class AssignThisSniff

class AssignThisSniff implements Sniff {
    
    /**
     * A list of tokenizers this sniff supports.
     *
     * @var array
     */
    public $supportedTokenizers = [
        'JS',
    ];
    
    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        return [
            T_THIS,
        ];
    }
    
    //end register()
    
    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
     * @param int                         $stackPtr  The position of the current token
     *                                               in the stack passed in $tokens.
     *
     * @return void
     */
    public function process(File $phpcsFile, $stackPtr) {
        $tokens = $phpcsFile->getTokens();
        // Ignore this.something and other uses of "this" that are not
        // direct assignments.
        $next = $phpcsFile->findNext(T_WHITESPACE, $stackPtr + 1, null, true);
        if ($tokens[$next]['code'] !== T_SEMICOLON) {
            if ($tokens[$next]['line'] === $tokens[$stackPtr]['line']) {
                return;
            }
        }
        // Something must be assigned to "this".
        $prev = $phpcsFile->findPrevious(T_WHITESPACE, $stackPtr - 1, null, true);
        if ($tokens[$prev]['code'] !== T_EQUAL) {
            return;
        }
        // A variable needs to be assigned to "this".
        $prev = $phpcsFile->findPrevious(T_WHITESPACE, $prev - 1, null, true);
        if ($tokens[$prev]['code'] !== T_STRING) {
            return;
        }
        // We can only assign "this" to a var called "self".
        if ($tokens[$prev]['content'] !== 'self' && $tokens[$prev]['content'] !== '_self') {
            $error = 'Keyword "this" can only be assigned to a variable called "self" or "_self"';
            $phpcsFile->addError($error, $prev, 'NotSelf');
        }
    }
    
    //end process()

}