joining game

src/data/keyword.rs

@@ -54,6 +54,12 @@ impl Keyword {
     pub(crate) fn is_reserved(&self) -> bool {
         self.0.is_empty() || self.0.starts_with(['_', ':', '<', '.', '*', '?', '!'])
     }
+    pub(crate) fn is_user_binding(&self) -> bool {
+        self.0.starts_with('?')
+    }
+    pub(crate) fn is_anon_binding(&self) -> bool {
+        self.0.starts_with('_')
+    }
     pub(crate) fn to_string_no_prefix(&self) -> String {
         format!("{}", self.0)
     }

src/data/tuple.rs

@@ -2,6 +2,7 @@ use std::cmp::{min, Ordering};
 
 use rmp_serde::Serializer;
 use serde::Serialize;
+use anyhow::Result;
 
 use crate::data::value::DataValue;
 
@@ -11,7 +12,9 @@ pub enum TupleError {
     BadData(String, Vec<u8>),
 }
 
-pub(crate) struct Tuple(Vec<DataValue>);
+pub(crate) struct Tuple(pub(crate) Vec<DataValue>);
+
+pub(crate) type TupleIter<'a> = Box<dyn Iterator<Item = Result<Tuple>> + 'a>;
 
 impl Tuple {
     pub(crate) fn arity(&self) -> usize {

src/transact/query.rs

@@ -1,6 +1,13 @@
+use std::collections::BTreeMap;
+
+use anyhow::Result;
+use itertools::Itertools;
+
 use crate::data::attr::Attribute;
 use crate::data::keyword::Keyword;
+use crate::data::tuple::{Tuple, TupleIter};
 use crate::data::value::DataValue;
+use crate::runtime::transact::SessionTx;
 use crate::transact::pull::PullSpec;
 use crate::Validity;
 
@@ -13,33 +20,197 @@ pub(crate) struct QuerySpec {
     offset: Option<usize>,
 }
 
+pub(crate) struct InlineFixedRelation {
+    bindings: Vec<Keyword>,
+    data: Vec<Vec<DataValue>>,
+}
+
+impl InlineFixedRelation {
+    pub(crate) fn join<'a>(
+        &'a self,
+        left_iter: TupleIter<'a>,
+        (left_join_indices, right_join_indices): (Vec<usize>, Vec<usize>),
+    ) -> TupleIter<'a> {
+        if self.data.is_empty() {
+            Box::new([].into_iter())
+        } else if self.data.len() == 1 {
+            let data = self.data[0].clone();
+            let right_join_values = right_join_indices
+                .into_iter()
+                .map(|v| data[v].clone())
+                .collect_vec();
+            Box::new(left_iter.filter_map_ok(move |tuple| {
+                let left_join_values = left_join_indices.iter().map(|v| &tuple.0[*v]).collect_vec();
+                if left_join_values.into_iter().eq(right_join_values.iter()) {
+                    let mut left_data = tuple.0;
+                    left_data.extend_from_slice(&data);
+                    Some(Tuple(left_data))
+                } else {
+                    None
+                }
+            }))
+        } else {
+            let mut right_mapping = BTreeMap::new();
+            for data in &self.data {
+                let right_join_values = right_join_indices.iter().map(|v| &data[*v]).collect_vec();
+                match right_mapping.get_mut(&right_join_values) {
+                    None => {
+                        right_mapping.insert(right_join_values, vec![data]);
+                    }
+                    Some(coll) => {
+                        coll.push(data);
+                    }
+                }
+            }
+            Box::new(
+                left_iter
+                    .filter_map_ok(move |tuple| {
+                        let left_join_values =
+                            left_join_indices.iter().map(|v| &tuple.0[*v]).collect_vec();
+                        right_mapping.get(&left_join_values).map(|v| {
+                            v.iter()
+                                .map(|right_values| {
+                                    let mut left_data = tuple.0.clone();
+                                    left_data.extend_from_slice(right_values);
+                                    Tuple(left_data)
+                                })
+                                .collect_vec()
+                        })
+                    })
+                    .flatten_ok(),
+            )
+        }
+    }
+}
+
+pub(crate) struct TripleRelation {
+    attr: Attribute,
+    vld: Validity,
+    bindings: [Keyword; 2],
+}
+
+pub(crate) struct ProjectedRelation {
+    relation: Relation,
+    eliminate: Vec<Keyword>,
+}
+
 pub(crate) enum Relation {
-    Attr(Attribute, Validity),
-    FullAttr(Attribute),
-    Derived(DerivedRelation),
+    Fixed(InlineFixedRelation),
+    Triple(TripleRelation),
+    Derived(StoredDerivedRelation),
+    Join(Box<InnerJoin>),
+    Project(Box<ProjectedRelation>),
 }
 
