Functions such as Segment::to_running_time_full replicate the C
signature for the return type: an integer indicates whether the
resulting value must be interpreted as positive or negative.
In Rust, alternatives are usually represented using an enum.
This commit implements an enum wrapper to represent the sign
and adds functions to FormattedValue to ease Signed handling.
The trait CompatibleFormattedValue can be used to check argument
compatibility to a certain Format. This is convenient to define
function which accept several FormattedValues which must hold
values of the same Format.
This trait enforces format compatibility at compilation time for
SpecificFormattedValues and at runtime when a GenericFormattedValue
is provided.
See https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1059
The trait FormattedValue was only implemented on types which
could implement the full range of values for a Format. In order
to declare a function which could take both the intrinsic type
of any Format (e.g. `ClockTime`) as well the full range of values
(e.g. `Option<ClockTime>`), the argument was declared:
```rust
impl Into<GenericFormattedValue>,
```
This commit implements `FormattedValue` for any type representing
a format. E.g.: both `ClockTime` and `Option<ClockTime>` will now
implement `FormattedValue`. The trait `FormattedValueFullRange`
is implemented on types which can be built from any raw value.
These changes are intended to help for the implementation of a
means to enforce format conformity at compilation time for
functions with multiple formatted value arguments.
The following signatures were found to be incorrect and are fixed:
- `message::StepDone`: forced the type for `amount` and `duration`
to be of the same type, when `duration` is expected to be of the
`Time` format.
- `query::Convert::set`: the two arguments were forced to the same
type, so potentialy the same format, unless a
`GenericFormattedValue` was used.
See https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1059
