mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer-rs.git
synced 2024-12-23 00:26:31 +00:00
gst/format: add CompatibleFormattedValue
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
This commit is contained in:
François Laignel
parent
fe319af598
commit
865df62f8d
3 changed files with 324 additions and 16 deletions
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@ -73,8 +73,8 @@ impl fmt::Display for GenericFormattedValue {
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}
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#[derive(Clone, Copy, Debug, PartialEq, Eq, Error)]
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#[error("invalid generic value format")]
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pub struct TryFromGenericFormattedValueError(());
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#[error("invalid formatted value format {:?}", .0)]
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pub struct FormattedValueError(Format);
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pub trait FormattedValue: Copy + Clone + Sized + Into<GenericFormattedValue> + 'static {
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// rustdoc-stripper-ignore-next
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@ -125,6 +125,201 @@ pub trait SpecificFormattedValueFullRange: FormattedValueFullRange {}
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/// - `Bytes` is the intrinsic type for `Option<Bytes>`.
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pub trait SpecificFormattedValueIntrinsic: TryFromGlib<i64> + FormattedValueIntrinsic {}
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// rustdoc-stripper-ignore-next
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/// A trait implemented on types which can hold [`FormattedValue`]s compatible with parameter `F`.
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///
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/// This trait is auto-implemented based on [`FormattedValue`]s additional traits
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/// such as [`SpecificFormattedValue`].
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///
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/// # Example:
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///
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/// Consider the following function:
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///
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/// ```rust
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/// # use gstreamer::{ClockTime, CompatibleFormattedValue, FormattedValue, GenericFormattedValue};
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/// fn with_compatible_formats<V: FormattedValue>(
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/// arg1: V,
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/// arg2: impl CompatibleFormattedValue<V>,
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/// ) {
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/// // This is required to access arg2 as a FormattedValue:
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/// let _arg2 = arg2.try_into_checked(arg1).unwrap();
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/// }
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///
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/// // This is Ok because arg1 is a ClockTime and arg2 is
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/// // an Option<ClockTime> which are compatible format-wise.
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/// with_compatible_formats(ClockTime::ZERO, ClockTime::NONE);
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///
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/// // This is Ok because arg1 is a ClockTime and arg2 is
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/// // a GenericFormattedValue which are compatible format-wise.
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/// with_compatible_formats(
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/// ClockTime::ZERO,
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/// GenericFormattedValue::Time(None),
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/// );
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/// ```
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///
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/// Users are able to call the function with arguments:
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///
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/// 1. of the same type (e.g. `ClockTime`),
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/// 2. of different types, but able to hold a value of the same [`Format`]
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/// (e.g. `ClockTime` and `Option<ClockTime>`).
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/// 3. One of a Formatted Value (specific or generic), the other being
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/// a `GenericFormattedValue`.
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///
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/// Format compatibility for cases 1 and 2 is enforced by
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/// the type system, while case 3 will be checked at runtime time.
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///
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/// ```compile_fail
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/// # use gstreamer::{ClockTime, CompatibleFormattedValue, FormattedValue, format::Bytes};
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/// # fn with_compatible_formats<V: FormattedValue>(
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/// # arg1: V,
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/// # arg2: impl CompatibleFormattedValue<V>,
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/// # ) {}
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/// // This doesn't compile because the arguments are not compatible:
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/// let _ = with_compatible_formats(ClockTime::ZERO, Bytes(Some(42)));
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/// ```
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///
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/// Note: users will not be able use `arg2` directly unless format
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/// check succeeds:
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///
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/// ```compile_fail
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/// # use gstreamer::{CompatibleFormattedValue, FormattedValue};
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/// fn with_compatible_formats<V: FormattedValue>(
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/// arg1: V,
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/// arg2: impl CompatibleFormattedValue<V>,
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/// ) {
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/// // This doesn't compile because arg2 hasn't been checked:
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/// let _format = arg2.format();
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/// }
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/// ```
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pub trait CompatibleFormattedValue<V: FormattedValue> {
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type Original: FormattedValue;
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// rustdoc-stripper-ignore-next
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/// Returns `Ok(self)` with its type restored if it is compatible with the format of `other`.
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///
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/// When used with compatible [`SpecificFormattedValue`]s, checks
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/// are enforced by the type system, no runtime checks are performed.
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///
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/// When used with [`FormattedValue`] / [`GenericFormattedValue`] and
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/// vice versa, a runtime format check is performed. If the check fails,
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/// `Err(FormattedValueError)` is returned.
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fn try_into_checked(self, other: V) -> Result<Self::Original, FormattedValueError>;
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// rustdoc-stripper-ignore-next
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/// Returns `Ok(self)` with its type restored if it is compatible with the format of `V`.
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///
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/// When possible, prefer using [`Self::try_into_checked`] which
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/// reduces the risk of missuse.
