合并两个正则表达式以截断字符串中的单词 [英] Merging two Regular Expressions to Truncate Words in Strings

问题描述

我正试图提出以下函数，将字符串截断为整个单词(如果可能，否则应截断为chars):

I'm trying to come up with the following function that truncates string to whole words (if possible, otherwise it should truncate to chars):

function Text_Truncate($string, $limit, $more = '...')
{
    $string = trim(html_entity_decode($string, ENT_QUOTES, 'UTF-8'));

    if (strlen(utf8_decode($string)) > $limit)
    {
        $string = preg_replace('~^(.{1,' . intval($limit) . '})(?:\s.*|$)~su', '$1', $string);

        if (strlen(utf8_decode($string)) > $limit)
        {
            $string = preg_replace('~^(.{' . intval($limit) . '}).*~su', '$1', $string);
        }

        $string .= $more;
    }

    return trim(htmlentities($string, ENT_QUOTES, 'UTF-8', true));
}

以下是一些测试:

// Iñtërnâtiônàlizætiøn and then the quick brown fox... (49 + 3 chars)
echo dyd_Text_Truncate('Iñtërnâtiônàlizætiøn and then the quick brown fox jumped overly the lazy dog and one day the lazy dog humped the poor fox down until she died.', 50, '...');

// Iñtërnâtiônàlizætiøn_and_then_the_quick_brown_fox_...  (50 + 3 chars)
echo dyd_Text_Truncate('Iñtërnâtiônàlizætiøn_and_then_the_quick_brown_fox_jumped_overly_the_lazy_dog and one day the lazy dog humped the poor fox down until she died.', 50, '...');

它们都按原样工作，但是如果我放下第二个preg_replace()，则会得到以下信息:

They both work as it is, however if I drop the second preg_replace() I get the following:

Iñtërnâtiônàlizætiøn_and_then_the_quick_brown_fox_jumped_overly_the_lazy_dog 有一天，那只懒狗把驼背 可怜的狐狸下来，直到她死了....

Iñtërnâtiônàlizætiøn_and_then_the_quick_brown_fox_jumped_overly_the_lazy_dog and one day the lazy dog humped the poor fox down until she died....

我不能使用substr()，因为它只能在字节级别上使用，而且我无法访问mb_substr() ATM，我已经尝试过多次尝试将第二个正则表达式与第一个一起加入，但是没有成功.

I can't use substr() because it only works on byte level and I don't have access to mb_substr() ATM, I've made several attempts to join the second regex with the first one but without success.

请帮助S.M.S.，我已经为此苦苦挣扎了近一个小时.

Please help S.M.S., I've been struggling with this for almost an hour.

很抱歉，我已经醒了40个小时，无耻地错过了这一点:

$string = preg_replace('~^(.{1,' . intval($limit) . '})(?:\s.*|$)?~su', '$1', $string);

不过，如果有人使用更优化的正则表达式(或忽略尾随空格的正则表达式)，请分享:

Still, if someone has a more optimized regex (or one that ignores the trailing space) please share:

"Iñtërnâtiônàlizætiøn and then "
"Iñtërnâtiônàlizætiøn_and_then_"

我仍然无法摆脱尾随的空格，有人可以帮我吗?

好吧，我所做的任何编辑都没有真正起作用，我被RegexBuddy欺骗了-我可能应该把它放到另一天，现在就睡一觉.今天关闭.

推荐答案

在漫长的RegExp噩梦之后，也许我可以给你一个快乐的早晨:

Perhaps I can give you a happy morning after a long night of RegExp nightmares:

'~^(.{1,' . intval($limit) . '}(?<=\S)(?=\s)|.{'.intval($limit).'}).*~su'

将其归结为一个

^      # Start of String
(       # begin capture group 1
 .{1,x} # match 1 - x characters
 (?<=\S)# lookbehind, match must end with non-whitespace 
 (?=\s) # lookahead, if the next char is whitespace, match
 |      # otherwise test this:
 .{x}   # got to x chars anyway.
)       # end cap group
.*     # match the rest of the string (since you were using replace)

您始终可以将|$添加到(?=\s)的末尾，但是由于您的代码已经在检查字符串长度是否大于$limit，因此我认为这种情况不是必需的.

You could always add the |$ to the end of (?=\s) but since your code was already checking that the string length was longer than the $limit, I didn't feel that case would be neccesary.

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