2 files changed, 44 insertions, 32 deletions

diff --git a/graph/src/main/java/com/seaofnodes/graph/GraphCapture.java b/graph/src/main/java/com/seaofnodes/graph/GraphCapture.java
index 0e2f538d..6fc40b5f 100644
--- a/graph/src/main/java/com/seaofnodes/graph/GraphCapture.java
+++ b/graph/src/main/java/com/seaofnodes/graph/GraphCapture.java
@@ -5,23 +5,43 @@ import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.UUID;
 
-/** Shared capture, event nesting and neighborhoods. Chapter hooks only read the IR. */
+/** Shared compilation lifecycle, capture, event nesting and neighborhoods. */
 public abstract class GraphCapture<N> extends GraphObserver<N> {
 
     private final GraphAdapter<N> _graph;
-    private final String _comp = UUID.randomUUID().toString();
+    private String _comp;
+    private GraphSocket _server;
     private final ArrayList<Peep> _peeps = new ArrayList<>();
     private long _next, _step;
-    private boolean _off;
+    private boolean _off = true;
 
     protected GraphCapture(GraphAdapter<N> graph) { _graph = graph; }
 
+    // Create the chapter's compiler, attach this observer, and run its phases.
+    protected abstract void compile(String src);
+    // The remaining hooks only inspect context, except detach which clears it.
     protected abstract String phase();
     protected abstract int pos();
     protected abstract void roots(ArrayList<N> roots);
     protected abstract void detach();
 
-    protected abstract void frame(GraphSnapshot snap, int pos, GraphEvent evt) throws IOException;
+    final void run(String src, GraphSocket server) {
+        _comp = UUID.randomUUID().toString();
+        _next = _step = 0;
+        _server = server;
+        _off = false;
+        try {
+            compile(src);
+        } finally {
+            _off = true;
+            try {
+                detach();
+            } finally {
+                _peeps.clear();
+                _server = null;
+            }
+        }
+    }
 
     private class Peep {
         final N node;
@@ -114,11 +134,10 @@ public abstract class GraphCapture<N> extends GraphObserver<N> {
         // Assign steps on emission; attempts without progress do not consume frames.
         snap = new GraphSnapshot(snap.ver(), _comp, _step++, snap.roots(), snap.nodes());
         try {
-            frame(snap, pos, evt);
+            _server.put(GraphJson.frame(snap, pos, evt));
         } catch( IOException e ) {
             // A disconnected display must not interrupt optimization.
             _off = true;
-            detach();
             System.err.println("Graph viewer disconnected: " + e.getMessage());
         }
     }
diff --git a/graph/src/main/java/com/seaofnodes/graph/GraphViewer.java b/graph/src/main/java/com/seaofnodes/graph/GraphViewer.java
index dcb2e337..e70a12cf 100644
--- a/graph/src/main/java/com/seaofnodes/graph/GraphViewer.java
+++ b/graph/src/main/java/com/seaofnodes/graph/GraphViewer.java
@@ -5,16 +5,9 @@ import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
-/** Shared launcher and source/compile loop. Subclasses supply their compiler. */
-public abstract class GraphViewer implements AutoCloseable {
-    private final GraphSocket _server;
-
-    protected GraphViewer() throws IOException { _server = new GraphSocket(viewerURI(), 12345); }
-    protected abstract void compile(String src);
-
-    protected final void frame(GraphSnapshot snap, int pos, GraphEvent evt) throws IOException {
-        _server.put(GraphJson.frame(snap, pos, evt));
-    }
+/** Shared launcher and source/compile loop. Chapter observers supply their compiler. */
+public final class GraphViewer {
+    private GraphViewer() {}
 
     private static URI viewerURI() throws IOException {
         String url = System.getProperty("simple.graph.url");
@@ -27,23 +20,23 @@ public abstract class GraphViewer implements AutoCloseable {
                               + "or set -Dsimple.graph.url=<viewer URL>");
     }
 
-    public final void run() throws IOException {
-        _server.put("!");
-        while( true ) {
-            String src = _server.get();
-            if( src == null || src.equals("null") ) return;
-            if( src.equals("+") ) continue; // Frames are currently sent eagerly.
-            System.out.println(src);
-            try {
-                compile(src);
-            } catch( RuntimeException e ) {
-                System.err.println(e);
-                _server.put(GraphJson.error(e.toString()));
-            } finally {
-                _server.put("#");
+    public static void run(GraphCapture<?> obs) throws IOException {
+        try( var server = new GraphSocket(viewerURI(), 12345) ) {
+            server.put("!");
+            while( true ) {
+                String src = server.get();
+                if( src == null || src.equals("null") ) return;
+                if( src.equals("+") ) continue; // Frames are currently sent eagerly.
+                System.out.println(src);
+                try {
+                    obs.run(src, server);
+                } catch( RuntimeException e ) {
+                    System.err.println(e);
+                    server.put(GraphJson.error(e.toString()));
+                } finally {
+                    server.put("#");
+                }
             }
         }
     }
-
-    @Override public final void close() throws IOException { _server.close(); }
 }