Trait Accumulator 

pub trait Accumulator: Send {
    // Required methods
    fn update(&mut self, value: Option<SqlValue>) -> Result<()>;
    fn finalize(&self) -> Result<SqlValue>;
    fn clone_box(&self) -> Box<dyn Accumulator>;
}

Accumulator interface for aggregate function execution.

Required Methods

fn update(&mut self, value: Option<SqlValue>) -> Result<()>

Update the accumulator with a new value (None for COUNT(*) rows).

fn finalize(&self) -> Result<SqlValue>

Finalize the accumulator and return the resulting SqlValue.

fn clone_box(&self) -> Box<dyn Accumulator>

Clone the accumulator as a trait object.

Trait Implementations

impl Clone for Box<dyn Accumulator>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

Implementors

impl Accumulator for AvgAccumulator

impl Accumulator for CountAccumulator

impl Accumulator for GroupConcatAccumulator

impl Accumulator for MinMaxAccumulator

impl Accumulator for StringAggAccumulator

impl Accumulator for SumAccumulator

impl Accumulator for TotalAccumulator