PHP和RegEx:用不在括号内的逗号(以及嵌套括号)拆分字符串

Question

两天前,我开始研究代码解析器,但我陷入困境.

如何用不在括号内的逗号分隔字符串,让我告诉你我的意思:

我有这个字符串来解析:

one, two, three, (four, (five, six), (ten)), seven

我想得到这个结果:

array(
 "one"; 
 "two"; 
 "three"; 
 "(four, (five, six), (ten))"; 
 "seven"
)

但相反,我得到:

array(
  "one"; 
  "two"; 
  "three"; 
  "(four"; 
  "(five"; 
  "six)"; 
  "(ten))";
  "seven"
)

我怎么能在PHP RegEx中这样做.

先感谢您 !

Answer 1

你可以更容易地做到:

preg_match_all('/[^(,\s]+|\([^)]+\)/', $str, $matches)

但是如果你使用真正的解析器会更好.也许是这样的:

$str = 'one, two, three, (four, (five, six), (ten)), seven';
$buffer = '';
$stack = array();
$depth = 0;
$len = strlen($str);
for ($i=0; $i<$len; $i++) {
    $char = $str[$i];
    switch ($char) {
    case '(':
        $depth++;
        break;
    case ',':
        if (!$depth) {
            if ($buffer !== '') {
                $stack[] = $buffer;
                $buffer = '';
            }
            continue 2;
        }
        break;
    case ' ':
        if (!$depth) {
            continue 2;
        }
        break;
    case ')':
        if ($depth) {
            $depth--;
        } else {
            $stack[] = $buffer.$char;
            $buffer = '';
            continue 2;
        }
        break;
    }
    $buffer .= $char;
}
if ($buffer !== '') {
    $stack[] = $buffer;
}
var_dump($stack);

Answer 2

嗯...确定已标记为已回答,但由于您要求一个简单的解决方案,我将尝试:

<?php
  $test = "one, two, three, , , ,(four, five, six), seven, (eight, nine)";
  $split = "/([(].*?[)])|(\w)+/";
  preg_match_all($split, $test, $out);
  print_r($out[0]);              
  die();
?>

产量

Array
(
    [0] => one
    [1] => two
    [2] => three
    [3] => (four, five, six)
    [4] => seven
    [5] => (eight, nine)
)

Answer 3

你不能,直接.你至少需要可变宽度的lookbehind,最后我知道PHP的PCRE只有固定宽度的lookbehind.

我的第一个建议是首先从字符串中提取带括号的表达式.但是,我对你的实际问题一无所知,所以我不知道这是否可行.