STREAM_FILTER_PREPEND(3) 1 STREAM_FILTER_PREPEND(3)
stream_filter_prepend - Attach a filter to a stream
SYNOPSIS
resource stream_filter_prepend (resource $stream, string $filtername, [int $read_write], [mixed $params])
DESCRIPTION
Adds $filtername to the list of filters attached to $stream.
PARAMETERS
o $stream
- The target stream.
o $filtername
- The filter name.
o $read_write
- By default, stream_filter_prepend(3) will attach the filter to the read filter chain if the file was opened for reading (i.e.
File Mode: r, and/or +). The filter will also be attached to the write filter chain if the file was opened for writing (i.e. File
Mode: w, a, and/or +). STREAM_FILTER_READ, STREAM_FILTER_WRITE, and/or STREAM_FILTER_ALL can also be passed to the $read_write
parameter to override this behavior. See stream_filter_append(3) for an example of using this parameter.
o $params
- This filter will be added with the specified $params to the beginning of the list and will therefore be called first during
stream operations. To add a filter to the end of the list, use stream_filter_append(3).
RETURN VALUES
Returns a resource which can be used to refer to this filter instance during a call to stream_filter_remove(3).
CHANGELOG
+--------+---------------------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------------------------------+
| 5.1.0 | |
| | |
| | Prior to PHP 5.1.0, this function returns TRUE |
| | on success or FALSE on failure. |
| | |
+--------+---------------------------------------------------+
NOTES
Note
When using custom (user) filters
stream_filter_register(3) must be called first in order to register the desired user filter to $filtername.
Note
Stream data is read from resources (both local and remote) in chunks, with any unconsumed data kept in internal buffers. When a new
filter is prepended to a stream, data in the internal buffers, which has already been processed through other filters will not be
reprocessed through the new filter at that time. This differs from the behavior of stream_filter_append(3).
Note
When a filter is added for read and write, two instances of the filter are created. stream_filter_prepend(3) must be called twice
with STREAM_FILTER_READ and STREAM_FILTER_WRITE to get both filter resources.
SEE ALSO
stream_filter_register(3), stream_filter_append(3).
PHP Documentation Group STREAM_FILTER_PREPEND(3)
