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use std::collections::{BTreeMap, HashMap};
use crate::{join_iters, JoinType, Row};
use {
crate::{
DBBase, IndexFilter, MemoryDatabase, MemoryDatabaseError, Plane, Result, Schema, Value,
},
async_trait::async_trait,
};
#[async_trait(?Send)]
impl DBBase for MemoryDatabase {
async fn fetch_schema(&self, table_name: &str) -> Result<Option<Schema>> {
Ok(self.tables.get(&table_name.to_string()).cloned())
}
async fn scan_schemas(&self) -> Result<Vec<Schema>> {
Ok(self.tables.values().cloned().collect())
}
async fn scan_data(&self, table_name: &str) -> Result<Plane> {
self.data
.get(&table_name.to_string())
.cloned()
.ok_or(MemoryDatabaseError::TableNotFound.into())
.map(|rows| rows.into_iter().collect())
}
async fn scan_data_indexed(
&self,
table_name: &str,
index_filter: IndexFilter,
) -> Result<Plane> {
let index_results = self.scan_index(table_name, index_filter).await?;
let default = HashMap::new();
let rows = self.data.get(&table_name.to_string()).unwrap_or(&default);
Ok(index_results
.into_iter()
.filter_map(|pk| rows.get(&pk).map(|row| (pk.clone(), row.clone())))
.collect::<Vec<(Value, Row)>>())
}
async fn scan_index(&self, table_name: &str, index_filter: IndexFilter) -> Result<Vec<Value>> {
use IndexFilter::*;
match index_filter.clone() {
LessThan(index_name, ..) | MoreThan(index_name, ..) => {
let default = BTreeMap::new();
let index = self
.indexes
.get(&table_name.to_string())
.and_then(|indexes| indexes.get(&index_name))
.unwrap_or(&default);
let index_results = match index_filter {
LessThan(_, max) => index.range(..max),
MoreThan(_, min) => index.range(min..),
_ => unreachable!(),
}
.map(|(_, pk)| pk.clone())
.collect();
Ok(index_results)
}
Inner(left, right) => {
let (left, right) = (
self.scan_index(table_name, *left),
self.scan_index(table_name, *right),
);
let (left, right) = (left.await?, right.await?);
Ok(join_iters(JoinType::Inner, left, right))
}
Outer(left, right) => {
let (left, right) = (
self.scan_index(table_name, *left),
self.scan_index(table_name, *right),
);
let (left, right) = (left.await?, right.await?);
Ok(join_iters(JoinType::Outer, left, right))
}
}
}
}