1 files changed, 72 insertions, 0 deletions
diff --git a/vendor/chalk-engine/src/tables.rs b/vendor/chalk-engine/src/tables.rs
new file mode 100644
index 000000000..76508eaa8
--- /dev/null
+++ b/vendor/chalk-engine/src/tables.rs
@@ -0,0 +1,72 @@
+use crate::table::Table;
+use crate::TableIndex;
+use rustc_hash::FxHashMap;
+use std::ops::{Index, IndexMut};
+
+use chalk_ir::interner::Interner;
+use chalk_ir::{Goal, InEnvironment, UCanonical};
+
+/// See `Forest`.
+#[derive(Debug)]
+pub(crate) struct Tables<I: Interner> {
+    /// Maps from a canonical goal to the index of its table.
+    table_indices: FxHashMap<UCanonical<InEnvironment<Goal<I>>>, TableIndex>,
+
+    /// Table: as described above, stores the key information for each
+    /// tree in the forest.
+    tables: Vec<Table<I>>,
+}
+
+impl<I: Interner> Tables<I> {
+    pub(crate) fn new() -> Tables<I> {
+        Tables {
+            table_indices: FxHashMap::default(),
+            tables: Vec::default(),
+        }
+    }
+
+    /// The index that will be given to the next table to be inserted.
+    pub(super) fn next_index(&self) -> TableIndex {
+        TableIndex {
+            value: self.tables.len(),
+        }
+    }
+
+    pub(super) fn insert(&mut self, table: Table<I>) -> TableIndex {
+        let goal = table.table_goal.clone();
+        let index = self.next_index();
+        self.tables.push(table);
+        self.table_indices.insert(goal, index);
+        index
+    }
+
+    pub(super) fn index_of(
+        &self,
+        literal: &UCanonical<InEnvironment<Goal<I>>>,
+    ) -> Option<TableIndex> {
+        self.table_indices.get(literal).cloned()
+    }
+}
+
+impl<I: Interner> Index<TableIndex> for Tables<I> {
+    type Output = Table<I>;
+
+    fn index(&self, index: TableIndex) -> &Table<I> {
+        &self.tables[index.value]
+    }
+}
+
+impl<I: Interner> IndexMut<TableIndex> for Tables<I> {
+    fn index_mut(&mut self, index: TableIndex) -> &mut Table<I> {
+        &mut self.tables[index.value]
+    }
+}
+
+impl<'a, I: Interner> IntoIterator for &'a mut Tables<I> {
+    type IntoIter = <&'a mut Vec<Table<I>> as IntoIterator>::IntoIter;
+    type Item = <&'a mut Vec<Table<I>> as IntoIterator>::Item;
+
+    fn into_iter(self) -> Self::IntoIter {
+        IntoIterator::into_iter(&mut self.tables)
+    }
+}