之前兩天在極客頭條上看了一篇帖子，最嚴謹的校驗email地址的正則表示式 ，最近接手的最多的就是yii2.0框架，所以很好奇想看看yii2.0是怎麼實現驗證規則。

首先，一般在自定義的繼承model類中，會有個rules()方法：

    public function rules()
    {
        /*echo "<pre>";
        $e=new \Exception();
        var_export($e->getTraceAsString());*/
        return [
            // username and password are both required
            [['username', 'password'], 'required'],
            // password is validated by validatePassword()
            ['password', 'validatePassword'],

        ];
    }
 

通過上面的呼叫棧資訊，我們看到，對於post提交的表單，我們在使用load()載入的時候會呼叫rules()方法，然後我們再進入load()裡面看，load()方法只給屬性賦值，不涉及到任何對屬性的判斷，通過簡單的驗證就可以看出來，這裡就不截圖了，所以對屬性的判斷並不在load()中！

我們獲取錯誤資訊是通過getErrors()，那就看下addErrors()的呼叫棧資訊，如下：

裡面在呼叫棧中出現了validateAttribute()方法，

從這次的棧資訊中，可以看出來，validateAttribute是對rules裡面定義的規則，每一個執行一次，validateAttribute()裡面呼叫了validateValue()方法

    public function validateAttribute($model, $attribute)
    {
        $result = $this->validateValue($model->$attribute);
        if (!empty($result)) {
            $this->addError($model, $attribute, $result[0], $result[1]);
        }
    }

所以這裡的$this拿到的就是RequiredValidator的控制代碼了，所以所有對rules的規則的驗證都是在validators目錄下。

----------------------------------------------------------------------------------下面是對email的驗證和php正則---------------------------------------------------------------------------------------------------

檔案路徑：\yii\validators\EmailValidator

    protected function validateValue($value)
    {
        if (!is_string($value)) {
            $valid = false;

        } elseif (!preg_match('/^(?P<name>(?:"?([^"]*)"?\s)?)(?:\s+)?(?:(?P<open><?)((?P<local>.+)@(?P<domain>[^>]+))(?P<close>>?))$/i', $value, $matches)) {
            $valid = false;
        } else {
            if ($this->enableIDN) {
                $matches['local'] = idn_to_ascii($matches['local']);
                $matches['domain'] = idn_to_ascii($matches['domain']);
                $value = $matches['name'] . $matches['open'] . $matches['local'] . '@' . $matches['domain'] . $matches['close'];
            }

            if (strlen($matches['local']) > 64) {
                // The maximum total length of a user name or other local-part is 64 octets. RFC 5322 section 4.5.3.1.1
                // http://tools.ietf.org/html/rfc5321#section-4.5.3.1.1
                $valid = false;
            } elseif (strlen($matches['local'] . '@' . $matches['domain']) > 254) {
                // There is a restriction in RFC 2821 on the length of an address in MAIL and RCPT commands
                // of 254 characters. Since addresses that do not fit in those fields are not normally useful, the
                // upper limit on address lengths should normally be considered to be 254.
                //
                // Dominic Sayers, RFC 3696 erratum 1690
                // http://www.rfc-editor.org/errata_search.php?eid=1690
                $valid = false;
            } else {
                $valid = preg_match($this->pattern, $value) || $this->allowName && preg_match($this->fullPattern, $value);
                if ($valid && $this->checkDNS) {
                    $valid = checkdnsrr($matches['domain'], 'MX') || checkdnsrr($matches['domain'], 'A');
                }
            }
        }

        return $valid ? null : [$this->message, []];
    }

/^(?P<name>(?:"?([^"]*)"?\s)?)(?:\s+)?(?:(?P<open><?)((?P<local>.+)@(?P<domain>[^>]+))(?P<close>>?))$/i

        $value="1  <[email protected]>";
        preg_match('/^(?P<name>(?:"?([^"]*)"?\s)?)(?:\s+)?(?:(?P<open><?)((?P<local>.+)@(?P<domain>[^>]+))(?P<close>>?))$/i', $value, $matches);
        var_dump($matches);

1(name):(?P<name>(?:"?([^"]*)"?\s)?) 匹配空格和空格前的字元

2:([^"]*)   匹配除了"之外的任意字元0次或多次

3(open):(?P<open><?) 匹配<

4: ((?P<local>.+)@(?P<domain>[^>]+))(?P<close>>?))

5(local):(?P<local>.+)匹配任意字元1次到多次

6(domain):(?P<domain>[^>]+)匹配除了>外的字元1次到多次

7: (?P<close>>?)匹配>標籤

idn_to_ascii 將domain name轉換成ASCII形式

補充一些php正則表示式的知識：

chr()將ASCII值轉換成字元，
hexdec()把十六進位制轉換成十進位制，
ord()返回字串的首個字元的ASCII值，
雙引號包圍十六進位制的ASCII碼echo輸出的時候會轉換成字元。
//echo ord($b);
//echo chr('\x7E');
//echo hexdec('\x5C');


(?:pattern)匹配pattern但不獲取結果， (pattern)匹配pattern並獲取匹配結果，(?:pattern)匹配pattern但不獲取匹配結果，(?=pattern)正向預查，(?!pattern)反向預查
預查不消耗字元，也就是a(?=b|c)匹配了ab或ac之後，下次匹配的時候還可以從b或c處開始匹配
var_dump(preg_replace('/^(?:a(a|b))?/','xxx',"aaab"));//xxxab 3個x
var_dump(preg_replace('/^(?:a(?=a|b))?/','xxx',"aaab"));//xxxaab 3個x
var_dump(preg_replace('/(?:a(?=a|b))/','xxx',"aaab"));//xxxxxxxxxb 9個x
var_dump(preg_replace('/(?:a(a|b))?/','xxx',"aaab"));//xxxxxxxxx 9個x
var_dump(preg_replace('/(?:a(?!a|c))/','xxx','aaab'));//aaxxxb
var_dump(preg_replace('/(?!a|c)/','xxx','aaab'));//aaaxxxbxxx