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use crate::{
Result,
engine::{
eval,
exec::{Action, Exec, Output, VarId},
},
};
use toasty_core::{driver::Rows, stmt};
#[derive(Debug)]
pub(crate) struct Project {
/// Source of the input
pub(crate) input: VarId,
/// Where to store the output
pub(crate) output: Output,
/// How to project it before storing
pub(crate) projection: eval::Func,
}
impl Exec<'_> {
pub(super) async fn action_project(&mut self, action: &Project) -> Result<()> {
// TODO: come up with a more advanced execution task manager to avoid
// having to eagerly buffer everything.
let mut projected_rows = vec![];
match self.vars.load(action.input).await? {
Rows::Value(value) => {
match value {
stmt::Value::List(items) => {
for value in items {
// Apply the projection
let row = action.projection.eval(&[value])?;
projected_rows.push(row);
}
}
_ => todo!("value={value:#?}"),
}
}
Rows::Stream(mut value_stream) => {
while let Some(res) = value_stream.next().await {
let value = res?;
// Apply the projection
let row = action.projection.eval(&[value])?;
projected_rows.push(row);
}
}
Rows::Count(count) => {
for _ in 0..count {
let row = action.projection.eval_const();
projected_rows.push(row);
}
}
}
// Store the projected stream to the output variable
self.vars.store(
action.output.var,
action.output.num_uses,
Rows::value_stream(projected_rows),
);
Ok(())
}
}
impl From<Project> for Action {
fn from(value: Project) -> Self {
Action::Project(value)
}
}