[react-native] enable react devtools from JavascriptCore

Libraries/Devtools/setupDevtools.js

@@ -0,0 +1,105 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule setupDevtools
+ * @flow
+ */
+'use strict';
+
+function setupDevtools() {
+  var messageListeners = [];
+  var closeListeners = [];
+  var ws = new window.WebSocket('ws://localhost:8081/devtools');
+  // this is accessed by the eval'd backend code
+  var FOR_BACKEND = { // eslint-disable-line no-unused-vars
+    resolveRNStyle: require('flattenStyle'),
+    wall: {
+      listen(fn) {
+        messageListeners.push(fn);
+      },
+      onClose(fn) {
+        closeListeners.push(fn);
+      },
+      send(data) {
+        ws.send(JSON.stringify(data));
+      },
+    },
+  };
+  ws.onclose = () => {
+    console.warn('devtools socket closed');
+    closeListeners.forEach(fn => fn());
+  };
+  ws.onerror = error => {
+    console.warn('devtools socket errored', error);
+    closeListeners.forEach(fn => fn());
+  };
+  ws.onopen = function () {
+    tryToConnect();
+  };
+
+  function tryToConnect() {
+    ws.send('attach:agent');
+    var _interval = setInterval(() => ws.send('attach:agent'), 500);
+    ws.onmessage = evt => {
+      if (evt.data.indexOf('eval:') === 0) {
+        clearInterval(_interval);
+        initialize(evt.data.slice('eval:'.length));
+      }
+    };
+  }
+
+  function initialize(text) {
+    try {
+      // FOR_BACKEND is used by the eval'd code
+      eval(text); // eslint-disable-line no-eval
+    } catch (e) {
+      console.error('Failed to eval' + e.message);
+      return;
+    }
+    window.__REACT_DEVTOOLS_GLOBAL_HOOK__.inject({
+      CurrentOwner: require('ReactCurrentOwner'),
+      InstanceHandles: require('ReactInstanceHandles'),
+      Mount: require('ReactNativeMount'),
+      Reconciler: require('ReactReconciler'),
+      TextComponent: require('ReactNativeTextComponent'),
+    });
+    ws.onmessage = handleMessage;
+  }
+
+  function handleMessage(evt) {
+    var data;
+    try {
+      data = JSON.parse(evt.data);
+    } catch (e) {
+      return console.error('failed to parse json: ' + evt.data);
+    }
+    // the devtools closed
+    if (data.$close || data.$error) {
+      closeListeners.forEach(fn => fn());
+      window.__REACT_DEVTOOLS_GLOBAL_HOOK__.emit('shutdown');
+      tryToConnect();
+      return;
+    }
+    if (data.$open) {
+      return; // ignore
+    }
+    messageListeners.forEach(fn => {
+      try {
+        fn(data);
+      } catch (e) {
+        // jsc doesn't play so well with tracebacks that go into eval'd code,
+        // so the stack trace here will stop at the `eval()` call. Getting the
+        // message that caused the error is the best we can do for now.
+        console.log(data);
+        throw e;
+      }
+    });
+  }
+}
+
+module.exports = setupDevtools;