preg_split 在正则表达式行开始

Question

我正在尝试格式化以下文件；

[30-05-2013 15:45:54] A A
[26-06-2013 14:44:44] B A
[26-06-2013 14:44:44] C A
[26-06-2013 14:43:16] Some lines are so large, they take multiple lines, so explode('\n') won't work because
I need the complete message
[26-06-2013 14:44:44] E A
[26-06-2013 14:44:44] F A
[26-06-2013 14:44:44] G A

预期输出：

Array
(
    [0] => [30-05-2013 15:45:54] A A
    [1] => [26-06-2013 14:44:44] B A
    [2] => [26-06-2013 14:44:44] C A
    [3] => [26-06-2013 14:43:16] Some lines are so large, they take multiple lines, so 
            explode('\n') won't work because
            I need the complete message
    [4] => [26-06-2013 14:44:44] E A
    ...
)

基于 How do I include the split delimiter in results for preg_split()? I tried to use a positive lookbehind to persist the timestamps and came up with Regex101:

(?<=\[)(.+)(?<=\])(.+)

在下面的PHP代码中用到了；

#!/usr/bin/env php
<?php

    class Chat {

        function __construct() {

            // Read chat file
            $this->f = file_get_contents(__DIR__ . '/testchat.txt');

            // Split on '[\d]'
            $r = "/(?<=\[)(.+)(?<=\])(.+)/";
            $l = preg_split($r, $this->f, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);

            var_dump(count($l));
            var_dump($l);
        }
    }
$c = new Chat();

这给了我以下输出；

array(22) {
  [0]=>
  string(1) "["
  [1]=>
  string(20) "30-05-2013 15:45:54]"
  [2]=>
  string(4) " A A"
  [3]=>
  string(2) "
["
  [4]=>
  string(20) "26-06-2013 14:44:44]"
  [5]=>
  string(4) " B A"
  [6]=>
  string(2) "
["
  [7]=>
  string(20) "26-06-2013 14:44:44]"
  [8]=>
  string(4) " C A"
  [9]=>
  string(2) "
["
  [10]=>
  string(20) "26-06-2013 14:43:16]"
  [11]=>
  string(87) " Some lines are so large, they take multiple lines, so explode('\n') won't work because"
  [12]=>
  string(30) "
I need the complete message
["

问题

为什么第一个 [ 被忽略了？
我应该如何更改正则表达式以获得所需的输出？
为什么还有 PREG_SPLIT_NO_EMPTY 的空字符串？

Answer 1

使用preg_split，您可以使用

'~\R+(?=\[\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2}])~'

见regex demo

详情

\R+ - 1+ 个换行字符
(?=\[\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2}]) - 一个积极的前瞻，紧接在当前位置的右侧，需要
- \[ - 一个 [ 字符
- \d{2}-\d{2}-\d{4} - 类似日期的模式，2 位数字，连字符，2 位数字，连字符和 2 位数字
- - 一个 space
- \d{2}:\d{2}:\d{2}] - 类似时间的模式，2 位数字，:，2 位数字，:，2 位数字。

PHP 演示：

$text = "[30-05-2013 15:45:54] A A
[26-06-2013 14:44:44] B A
[26-06-2013 14:44:44] C A
[26-06-2013 14:43:16] Some lines are so large, they take multiple lines, so explode('\n') won't work because
I need the complete message
[26-06-2013 14:44:44] E A
[26-06-2013 14:44:44] F A
[26-06-2013 14:44:44] G A";

print_r(preg_split('~\R+(?=\[\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2}])~', $text));

输出：

Array
(
    [0] => [30-05-2013 15:45:54] A A
    [1] => [26-06-2013 14:44:44] B A
    [2] => [26-06-2013 14:44:44] C A
    [3] => [26-06-2013 14:43:16] Some lines are so large, they take multiple lines, so explode('
') won't work because
I need the complete message
    [4] => [26-06-2013 14:44:44] E A
    [5] => [26-06-2013 14:44:44] F A
    [6] => [26-06-2013 14:44:44] G A
)

以防万一您需要获得更多详细信息而不仅仅是拆分，您可以使用匹配方法

'~^\[(\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2})]\s*+(.*?)(?=\s*^\[(?1)]|\z)~ms'

参见the regex demo，用作

preg_match_all('~^\[(\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2})]\s*+(.*?)(?=\s*^\[(?1)]|\z)~ms', $text, $matches)

它将匹配

^ - 行首
\[(\d{2}-\d{2}-\d{4} \d{2}:\d{2}:\d{2})] - 日期时间详细信息（捕获到第 1 组）
\s*+ - 0+白spaces（占有）
(.*?) - 在第一次出现
(?=\s*^\[(?1)]|\z) - 前瞻匹配紧随其后的位置
- \s* - 0+白spaces
- ^ - 行首
- \[(?1)] - [，第 1 组模式，]
- | - 或
- \z - 字符串的末尾。

Answer 2

迟到的答案，但您也可以使用：

$text =  file_get_contents("testchat.txt");

preg_match_all('/(\[.*?\])([^\[]+)/im', $text, $matches, PREG_PATTERN_ORDER);
for ($i = 0; $i < count($matches[0]); $i++) {
    $date = $matches[1][$i];
    $line = $matches[2][$i];
    print("$date $line");
}

preg_split 在正则表达式行开始

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