system/Debug/Exceptions.php
public static function highlightFile(string $file, int $lineNumber, int $lines = 15)
	{
		if (empty($file) || ! is_readable($file))
		{
			return false;
		}

		// Set our highlight colors:
		if (function_exists('ini_set'))
		{
			ini_set('highlight.comment', '#767a7e; font-style: italic');
			ini_set('highlight.default', '#c7c7c7');
			ini_set('highlight.html', '#06B');
			ini_set('highlight.keyword', '#f1ce61;');
			ini_set('highlight.string', '#869d6a');
		}

		try
		{
			$source = file_get_contents($file);
		}
		catch (Throwable $e)
		{
			return false;
		}

		$source = str_replace(["\r\n", "\r"], "\n", $source);
		$source = explode("\n", highlight_string($source, true));
		$source = str_replace('<br />', "\n", $source[1]);

		$source = explode("\n", str_replace("\r\n", "\n", $source));

		// Get just the part to show
		$start = $lineNumber - (int) round($lines / 2);
		$start = $start < 0 ? 0 : $start;

		// Get just the lines we need to display, while keeping line numbers...
		$source = array_splice($source, $start, $lines, true);

		// Used to format the line number in the source
		$format = '% ' . strlen($start + $lines) . 'd';

		$out = '';
		// Because the highlighting may have an uneven number
		// of open and close span tags on one line, we need
		// to ensure we can close them all to get the lines
		// showing correctly.
		$spans = 1;

		foreach ($source as $n => $row)
		{
			$spans += substr_count($row, '<span') - substr_count($row, '</span');
			$row    = str_replace(["\r", "\n"], ['', ''], $row);

			if (($n + $start + 1) === $lineNumber)
			{
				preg_match_all('#<[^>]+>#', $row, $tags);
				$out .= sprintf("<span class='line highlight'><span class='number'>{$format}</span> %s\n</span>%s", $n + $start + 1, strip_tags($row), implode('', $tags[0])
				);
			}
			else
			{
				$out .= sprintf('<span class="line"><span class="number">' . $format . '</span> %s', $n + $start + 1, $row) . "\n";
			}
		}

		if ($spans > 0)
		{
			$out .= str_repeat('</span>', $spans);
		}

		return '<pre><code>' . $out . '</code></pre>';
	}
public static function highlightFile(string $file, int $lineNumber, int $lines = 15)
	{
		if (empty($file) || ! is_readable($file))
		{
			return false;
		}

		// Set our highlight colors:
		if (function_exists('ini_set'))
		{
			ini_set('highlight.comment', '#767a7e; font-style: italic');
			ini_set('highlight.default', '#c7c7c7');
			ini_set('highlight.html', '#06B');
			ini_set('highlight.keyword', '#f1ce61;');
			ini_set('highlight.string', '#869d6a');
		}

		try
		{
			$source = file_get_contents($file);
		}
		catch (Throwable $e)
		{
			return false;
		}

		$source = str_replace(["\r\n", "\r"], "\n", $source);
		$source = explode("\n", highlight_string($source, true));
		$source = str_replace('<br />', "\n", $source[1]);

		$source = explode("\n", str_replace("\r\n", "\n", $source));

		// Get just the part to show
		$start = $lineNumber - (int) round($lines / 2);
		$start = $start < 0 ? 0 : $start;

		// Get just the lines we need to display, while keeping line numbers...
		$source = array_splice($source, $start, $lines, true);

		// Used to format the line number in the source
		$format = '% ' . strlen($start + $lines) . 'd';

		$out = '';
		// Because the highlighting may have an uneven number
		// of open and close span tags on one line, we need
		// to ensure we can close them all to get the lines
		// showing correctly.
		$spans = 1;

		foreach ($source as $n => $row)
		{
			$spans += substr_count($row, '<span') - substr_count($row, '</span');
			$row    = str_replace(["\r", "\n"], ['', ''], $row);

			if (($n + $start + 1) === $lineNumber)
			{
				preg_match_all('#<[^>]+>#', $row, $tags);
				$out .= sprintf("<span class='line highlight'><span class='number'>{$format}</span> %s\n</span>%s", $n + $start + 1, strip_tags($row), implode('', $tags[0])
				);
			}
			else
			{
				$out .= sprintf('<span class="line"><span class="number">' . $format . '</span> %s', $n + $start + 1, $row) . "\n";
			}
		}

		if ($spans > 0)
		{
			$out .= str_repeat('</span>', $spans);
		}

		return '<pre><code>' . $out . '</code></pre>';
	}
Creates a syntax-highlighted version of a PHP file.

@param string  $file
@param integer $lineNumber
@param integer $lines

@return boolean|string