Catching errors thrown by token_get_all (Tokenizer) - php

Question

PHPs token_get_all function (which allows converting a PHP source code into tokens) can throw two errors: One if an unterminated multiline comment is encountered, the other if an unexpected char is found.
I would like to catch those errors and throw them as Exceptions.
Problem is: As those errors are parse errors they cannot be handled with an error handling function you would normally specify using set_error_handler.
What I have currently implemented is the following:
// Reset the error message in error_get_last()
#$errorGetLastResetUndefinedVariable;
$this->tokens = #token_get_all($code);
$error = error_get_last();
if (preg_match(
'~^(Unterminated comment) starting line ([0-9]+)$~',
$error['message'],
$matches
)
) {
throw new ParseErrorException($matches[1], $matches[2]);
}
if (preg_match(
'~^(Unexpected character in input:\s+\'(.)\' \(ASCII=[0-9]+\))~s',
$error['message'],
$matches
)
) {
throw new ParseErrorException($matches[1]);
}
It should be obvious that I'm not really excited to use that solution. Especially the fact that I reset the error message in error_get_last by accessing an undefined variable seems pretty unsatisfactory.
So: Is there a better solution to this problem?

Answer 1

Set a custom errorhandler using set_error_handler.
Call token_get_all.
Then unset the error handler by calling restore_error_handler.
This will allow you to catch warnings. Make sure you remove the # suppressor.
You can for instance register an error handler that is in a class that will just record any warnings for inspection later on.
Untested example code:
class CatchWarnings {
private $warnings = array();
public function handler($errno, $errstr, $errfile, $errline) {
switch ($errno) {
case E_USER_WARNING:
$this->warnings[] = $errstr;
return true; // cancel error handling bubble
}
return false; // error handling as usual
}
public function has_warnings() {
return count($this->warnings) > 0;
}
}
$cw = new CatchWarnings();
set_error_handler(array($cw, "handler"));
token_get_all();
restore_error_handler();
Usually validation and execution are two separate things, but it seems like there is no way to validate/lint a piece of PHP code (not since 5.x anyway).