DevTools: [Elements] Implement "Copy CSS Path" context menu item for elements

Source/devtools/front_end/DOMAgent.js

Index: Source/devtools/front_end/DOMAgent.js
diff --git a/Source/devtools/front_end/DOMAgent.js b/Source/devtools/front_end/DOMAgent.js
index 320e88c01c7322119317b9cb53ee4c0e334ee025..9743bf035eceaf949b652b8a19e965befb17106b 100644
--- a/Source/devtools/front_end/DOMAgent.js
+++ b/Source/devtools/front_end/DOMAgent.js
@@ -125,13 +125,13 @@ WebInspector.DOMNode.ShadowRootTypes = {
  * @param {string} value
  * @param {boolean} optimized
  */
-WebInspector.DOMNode.XPathStep = function(value, optimized)
+WebInspector.DOMNode.PathStep = function(value, optimized)
 {
     this.value = value;
     this.optimized = optimized;
 }
 
-WebInspector.DOMNode.XPathStep.prototype = {
+WebInspector.DOMNode.PathStep.prototype = {
     toString: function()
     {
         return this.value;
@@ -430,6 +430,14 @@ WebInspector.DOMNode.prototype = {
     /**
      * @param {boolean} optimized
      */
+    copyCSSPath: function(optimized)
+    {
+        InspectorFrontendHost.copyText(this.cssPath(optimized));
+    },
+
+    /**
+     * @param {boolean} optimized
+     */
     copyXPath: function(optimized)
     {
         InspectorFrontendHost.copyText(this.xPath(optimized));
@@ -685,6 +693,130 @@ WebInspector.DOMNode.prototype = {
      * @param {boolean} optimized
      * @return {string}
      */
+    cssPath: function(optimized)
+    {
+        if (this._nodeType !== Node.ELEMENT_NODE)
+            return "";
+
+        var steps = [];
+        var contextNode = this;
+        while (contextNode) {
+            var step = contextNode._cssPathValue(optimized);
+            if (!step)
+                break; // Error - bail out early.
+            steps.push(step);
+            if (step.optimized)
+                break;
+            contextNode = contextNode.parentNode;
+        }
+
+        steps.reverse();
+        return steps.join(" > ");
+    },
+
+    /**
+     * @param {boolean} optimized
+     * @return {WebInspector.DOMNode.PathStep}
+     */
+    _cssPathValue: function(optimized)
+    {
+        if (this._nodeType !== Node.ELEMENT_NODE)
+            return null;
+        if (optimized) {
+            var id = this.getAttribute("id");
+            if (id)
+                return new WebInspector.DOMNode.PathStep(idSelector(id), true);
+            var nodeNameLower = this._nodeName.toLowerCase();
+            if (nodeNameLower === "body" || nodeNameLower === "head" || nodeNameLower === "html")
+                return new WebInspector.DOMNode.PathStep(this.nodeNameInCorrectCase(), true);
+        }
+        var nodeName = this.nodeNameInCorrectCase();
+        var parent = this.parentNode;
+        if (!parent || parent._nodeType === Node.DOCUMENT_NODE)
+            return new WebInspector.DOMNode.PathStep(nodeName, true);
+
+        /**
+         * @param {WebInspector.DOMNode} node
+         * @return {Object.<string, boolean>}
+         */
+        function elementClassNames(node)
+        {
+            var classAttribute = node.getAttribute("class");
+            if (!classAttribute)
+                return {};
+
+            return classAttribute.split(/\s+/g).filter(Boolean).keySet();
+        }
+
+        /**
+         * @param {string} id
+         * @return {string}
+         */
+        function idSelector(id)
+        {
+            if (/^[A-Za-z0-9_-]+$/.test(id))

[aandrey, 2013/11/19 11:15:09]

FYI.

document.querySelectorAll("#---")
===> SyntaxError: Failed to execute query: '#---' is not a valid selector.

+                return "#" + id;
+
+            var quoteChar = "\"";
+            var hasQuotes = /"/.test(id);

[aandrey, 2013/11/19 11:11:18]

indexOf

+            var hasApostrophes = /'/.test(id);

[aandrey, 2013/11/19 11:11:18]

indexOf

+            if (hasQuotes) {
+                if (!hasApostrophes)
+                    quoteChar = "'";
+                else
+                    id = id.replace(/"/g, "\\\\\"");

[aandrey, 2013/11/19 11:11:18]

this code path is not tested, and quite hard to review

+            }
+            return "[id=" + quoteChar + id + quoteChar + "]";
+        }
+
+        var uniqueClassNames = elementClassNames(this);
+        var uniqueClassNamesLeft = 0;
+        for (var name in uniqueClassNames)
+            ++uniqueClassNamesLeft;
+        var needsClassNames = false;
+        var needsNthChild = false;
+        var ownIndex = -1;
+        var siblings = parent.children();
+        for (var i = 0; (ownIndex === -1 || !needsNthChild) && i < siblings.length; ++i) {
+            var sibling = siblings[i];
+            if (sibling === this) {
+                ownIndex = i;
+                continue;
+            }
+            if (sibling.nodeNameInCorrectCase() !== nodeName)
+                continue;
+            if (!uniqueClassNamesLeft) {
+                needsNthChild = true;
+                continue;
+            }
+
+            needsClassNames = true;
+            var siblingClassNames = elementClassNames(sibling);
+            for (var siblingClass in siblingClassNames) {
+                if (!uniqueClassNames.hasOwnProperty(siblingClass))
+                    continue;
+                delete uniqueClassNames[siblingClass];
+                if (!--uniqueClassNamesLeft) {
+                    needsNthChild = true;
+                    break;
+                }
+            }
+        }
+
+        var result = nodeName;
+        if (needsClassNames && uniqueClassNamesLeft) {
+            for (var className in uniqueClassNames)
+                result += "." + className;

[aandrey, 2013/11/19 11:11:18]

And what about className containing odd characters, like "#"?
I thought we were going the full way :)

+        }
+        if (needsNthChild)
+            result += ":nth-child(" + (ownIndex + 1) + ")";
+        return new WebInspector.DOMNode.PathStep(result, false);
+    },
+
+    /**
+     * @param {boolean} optimized
+     * @return {string}
+     */
     xPath: function(optimized)
     {
         if (this._nodeType === Node.DOCUMENT_NODE)
@@ -708,7 +840,7 @@ WebInspector.DOMNode.prototype = {
 
     /**
      * @param {boolean} optimized
-     * @return {WebInspector.DOMNode.XPathStep}
+     * @return {WebInspector.DOMNode.PathStep}
      */
     _xPathValue: function(optimized)
     {
@@ -720,7 +852,7 @@ WebInspector.DOMNode.prototype = {
         switch (this._nodeType) {
         case Node.ELEMENT_NODE:
             if (optimized && this.getAttribute("id"))
-                return new WebInspector.DOMNode.XPathStep("//*[@id=\"" + this.getAttribute("id") + "\"]", true);
+                return new WebInspector.DOMNode.PathStep("//*[@id=\"" + this.getAttribute("id") + "\"]", true);
             ownValue = this._localName;
             break;
         case Node.ATTRIBUTE_NODE:
@@ -747,7 +879,7 @@ WebInspector.DOMNode.prototype = {
         if (ownIndex > 0)
             ownValue += "[" + ownIndex + "]";
 
-        return new WebInspector.DOMNode.XPathStep(ownValue, this._nodeType === Node.DOCUMENT_NODE);
+        return new WebInspector.DOMNode.PathStep(ownValue, this._nodeType === Node.DOCUMENT_NODE);
     },
 
     /**