php web开发中广泛采取mvc的设计模式，controller传递给view层的数据，必须通过模板引擎才能解析出来。实现一个简单的仅仅包含if，foreach标签，解析$foo变量的模板引擎。
编写template模板类和compiler编译类。代码如下：
<?phpnamespace foo\base;use foo\base\Object;use foo\base\Compiler;/**
*
*/class Template extends Object{
private $_config = [ 'suffix' => '.php',//文件后缀名
'templateDir' => '../views/',//模板所在文件夹
'compileDir' => '../runtime/cache/views/',//编译后存放的目录
'suffixCompile' => '.php',//编译后文件后缀
'isReCacheHtml' => false,//是否需要重新编译成静态html文件
'isSupportPhp' => true,//是否支持php的语法
'cacheTime' => 0,//缓存时间,单位秒
]; private $_file;//带编译模板文件
private $_valueMap = [];//键值对
private $_compiler;//编译器
public function __construct($compiler, $config = [])
{
$this->_compiler = $compiler; $this->_config = array_merge($this->_config, $config);
} /**
* [assign 存储控制器分配的键值]
* @param [type] $values [键值对集合]
* @return [type] [description]
*/
public function assign($values)
{
if (is_array($values)) { $this->_valueMap = $values;
} else { throw new \Exception('控制器分配给视图的值必须为数组!');
} return $this;
} /**
* [show 展现视图]
* @param [type] $file [带编译缓存的文件]
* @return [type] [description]
*/
public function show($file)
{
$this->_file = $file; if (!is_file($this->path())) { throw new \Exception('模板文件'. $file . '不存在!');
} $compileFile = $this->_config['compileDir'] . md5($file) . $this->_config['suffixCompile']; $cacheFile = $this->_config['compileDir'] . md5($file) . '.html'; //编译后文件不存在或者缓存时间已到期,重新编译,重新生成html静态缓存
if (!is_file($compileFile) || $this->isRecompile($compileFile)) { $this->_compiler->compile($this->path(), $compileFile, $this->_valueMap); $this->_config['isReCacheHtml'] = true; if ($this->isSupportPhp()) {
extract($this->_valueMap, EXTR_OVERWRITE);//从数组中将变量导入到当前的符号表
}
} if ($this->isReCacheHtml()) {
ob_start();
ob_clean(); include($compileFile);
file_put_contents($cacheFile, ob_get_contents());
ob_end_flush();
} else {
readfile($cacheFile);
}
} /**
* [isRecompile 根据缓存时间判断是否需要重新编译]
* @param [type] $compileFile [编译后的文件]
* @return boolean [description]
*/
private function isRecompile($compileFile)
{
return time() - filemtime($compileFile) > $this->_config['cacheTime'];
} /**
* [isReCacheHtml 是否需要重新缓存静态html文件]
* @return boolean [description]
*/
private function isReCacheHtml()
{
return $this->_config['isReCacheHtml'];
} /**
* [isSupportPhp 是否支持php语法]
* @return boolean [description]
*/
private function isSupportPhp()
{
return $this->_config['isSupportPhp'];
} /**
* [path 获得模板文件路径]
* @return [type] [description]
*/
private function path()
{
return $this->_config['templateDir'] . $this->_file . $this->_config['suffix'];
}
}<?phpnamespace foo\base;use foo\base\Object;/**
*
*/class Compiler extends Object{
private $_content; private $_valueMap = []; private $_patten = [ '#\{\\$([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)\}#', '#\{if (.*?)\}#', '#\{(else if|elseif) (.*?)\}#', '#\{else\}#', '#\{foreach \\$([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)}#', '#\{\/(foreach|if)}#', '#\{\\^(k|v)\}#',
]; private $_translation = [ "<?php echo \$this->_valueMap['\\1']; ?>", '<?php if (\\1) {?>', '<?php } else if (\\2) {?>', '<?php }else {?>', "<?php foreach (\$this->_valueMap['\\1'] as \$k => \$v) {?>", '<?php }?>', '<?php echo \$\\1?>'
]; /**
* [compile 编译模板文件]
* @param [type] $source [模板文件]
* @param [type] $destFile [编译后文件]
* @param [type] $values [键值对]
* @return [type] [description]
*/
public function compile($source, $destFile, $values)
{
$this->_content = file_get_contents($source); $this->_valueMap = $values; if (strpos($this->_content, '{$') !== false) { $this->_content = preg_replace($this->_patten, $this->_translation, $this->_content);
}
file_put_contents($destFile, $this->_content);
}
}我们的控制器就可以调用template中的assign方法进行赋值，show方法进行模板编译了。
