PHP句子邊界包括空行嗎？

Question

這是SO上的PHP sentences boundaries question的擴展。

我想知道如何改變正則表達式，以保持換行也是如此。

示例代碼逐句分割一些文本，刪除一個句子，然後一起放回：

<?php 
$re = '/# Split sentences on whitespace between them. 
    (?<=    # Begin positive lookbehind. 
     [.!?]    # Either an end of sentence punct, 
    | [.!?][\'"]  # or end of sentence punct and quote. 
    )     # End positive lookbehind. 
    (?<!    # Begin negative lookbehind. 
     Mr\.    # Skip either "Mr." 
    | Mrs\.    # or "Mrs.", 
    | Ms\.    # or "Ms.", 
    | Jr\.    # or "Jr.", 
    | Dr\.    # or "Dr.", 
    | Prof\.   # or "Prof.", 
    | Sr\.    # or "Sr.", 
    | T\.V\.A\.   # or "T.V.A.", 
         # or... (you get the idea). 
    )     # End negative lookbehind. 
    [\s+|^$]   # Split on whitespace between sentences/empty lines. 
    /ix'; 

$text = <<<EOL 
This is paragraph one. This is sentence one. Sentence two! 

This is paragraph two. This is sentence three. Sentence four! 
EOL; 

echo "\nBefore: \n" . $text . "\n"; 

$sentences = preg_split($re, $text, -1); 

$sentences[1] = " "; // remove 'sentence one' 

// put text back together 
$text = implode($sentences); 

echo "\nAfter: \n" . $text . "\n"; 
?> 

運行此，輸出是

Before: 
This is paragraph one. This is sentence one. Sentence two! 

This is paragraph two. This is sentence three. Sentence four! 

After: 
This is paragraph one. Sentence two! 
This is paragraph two. This is sentence three. Sentence four! 

我試圖讓「之後'文本與'之前'文本相同，只是刪除了一個句子。

After: 
This is paragraph one. Sentence two! 

This is paragraph two. This is sentence three. Sentence four! 

我希望這可以做一個正則表達式的調整，但我錯過了什麼？

Answer 1

圖案的端部應替換：

(?:\h+|^$)   # Split on whitespace between sentences\/empty lines. 
/mix'; 

參見IDEONE demo

注意[\s+|^$]確實匹配空白（水平和垂直，像新行），+，|，^和$符號，因爲它是一個字符類別。

而不是一個字符類，一組（更好，這裏非捕獲）是必要的。在組內（標記爲(...)），|可用作替代運算符。

而不是\s，我建議使用\h匹配水平空白（沒有linebreaks）只。

如果沒有使用/m多行修飾符，^$將只匹配空字符串。所以，我已將/m修飾符添加到選項中。

而且注意，我不得不逃離最後一個註釋裏面的/，否則有一個警告，正則表達式是不正確。或者，使用不同的正則表達式分隔符。