php - 正则表达式:如何捕获以一组匹配的字符开头的组

Question

这是我想拆分为数组的一串字符:

35g walnut halves A handful of thyme leaves 200g portobello mushrooms 200g white mushrooms 200g chifferini pasta 100g Petit Brebis sheep's cheese 40g honey

我想用 preg_split从字符串中提取各个成分。一个单独的成分开始于:

由数字加上字符 g 定义的数量

一个字符序列，例如 A handful

到目前为止，我有这个正则表达式模式 ([0-9]+g|A handful)它正确地找到了字符串中的断点，但不包括整个成分描述。我需要捕获组包含其余字符，直到下一场比赛。
为了获得数组返回，我使用了这个 PHP: preg_split("/([0-9]+g|A handful)/", $ingredients_str, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY)所需的输出是:

[
  0 => 35g walnut halves
  1 => A handful of thyme leaves
  2 => 200g portobello mushrooms
  etc..
]

见 regex 101

Answer 1

您可以使用 preg_match_all提取所有描述:

preg_match_all('~(?:\d+g|A handful).*?(?=\s*(?:\d+g|A handful|$))~s', $str, $matches)

见 regex demo .
详情

(?:\d+g|A handful) - 1+ 位后跟 g或 A handful

.*? - 任何零个或多个字符，尽可能少

(?=\s*(?:\d+g|A handful|$)) - 直到字符串中紧跟 0+ 空格后跟 1+ 数字和 g 的位置, 或 A handful或字符串结尾。

见 PHP demo :

$re = '/(?:[0-9]+g|A handful).*?(?=\s*(?:[0-9]+g|A handful|$))/s';
$str = '35g walnut halves A handful of thyme leaves 200g portobello mushrooms 200g white mushrooms 200g chifferini pasta 100g Petit Brebis sheep\'s cheese 40g honey';
if (preg_match_all($re, $str, $matches)) {
   print_r($matches[0]);
}

输出:

Array
(
    [0] => 35g walnut halves
    [1] => A handful of thyme leaves
    [2] => 200g portobello mushrooms
    [3] => 200g white mushrooms
    [4] => 200g chifferini pasta
    [5] => 100g Petit Brebis sheep's cheese
    [6] => 40g honey
)

一个 preg_split解决方案可能看起来像

$re = '/(?!^)\b(?=[0-9]+g|A handful)/';
$str = '35g walnut halves A handful of thyme leaves 200g portobello mushrooms 200g white mushrooms 200g chifferini pasta 100g Petit Brebis sheep\'s cheese 40g honey';
print_r(preg_split($re, $str));

见 demo online .这里，

(?!^) - 匹配不在字符串开头的位置

\b - 字边界

(?=[0-9]+g|A handful) - 紧跟 1+ 位数字然后是 g 的位置或 A handful子串。