From d8441445a506336d9c4229aa5b4d3a5ef202bbf7 Mon Sep 17 00:00:00 2001
From: Alexis Sellier <alexis@cloudhead.io>
Date: Tue, 3 Jan 2012 22:41:14 +0100
Subject: [PATCH] change negation operators to be more cssy

---
 lib/less/parser.js           | 6 +++---
 lib/less/tree/condition.js   | 4 ++--
 test/css/mixins-guards.css   | 2 ++
 test/less/mixins-guards.less | 8 ++++++--
 4 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/lib/less/parser.js b/lib/less/parser.js
index 62321666..e828b52e 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -1171,17 +1171,17 @@ less.Parser = function Parser(env) {
             condition: function () {
                 var a, b, c, op, index = i, negate = false;
 
+                if ($(/^not/)) { negate = true }
                 expect('(');
-                if ($('!')) { negate = true }
                 if (a = $(this.addition) || $(this.entities.keyword) || $(this.entities.quoted)) {
-                    if (op = $(/^(?:>=|=<|\!=|[<=>])/)) {
+                    if (op = $(/^(?:>=|=<|\^=|[<=>])/)) {
                         if (b = $(this.addition) || $(this.entities.keyword) || $(this.entities.quoted)) {
                             c = new(tree.Condition)(op, a, b, index);
                         } else {
                             error('expected expression');
                         }
                     } else {
-                        c = new(tree.Condition)(negate ? '!=' : '=', a, new(tree.Keyword)('true'), index);
+                        c = new(tree.Condition)(negate ? '^=' : '=', a, new(tree.Keyword)('true'), index);
                     }
                     expect(')');
                     return $(/^and/) ? new(tree.Condition)('and', c, $(this.condition)) : c;
diff --git a/lib/less/tree/condition.js b/lib/less/tree/condition.js
index 9dcdbf70..83cd0925 100644
--- a/lib/less/tree/condition.js
+++ b/lib/less/tree/condition.js
@@ -28,9 +28,9 @@ tree.Condition.prototype.eval = function (env) {
                         index: i };
             }
             switch (result) {
-                case -1: return this.op === '<' || this.op === '=<' || this.op === '!=';
+                case -1: return this.op === '<' || this.op === '=<' || this.op === '^=';
                 case  0: return this.op === '=' || this.op === '>=' || this.op === '=<';
-                case  1: return this.op === '>' || this.op === '>=' || this.op === '!=';
+                case  1: return this.op === '>' || this.op === '>=' || this.op === '^=';
             }
     }
 };
diff --git a/test/css/mixins-guards.css b/test/css/mixins-guards.css
index d7e92db3..0c563e52 100644
--- a/test/css/mixins-guards.css
+++ b/test/css/mixins-guards.css
@@ -53,4 +53,6 @@
   content: false, true and true;
   content: false, false, true;
   content: false, true and true and true, false;
+  content: not false;
+  content: not false and false, not false;
 }
diff --git a/test/less/mixins-guards.less b/test/less/mixins-guards.less
index c131c287..0166b7df 100644
--- a/test/less/mixins-guards.less
+++ b/test/less/mixins-guards.less
@@ -43,7 +43,7 @@
 .ops (@a) when (@a =< 0) {
   height: lt-or-eq;
 }
-.ops (@a) when (@a != 0) {
+.ops (@a) when (@a ^= 0) {
   height: not-eq;
 }
 .ops1 { .ops(0) }
@@ -63,7 +63,7 @@
 .test (@a) when (@a) {
     content: "true.";
 }
-.test (@a) when (!@a) {
+.test (@a) when not (@a) {
     content: "false.";
 }
 
@@ -86,5 +86,9 @@
 .bool () when (false), (false), (true)                       { content: false, false, true } // TRUE
 .bool () when (false), (false) and (true), (false)           { content: false, false and true, false } // FALSE
 .bool () when (false), (true) and (true) and (true), (false) { content: false, true and true and true, false } // TRUE
+.bool () when not (false)                                    { content: not false }
+.bool () when not (true) and not (false)                     { content: not true and not false }
+.bool () when not (true) and not (true)                      { content: not true and not true }
+.bool () when not (false) and (false), not (false)           { content: not false and false, not false }
 
 .bool1 { .bool }