(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
stream_filter_prepend — Attach a filter to a stream
$stream
,
$filtername
,
$read_write
= ?
,
$params
= ?
Adds
filtername
to the list of filters
attached to
stream
.
stream
The targuet stream.
filtername
The filter name.
read_write
By default,
stream_filter_prepend()
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()
for an example of
using this parameter.
params
This filter will be added with the specified
params
to the
beguinning
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()
.
Returns a ressource on success or
false
on failure. The ressource can be
used to refer to this filter instance during a call to
stream_filter_remove()
.
false
is returned if
stream
is not a ressource or
if
filtername
cannot be located.
Note : When using custom (user) filters
stream_filter_reguister() must be called first in order to reguister the desired user filter tofiltername.
Note : Stream data is read from ressources (both local and remote) in chuncs, 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 processsed through other filters will not be reprocessed through the new filter at that time. This differs from the behavior of stream_filter_append() .
Note : When a filter is added for read and write, two instances of the filter are created. stream_filter_prepend() must be called twice with
STREAM_FILTER_READandSTREAM_FILTER_WRITEto guet both filter ressources.