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gstreamer: Add StructureRef::get_optional()

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This only returns Err on type mismatches. If the field does not exist or
None it returns None, otherwise the value.

StructureRef::get() returns Err also if the field does not exist.
This commit is contained in:
Sebastian Dröge 2019-08-13 18:02:57 +03:00
parent 39ef834cfe
commit 2829c7ee2f
1 changed files with 18 additions and 0 deletions
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18
gstreamer/src/structure.rs
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@ -387,6 +387,20 @@ impl StructureRef {
.map_err(|err| GetError::from_value_get_error(name, err))
}
pub fn get_optional<'structure, 'name, T: FromValueOptional<'structure>>(
&'structure self,
name: &'name str,
) -> Result<Option<T>, GetError<'name>> {
let value = self.get_value(name);
if let Ok(value) = value {
value
.get()
.map_err(|err| GetError::from_value_get_error(name, err))
} else {
Ok(None)
}
}
pub fn get_some<'structure, 'name, T: FromValue<'structure>>(
&'structure self,
name: &'name str,
@ -751,6 +765,10 @@ mod tests {
assert_eq!(s.get::<&str>("f1"), Ok(Some("abc")));
assert_eq!(s.get::<&str>("f2"), Ok(Some("bcd")));
assert_eq!(s.get_some::<i32>("f3"), Ok(123i32));
assert_eq!(s.get_optional::<&str>("f1"), Ok(Some("abc")));
assert_eq!(s.get_optional::<&str>("f4"), Ok(None));
assert_eq!(s.get_optional::<i32>("f3"), Ok(Some(123i32)));
assert_eq!(s.get_optional::<i32>("f4"), Ok(None));
// FIXME: use a proper `assert_eq!`, but that requires
// `glib::value::GetError fields to be public