1 files changed, 31 insertions, 0 deletions
diff --git a/llparse-builder/src/reachability.ts b/llparse-builder/src/reachability.ts
new file mode 100644
index 0000000..88bcd65
--- /dev/null
+++ b/llparse-builder/src/reachability.ts
@@ -0,0 +1,31 @@
+import { Node } from './node';
+
+/**
+ * This class finds all reachable nodes
+ */
+export class Reachability {
+  /**
+   * Build and return list of reachable nodes.
+   */
+  public build(root: Node): ReadonlyArray<Node> {
+    const res = new Set();
+    const queue = [ root ];
+    while (queue.length !== 0) {
+      const node = queue.pop()!;
+      if (res.has(node)) {
+        continue;
+      }
+      res.add(node);
+
+      for (const edge of node) {
+        queue.push(edge.node);
+      }
+
+      const otherwise = node.getOtherwiseEdge();
+      if (otherwise !== undefined) {
+        queue.push(otherwise.node);
+      }
+    }
+    return Array.from(res) as ReadonlyArray<Node>;
+  }
+}