在編程的過程中，尤其是文本的處理，我們很多時候都需要正則表達式，比如，驗證用戶輸入的Email是否格式正確，電話號碼是否符合規范，或者其他的自定義規則。對新手來說，熟記正則表達式的規則比較困難，那么有沒有一種更符合自然語義的正則表達式呢，本文會

在編程的過程中，尤其是文本的處理，我們很多時候都需要正則表達式，比如，驗證用戶輸入的Email是否格式正確，電話號碼是否符合規范，或者其他的自定義規則。對新手來說，熟記正則表達式的規則比較困難，那么有沒有一種更符合自然語義的正則表達式呢，本文會給你答案。

Most newbie (and some seasoned) programmers have difficultly constructing Regular Expressions. Many a times one needs to create a Regexp quickly to test a a particular piece of code. However, not being comfortable withe Regexps can be a problem.?VerbalExpressions?is a PHP library that enables you to construct regular expressions using natural language like constructs. Think of it like a DSL for building Regexps.
verbalexpressions 已經實現了多個語言版本的庫，可以從這里得到。

Below is a sample PHP code that constructs a regular expression which tests whether a given string is a valid url.

如下示例用來測試給定的一個string是否是有效的url地址。

startOfLine()
        ->then("http")
        ->maybe("s")
        ->then("://")
        ->maybe("www.")
        ->anythingBut(" ")
        ->endOfLine();
if($regex->test("http://www.codediesel.com"))
    echo "valid url";
else
    echo "invalid url";
?>

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The main part of the code the DSL like interface that helps you build a Regexp.

$regex  ->startOfLine()
        ->then("http")
        ->maybe("s")
        ->then("://")
        ->maybe("www.")
        ->anythingBut(" ")
        ->endOfLine();

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If you want to see what regular expression the code has built, we can use the?getRegex function of the class.

startOfLine()
        ->then("http")
        ->maybe("s")
        ->then("://")
        ->maybe("www.")
        ->anythingBut(" ")
        ->endOfLine();
echo $regex->getRegex();

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This will print the Regexp given below.

打印輸出正則表達式。

/^(http)(s)?(\:\/\/)(www\.)?([^ ]*)$/m

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We can now use the above Regexp in our code to accomplish the same thing as above.

$myRegexp = '/^(http)(s)?(\:\/\/)(www\.)?([^ ]*)$/m';
if (preg_match($myRegexp, 'http://www.codediesel.com')) {
    echo 'valid url';
} else {
    echo 'invalud url';
}

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We can also use the?$regex?object given in the above example directly in our code where the particular Regexp is required.

可以使用函數 getRegex 獲取正則表達式規則，或者直接可以用 $regex 對象，庫內部已經實現了轉換。

內部的轉換函數：

/**
* Object to string
*
* PHP Magic method to return a string representation of the object.
*
* @access public
* @return string
*/
????public function __toString()
????{
????????return $this->getRegex();
????}

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include_once('VerbalExpressions.php');
$regex = new VerEx;
$regex  ->startOfLine()
        ->then("http")
        ->maybe("s")
        ->then("://")
        ->maybe("www.")
        ->anythingBut(" ")
        ->endOfLine();
if (preg_match($regex, 'http://www.codediesel.com')) {
    echo 'valid url';
} else {
    echo 'invalud url';
}

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The PHP version of VerbalExpressions is a port of the original JavaScript version,JSVerbalExpressions. Additional modifiers that will help you build regular expressions can be found?here.

文章節選：constructing-hard-regular-expressions-with-verbalexpressions

The post 一種更符合自然語意的PHP正則表達式 appeared first on 潤物無聲.

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