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///
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/// When used with compatible [`SpecificFormattedValue`]s, checks
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/// are enforced by the type system, no runtime checks are performed.
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///
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/// When used with [`SpecificFormattedValue`] as a parameter and
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/// a [`GenericFormattedValue`] as `Self`, a runtime check is perfomed
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/// against the default format of the parameter. If the check fails,
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/// `Err(FormattedValueError)` is returned.
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///
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/// When used with [`GenericFormattedValue`] as a parameter and
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/// a [`SpecificFormattedValue`] as `Self`, the `format` argument
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/// used. If the check fails, `Err(FormattedValueError)` is returned.
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fn try_into_checked_explicit(
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self,
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format: Format,
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) -> Result<Self::Original, FormattedValueError>;
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}
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impl<T, V> CompatibleFormattedValue<V> for T
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where
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V: SpecificFormattedValue,
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T: SpecificFormattedValue<FullRange = V::FullRange>,
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{
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type Original = Self;
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fn try_into_checked(self, _other: V) -> Result<Self, FormattedValueError> {
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skip_assert_initialized!();
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Ok(self)
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}
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fn try_into_checked_explicit(
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self,
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_format: Format,
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) -> Result<Self::Original, FormattedValueError> {
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skip_assert_initialized!();
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Ok(self)
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}
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}
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impl<T: SpecificFormattedValue> CompatibleFormattedValue<GenericFormattedValue> for T {
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type Original = Self;
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fn try_into_checked(self, other: GenericFormattedValue) -> Result<Self, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == other.format() {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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fn try_into_checked_explicit(
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self,
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format: Format,
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) -> Result<Self::Original, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == format {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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}
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impl<V: SpecificFormattedValue> CompatibleFormattedValue<V> for GenericFormattedValue {
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type Original = Self;
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fn try_into_checked(self, _other: V) -> Result<Self, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == V::default_format() {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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fn try_into_checked_explicit(
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self,
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_format: Format,
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) -> Result<Self::Original, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == V::default_format() {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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}
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impl CompatibleFormattedValue<GenericFormattedValue> for GenericFormattedValue {
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type Original = Self;
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fn try_into_checked(self, other: GenericFormattedValue) -> Result<Self, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == other.format() {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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fn try_into_checked_explicit(
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self,
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format: Format,
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) -> Result<Self::Original, FormattedValueError> {
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skip_assert_initialized!();
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if self.format() == format {
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Ok(self)
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} else {
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Err(FormattedValueError(self.format()))
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}
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}
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}
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impl FormattedValue for GenericFormattedValue {
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type FullRange = GenericFormattedValue;
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@ -242,14 +437,14 @@ impl From<Undefined> for GenericFormattedValue {
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}
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impl TryFrom<GenericFormattedValue> for Undefined {
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type Error = TryFromGenericFormattedValueError;
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type Error = FormattedValueError;
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fn try_from(v: GenericFormattedValue) -> Result<Undefined, TryFromGenericFormattedValueError> {
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fn try_from(v: GenericFormattedValue) -> Result<Undefined, Self::Error> {
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skip_assert_initialized!();
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if let GenericFormattedValue::Undefined(v) = v {
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Ok(v)
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} else {
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Err(TryFromGenericFormattedValueError(()))
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Err(FormattedValueError(v.format()))
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}
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}
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}
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@ -391,16 +586,14 @@ impl TryFromGlib<i64> for Percent {
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}
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impl TryFrom<GenericFormattedValue> for Option<Percent> {
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type Error = TryFromGenericFormattedValueError;
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type Error = FormattedValueError;
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fn try_from(
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v: GenericFormattedValue,
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) -> Result<Option<Percent>, TryFromGenericFormattedValueError> {
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fn try_from(v: GenericFormattedValue) -> Result<Option<Percent>, Self::Error> {
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skip_assert_initialized!();
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if let GenericFormattedValue::Percent(v) = v {
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Ok(v)
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} else {
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Err(TryFromGenericFormattedValueError(()))
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Err(FormattedValueError(v.format()))
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}
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}
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}
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@ -469,3 +662,117 @@ impl TryFrom<f32> for Percent {
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::{
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Buffers, CompatibleFormattedValue, Format, FormattedValue, FormattedValueError,
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GenericFormattedValue,
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};
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use crate::ClockTime;
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fn with_compatible_formats<V1, V2>(
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arg1: V1,
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arg2: V2,
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) -> Result<V2::Original, FormattedValueError>
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where
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V1: FormattedValue,
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V2: CompatibleFormattedValue<V1>,
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{
