sdp: Add SDPMessage::get_media_mut() and ::medias_mut()

This allows getting mutable references to the medias so that they can be
modified, which is allowed by the C API and safe to do.
This commit is contained in:
Sebastian Dröge 2019-05-15 17:15:41 +03:00
parent 0bd22b2b05
commit e9edb8ddca

View file

@ -381,6 +381,21 @@ impl SDPMessageRef {
}
}
pub fn get_media_mut(&mut self, idx: u32) -> Option<&mut SDPMediaRef> {
if idx >= self.medias_len() {
return None;
}
unsafe {
let ptr = gst_sdp_sys::gst_sdp_message_get_media(&self.0, idx);
if ptr.is_null() {
None
} else {
Some(&mut *(ptr as *mut SDPMediaRef))
}
}
}
pub fn get_origin(&self) -> Option<&SDPOrigin> {
unsafe {
let ptr = gst_sdp_sys::gst_sdp_message_get_origin(&self.0);
@ -862,6 +877,10 @@ impl SDPMessageRef {
MediasIter::new(self)
}
pub fn medias_mut(&mut self) -> MediasIterMut {
MediasIterMut::new(self)
}
pub fn phones(&self) -> PhonesIter {
PhonesIter::new(self)
}
@ -961,6 +980,83 @@ macro_rules! define_iter(
}
);
macro_rules! define_iter_mut(
($name:ident, $typ:ty, $get_item:expr, $get_len:expr) => {
#[derive(Debug)]
pub struct $name<'a> {
message: &'a mut SDPMessageRef,
idx: u32,
len: u32,
}
impl<'a> $name<'a> {
fn new(message: &'a mut SDPMessageRef) -> $name<'a> {
skip_assert_initialized!();
let len = $get_len(message);
$name {
message,
idx: 0,
len,
}
}
}
impl<'a> Iterator for $name<'a> {
type Item = $typ;
fn next(&mut self) -> Option<Self::Item> {
// The lifetime of the passed self is not 'a but we need to return a message reference
// with that lifetime here. The reason here is that the compiler does not and can't
// know that it's statically impossible to mutate the message between different calls
// to next(), so it has to assume that every call to next() will invalidate any
// returned references.
//
// In theory we could have a function on the iterator that mutates the message and for
// example removes the message that was returned here at an earlier time. The compiler
// would be correct to complain in that case, but we don't provide such a function.
let message = unsafe {
mem::transmute::<(&mut SDPMessageRef), (&'a mut SDPMessageRef)>(&mut self.message)
};
if self.idx >= self.len {
return None;
}
let item = $get_item(message, self.idx)?;
self.idx += 1;
Some(item)
}
fn size_hint(&self) -> (usize, Option<usize>) {
if self.idx == self.len {
return (0, Some(0))
}
let remaining = (self.len - self.idx) as usize;
(remaining, Some(remaining))
}
}
impl<'a> DoubleEndedIterator for $name<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
let message = unsafe {
mem::transmute::<(&mut SDPMessageRef), (&'a mut SDPMessageRef)>(&mut self.message)
};
if self.idx == self.len {
return None;
}
self.len -= 1;
$get_item(message, self.len)
}
}
impl<'a> ExactSizeIterator for $name<'a> {}
}
);
define_iter!(
AttributesIter,
&'a SDPAttribute,
@ -985,6 +1081,12 @@ define_iter!(
|message: &'a SDPMessageRef, idx| message.get_media(idx),
|message: &SDPMessageRef| message.medias_len()
);
define_iter_mut!(
MediasIterMut,
&'a mut SDPMediaRef,
|message: &'a mut SDPMessageRef, idx| { message.get_media_mut(idx) },
|message: &mut SDPMessageRef| message.medias_len()
);
define_iter!(
PhonesIter,
&'a str,