用于重定向所有非目录和非文件请求的htaccess规则

我有一个站点，我需要一个catch-all来处理非目录和非文件请求，以便重新定向回HTTP_HOST。我有一个重写规则，只提供无扩展名的PHP文件，并且总是从裸域请求中解析到www.HTTP_HOST。这是我的htaccess文件：

#Main Page
DirectoryIndex index.php
AddDefaultCharset UTF-8
Options +FollowSymLinks
RewriteEngine On
RewriteBase /
# Cache Control for Images and Assets
<FilesMatch "'.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=604800, public"
</FilesMatch>
# Never Use the naked domain
RewriteCond %{HTTP_HOST} ^example'.com$ [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [L,R=301,NE]
# Never Use the naked domain and Remove PHP extension
RewriteCond %{THE_REQUEST} '.(php|cfm)['s?] [NC]
RewriteCond %{DOCUMENT_ROOT}/$1'.php -f
RewriteRule ^(.+?)'.(cfm|php)$ /$1 [R=301,L,NE]
# Re-direct Non-file Non-directories to HTTP_HOST
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.+?)(('?.*)|())$ http://www.example.com [R=301,L]
# unless directory, remove trailing slash
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)/$ /$1 [R=301,L]
# Resolve .php file for extensionless php urls
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{DOCUMENT_ROOT}/$1'.php -f
RewriteRule ^(.+?)/?$ $1.php [L] 

我的第四条规则似乎没有按我需要的方式运行，不知道为什么。感谢您提前提供的帮助。