileName)
 	}
 end
 
+local function ReadBuild(subPath, fileName, modified)
+	local fullFileName = main.buildPath..subPath..fileName
+	local header = ReadBuildHeader(fullFileName)
+	if not header then return end
+	return {
+		fileName = fileName,
+		subPath = subPath,
+		fullFileName = fullFileName,
+		modified = modified,
+		buildName = fileName:gsub("%.xml$",""),
+		level = header.level,
+		className = header.className,
+		ascendClassName = header.ascendClassName,
+	}
+end
+
 local function MatchEntry(entry, terms)
 	for _, term in ipairs(terms) do
 		local termLower = term:lower()
@@ -66,19 +82,9 @@ local function ScanFolder(subPath)
 		local handle = NewFileSearch(main.buildPath..currentSubPath.."*.xml")
 		while handle do
 			local fileName = handle:GetFileName()
-			local fullFileName = main.buildPath..currentSubPath..fileName
-			local header = ReadBuildHeader(fullFileName)
-			if header then
-				t_insert(list, {
-					fileName = fileName,
-					subPath = currentSubPath,
-					fullFileName = fullFileName,
-					modified = handle:GetFileModifiedTime(),
-					buildName = fileName:gsub("%.xml$",""),
-					level = header.level,
-					className = header.className,
-					ascendClassName = header.ascendClassName,
-				})
+			local build = ReadBuild(currentSubPath, fileName, handle:GetFileModifiedTime())
+			if build then
+				t_insert(list, build)
 			end
 
 			if not handle:NextFile() then break end
@@ -110,6 +116,27 @@ local function ScanFolder(subPath)
 	return list
 end
 
+local function RefreshBuild(index, subPath, fileName)
+	local fullFileName = main.buildPath..subPath..fileName
+	local handle = NewFileSearch(fullFileName)
+	local build = handle and ReadBuild(subPath, fileName, handle:GetFileModifiedTime())
+	if handle and not build then return end
+
+	for buildIndex, entry in ipairs(index) do
+		if entry.fullFileName == fullFileName then
+			if build then
+				index[buildIndex] = build
+			else
+				table.remove(index, buildIndex)
+			end
+			return
+		end
+	end
+	if build then
+		t_insert(index, build)
+	end
+end
+
 -- Filtering the cached index avoids filesystem work on every keystroke.
 local function FilterList(index, subPath, filterText)
 	local terms = { }
@@ -196,6 +223,7 @@ return {
 	buildSortDropList = buildSortDropList,
 	CanMoveToSubPath = CanMoveToSubPath,
 	FilterList = FilterList,
+	RefreshBuild = RefreshBuild,
 	ScanFolder = ScanFolder,
 	SortList = SortList,
 }