Remove excess whitespace/indentation from strings-CodePudding

I have a string like:

     section
        subsection
            text

I'd like to remove the white space from the first line, and the same amount of white space from the following lines. It's to automatically de-indent some text used as a description pulled from something else, but retaining the relative indentation, like this :

section
   subsection
       text

Is there a clean way to do this? I thought originally of counting the space characters at the start, but they might be indent with tabs (though i'd assume all lines are indented the same way).

CodePudding user response：

Grab initial white-space:

preg_match('/^(?<initial>\s*)/', $input, $match);
['initial' => $initialWhiteSpace] = $match;
$whiteSpaceLength = strlen($initialWhiteSpace);

Convert string to array of lines:

$lines = explode(PHP_EOL, $input);

Remove the white-space:

$output = array_map(
    static fn (string $str): string => preg_replace(sprintf("/^[ \t]{%d}/", $whiteSpaceLength), '', $str),
    $lines,
);

Recreate the string:

$output = implode(PHP_EOL, $output);

Et voila:

echo $output;

Proof of concept: https://3v4l.org/GoFbG

CodePudding user response：

I rewrote emix's PHP7.4 code to work in 5.6 but the basics are the same :

function strip_indentation ($input) {
  preg_match('/^(?<initial>\s*)/', $input, $match);
  $whiteSpaceLength = strlen($match['initial']);
  $lines = [];
  foreach(explode(PHP_EOL, $input) as $key => $line)
  {
     $lines[$key] = preg_replace(sprintf("/^[ \t]{%d}/", $whiteSpaceLength), '', $line);
  }

  $output = implode(PHP_EOL, $lines);
  return $output;
}