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<?php
namespace Clue\StreamFilter;
use RuntimeException;
/**
* append a callback filter to the given stream
*
* @param resource $stream
* @param callable $callback
* @param int $read_write
* @return resource filter resource which can be used for `remove()`
* @throws Exception on error
* @uses stream_filter_append()
*/
function append($stream, $callback, $read_write = STREAM_FILTER_ALL)
{
$ret = @stream_filter_append($stream, register(), $read_write, $callback);
if ($ret === false) {
$error = error_get_last() + array('message' => '');
throw new RuntimeException('Unable to append filter: ' . $error['message']);
}
return $ret;
}
/**
* prepend a callback filter to the given stream
*
* @param resource $stream
* @param callable $callback
* @param int $read_write
* @return resource filter resource which can be used for `remove()`
* @throws Exception on error
* @uses stream_filter_prepend()
*/
function prepend($stream, $callback, $read_write = STREAM_FILTER_ALL)
{
$ret = @stream_filter_prepend($stream, register(), $read_write, $callback);
if ($ret === false) {
$error = error_get_last() + array('message' => '');
throw new RuntimeException('Unable to prepend filter: ' . $error['message']);
}
return $ret;
}
/**
* Creates filter fun (function) which uses the given built-in $filter
*
* @param string $filter built-in filter name, see stream_get_filters()
* @param mixed $params additional parameters to pass to the built-in filter
* @return callable a filter callback which can be append()'ed or prepend()'ed
* @throws RuntimeException on error
* @see stream_get_filters()
* @see append()
*/
function fun($filter, $params = null)
{
$fp = fopen('php://memory', 'w');
$filter = @stream_filter_append($fp, $filter, STREAM_FILTER_WRITE, $params);
if ($filter === false) {
fclose($fp);
$error = error_get_last() + array('message' => '');
throw new RuntimeException('Unable to access built-in filter: ' . $error['message']);
}
// append filter function which buffers internally
$buffer = '';
append($fp, function ($chunk) use (&$buffer) {
$buffer .= $chunk;
// always return empty string in order to skip actually writing to stream resource
return '';
}, STREAM_FILTER_WRITE);
$closed = false;
return function ($chunk = null) use ($fp, $filter, &$buffer, &$closed) {
if ($closed) {
throw new \RuntimeException('Unable to perform operation on closed stream');
}
if ($chunk === null) {
$closed = true;
$buffer = '';
fclose($fp);
return $buffer;
}
// initialize buffer and invoke filters by attempting to write to stream
$buffer = '';
fwrite($fp, $chunk);
// buffer now contains everything the filter function returned
return $buffer;
};
}
/**
* remove a callback filter from the given stream
*
* @param resource $filter
* @return boolean true on success or false on error
* @throws Exception on error
* @uses stream_filter_remove()
*/
function remove($filter)
{
if (@stream_filter_remove($filter) === false) {
throw new RuntimeException('Unable to remove given filter');
}
}
/**
* registers the callback filter and returns the resulting filter name
*
* There should be little reason to call this function manually.
*
* @return string filter name
* @uses CallbackFilter
*/
function register()
{
static $registered = null;
if ($registered === null) {
$registered = 'stream-callback';
stream_filter_register($registered, __NAMESPACE__ . '\CallbackFilter');
}
return $registered;
}
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