Manually develop PHP template engine 1 (35)

The template is called TPL, which is modeled after the smarty template engine.

What we call templates are web templates, which are pages written in a language that is primarily composed of HTML markup, but also has a way of representing dynamically generated content (parsing tags). A template engine is a software library that allows us to generate HTML code from templates and specify dynamic content to include.

1 Features of template engine:

1. Encourage separation: Improve the readability and maintainability of the system.

2. Promote division of labor: Allow programmers and artists to concentrate on their own designs.
3. Easier to parse than PHP: compiled files and cached files load faster and occupy fewer resources.

4. Increase security: It can limit the ability of template designers to perform unsafe operations to avoid accidental deletion and accidental access.

2 Template engine products:

PHP has many template engines specially developed by teams, such as Smarty, Heyes Templates Class,

FastTemplate, etc. If we use these template engines directly, we can fully realize many of the above features. But for beginners, understanding the principles of template engines can provide a deeper understanding of why templates should be used.

3 TPL template flow chart

When we create our own template engine, the biggest benefit is simplicity. Because template engines written by many teams have many powerful functions, they are also highly secure. But the disadvantage is that we can’t use many of them, and they are very bloated.

　

4． Create TPL template engine

　　1. Create the folders and files required for the initial template

a) index.php main file, used to write business logic. b) template.inc.php template initialization file, used for initial template information.

c) The templates directory stores all template files.

d) The templates_c directory stores all compiled files.

e) The cache directory stores all cache files.

f) includes directory stores all class files.
g) The config directory stores template system variable configuration files.

　 2. Index.php file code in the root directory of the website

<span>//</span><span>设置编码为utf-8</span>header(<span>'</span><span>Content-Type:text/html;charset=utf-8</span><span>'</span><span>);
</span><span>//</span><span>网站根目录</span>define(<span>'</span><span>ROOT_PATH</span><span>'</span><span>,dirname(__FILE__));
</span><span>//</span><span>存放模板文件夹</span>define(<span>'</span><span>TPL_DIR</span><span>'</span>,ROOT_PATH.<span>'</span><span>/templates/</span><span>'</span><span>);
</span><span>//</span><span>编译文件夹</span>define(<span>'</span><span>TPL_C_DIR</span><span>'</span>,ROOT_PATH.<span>'</span><span>/templates_c/</span><span>'</span><span>);
</span><span>//</span><span>缓存文件夹</span>define(<span>'</span><span>CACHE_DIR</span><span>'</span>,ROOT_PATH.<span>'</span><span>/cache/</span><span>'</span>);

3 Templates.class.php in the includes folder—added method to determine whether the directory exists

<span>//</span><span>创建一个构造方法</span><span>public</span><span> function __construct() {
</span><span>//</span><span>验证一下目录是否存在</span><span>if</span> (!is_dir(TPL_DIR) || !is_dir(TPL_C_DIR) || !<span>is_dir(CACHE_DIR)) {
　　　　exit(</span><span>'</span><span>ERROR：模板文件夹或者编译文件夹或者缓存文件夹没有创建！</span><span>'</span><span>);
　　}
}</span>

4 Templates in the includes folder. class.php—Create a display() method to load the .tpl template file

This is also the display prototype method in samrty

<span>//</span><span>将模板导入到php文件中</span><span>public</span><span> function display($_file) {
</span><span>//</span><span>设置模板文件的路径</span>　　$_tplFile =<span> TPL_DIR.$_file;
</span><span>//</span><span>判断模板文件是否存在</span><span>if</span> (!<span>file_exists($_tplFile)) {
　　　　exit(</span><span>'</span><span>ERROR：模板文件不存在！</span><span>'</span><span>);
　　}
</span><span>//</span><span>设置编译文件的文件名</span>　　$_parFile = TPL_C_DIR.md5($_file).$_file.<span>'</span><span>.php</span><span>'</span><span>;
</span><span>//</span><span>判断编译文件是否存在，模板文件是否修改过</span><span>if</span> (!file_exists($_parFile) || filemtime($_parFile)  filemtime($_tplFile)) {
<span>//</span><span>生成编译文件</span><span>　　file_put_contents($_parFile,file_get_contents($_tplFile));
　　}
</span><span>//</span><span>载入编译文件</span><span>　　include $_parFile;
}
</span><span>//</span><span>引入模板类</span>require ROOT_PATH.<span>'</span><span>/includes/Template.class.php</span><span>'</span><span>;
</span><span>//</span><span>实例化模板类</span>$_tpl = <span>new</span><span> Template();
</span><span>//</span><span>载入index.tpl</span>$_tpl->display(<span>'</span><span>index.tpl);</span>

To be continued

The above introduces the manual development of PHP template engine 1 (35), including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.