使用Lua编写Web端模板引擎的实例代码分享

admin Lua

2023-12-05 0 467

ltemplate.lua

local insert = table.insert
local remove = table.remove
local concat = table.concat
local format = string.format

local loaded = {}
local partten = \”(.-){#([^#].-[^#])#}()\”

local content = {}
local cur_content = nil

local function ob_start()
cur_content = {}
insert(content, cur_content)
end

local function ob_get_clean()
local ret = concat(cur_content)
remove(content)
cur_content = content[#content]
return ret
end

local function echo(value)
insert(cur_content, value)
end

local function include(path, params)
local bitcode = loaded[path]

if not bitcode then
local fp = io.open(path, \”rb\”)
local template = fp:read(\’*a\’)
fp:close()
local results = {}
local last_endpos = 0
for outside, inside, endpos in template:gmatch(partten) do
insert(results, format(\”echo(%q)\”, outside))
insert(results, inside)
last_endpos = endpos
end
insert(results, format(\”echo(%q)\”, template:sub(last_endpos)))
results = concat(results, \”\\n\”)
bitcode = assert(loadstring(results))
loaded[path] = bitcode
end

local env = {
include = include,
echo = echo,
ob_start = ob_start,
ob_get_clean = ob_get_clean
}
setmetatable(env, {__index = function(tb, k)
return params[k] or _G[k]
end})
setfenv(bitcode, env)
bitcode()
end

for i = 1, 100000 do
ob_start()
include(arg[1], {
params = {
a = \’1234\’,
b = \’4321\’
}
})
ob_get_clean()
end

master.html

<!DOCTYPE html PUBLIC \”-//W3C//DTD XHTML 1.0 Transitional//EN\” \”http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\”>
<html lang=\’zh-CN\’ xml:lang=\’zh-CN\’ xmlns=\’http://www.w3.org/1999/xhtml\’>
<head>
<meta http-equiv=\”Content-Type\” content=\”text/html; charset=UTF-8\”/>
<meta http-equiv=\”Content-Language\” content=\”zh-CN\”/>
<meta name=\”robots\” content=\”index, follow\” />
<link rel=\”shortcut icon\” type=\”image/x-icon\” href=\”/img/favicon.ico\” />
<title> child's personal page – 开源中国社区</title>
<link rel=\”stylesheet/less\” href=\”http://my.oschina.net/lostchild/styles.less?ver=20131219&date=20131110185237\” type=\”text/css\” media=\”screen\” />
<link rel=\”stylesheet\” href=\”/js/2012/poshytip/tip-yellowsimple/tip-yellowsimple.css\” type=\”text/css\” />
<link rel=\”stylesheet\” type=\”text/css\” href=\”/js/2011/fancybox/jquery.fancybox-1.3.4.css\” media=\”screen\” />
<script type=\”text/javascript\” src=\”/js/2012/jquery-1.7.1.min.js\”></script>
<script type=\”text/javascript\” src=\”/js/2012/jquery.form.js\”></script>
<script type=\”text/javascript\” src=\”/js/2011/fancybox/jquery.fancybox-1.3.4.pack.js\”></script>
<script type=\”text/javascript\” src=\”/js/2012/poshytip/jquery.poshytip.min.js\”></script>
<script type=\”text/javascript\” src=\”/js/2011/oschina.js?ver=20121007\”></script>
<script type=\”text/javascript\” src=\”/js/2012/less-1.3.0.min.js\”></script>
<script type=\”text/javascript\” src=\”/js/scrolltopcontrol.js\”></script>
<script type=\’text/javascript\’ src=\’/js/jquery/jquery.atwho.js?ver=2013112501\’></script>
<link rel=\”stylesheet\” type=\”text/css\” href=\”/js/jquery/jquery.atwho.css\” />
<link rel=\”alternate\” type=\”application/rss+xml\” title=\”lostchild最新博客\” href=\”http://my.oschina.net/lostchild/rss\” />
<link rel=\”EditURI\” type=\”application/rsd+xml\” title=\”RSD\” href=\”http://my.oschina.net/action/xmlrpc/rsd?space=1397642\” />
<link rel=\”wlwmanifest\” type=\”application/wlwmanifest+xml\” href=\”http://my.oschina.net/action/xmlrpc/wlwmanifest?space=1397642\” />
{# echo(header) #}
</head>
<body>
{# echo(content) #}
<body>
</html>

temp.html，继承master.html

{# ob_start() #}
<script>
alert(\”hello World\”)
</script>
{# local header = ob_get_clean() #}

{# ob_start() #}
<table>
{# for k, v in pairs(params) do #}
<tr>
<td>{# echo(k) #}</td>
<td>{# echo(v) #}</td>
</tr>
{# end #}
</table>
{# local content = ob_get_clean() #}

{# include(\’master.html\’, {header = header, content = content}) #}

循环十万次测试渲染速度（阿里云最便宜一款vps）

[root@AY130801221248587d02Z ~]# time lua ltemplate.lua temp.htmlreal 0m1.867s

user 0m1.862s
sys 0m0.004s

总结

由此可见渲染的速度还是非常快的，可以将此原型用于嵌入式设备中的页面上（用大量js实现的嵌入式设备页面兼容性不好）。而且嵌入式设备的界面需要简单明确，所以也不用太丰富的模版功能。

原理很简单：

1.用lua版的正则把模版内{#与#}之间的内容挖出来，原样输出成lua代码，其它部分则生成使用echo打印到某个缓冲区的lua代码。

2.将这个生成出来的代码使用loadstring编译。

3.通过setfenv实现loadstring后的模拟环境配置（用以提供模版内使用的echo，ob_start等函数，以及传入的参数）

4.执行这个编译后的函数即可。

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