Start on a graph viz animation of peeps

4 files changed, 156 insertions, 2 deletions

diff --git a/chapter18/src/main/java/com/seaofnodes/simple/GraphVisualizer.java b/chapter18/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
index de6d65a3..ec326a6f 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
@@ -29,7 +29,7 @@ public class GraphVisualizer {
         // nodes in the graph.
         Collection<Node> all = findAll(stop, scope);
         StringBuilder sb = new StringBuilder();
-        sb.append("digraph chapter11 {\n");
+        sb.append("digraph chapter18 {\n");
         sb.append("/*\n");
         sb.append(stop._src);
         sb.append("\n*/\n");
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java b/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java
new file mode 100644
index 00000000..da361afa
--- /dev/null
+++ b/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java
@@ -0,0 +1,50 @@
+package com.seaofnodes.simple;
+
+import java.nio.file.Paths;
+
+public class JSViewer {
+    public static void main( String[] args ) throws Exception {
+        // Launch server
+        try( SimpleWebSocket server = new SimpleWebSocket(Paths.get("docs/index.html").toUri(),12345) ) {
+            int N=0;
+            while( true ) {
+                String src = server.get();
+                if( src==null || src.equals("null") )
+                    break;
+                System.out.println(src);
+                // Client requests another frame
+                if( src.charAt(0)=='+' ) {
+                    if( N<2 ) {
+                        StringBuilder sb = new StringBuilder();
+                        sb.append("digraph jsviewer_1 {\n");
+                        sb.append("\tnode [shape=circle, style=filled];\n");
+                        sb.append("\tSRC [label=\"").append("next frame").append("\", shape=oval];\n");
+                        sb.append("}");
+                        server.put(sb.toString());
+                        System.out.println("Sent graph "+N);
+                        N++;
+                    } else {
+                        // no more frames, send nothing
+                    }
+                } else {
+
+                    StringBuilder sb = new StringBuilder();
+                    sb.append("digraph jsviewer_0 {\n");
+                    sb.append("\tnode [shape=circle, style=filled];\n");
+                    sb.append("\tSRC [label=\"").append(src).append("\", shape=oval];\n");
+                    sb.append("}");
+                    server.put(sb.toString());
+                    System.out.println("Sent graph "+N);
+                    N++;
+                }
+
+                //// Client reset, send new program
+                //server.put("!");
+            }
+            System.out.println("Client requested shutdown");
+            server.close();
+        }
+
+    }
+
+}
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
index 1cdf27fb..94575559 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
@@ -246,7 +246,7 @@ public class Parser {
      */
     private Node parseFor() {
         // {   var x=init,y=init,...;
-        //     while( pred ) {
+        //     while( test ) {
         //         body;
         //         next;
         //     }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java b/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java
new file mode 100644
index 00000000..86ae7c9b
--- /dev/null
+++ b/chapter18/src/main/java/com/seaofnodes/simple/SimpleWebSocket.java
@@ -0,0 +1,104 @@
+package com.seaofnodes.simple;
+
+import java.io.*;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+
+// Why-Oh-Why is this needed?
+
+// Pass in a URI and a port.
+// Opens the client; client has to open a websocket at the given port.
+// Connects, handshakes.
+// Thereafter you can call get/put to swap frames with client.
+
+class SimpleWebSocket extends ServerSocket {
+    final  InputStream _in;
+    final OutputStream _out;
+
+    SimpleWebSocket(URI uri, int port) throws IOException, NoSuchAlgorithmException {
+        super(port);
+        // Launch client
+        java.awt.Desktop.getDesktop().browse(uri);
+        // Look for client; get in/out streams
+        Socket sock = accept();
+        _in  = sock. getInputStream();
+        _out = sock.getOutputStream();
+
+
+        // Establish web socket with handshake; easier with a buffered reader
+        BufferedReader br = new BufferedReader(new InputStreamReader(_in));
+        String key = null;
+        while( br.ready() ) {
+            String line = br.readLine();
+            if( line.startsWith("Sec-WebSocket-Key: ") )
+                key = line.substring(19);
+        }
+        assert key!=null;
+        // Magic handshake
+        byte[] response = ("HTTP/1.1 101 Switching Protocols\r\n"
+                           + "Connection: Upgrade\r\n"
+                           + "Upgrade: websocket\r\n"
+                           + "Sec-WebSocket-Accept: "
+                           + Base64.getEncoder().encodeToString(MessageDigest.getInstance("SHA-1").digest((key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes( StandardCharsets.UTF_8 )))
+                           + "\r\n\r\n").getBytes( StandardCharsets.UTF_8 );
+        _out.write(response,0,response.length);
+    }
+
+    final byte[] _ins = new byte[1024];
+    final byte[] _str = new byte[1024];
+    final byte[] _key = new byte[4];
+    int _x, _len;
+    private int rawget() { assert _x<_len; return _ins[_x++]&0xFF; }
+
+    // Classic read from browser client.  Encoded, so decoded here
+    public String get() throws IOException {
+        _len = _in.read(_ins);  _x=0;
+        int op = rawget();
+        if( (op&0x80)!=0x80 ) // FIN bit not set?
+            throw Utils.TODO("Multi-part from client: "+op); // Multi-part message
+        op &= 0x7F;         // Strip FIN bit
+        switch( op&15) {
+        case 1: {
+            // Message length
+            int len = (rawget()&0xFF)-128;
+            if( len > 125 )
+                throw Utils.TODO(); // Multi-byte length
+            // Encoding key
+            _key[0] = (byte)rawget();
+            _key[1] = (byte)rawget();
+            _key[2] = (byte)rawget();
+            _key[3] = (byte)rawget();
+            // Decode bytes
+            for( int i=0; i<len; i++ )
+                _str[i] = (byte)(rawget() ^ _key[i & 3]);
+
+            return new String(_str,0,len);
+        }
+            // Client closes
+        case 8: return null;
+            // Not (yet) implemented: continuation frames, ping/pong
+        default:
+            throw Utils.TODO("Unexpected op from client: "+op); // Multi-part message
+        }
+    }
+
+    // Classic put to browser client.  No encoding.
+    public void put(String msg) throws IOException {
+        assert msg.length() < 125;
+        _out.write(129); // FIN
+        _out.write(msg.length());
+        for( int i=0; i<msg.length(); i++ )
+            _out.write(msg.charAt(i));
+    }
+
+    @Override public void close() throws IOException {
+        _out.write(0b10001000);
+        _out.flush();
+        super.close();
+    }
+}