Fix isolated nodes (#5)

* Don't emit graphs when we already have them * Add eqsolve example and fix loner nodes
egraphs-good · Aug 10, 2023 · e406ffc · e406ffc
1 parent e2f8bb0
commit e406ffc
Show file tree

Hide file tree

Showing 6 changed files with 6,368 additions and 9 deletions.
diff --git a/src/algorithms.rs b/src/algorithms.rs
@@ -31,11 +31,15 @@ impl EGraph {
         // 3. Create mapping from all parents which are updated to the children which are inlined
         let mut parents_to_children = std::collections::HashMap::new();
         for (_, node_id) in &leaves {
-            for parent in node_to_parents.get(node_id).unwrap() {
-                parents_to_children
-                    .entry(parent.clone())
-                    .or_insert_with(Vec::new)
-                    .push(node_id.clone());
+            let parents = node_to_parents.get(node_id);
+            // There will be no parents for isolated nodes with no parents or children
+            if let Some(parents) = parents {
+                for parent in parents {
+                    parents_to_children
+                        .entry(parent.clone())
+                        .or_insert_with(Vec::new)
+                        .push(node_id.clone());
+                }
             }
         }
         // 4. Inline leaf nodes into their parents
@@ -67,6 +71,10 @@ impl EGraph {
         }
         // 5. Remove leaf nodes from egraph, class data, and root eclasses
         for (eclass, node_id) in &leaves {
+            // If this node has no parents, don't remove it, since it wasn't inlined
+            if node_to_parents.get(node_id).is_none() {
+                continue;
+            }
             self.nodes.remove(node_id);
             self.class_data.remove(eclass);
             self.root_eclasses.retain(|root| root != eclass);

diff --git a/tests-viz/README.md b/tests-viz/README.md
@@ -6,6 +6,7 @@ This is a list of all the tests in the `tests` directory. Each test is a JSON fi
 | Test | Image | Inlined Leaves Image |
 | ---- | ----- | -------------------- |
 | [`diff_power_simple`](../tests/diff_power_simple.json) | ![svg file](./diff_power_simple.svg) | ![inlined leaves svg file](./diff_power_simple-inlined.svg) |
+| [`eqsolve`](../tests/eqsolve.json) | ![svg file](./eqsolve.svg) | ![inlined leaves svg file](./eqsolve-inlined.svg) |
 | [`fibonacci-demand`](../tests/fibonacci-demand.json) | ![svg file](./fibonacci-demand.svg) | ![inlined leaves svg file](./fibonacci-demand-inlined.svg) |
 | [`fibonacci`](../tests/fibonacci.json) | ![svg file](./fibonacci.svg) | ![inlined leaves svg file](./fibonacci-inlined.svg) |
 | [`lambda_if`](../tests/lambda_if.json) | ![svg file](./lambda_if.svg) | ![inlined leaves svg file](./lambda_if-inlined.svg) |