Multibyte String Stream Filter

A php_user_filter implementation for quickly converting stream character sets without loading the entire string into memory.

Note: this library does not have the ability to persist state for stateful character sets, and as such, could potentially lose data. See #1 for an open issue, and this document for more info about stateful character sets.

Example

// Not required if the file was autoloaded (e.g. using composer)
MultibyteStringStream::registerStreamFilter();
$native_file = fopen('iso-8859-1-file.txt', 'r');
stream_filter_append($native_file, 'convert.mbstring.UTF-8/ISO-8859-1');
$unicode_file = fopen('utf8-file.txt', 'w');
stream_copy_to_stream($native_file, $unicode_file);

mbstring-stream also works as a write filter:

$native_file = fopen('sjis-file.txt', 'r');
$unicode_file = fopen('utf8-file.txt', 'w');
stream_filter_append($unicode_file, 'convert.mbstring.UTF-8/SJIS');
stream_copy_to_stream($native_file, $unicode_file);

Usage

/** * resource $stream The stream to filter. * string $to_encoding The encoding to convert to. * string $from_encoding The encoding to convert from. Optional, defaults to mb_internal_encoding() * int $read_write See http://php.net/manual/en/function.stream-filter-append.php * string|int $sub_char The substitute character to use. Optional, defaults to mb_substitute_character() */stream_filter_append($stream, "convert.mbstring.$to_encoding/$from_encoding", $read_write, $sub_char);

Note: Be careful when using on streams in 'r+' or 'w+' (or similar) modes; by default PHP will assign the filter to both the reading and writing chain. This means it will attempt to convert the data twice - once when writing to the stream, and once when reading from it.