From b608d4a5eab77389f843e87bb8ba389adea1897c Mon Sep 17 00:00:00 2001
From: Jeremy Ashkenas <jashkenas@gmail.com>
Date: Tue, 17 Aug 2010 21:46:00 -0400
Subject: [PATCH] Issue #626. Making the isInvertible check a little stricter.

---
 lib/nodes.js     |  9 +++++----
 src/nodes.coffee | 12 +++++++-----
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/lib/nodes.js b/lib/nodes.js
index a7a405a2..05520eb3 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -1285,12 +1285,13 @@
     OpNode.prototype.isUnary = function() {
       return !this.second;
     };
-    OpNode.prototype.isInvertable = function() {
+    OpNode.prototype.isInvertible = function() {
       var _b;
-      return ('===' === (_b = this.operator) || '!==' === _b);
+      return (('===' === (_b = this.operator) || '!==' === _b)) && !(this.first instanceof OpNode) && !(this.second instanceof OpNode);
     };
     OpNode.prototype.isMutator = function() {
-      return ends(this.operator, '=') && !this.isInvertable();
+      var _b;
+      return ends(this.operator, '=') && !(('===' === (_b = this.operator) || '!==' === _b));
     };
     OpNode.prototype.isChainable = function() {
       return include(this.CHAINABLE, this.operator);
@@ -1683,7 +1684,7 @@
       this.condition = _b;
       this.tags || (this.tags = {});
       if (this.tags.invert) {
-        if (this.condition instanceof OpNode && this.condition.isInvertable()) {
+        if (this.condition instanceof OpNode && this.condition.isInvertible()) {
           this.condition.invert();
         } else {
           this.condition = new OpNode('!', new ParentheticalNode(this.condition));
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 572eaa13..0c32e902 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -1083,7 +1083,7 @@ exports.OpNode = class OpNode extends BaseNode
     '==': '==='
     '!=': '!=='
 
-  # The map of invertable operators.
+  # The map of invertible operators.
   INVERSIONS:
     '!==': '==='
     '===': '!=='
@@ -1113,11 +1113,13 @@ exports.OpNode = class OpNode extends BaseNode
   isUnary: ->
     not @second
 
-  isInvertable: ->
-    @operator in ['===', '!==']
+  isInvertible: ->
+    (@operator in ['===', '!==']) and
+      not (@first instanceof OpNode) and not (@second instanceof OpNode)
+
 
   isMutator: ->
-    ends(@operator, '=') and not @isInvertable()
+    ends(@operator, '=') and not (@operator in ['===', '!=='])
 
   isChainable: ->
     include(@CHAINABLE, @operator)
@@ -1413,7 +1415,7 @@ exports.IfNode = class IfNode extends BaseNode
   constructor: (@condition, @body, @tags) ->
     @tags or= {}
     if @tags.invert
-      if @condition instanceof OpNode and @condition.isInvertable()
+      if @condition instanceof OpNode and @condition.isInvertible()
         @condition.invert()
       else
         @condition = new OpNode '!', new ParentheticalNode @condition