VTable

vortex_array::expr

Trait VTable 

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pub trait VTable:
    'static
    + Sized
    + Send
    + Sync {
    type Instance: 'static + Send + Sync + Debug + PartialEq + Eq + Hash;


Show 14 methods    // Required methods
    fn id(&self) -> ExprId;
    fn validate(&self, expr: &ExpressionView<'_, Self>) -> VortexResult<()>;
    fn child_name(
        &self,
        _instance: &Self::Instance,
        child_idx: usize,
    ) -> ChildName;
    fn fmt_sql(
        &self,
        expr: &ExpressionView<'_, Self>,
        f: &mut Formatter<'_>,
    ) -> Result;
    fn return_dtype(
        &self,
        expr: &ExpressionView<'_, Self>,
        scope: &DType,
    ) -> VortexResult<DType>;
    fn evaluate(
        &self,
        expr: &ExpressionView<'_, Self>,
        scope: &ArrayRef,
    ) -> VortexResult<ArrayRef>;

    // Provided methods
    fn serialize(
        &self,
        _instance: &Self::Instance,
    ) -> VortexResult<Option<Vec<u8>>> { ... }
    fn deserialize(
        &self,
        _metadata: &[u8],
    ) -> VortexResult<Option<Self::Instance>> { ... }
    fn fmt_data(
        &self,
        instance: &Self::Instance,
        f: &mut Formatter<'_>,
    ) -> Result { ... }
    fn stat_falsification(
        &self,
        _expr: &ExpressionView<'_, Self>,
        _catalog: &mut dyn StatsCatalog,
    ) -> Option<Expression> { ... }
    fn stat_max(
        &self,
        _expr: &ExpressionView<'_, Self>,
        _catalog: &mut dyn StatsCatalog,
    ) -> Option<Expression> { ... }
    fn stat_min(
        &self,
        _expr: &ExpressionView<'_, Self>,
        _catalog: &mut dyn StatsCatalog,
    ) -> Option<Expression> { ... }
    fn stat_nan_count(
        &self,
        _expr: &ExpressionView<'_, Self>,
        _catalog: &mut dyn StatsCatalog,
    ) -> Option<Expression> { ... }
    fn stat_field_path(
        &self,
        _expr: &ExpressionView<'_, Self>,
    ) -> Option<FieldPath> { ... }

}
Expand description

This trait defines the interface for expression vtables, including methods for serialization, deserialization, validation, child naming, return type computation, and evaluation.

This trait is non-object safe and allows the implementer to make use of associated types for improved type safety, while allowing Vortex to enforce runtime checks on the inputs and outputs of each function.

The VTable trait should be implemented for a struct that holds global data across all instances of the expression. In almost all cases, this struct will be an empty unit struct, since most expressions do not require any global state.

Required Associated Types§

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type Instance: 'static + Send + Sync + Debug + PartialEq + Eq + Hash

Instance data for this expression.

Required Methods§

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fn id(&self) -> ExprId

Returns the ID of the expr vtable.

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fn validate(&self, expr: &ExpressionView<'_, Self>) -> VortexResult<()>

Validate the metadata and children for the expression.

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fn child_name(&self, _instance: &Self::Instance, child_idx: usize) -> ChildName

Returns the name of the nth child of the expr.

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fn fmt_sql( &self, expr: &ExpressionView<'_, Self>, f: &mut Formatter<'_>, ) -> Result

Format this expression in nice human-readable SQL-style format

The implementation should recursively format child expressions by calling expr.child(i).fmt_sql(f).

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fn return_dtype( &self, expr: &ExpressionView<'_, Self>, scope: &DType, ) -> VortexResult<DType>

Compute the return DType of the expression if evaluated in the given scope.

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fn evaluate( &self, expr: &ExpressionView<'_, Self>, scope: &ArrayRef, ) -> VortexResult<ArrayRef>

Evaluate the expression in the given scope.

Provided Methods§

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fn serialize(&self, _instance: &Self::Instance) -> VortexResult<Option<Vec<u8>>>

Serialize the metadata for the expression.

Should return Ok(None) if the expression is not serializable, and Ok(vec![]) if it is serializable but has no metadata.

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fn deserialize(&self, _metadata: &[u8]) -> VortexResult<Option<Self::Instance>>

Deserialize an instance of this expression.

Returns Ok(None) if the expression is not serializable.

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fn fmt_data(&self, instance: &Self::Instance, f: &mut Formatter<'_>) -> Result

Format only the instance data for this expression.

Defaults to a debug representation of the instance data.

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fn stat_falsification( &self, _expr: &ExpressionView<'_, Self>, _catalog: &mut dyn StatsCatalog, ) -> Option<Expression>

See crate::expr::Expression::stat_falsification.

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fn stat_max( &self, _expr: &ExpressionView<'_, Self>, _catalog: &mut dyn StatsCatalog, ) -> Option<Expression>

See crate::expr::Expression::stat_max.

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fn stat_min( &self, _expr: &ExpressionView<'_, Self>, _catalog: &mut dyn StatsCatalog, ) -> Option<Expression>

See crate::expr::Expression::stat_min.

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fn stat_nan_count( &self, _expr: &ExpressionView<'_, Self>, _catalog: &mut dyn StatsCatalog, ) -> Option<Expression>

See crate::expr::Expression::stat_nan_count.

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fn stat_field_path(&self, _expr: &ExpressionView<'_, Self>) -> Option<FieldPath>

See crate::expr::Expression::stat_field_path.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§