组合正则表达式将驼峰式字符串拆分为单词

通过使用 @ridgerunner 在这个问题中建议的解决方案，我设法实现了一个将驼峰大小写转换为单词的函数：

使用 php preg_match （正则表达式）将驼峰式单词拆分为单词 https://stackoverflow.com/questions/4519739/split-camelcase-word-into-words-with-php-preg-match-regular-expression/7729790#7729790

但是，我还想处理像这样的嵌入缩写：

“hasABREVIATION Embedded”翻译为“Has ABBREVIATION Embedded”

我想出了这个解决方案：

    <?php 

    function camelCaseToWords($camelCaseStr)
    {

        // Convert: "TestASAPTestMore" to "TestASAP TestMore"

        $abreviationsPattern = '/' . // Match position between UPPERCASE "words"
            '(?<=[A-Z])' . // Position is after group of uppercase,
            '(?=[A-Z][a-z])' . // and before group of lowercase letters, except the last upper case letter in the group.
            '/x';
        $arr = preg_split($abreviationsPattern, $camelCaseStr);
        $str = implode(' ', $arr);

        // Convert "TestASAP TestMore" to "Test ASAP Test More"
        $camelCasePattern = '/' . // Match position between camelCase "words".
            '(?<=[a-z])' . // Position is after a lowercase,
            '(?=[A-Z])' . // and before an uppercase letter.
            '/x';

        $arr = preg_split($camelCasePattern, $str);
        $str = implode(' ', $arr);

        $str = ucfirst(trim($str));
        return $str;
    }

    $inputs = array(
    'oneTwoThreeFour',
    'StartsWithCap',
    'hasConsecutiveCAPS',
    'ALLCAPS',
    'ALL_CAPS_AND_UNDERSCORES',
    'hasABREVIATIONEmbedded',
    );

    echo "INPUT";

    foreach($inputs as $val) {
        echo "'" . $val . "' translates to '" . camelCaseToWords($val). "'\n";
    }

输出是：

    INPUT'oneTwoThreeFour' translates to 'One Two Three Four'
    'StartsWithCap' translates to 'Starts With Cap'
    'hasConsecutiveCAPS' translates to 'Has Consecutive CAPS'
    'ALLCAPS' translates to 'ALLCAPS'
    'ALL_CAPS_AND_UNDERSCORES' translates to 'ALL_CAPS_AND_UNDERSCORES'
    'hasABREVIATIONEmbedded' translates to 'Has ABREVIATION Embedded'

它按预期工作。

我的问题是： 我可以组合 2 个正则表达式 $abreviationsPattern 和 camelCasePattern 这样我就可以避免运行 preg_split() 函数两次？

这些总是很有趣的谜题需要解决；我将案例范围缩小到只有两种：

1. 检测以大写字母开头，后跟小写字母的单词（但前面没有单词边界或主题开头）-(?<!\b)[A-Z][a-z]+

2. 检测从小写到大写的转换 -(?<=[a-z])[A-Z]

   function camelFix($str)
   {
       return preg_replace_callback('/(?<!\b)[A-Z][a-z]+|(?<=[a-z])[A-Z]/', function($match) {
           return ' '. $match[0];
       }, $str);
   }
   

它适用于您给出的输入；它可能会失败我没有预见到的情况:)