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skip_assert_initialized!();
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arg2.try_into_checked(arg1)
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}
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#[test]
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fn compatible() {
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assert_eq!(
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with_compatible_formats(ClockTime::ZERO, ClockTime::ZERO),
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Ok(ClockTime::ZERO),
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);
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assert_eq!(
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with_compatible_formats(ClockTime::ZERO, ClockTime::NONE),
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Ok(ClockTime::NONE),
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);
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assert_eq!(
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with_compatible_formats(ClockTime::NONE, ClockTime::ZERO),
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Ok(ClockTime::ZERO),
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);
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assert_eq!(
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with_compatible_formats(
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ClockTime::ZERO,
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GenericFormattedValue::Time(Some(ClockTime::ZERO)),
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),
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Ok(GenericFormattedValue::Time(Some(ClockTime::ZERO))),
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);
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assert_eq!(
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with_compatible_formats(
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GenericFormattedValue::Time(Some(ClockTime::ZERO)),
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ClockTime::NONE,
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),
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Ok(ClockTime::NONE),
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);
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}
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#[test]
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fn incompatible() {
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with_compatible_formats(
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ClockTime::ZERO,
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GenericFormattedValue::Buffers(Some(Buffers(42))),
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)
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.unwrap_err();
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with_compatible_formats(
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GenericFormattedValue::Buffers(Some(Buffers(42))),
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ClockTime::NONE,
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)
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.unwrap_err();
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}
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fn with_compatible_explicit<T, V>(arg: V, f: Format) -> Result<V::Original, FormattedValueError>
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where
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T: FormattedValue,
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V: CompatibleFormattedValue<T>,
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{
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skip_assert_initialized!();
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arg.try_into_checked_explicit(f)
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}
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#[test]
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fn compatible_explicit() {
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assert_eq!(
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with_compatible_explicit::<ClockTime, _>(ClockTime::ZERO, Format::Time),
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Ok(ClockTime::ZERO),
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);
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assert_eq!(
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with_compatible_explicit::<ClockTime, _>(ClockTime::NONE, Format::Time),
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Ok(ClockTime::NONE),
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);
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assert_eq!(
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with_compatible_explicit::<ClockTime, _>(ClockTime::ZERO, Format::Time),
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Ok(ClockTime::ZERO),
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);
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assert_eq!(
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with_compatible_explicit::<ClockTime, _>(
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GenericFormattedValue::Time(None),
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Format::Time
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),
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Ok(GenericFormattedValue::Time(None)),
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);
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assert_eq!(
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with_compatible_explicit::<GenericFormattedValue, _>(ClockTime::NONE, Format::Time),
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Ok(ClockTime::NONE),
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);
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}
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#[test]
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fn incompatible_explicit() {
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with_compatible_explicit::<Buffers, _>(GenericFormattedValue::Time(None), Format::Buffers)
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.unwrap_err();
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with_compatible_explicit::<GenericFormattedValue, _>(Buffers::ZERO, Format::Time)
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.unwrap_err();
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with_compatible_explicit::<GenericFormattedValue, _>(
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GenericFormattedValue::Time(None),
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Format::Buffers,
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)
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.unwrap_err();
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}
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}
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@ -226,8 +226,9 @@ mod typefind_factory;
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pub mod format;
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pub use crate::format::{
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FormattedValue, FormattedValueFullRange, FormattedValueIntrinsic, GenericFormattedValue,
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SpecificFormattedValue, SpecificFormattedValueFullRange, SpecificFormattedValueIntrinsic,
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CompatibleFormattedValue, FormattedValue, FormattedValueFullRange, FormattedValueIntrinsic,
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GenericFormattedValue, SpecificFormattedValue, SpecificFormattedValueFullRange,
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SpecificFormattedValueIntrinsic,
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};
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#[cfg(feature = "ser_de")]
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mod format_serde;
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@ -344,8 +345,8 @@ pub mod prelude {
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pub use muldiv::MulDiv;
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pub use crate::format::{
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FormattedValue, FormattedValueFullRange, FormattedValueIntrinsic, SpecificFormattedValue,
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SpecificFormattedValueFullRange, SpecificFormattedValueIntrinsic,
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CompatibleFormattedValue, FormattedValue, FormattedValueFullRange, FormattedValueIntrinsic,
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SpecificFormattedValue, SpecificFormattedValueFullRange, SpecificFormattedValueIntrinsic,
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};
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pub use crate::utils::Displayable;
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@ -433,14 +433,14 @@ macro_rules! impl_format_value_traits(
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impl SpecificFormattedValueIntrinsic for $name {}
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impl TryFrom<GenericFormattedValue> for Option<$name> {
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type Error = TryFromGenericFormattedValueError;
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type Error = FormattedValueError;
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fn try_from(v: GenericFormattedValue) -> Result<Option<$name>, Self::Error> {
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skip_assert_initialized!();
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if let GenericFormattedValue::$format_value(v) = v {
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Ok(v)
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} else {
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Err(TryFromGenericFormattedValueError(()))
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Err(FormattedValueError(v.format()))
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}
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}
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}
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