Struct FirstValueFunc 

pub struct FirstValueFunc;

Trait Implementations

impl WindowFunction for FirstValueFunc

type State = FirstValueState

The per-partition accumulator type.

fn initial_state(&self) -> Self::State

Create a fresh accumulator.

fn step(&self, state: &mut Self::State, args: &[SqliteValue]) -> Result<()>

Add a row to the window frame.

fn inverse(&self, state: &mut Self::State, _args: &[SqliteValue]) -> Result<()>

Remove a row from the window frame (sliding window support).

fn value(&self, state: &Self::State) -> Result<SqliteValue>

Return the current result without consuming state.

fn finalize(&self, state: Self::State) -> Result<SqliteValue>

Consume the accumulator and produce the final result.

fn num_args(&self) -> i32

The number of arguments this function accepts (-1 = variadic).

fn name(&self) -> &str

The function name, used in error messages and EXPLAIN output.

fn min_args(&self) -> i32

Minimum accepted SQL argument count for variadic functions.

fn max_args(&self) -> Option<i32>

Maximum accepted SQL argument count, or None for unbounded variadic functions.

fn accepts_arg_count(&self, num_args: i32) -> bool

Return whether this function accepts num_args SQL arguments.