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transform_limit.rs
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transform_limit.rs
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// Copyright 2020 The FuseQuery Authors.
//
// Code is licensed under AGPL License, Version 3.0.
use async_trait::async_trait;
use std::sync::Arc;
use crate::datastreams::{LimitStream, SendableDataBlockStream};
use crate::error::FuseQueryResult;
use crate::processors::{EmptyProcessor, IProcessor};
pub struct LimitTransform {
limit: usize,
input: Arc<dyn IProcessor>,
}
impl LimitTransform {
pub fn try_create(limit: usize) -> FuseQueryResult<Self> {
Ok(LimitTransform {
limit,
input: Arc::new(EmptyProcessor::create()),
})
}
}
#[async_trait]
impl IProcessor for LimitTransform {
fn name(&self) -> &str {
"LimitTransform"
}
fn connect_to(&mut self, input: Arc<dyn IProcessor>) -> FuseQueryResult<()> {
self.input = input;
Ok(())
}
async fn execute(&self) -> FuseQueryResult<SendableDataBlockStream> {
Ok(Box::pin(LimitStream::try_create(
self.input.execute().await?,
self.limit,
)?))
}
}