Add beginnings of an inspector backend for Sky

sky/framework/inspector/dom-agent.sky

Index: sky/framework/inspector/dom-agent.sky
diff --git a/sky/framework/inspector/dom-agent.sky b/sky/framework/inspector/dom-agent.sky
new file mode 100644
index 0000000000000000000000000000000000000000..6e6048fda614c2a62a912f3ff7e9ac33bf03f026
--- /dev/null
+++ b/sky/framework/inspector/dom-agent.sky
@@ -0,0 +1,169 @@
+<script>
+function DOMAgent(delegate) {
+  this.enabled = false;
+  this.delegate_ = delegate;
+  this.nextNodeId_ = 1;
+  this.nodeToId_ = new Map();
+  this.idToNode_ = new Map();
+}
+
+DOMAgent.prototype.getIdForNode_ = function(node) {
+  if (this.nodeToId_.has(node))
+    return this.nodeToId_.get(node);
+  var id = this.nextNodeId_++;
+  this.nodeToId_.set(node, id);
+  this.idToNode_.set(id, node);
+  return id;
+};
+
+DOMAgent.prototype.serializeChildren_ = function(node) {
+  var children = [];
+  for (var child = node.firstChild; child; child = child.nextSibling) {
+    var record = this.serializeNode_(child);
+    if (record)
+      children.push(record);
+  }
+  return children;
+};
+
+DOMAgent.prototype.serializeAttributes_ = function(element) {
+  var attributes = [];
+  var attrs = element.attributes;
+  for (var i = 0; i < attrs.length; ++i) {
+    var attr = attrs[i];
+    attributes.push(attr.name);
+    attributes.push(attr.value);
+  }
+  return attributes;
+};
+
+DOMAgent.prototype.serializeNode_ = function(node) {
+  var id = this.getIdForNode_(node);
+
+  var record = {
+    nodeId: id,
+  };
+
+  var isContainer = false;
+
+  if (node instanceof Element) {
+    isContainer = true;
+    record.nodeType = 1;
+    record.nodeName = node.tagName;
+    record.localName = node.tagName;
+    record.nodeValue = "";
+    record.attributes = this.serializeAttributes_(node);
+  } else if (node instanceof Text) {
+    record.nodeType = 3;
+    record.nodeName = "#text";
+    var nodeValue = node.data;
+    if (!nodeValue.trim())
+      return null;
+    record.nodeValue = nodeValue;
+  } else if (node instanceof Comment) {
+    record.nodeType = 8;
+    record.nodeName = "#comment";
+    record.nodeValue = node.data;
+  } else if (node instanceof Document) {
+    isContainer = true;
+    record.nodeType = 9;
+    record.nodeName = "#document";
+    record.localName = "";
+    record.nodeValue = "";
+    record.documentURL = node.URL;
+    record.baseURL = node.baseURI;
+  } else if (node instanceof DocumentFragment) {
+    isContainer = true;
+    record.nodeType = 11;
+    record.nodeName = "#document-fragment";
+    record.localName = "";
+    record.nodeValue = "";
+  } else {
+    console.log("Unknown node type");
+    return null;
+  }
+
+  if (isContainer) {
+    var children = this.serializeChildren_(node);
+    if (children.length) {
+      record.childNodeCount = children.length;
+      record.children = children;
+    }
+  }
+
+  return record;
+};
+
+DOMAgent.prototype.enable = function() {
+  this.enabled = true;
+  this.observer_ = new MutationObserver(this.mutationCallback_.bind(this));
+  this.observer_.observe(document, {
+    childList: true,
+    attributes: true,
+    characterData: true,
+    subtree : true,
+  });
+};
+
+DOMAgent.prototype.getDocument = function() {
+  return {
+    root: this.serializeNode_(document),
+  };
+};
+
+DOMAgent.prototype.hideHighlight = function() {
+};
+
+DOMAgent.prototype.highlightNode = function() {
+};
+
+DOMAgent.prototype.mutationCallback_ = function(mutationRecords) {
+  for (var i = 0; i < mutationRecords.length; ++i) {
+    var record = mutationRecords[i];
+    var type = record.type;
+    var target = record.target;
+    var nodeId = this.getIdForNode_(target);
+    if (type == "attributes") {
+      var attributeName = record.attributeName;
+      if (target.hasAttribute(attributeName)) {
+        this.delegate_.sendMessage("DOM.attributeModified", {
+          nodeId: nodeId,
+          name: attributeName,
+          value: target.getAttribute(attributeName),
+        });
+      } else {
+        this.delegate_.sendMessage("DOM.attributeRemoved", {
+          nodeId: nodeId,
+          name: attributeName,
+        });
+      }
+    } else if (type == "characterData") {
+      this.delegate_.sendMessage("DOM.characterDataModified", {
+        nodeId: nodeId,
+        characterData: target.data,
+      });
+    } else if (type == "childList") {
+      // FIXME: If this subtree isn't expanded, we only need to send across the
+      // {"method":"DOM.childNodeCountUpdated","params":"nodeId":648,"childNodeCount":2}
+
+      Array.prototype.forEach.call(record.removedNodes, function(node) {
+        this.delegate_.sendMessage("DOM.childNodeRemoved", {
+          parentNodeId: nodeId,
+          nodeId: this.getIdForNode_(node),
+        });
+      }.bind(this));
+
+      Array.prototype.forEach.call(record.addedNodes, function(node) {
+        var previousNodeId = node.previousSibling ? this.getIdForNode_(node.previousSibling) : 0;
+        this.delegate_.sendMessage("DOM.childNodeInserted", {
+          parentNodeId: nodeId,
+          previousNodeId: previousNodeId,
+          node: this.serializeNode_(node),
+        });
+      }.bind(this));
+    }
+  }
+};
+
+this.exports = DOMAgent;
+</script>