Trait Expression 

pub trait Expression:
    Debug
    + Sync
    + Send {
    // Required methods
    fn return_type(&self) -> DataType;
    fn eval_row<'life0, 'life1, 'async_trait>(
        &'life0 self,
        input: &'life1 OwnedRow,
    ) -> Pin<Box<dyn Future<Output = Result<Datum>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;

    // Provided methods
    fn eval<'life0, 'life1, 'async_trait>(
        &'life0 self,
        input: &'life1 DataChunk,
    ) -> Pin<Box<dyn Future<Output = Result<ArrayRef>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn eval_v2<'life0, 'life1, 'async_trait>(
        &'life0 self,
        input: &'life1 DataChunk,
    ) -> Pin<Box<dyn Future<Output = Result<ValueImpl>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn eval_const(&self) -> Result<Datum> { ... }
    fn input_ref_index(&self) -> Option<usize> { ... }
}

Interface of an expression.

There’re two functions to evaluate an expression: eval and eval_v2, exactly one of them should be implemented. Prefer calling and implementing eval_v2 instead of eval if possible, to gain the performance benefit of scalar expression.

Required Methods

fn return_type(&self) -> DataType

Get the return data type.

fn eval_row<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 OwnedRow, ) -> Pin<Box<dyn Future<Output = Result<Datum>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Evaluate the expression in row-based execution. Returns a nullable scalar.

Provided Methods

fn eval<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ArrayRef>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Evaluate the expression in vectorized execution. Returns an array.

The default implementation calls eval_v2 and always converts the result to an array.

fn eval_v2<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ValueImpl>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Evaluate the expression in vectorized execution. Returns a value that can be either an array, or a scalar if all values in the array are the same.

The default implementation calls eval and puts the result into the Array variant.

fn eval_const(&self) -> Result<Datum>

Evaluate if the expression is constant.

fn input_ref_index(&self) -> Option<usize>

Get the index if the expression is an InputRef.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<'a, T: 'a + Expression + ?Sized> Expression for &'a T

where &'a T: Debug + Sync + Send,

fn return_type(&self) -> DataType

fn eval<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ArrayRef>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_v2<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ValueImpl>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_row<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 OwnedRow, ) -> Pin<Box<dyn Future<Output = Result<Datum>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_const(&self) -> Result<Datum>

fn input_ref_index(&self) -> Option<usize>

impl<T: Expression + ?Sized> Expression for Box<T>

where Box<T>: Debug + Sync + Send,

fn return_type(&self) -> DataType

fn eval<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ArrayRef>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_v2<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 DataChunk, ) -> Pin<Box<dyn Future<Output = Result<ValueImpl>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_row<'life0, 'life1, 'async_trait>( &'life0 self, input: &'life1 OwnedRow, ) -> Pin<Box<dyn Future<Output = Result<Datum>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

fn eval_const(&self) -> Result<Datum>

fn input_ref_index(&self) -> Option<usize>

Implementors

impl Expression for BinaryShortCircuitExpression

impl Expression for InputRefExpression

impl Expression for LiteralExpression

impl Expression for SomeAllExpression

impl Expression for UserDefinedFunction

impl<E, R> Expression for NonStrict<E, R>

where E: Expression, R: EvalErrorReport,

impl<E: Expression> Expression for Checked<E>

impl<E> Expression for Strict<E>

where E: Expression,