<?php
/**
 * Generic_Sniffs_Functions_CallTimePassByReferenceSniff.
 *
 * PHP version 5
 *
 * @category  PHP
 * @package   PHP_CodeSniffer
 * @author    Florian Grandel <jerico.dev@gmail.com>
 * @copyright 2009 Florian Grandel
 * @license   http://matrix.squiz.net/developer/tools/php_cs/licence BSD Licence
 * @link      http://pear.php.net/package/PHP_CodeSniffer
 */

/**
 * Generic_Sniffs_Functions_CallTimePassByReferenceSniff.
 *
 * Ensures that variables are not passed by reference when calling a function.
 *
 * @category  PHP
 * @package   PHP_CodeSniffer
 * @author    Florian Grandel <jerico.dev@gmail.com>
 * @copyright 2009 Florian Grandel
 * @license   http://matrix.squiz.net/developer/tools/php_cs/licence BSD Licence
 * @version   Release: 1.3.3
 * @link      http://pear.php.net/package/PHP_CodeSniffer
 */
class Generic_Sniffs_Functions_CallTimePassByReferenceSniff implements PHP_CodeSniffer_Sniff
{


    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array
     */
    public function register()
    {
        return array(T_STRING);

    }//end register()


    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param PHP_CodeSniffer_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(PHP_CodeSniffer_File $phpcsFile, $stackPtr)
    {
        $tokens = $phpcsFile->getTokens();

        // Skip tokens that are the names of functions or classes
        // within their definitions. For example: function myFunction...
        // "myFunction" is T_STRING but we should skip because it is not a
        // function or method *call*.
        $functionName = $stackPtr;
        $findTokens   = array_merge(
            PHP_CodeSniffer_Tokens::$emptyTokens,
            array(T_BITWISE_AND)
        );

        $functionKeyword = $phpcsFile->findPrevious(
            $findTokens,
            ($stackPtr - 1),
            null,
            true
        );

        if ($tokens[$functionKeyword]['code'] === T_FUNCTION
            || $tokens[$functionKeyword]['code'] === T_CLASS
        ) {
            return;
        }

        // If the next non-whitespace token after the function or method call
        // is not an opening parenthesis then it cant really be a *call*.
        $openBracket = $phpcsFile->findNext(
            PHP_CodeSniffer_Tokens::$emptyTokens,
            ($functionName + 1),
            null,
            true
        );

        if ($tokens[$openBracket]['code'] !== T_OPEN_PARENTHESIS) {
            return;
        }

        $closeBracket = $tokens[$openBracket]['parenthesis_closer'];

        $nextSeparator = $openBracket;
        while (($nextSeparator = $phpcsFile->findNext(T_VARIABLE, ($nextSeparator + 1), $closeBracket)) !== false) {
            // Make sure the variable belongs directly to this function call
            // and is not inside a nested function call or array.
            $brackets    = $tokens[$nextSeparator]['nested_parenthesis'];
            $lastBracket = array_pop($brackets);
            if ($lastBracket !== $closeBracket) {
                continue;
            }

            // Checking this: $value = my_function(...[*]$arg...).
            $tokenBefore = $phpcsFile->findPrevious(
                PHP_CodeSniffer_Tokens::$emptyTokens,
                ($nextSeparator - 1),
                null,
                true
            );

            if ($tokens[$tokenBefore]['code'] === T_BITWISE_AND) {
                // Checking this: $value = my_function(...[*]&$arg...).
                $tokenBefore = $phpcsFile->findPrevious(
                    PHP_CodeSniffer_Tokens::$emptyTokens,
                    ($tokenBefore - 1),
                    null,
                    true
                );

                // We have to exclude all uses of T_BITWISE_AND that are not
                // references. We use a blacklist approach as we prefer false
                // positives to not identifiying a pass-by-reference call at all.
                // The blacklist may not yet be complete.
                switch ($tokens[$tokenBefore]['code']) {
                case T_VARIABLE:
                case T_CLOSE_PARENTHESIS:
                    // In these cases T_BITWISE_AND represents
                    // the bitwise and operator.
                    continue;
                    break;

                default:
                    // T_BITWISE_AND represents a pass-by-reference.
                    $error = 'Call-time pass-by-reference calls are prohibited';
                    $phpcsFile->addError($error, $tokenBefore, 'NotAllowed');
                    break;
                }
            }//end if
        }//end while

    }//end process()


}//end class

?>
