PHP: How to find text NOT between particular tags?

Question

Example input string: "[A][B][C]test1[/B][/C][/A] [A][B]test2[/B][/A] test3"

I need to find out what parts of text are NOT between the A, B and C tags. So, for example, in the above string it's 'test2' and 'test3'. 'test2' doesn't have the C tag and 'test3' doesn't have any tag at all.

If can also be nested like this: Example input string2: "[A][B][C]test1[/B][/C][/A] [A][B]test2[C]test4[/C][/B][/A] test3"

In this example "test4" was added but "test4" has the A,B and C tag so the output wouldn't change.

Anyone got an idea how I could parse this?

@Erik will the tags always be in the same order [A][B][C][/C][/B][A] ? — air4x
– air4x, Commented Sep 25, 2012 at 10:57
No, tags can be in any order and the closing tags can be in a different order than opening tags too — Erik
– Erik, Commented Sep 25, 2012 at 12:02

Baba · Accepted Answer · 2012-09-24 10:06:20Z

1

This solution is not clean but it does the trick

$string = "[A][B][C]test1[/B][/C][/A] [A][B]test2[/B][/A] test3" ;
$string = preg_replace('/<A[^>]*>([\s\S]*?)<\/A[^>]*>/', '', strtr($string, array("["=>"<","]"=>">")));
$string = trim($string);
var_dump($string);

Output

 string 'test3' (length=5)

answered Sep 24, 2012 at 10:06

Baba

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Toon Krijthe · Accepted Answer · 2012-09-24 10:08:44Z

0

Considering the fact that everyone of you tags is in [A][/A] What you can do is: Explode the [/A] and verify if each array contains the [A] tag like so:

$string = "[A][B][C]test1[/B][/C][/A] [A][B]test2[/B][/A] test3";

$found = ''; // this will be equal to test3
$boom = explode('[/A]', $string);

foreach ($boom as $val) {
 if (strpos($val, '[A] ') !== false) { $found = $val; break; }
}

echo $found; // test3

edited Sep 24, 2012 at 10:08

Toon Krijthe

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answered Sep 24, 2012 at 10:06

faq

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1 Comment

Erik Over a year ago

this won't work. Does not support nested tags and even the output is wrong as "test2" is not within the [C] tags so it should have been found too... I don't think it can be done with a simple explode()

air4x · Accepted Answer · 2012-09-25 19:44:41Z

try the below code

$str = 'test0[A]test1[B][C]test2[/B][/C][/A] [A][B]test3[/B][/A] test4';
$matches  = array();

// Find and remove the unneeded strings
$pattern = '/(\[A\]|\[B\]|\[C\])[^\[]*(\[A\]|\[B\]|\[C\])[^\[]*(\[A\]|\[B\]|\[C\])([^\[]*)(\[\/A\]|\[\/B\]|\[\/C\])[^\[]*(\[\/A\]|\[\/B\]|\[\/C\])[^\[]*(\[\/A\]|\[\/B\]|\[\/C\])/';
preg_match_all( $pattern, $str, $matches );
$stripped_str = $str;
foreach ($matches[0] as $key=>$matched_pattern) {
  $matched_pattern_str  = str_replace($matches[4][$key], '', $matched_pattern); // matched pattern with text between A,B,C tags removed
  $stripped_str = str_replace($matched_pattern, $matched_pattern_str, $stripped_str); // replace pattern string in text with stripped pattern string
}

// Get required strings
$pattern = '/(\[A\]|\[B\]|\[C\]|\[\/A\]|\[\/B\]|\[\/C\])([^\[]+)(\[A\]|\[B\]|\[C\]|\[\/A\]|\[\/B\]|\[\/C\])/';
preg_match_all( $pattern, $stripped_str, $matches );
$required_strings = array();
foreach ($matches[2] as $match) {
  if (trim($match) != '') {
    $required_strings[] = $match;
  }
}

// Special case, possible string on start and end
$pattern = '/^([^\[]*)(\[A\]|\[B\]|\[C\]).*(\[\/A\]|\[\/B\]|\[\/C\])([^\[]*)$/';
preg_match( $pattern, $stripped_str, $matches );
if (trim($matches[1]) != '') {
  $required_strings[] = $matches[1];
}
if (trim($matches[4]) != '') {
  $required_strings[] = $matches[4];
}

print_r($required_strings);

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