matdb 0.1.0

An experimental embedded SQL-like DBMS
Documentation 
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mod join;
use anyhow::{anyhow, Result};
pub use join::Join;
mod select;
pub use select::Select;
mod filter;
pub use filter::Filter;
mod rangescan;
pub use rangescan::RangeScan;
mod delete;
pub use delete::Delete;
mod update;
pub use update::Update;

use crate::eval::Context;
use crate::Db;

#[derive(Debug)]
pub enum PlanNode {
    None,
    RangeScan(RangeScan),
    Join(Join),

    Filter(Filter),
    Select(Select),
    Delete(Delete),
    Update(Update),
}

pub fn execute_plan_next<'a>(
    plan: &mut PlanNode,
    db: &mut Db,
    ctx: Context,
) -> Result<Option<Context>> {
    match plan {
        PlanNode::None => Ok(None),
        PlanNode::RangeScan(range_scan) => range_scan.execute(db, ctx),
        PlanNode::Join(join) => join.execute(db, ctx),

        PlanNode::Filter(filter) => {
            let Some(ctx) = execute_plan_next(&mut filter.child, db, ctx)? else {
                return Ok(None);
            };

            if ctx
                .eval(&filter.cond)?
                .into_bool()
                .ok_or(anyhow!("filter expression does not evaluate to a BOOLEAN"))?
            {
                Ok(Some(ctx))
            } else {
                execute_plan_next(plan, db, ctx)
            }
        }
        PlanNode::Select(select) => select.execute(db, ctx),
        PlanNode::Delete(delete) => delete.execute(db, ctx),
        PlanNode::Update(update) => update.execute(db, ctx),
    }
}