How to check whether a PHP file has syntax errors in PHP

How to check whether a PHP file has syntax errors in PHP_PHP Tutorial

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Release： 2016-07-21 15:41:52

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I used a simple template engine in a project of Dangdang before. In fact, it is also a template engine based on discuz. It is very simple. What it does is compile some custom tags into PHP code. As I said, it is very simple, so when compiling, you should also check the template syntax. Then during the development process, there will be syntax problems in the compiled PHP files. It doesn't matter if there are syntax problems. I will just modify and recompile it. . First of all, you cannot recompile the PHP template every time you request it, which will seriously affect the performance. The compromise is to check at the end of each compiled PHP file whether the template file has been modified, and update it according to the settings. Frequency, if necessary, recompile the template file. The current problem is that the compiled php file itself has syntax errors, and the template check step cannot be performed at all, so even if the problems in the template file are modified, it will not be recompiled. So I'm looking for a simple way to check if the generated php file is legal. If it is illegal, recompile it so that you don’t have to manually delete cache files when errors occur during the development process.

Looked for it online. At first I thought the token_get_all() function could handle syntax errors, but it turned out that it only does simple lexical analysis. There is no way. Later I went to the forum and asked about it

http://groups.google.com/group/professional-php/browse_thread/thread/b8581f6b07b10ff0/2601a63c406bb1c1?lnk=gst&q=reeze#2601a63c406bb1c1

Someone told me that there is such a function php_check_syntax() http://www.php.net/manual/en/function.php-check-syntax.php I think the problem is so determined. . I really should RTF(Read The Fuck Manual). Take a closer look. This function has been deprecated:
Note: For technical reasons, this function is deprecated and removed from PHP. Instead, use php -l somefile.php from the commandline.

This technical reason is What is it? Don't worry about it for now. We'll study it slowly later. You can't use this method anyway.
Their suggestion is to use the command line $php -l filename.php to check the syntax.
Gary Every gave me a code snippet for reference:

It is not a big problem to check on the command line. What if I want to put it in an online application? This involves the issue of portability. First comes the operating system, then comes the environment variables. This will depend on the server-side configuration. Someone posted his own php_check_syntax() function implementation at http://www.php.net/manual/en/function.php-check-syntax.php.
Some use the command line method above.
It is mentioned later that the eval method is used for verification. The eval method will execute the incoming code. If the code has a syntax error, a parser error will be thrown. You can use the '@' error suppressor to remove the error message. Like echo, eval is not a function and cannot be called using variable function methods. For example:
$func = 'eval'
A call like $func() is invalid. It will prompt that there is no eval function. If you define such a function yourself, there will be a problem. Because eval is a keyword.
The eval call is similar to include. If there is no explicit return in the included file, null will be returned. If we directly eval the file we need to check, it will cause the code in the checked file to be executed. This is not what we want. We only need to check whether the syntax of the file is correct. We can add a return statement before the file to be checked to let the code jump out in advance, so that the subsequent code will not be executed. Okay, that's it. The code is as follows:
checker.php

Copy code The code is as follows:

 

if(!function_exists('php_check_syntax')) { 
function php_check_syntax($file_name, &$error_message = null) { 
$file_content = file_get_contents($file_name); 

$check_code = " return true; ?>"; 
$file_content = $check_code . $file_content . "
if(!@eval($file_content)) { 
$error_message = "file: " . realpath($file_name) . " have syntax error"; 
return false; 
} 

return true; 
} 
} 

 if(!php_check_syntax("file.php", $msg)) { 
echo $msg; 
} 
else { 
echo "Woohoo, OK!"; 
} 
 

file.php

Copy code The code is as follows:

 
foreach: : a => b 
?> 

Because Parse error cannot be handled by the set_error_handler processing function. This exception cannot be caught. That's why @ is used to suppress errors. The problem with this is that we cannot get detailed error information. But currently the function I need is just to check whether the syntax is correct. If it is incorrect, recompile the template file. It is as simple as that. As for the syntax errors, you will naturally see them when displaying the web page.
The best way is to return the abandoned php_check_syntax method to PHP. Next time I will study why they removed this function.
////////My thinking is very confusing, and every bit of writing is coherent. Who makes my Chinese language so bad?