From 617d90757e209a5e476f319756b200aa4fd24bf8 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Thu, 23 Jun 2016 17:50:23 +0300
Subject: [PATCH] Save selected indexes as hash + range, to not eat memory on
 very long lists

---
 mail.js | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/mail.js b/mail.js
index 8e6e666..2d68144 100644
--- a/mail.js
+++ b/mail.js
@@ -745,6 +745,11 @@ var ListWithSelection = {
             selected: {}
         };
     },
+    isSelected: function(i)
+    {
+        return this.state.selected[i] || this.state.selected.begin !== undefined &&
+            this.state.selected.begin <= i && this.state.selected.end >= i;
+    },
     onListKeyDown: function(ev)
     {
         if (!this.getTotalItems())
@@ -812,19 +817,15 @@ var ListWithSelection = {
     {
         if (this.lastSel === undefined)
             return this.selectOne(ns);
-        var sel = { ns: 1 };
+        var sel = {};
         if (this.lastSel >= this.getTotalItems())
             this.lastSel = this.getTotalItems()-1;
         if (ns < this.lastSel)
-        {
-            for (var i = ns; i <= this.lastSel; i++)
-                sel[i] = true;
-        }
+            sel = { begin: ns, end: this.lastSel };
         else if (ns > this.lastSel)
-        {
-            for (var i = this.lastSel; i <= ns; i++)
-                sel[i] = true;
-        }
+            sel = { begin: this.lastSel, end: ns };
+        else
+            sel[ns] = true;
         this.setState({ selected: sel });
         this.curSel = ns;
     },
@@ -923,7 +924,7 @@ var AttachList = React.createClass({
                 </div>
                 {this.state.attachments.map((a, i) =>
                     <div ref={'a'+i} title={a.name+' ('+formatBytes(a.size)+')'} key={'a'+i} data-i={i}
-                        className={'attachment'+(this.state.selected[i] ? ' selected' : '')} onMouseDown={this.onListItemClick}>
+                        className={'attachment'+(this.isSelected(i) ? ' selected' : '')} onMouseDown={this.onListItemClick}>
                         <div className="name">{a.name}</div>
                         <div className="size">{formatBytes(a.size)}</div>
                     </div>