Detect and format music chords in a document

gistfile1.php

<?php

function fjarrett_format_chords( $content ) {
	$new_content = null;
	$pattern     = '/\b[A-G](?:##?|bb?)?(?:min|m)?(?:maj|add|sus|aug|dim)?[0-9]*(?:\/[A-G](?:##?|bb?)?)?(?!\S)/';

	// Iterate over each line in the document
	foreach ( preg_split( '/((\r?\n)|(\r\n?))/', $content ) as $line ) {
		// Find chords on this line
		preg_match_all( $pattern, $line, $matches );

		// Only format the chords if this line consists of only chords
		if ( str_word_count( $line ) === count( $matches[0] ) ) {
			$line = preg_replace( $pattern, '<span class="chord">$0</span>', $line );
		}

		// Wrap each line in a paragraph
		$new_content .= sprintf( '<p>%s</p>', empty( $line ) ? '&nbsp;' : $line );
	}

	// Format text for monospaced output
	printf( '<pre>%s</pre>', $new_content );
}