/**
* [render 渲染模板文件]
* @param [type] $file [待编译的文件]
* @param [type] $values [键值对]
* @param array $templateConfig [编译配置]
* @return [type] [description]
*/
protected function render($file, $values, $templateConfig = [])
{
$di = Container::getInstance(); //依赖注入实例化对象
$di->template = function () use ($di, $templateConfig) {
$di->compiler = 'foo\base\Compiler'; $compiler = $di->compiler; return new \foo\base\Template($compiler, $templateConfig);
}; $di->template->assign($values)->show($file);
}Container类如下：
<?phpnamespace foo\base;use foo\base\Object;class Container extends Object{
private static $_instance; private $s = []; public static $instances = []; public static function getInstance()
{
if (!(self::$_instance instanceof self)) { self::$_instance = new self();
} return self::$_instance;
} private function __construct(){} private function __clone(){} public function __set($k, $c)
{
$this->s[$k] = $c;
} public function __get($k)
{
return $this->build($this->s[$k]);
} /**
* 自动绑定（Autowiring）自动解析（Automatic Resolution）
*
* @param string $className
* @return object
* @throws Exception
*/
public function build($className)
{
// 如果是闭包函数（closures）
if ($className instanceof \Closure) { // 执行闭包函数
return $className($this);
} if (isset(self::$instances[$className])) { return self::$instances[$className];
} /** @var ReflectionClass $reflector */
$reflector = new \ReflectionClass($className); // 检查类是否可实例化, 排除抽象类abstract和对象接口interface
if (!$reflector->isInstantiable()) { throw new \Exception($reflector . ': 不能实例化该类!');
} /** @var ReflectionMethod $constructor 获取类的构造函数 */
$constructor = $reflector->getConstructor(); // 若无构造函数，直接实例化并返回
if (is_null($constructor)) { return new $className;
} // 取构造函数参数,通过 ReflectionParameter 数组返回参数列表
$parameters = $constructor->getParameters(); // 递归解析构造函数的参数
$dependencies = $this->getDependencies($parameters); // 创建一个类的新实例，给出的参数将传递到类的构造函数。
$obj = $reflector->newInstanceArgs($dependencies); self::$instances[$className] = $obj; return $obj;
} /**
* @param array $parameters
* @return array
* @throws Exception
*/
public function getDependencies($parameters)
{
$dependencies = []; /** @var ReflectionParameter $parameter */
foreach ($parameters as $parameter) { /** @var ReflectionClass $dependency */
$dependency = $parameter->getClass(); if (is_null($dependency)) { // 是变量,有默认值则设置默认值
$dependencies[] = $this->resolveNonClass($parameter);
} else { // 是一个类，递归解析
$dependencies[] = $this->build($dependency->name);
}
} return $dependencies;
} /**
* @param ReflectionParameter $parameter
* @return mixed
* @throws Exception
*/
public function resolveNonClass($parameter)
{
// 有默认值则返回默认值
if ($parameter->isDefaultValueAvailable()) { return $parameter->getDefaultValue();
} throw new \Exception('I have no idea what to do here.');
}
}要想以键值对的方式访问对象的属性必须实现ArrayAccess接口的四个方法，
Object基类代码如下：
public function offsetExists($offset)
{
return array_key_exists($offset, get_object_vars($this));
} public function offsetUnset($key)
{
if (array_key_exists($key, get_object_vars($this)) ) { unset($this->{$key});
}
} public function offsetSet($offset, $value)
{
$this->{$offset} = $value;
} public function offsetGet($var)
{
return $this->$var;
}在某一控制器中就可以调用父类Controller的render方法啦
$this->render('test\index', ['name' => 'tom', 'age' => 20, 'friends' => ['jack', 'rose']], ['cacheTime' => 10]);
编写视图模板文件‘test\index’:
<!DOCTYPE html><html lang="en"><head>
<meta charset="UTF-8">
<title>Document</title></head><body>
<p>展示模板文件视图</p>
<p>{$name}</p>
<p>{$age}</p>
<?php echo ++$age;?>
{if $age > 18} <p>已成年</p>
{else if $age < 10}
<p>小毛孩</p>
{/if}
{foreach $friends}
<p>{^v} </p>
{/foreach}</body></html>至此，一个简单的模板编译引擎就写好了。
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