Laravel Blade 在幕后是如何工作的？

Question

I have tried to find somewhere that explains this, but I can not find anything.

I really like one specific aspect of blade and that is the php echo tags {{ }}. I am curious how I could go about duplicating the process this does on the backend.

---

An Idea I Tried

---

One idea I had is basically making a route like in laravel as show below.

handler:

Custom::Include('folder/index.custom.php');

index.custom.php:

<custom>paragraph here</custom>

web browser:

<div id="custom">paragraph here</custom>

The idea is my handler would be placed in the index page. When it is called it would do file_get_contents , parse each line looking for custom tags, and then use a php echo to print the output.

This does work, however , the issue is when I get to php it can't work the same since it is server side and has passed by it once.

This way also seems way to excessive to be on the right track. I added my idea in here was just to show how I have tried to duplicate the process.

---

Does anyone have a simple explanation of how this is really done?

Answer 1

You can play around output buffers along with file_get_contents and eval

My dummy class:

<?php

class Something
{

    public function getMatches($pattern, $string){
        preg_match_all($pattern, $string, $matches);        

        if(empty($matches[1]))
            return [];

        return $matches[1];
    }

    public function include($file){
        $contents = file_get_contents( $file);
        $contents = $this->execCodes($contents);

        echo $contents;
    }

    public function execCodes($contents){
        
        //match all @php code() @endphp
        $matches = $this->getMatches('/\@php(.*?)\@endphp/is', $contents);

        if(empty($matches))
            return $contents;

        $matches = array_unique($matches);

        foreach ($matches as $value) {
            
            //trim spaces
            $code = trim($value);

            $evaluatedCode = $this->getEvaluatedCode( $code ); //get output of evaluated code

            $code = $this->escapeRegExMetaChars($code);

            $pattern = "/(\@php.*?" . $code . '.*?\@endphp)/is'; //regex pattern for matching @php func() @endphp

            $contents = preg_replace($pattern, $evaluatedCode, $contents);  //replace all @php func() @endphp with evaluatedCode output

        }

        return $contents;

    }

    function escapeRegExMetaChars($string){

        $meta_chars = [ '\\', '^', '$', '.', '[', ']', '|', '(', ')', '?', '*', '+', '{', '}', '-', '\'', '/'];

        $len = strlen($string);
        $new_string = '';

        for($x = 0; $x < $len; $x++){

            if( in_array($string[$x], $meta_chars) ){
                $new_string .= '\\' . $string[$x];
            }else{
                $new_string .= $string[$x];
            }

        }
        
        return $new_string;

    }

    public function getEvaluatedCode(string $code){

        if(preg_match('/^(die|exit)/i', $code)){
            return "$code not allowed here";
        }

        //disable output buffers then return the ouput of the eval'ed code
        ob_start();
        eval($code);
        $output = ob_get_contents();
        ob_end_clean();

        return $output;

    }


}

?>

say test.html is like

<div>
    @php
        echo "Something";
    @endphp
</div>
<strong>
    This is a test
</strong>

Then:

$some = new Something();
$some->include('test.html');

Output should be like:

Something
This is a test 

You can do the same with @if @endif , @foreach @endforeach , {{ }} , etc you just need to do some more coding

Answer 2

I think you're looking for custom blade directives.

The following example creates a @datetime($var) directive which formats a given $var , which should be an instance of DateTime :

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Blade;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Perform post-registration booting of services.
     *
     * @return void
     */
    public function boot()
    {
        Blade::directive('datetime', function ($expression) {
            return "<?php echo ($expression)->format('m/d/Y H:i'); ?>";
        });
    }

    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}