to-utf8.php

<?php

/**
 * $to_utf8 = Jetpack__To_UTF8::init();
 * $data = $to_utf8->convert( $data )
 */
class Jetpack__To_UTF8 {
	static $instance;

	private $from;

	function init() {
		if ( ! self::$instance ) {
			self::$instance = new Jetpack__To_UTF8;
		}

		self::$instance->from = null;

		return self::$instance;
	}

	private function __construct() {}

	function convert( $data, $from = null ) {
		if ( ! function_exists( 'mb_convert_encoding' ) ) {
			return $data;
		}

		// Removes any invalid characters
		$old = ini_set( 'mbstring.substitute_character', 'none' );

		if ( ! $from ) {
			$from = get_option( 'blog_charset' );
		}

		// We still convert UTF-8 to UTF-8 to remove invalid characters
		if ( in_array( $from, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) ) ) {
			$from = 'UTF-8';
		}

		$this->from = $from;

		$data = $this->recursively_modify_strings( array( $this, 'convert_string' ), $data );

		ini_set( 'mbstring.substitute_character', $old );

		return $data;
	}

	function recursively_modify_strings( $callback, $input ) {
		if ( is_string( $input ) ) {
			return call_user_func( $callback, $input );
		} elseif ( is_array( $input ) ) {
			foreach ( $input as $key => $value ) {
				$input[$key] = $this->recursively_modify_strings( $callback, $value );
			}
		} elseif ( is_object( $input ) ) {
			foreach ( get_object_vars( $input ) as $key => $value ) {
				$input->{$key} = $this->recursively_modify_strings( $callback, $value );
			}
		}

		return $input;
	}

	function convert_string( $string ) {
		if ( empty( $this->from ) )
			return $string;

		return mb_convert_encoding( $string, 'UTF-8', $this->from );
	}
}