-pub(crate) struct DerivedRelation {
+pub(crate) struct StoredDerivedRelation {
     name: Keyword,
     arity: usize,
+    bindings: Vec<Keyword>,
 }
 
-impl Relation {
-    pub(crate) fn arity(&self) -> usize {
-        match self {
-            Relation::Attr(_, _) => 3,
-            Relation::FullAttr(_) => 5,
-            Relation::Derived(r) => r.arity,
+pub(crate) struct Joiner {
+    // invariant: these are of the same lengths
+    left_keys: Vec<Keyword>,
+    right_keys: Vec<Keyword>,
+}
+
+impl Joiner {
+    pub(crate) fn len(&self) -> usize {
+        self.left_keys.len()
+    }
+    pub(crate) fn swap(self) -> Self {
+        Self {
+            left_keys: self.right_keys,
+            right_keys: self.left_keys,
+        }
+    }
+    pub(crate) fn join_indices(
+        &self,
+        left_bindings: &[Keyword],
+        right_bindings: &[Keyword],
+    ) -> (Vec<usize>, Vec<usize>) {
+        let left_binding_map = left_bindings
+            .iter()
+            .enumerate()
+            .map(|(k, v)| (v, k))
+            .collect::<BTreeMap<_, _>>();
+        let right_binding_map = right_bindings
+            .iter()
+            .enumerate()
+            .map(|(k, v)| (v, k))
+            .collect::<BTreeMap<_, _>>();
+        let mut ret_l = Vec::with_capacity(self.left_keys.len());
+        let mut ret_r = Vec::with_capacity(self.left_keys.len());
+        for (l, r) in self.left_keys.iter().zip(self.right_keys.iter()) {
+            let l_pos = left_binding_map
+                .get(l)
+                .expect("program logic error: join key is wrong");
+            let r_pos = right_binding_map
+                .get(r)
+                .expect("program logic error: join key is wrong");
+            ret_l.push(*l_pos);
+            ret_r.push(*r_pos)
         }
+        (ret_l, ret_r)
     }
 }
 
-pub(crate) enum RelationSlot {
-    Var(Keyword),
-    Const(DataValue),
+pub(crate) struct InnerJoin {
+    left: Relation,
+    right: Relation,
+    joiner: Joiner,
 }
 
-pub(crate) struct BoundRelation {
-    relation: Relation,
-    slots: Vec<RelationSlot>,
+impl Relation {
+    pub(crate) fn bindings(&self) -> &[Keyword] {
+        match self {
+            Relation::Fixed(f) => &f.bindings,
+            Relation::Triple(t) => &t.bindings,
+            Relation::Derived(d) => todo!(),
+            Relation::Join(j) => todo!(),
+            Relation::Project(p) => todo!(),
+        }
+    }
+    pub(crate) fn iter(&self, tx: &mut SessionTx) -> TupleIter {
+        match self {
+            Relation::Fixed(f) => Box::new(f.data.iter().map(|t| Ok(Tuple(t.clone())))),
+            Relation::Triple(r) => Box::new(
+                tx.triple_a_before_scan(r.attr.id, r.vld)
+                    .map_ok(|(_, e_id, y)| Tuple(vec![DataValue::EnId(e_id), y])),
+            ),
+            Relation::Derived(r) => {
+                todo!()
+            }
+            Relation::Join(j) => j.iter(tx),
+            Relation::Project(_) => {
+                todo!()
+            }
+        }
+    }
+}
+
+impl InnerJoin {
+    pub(crate) fn iter(&self, tx: &mut SessionTx) -> TupleIter {
+        let left_iter = self.left.iter(tx);
+        match &self.right {
+            Relation::Fixed(f) => {
+                let join_indices = self
+                    .joiner
+                    .join_indices(self.left.bindings(), self.right.bindings());
+                f.join(left_iter, join_indices)
+            }
+            Relation::Triple(_) => {
+                todo!()
+            }
+            Relation::Derived(_) => {
+                todo!()
+            }
+            Relation::Join(_) => {
+                todo!()
+            }
+            Relation::Project(_) => {
+                todo!()
+            }
+        }
+    }
 }