From afd599dcb5aaeb9bab04efa0430c2d34f01692c9 Mon Sep 17 00:00:00 2001
From: James Foster <james.mdb@gmail.com>
Date: Fri, 20 May 2011 07:55:02 +0800
Subject: [PATCH] Implement parent selector

---
 lib/less/parser.js       | 14 ++++++++++++-
 lib/less/tree/element.js |  5 ++++-
 lib/less/tree/ruleset.js | 44 +++++++++++++++++++++++++++++++++++-----
 test/css/selectors.css   | 21 +++++++++++++++++++
 test/less/selectors.less | 24 ++++++++++++++++++++++
 5 files changed, 101 insertions(+), 7 deletions(-)

diff --git a/lib/less/parser.js b/lib/less/parser.js
index 9cb2a30e..e828c23c 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -790,6 +790,10 @@ less.Parser = function Parser(env) {
                 e = $(/^(?:[.#]?|:*)(?:[\w-]|\\(?:[a-fA-F0-9]{1,6} ?|[^a-fA-F0-9]))+/) || $('*') || $(this.attribute) || $(/^\([^)@]+\)/);
 
                 if (e) { return new(tree.Element)(c, e) }
+
+                if (c.value && c.value[0] === '&') {
+                  return new(tree.Element)(c, null);
+                }
             },
 
             //
@@ -804,10 +808,18 @@ less.Parser = function Parser(env) {
             combinator: function () {
                 var match, c = input.charAt(i);
 
-                if (c === '>' || c === '&' || c === '+' || c === '~') {
+                if (c === '>' || c === '+' || c === '~') {
                     i++;
                     while (input.charAt(i) === ' ') { i++ }
                     return new(tree.Combinator)(c);
+                } else if (c === '&') {
+                    match = '&';
+                    i++;
+                    if(input.charAt(i) === ' ') {
+                        match = '& ';
+                    }
+                    while (input.charAt(i) === ' ') { i++ }
+                    return new(tree.Combinator)(match);
                 } else if (c === ':' && input.charAt(i + 1) === ':') {
                     i += 2;
                     while (input.charAt(i) === ' ') { i++ }
diff --git a/lib/less/tree/element.js b/lib/less/tree/element.js
index acf5e205..27cf8228 100644
--- a/lib/less/tree/element.js
+++ b/lib/less/tree/element.js
@@ -3,7 +3,7 @@
 tree.Element = function (combinator, value) {
     this.combinator = combinator instanceof tree.Combinator ?
                       combinator : new(tree.Combinator)(combinator);
-    this.value = value.trim();
+    this.value = value ? value.trim() : "";
 };
 tree.Element.prototype.toCSS = function (env) {
     return this.combinator.toCSS(env || {}) + this.value;
@@ -12,6 +12,8 @@ tree.Element.prototype.toCSS = function (env) {
 tree.Combinator = function (value) {
     if (value === ' ') {
         this.value = ' ';
+    } else if (value === '& ') {
+        this.value = '& ';
     } else {
         this.value = value ? value.trim() : "";
     }
@@ -21,6 +23,7 @@ tree.Combinator.prototype.toCSS = function (env) {
         ''  : '',
         ' ' : ' ',
         '&' : '',
+        '& ' : ' ',
         ':' : ' :',
         '::': '::',
         '+' : env.compress ? '+' : ' + ',
diff --git a/lib/less/tree/ruleset.js b/lib/less/tree/ruleset.js
index 4fbf1db8..246200fa 100644
--- a/lib/less/tree/ruleset.js
+++ b/lib/less/tree/ruleset.js
@@ -120,11 +120,7 @@ tree.Ruleset.prototype = {
             if (context.length === 0) {
                 paths = this.selectors.map(function (s) { return [s] });
             } else {
-                for (var s = 0; s < this.selectors.length; s++) {
-                    for (var c = 0; c < context.length; c++) {
-                        paths.push(context[c].concat([this.selectors[s]]));
-                    }
-                }
+                this.joinSelectors( paths, context, this.selectors );
             }
         }
 
@@ -174,6 +170,44 @@ tree.Ruleset.prototype = {
         css.push(rulesets);
 
         return css.join('') + (env.compress ? '\n' : '');
+    },
+
+    joinSelectors: function( paths, context, selectors ) {
+        for (var s = 0; s < selectors.length; s++) {
+            this.joinSelector(paths, context, selectors[s]);
+        }
+    },
+
+    joinSelector: function( paths, context, selector ) {
+        var before = [], after = [], beforeElements = [], afterElements = [], hasParentSelector = false, el;
+
+        for (var i = 0; i < selector.elements.length; i++) {
+            el = selector.elements[i];
+            if (el.combinator.value[0] === '&') {
+                hasParentSelector = true;
+            }
+            if(!hasParentSelector) {
+                beforeElements.push(el);
+            } else {
+                afterElements.push(el);
+            }
+        }
+
+        if(!hasParentSelector) {
+            afterElements = beforeElements;
+            beforeElements = [];
+        }
+
+        if(beforeElements.length > 0) {
+            before.push(new (tree.Selector)(beforeElements));
+        }
+        if(afterElements.length > 0) {
+            after.push(new (tree.Selector)(afterElements));
+        }
+
+        for (var c = 0; c < context.length; c++) {
+            paths.push(before.concat(context[c]).concat(after));
+        }
     }
 };
 })(require('less/tree'));
diff --git a/test/css/selectors.css b/test/css/selectors.css
index 85916c35..a384f938 100644
--- a/test/css/selectors.css
+++ b/test/css/selectors.css
@@ -30,3 +30,24 @@ td {
 td, input {
   line-height: 1em;
 }
+a {
+  color: red;
+}
+a:hover {
+  color: blue;
+}
+div a {
+  color: green;
+}
+p a span {
+  color: yellow;
+}
+.foo .bar .qux, .foo .baz .qux {
+  display: block;
+}
+.qux .foo .bar, .qux .foo .baz {
+  display: inline;
+}
+.qux .foo .bar .biz, .qux .foo .baz .biz {
+  display: none;
+}
diff --git a/test/less/selectors.less b/test/less/selectors.less
index 5691bb22..5bc2bb1f 100644
--- a/test/less/selectors.less
+++ b/test/less/selectors.less
@@ -22,3 +22,27 @@ td {
 td, input {
   line-height: 1em;
 }
+
+a {
+  color: red;
+
+  &:hover { color: blue; }
+
+  div & { color: green; }
+
+  p & span { color: yellow; }
+}
+
+.foo {
+  .bar, .baz {
+    & .qux {
+      display: block;
+    }
+    .qux & {
+      display: inline;
+    }
+    .qux & .biz {
+      display: none;
+    }
+  }
+}
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