Struct DataContext

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pub struct DataContext<Vertex> { /* private fields */ }
Expand description

A partial result of a Trustfall query within the interpreter defined in this module.

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impl<Vertex> DataContext<Vertex>

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pub fn active_vertex<V>(&self) -> Option<&V>
where Vertex: AsVertex<V>,

The vertex currently being processed.

For contexts passed to an Adapter resolver method, this is the vertex whose data needs to be resolved.

The active vertex may be None when processing an @optional part of a Trustfall query whose data did not exist. In that case:

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pub fn map<Other>( self, mapper: &mut impl FnMut(Vertex) -> Other, ) -> DataContext<Other>

Converts DataContext<Vertex> to DataContext<Other> by mapping each Vertex to Other.

If you are implementing an Adapter for a data source, you almost certainly should not be using this function. You’re probably looking for DataContext::active_vertex() instead.

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pub fn flat_map<T>( self, mapper: &mut impl FnMut(Vertex) -> Option<T>, ) -> DataContext<T>

Map each Vertex to Option<Other>, thus converting Self to DataContext<Other>.

This is the DataContext equivalent of Option::and_then, which is also referred to as “flat-map” in some languages.

If you are implementing an Adapter for a data source, you almost certainly should not be using this function. You’re probably looking for DataContext::active_vertex() instead.

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impl<Vertex> DataContext<Vertex>
where Vertex: Clone + Debug,

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pub fn new(vertex: Option<Vertex>) -> DataContext<Vertex>

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impl<Vertex> Clone for DataContext<Vertex>
where Vertex: Clone,

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fn clone(&self) -> DataContext<Vertex>

Returns a duplicate of the value. Read more
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const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<Vertex> Debug for DataContext<Vertex>
where Vertex: Debug,

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl<'de, Vertex> Deserialize<'de> for DataContext<Vertex>
where Vertex: Debug + Clone + Serialize + DeserializeOwned,

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fn deserialize<D>( deserializer: D, ) -> Result<DataContext<Vertex>, <D as Deserializer<'de>>::Error>
where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl<Vertex> From<SerializableContext<Vertex>> for DataContext<Vertex>

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fn from(context: SerializableContext<Vertex>) -> DataContext<Vertex>

Converts to this type from the input type.
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impl<Vertex> PartialEq for DataContext<Vertex>
where Vertex: PartialEq,

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fn eq(&self, other: &DataContext<Vertex>) -> bool

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<Vertex> Serialize for DataContext<Vertex>
where Vertex: Debug + Clone + Serialize + DeserializeOwned,

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fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
where S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl<Vertex> Eq for DataContext<Vertex>
where Vertex: Eq,

Auto Trait Implementations§

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impl<Vertex> Freeze for DataContext<Vertex>
where Vertex: Freeze,

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impl<Vertex> RefUnwindSafe for DataContext<Vertex>
where Vertex: RefUnwindSafe,

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impl<Vertex> Send for DataContext<Vertex>
where Vertex: Send,

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impl<Vertex> Sync for DataContext<Vertex>
where Vertex: Sync,

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impl<Vertex> Unpin for DataContext<Vertex>
where Vertex: Unpin,

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impl<Vertex> UnwindSafe for DataContext<Vertex>
where Vertex: UnwindSafe + RefUnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<V> AsVertex<V> for V
where V: Debug + Clone,

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fn as_vertex(&self) -> Option<&V>

Dereference this value into a &V, if the value happens to contain a V. Read more
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fn into_vertex(self) -> Option<V>

Consume self and produce the contained V, if one was indeed present. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,