Omit overlapping instances from matches

lib/inspector.js

@@ -131,7 +131,7 @@ class Inspector extends EventEmitter {
    * @fires Inspector#match
    */
   _analyze() {
-    var key, match, i, groups;
+    var key, match, i, groups, nodeArrays;
 
     var sortedKeys = Object.keys(this._map)
       .filter(key => this._map[key].length >= this._minInstances)
@@ -142,8 +142,11 @@ class Inspector extends EventEmitter {
         continue;
       }
 
+      nodeArrays = this._map[key].slice(0);
+      this._omitOverlappingInstances(nodeArrays);
+
       // groups will be of type Node[][][]
-      groups = [this._map[key].slice(0)];
+      groups = [nodeArrays];
       if (this._identifiers) {
         groups = this._groupByMatchingIdentifiers(groups);
       }
@@ -162,6 +165,36 @@ class Inspector extends EventEmitter {
     }
   }
 
+  /**
+   * Removes overlapping instances from a group of node arrays. That is,
+   * if one instance has nodes abcd, and another has bcde, then bcde will
+   * be removed from the array.
+   *
+   * @private
+   *
+   * @param {Node[][]} nodeArrays
+   */
+  _omitOverlappingInstances(nodeArrays) {
+    var set = new Set();
+
+    var hasOverlap = (nodes) => {
+      return nodes.some(node => set.has(node));
+    };
+
+    var addNodes = (nodes) => {
+      nodes.forEach(node => set.add(node));
+    };
+
+    for (var i = 0; i < nodeArrays.length; i++) {
+      if (hasOverlap(nodeArrays[i])) {
+        nodeArrays.splice(i--, 1);
+        continue;
+      } else {
+        addNodes(nodeArrays[i]);
+      }
+    }
+  }
+
   /**
    * Iterates over the multi-dimensional array of nodes, and returns a new
    * array grouping them based on matching identifiers.
@@ -224,6 +257,7 @@ class Inspector extends EventEmitter {
         return nodeArrays.some(array => array.indexOf(node) !== -1)
       });
     };
+
     var isComplete = (nodes) => {
       return (!nodeUtils.typesMatch(nodes) || alreadyIncluded(nodes)) ||
         (this._identifiers && !nodeUtils.identifiersMatch(nodes)) ||