From 261d4e0f9c6f85111cc1493a3b19099f31235f65 Mon Sep 17 00:00:00 2001
From: Mark Brennan <me@markbrennan.net>
Date: Sun, 5 Jan 2014 21:10:55 -0800
Subject: [PATCH] fixed using starting index for parser nodes, which enables
 the creation of accurate source maps

---
 lib/less/parser.js         | 19 ++++++++++---------
 lib/less/tree/directive.js |  1 +
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/lib/less/parser.js b/lib/less/parser.js
index 09899751..f1f2d379 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -1073,7 +1073,7 @@ less.Parser = function Parser(env) {
                 // selector for now.
                 //
                 call: function () {
-                    var s = input.charAt(i), important = false, index = i,
+                    var s = input.charAt(i), important = false, index = i, elemIndex,
                         elements, elem, e, c, args;
 
                     if (s !== '.' && s !== '#') { return; }
@@ -1081,11 +1081,12 @@ less.Parser = function Parser(env) {
                     save(); // stop us absorbing part of an invalid selector
 
                     while (true) {
+                        elemIndex = i;
                         e = $re(/^[#.](?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+/);
                         if (!e) {
                             break;
                         }
-                        elem = new(tree.Element)(c, e, i, env.currentFileInfo);
+                        elem = new(tree.Element)(c, e, elemIndex, env.currentFileInfo);
                         if (elements) { elements.push(elem); } else { elements = [ elem ]; }
                         c = $char('>');
                     }
@@ -1313,7 +1314,7 @@ less.Parser = function Parser(env) {
             // and an element name, such as a tag a class, or `*`.
             //
             element: function () {
-                var e, c, v;
+                var e, c, v, index = i;
 
                 c = this.combinator();
 
@@ -1329,7 +1330,7 @@ less.Parser = function Parser(env) {
                     }
                 }
 
-                if (e) { return new(tree.Element)(c, e, i, env.currentFileInfo); }
+                if (e) { return new(tree.Element)(c, e, index, env.currentFileInfo); }
             },
 
             //
@@ -1370,7 +1371,7 @@ less.Parser = function Parser(env) {
             // Selectors are made out of one or more Elements, see above.
             //
             selector: function (isLess) {
-                var $re = _$re, elements, extendList, c, e, extend, when, condition;
+                var index = i, $re = _$re, elements, extendList, c, e, extend, when, condition;
 
                 while ((isLess && (extend = this.extend())) || (isLess && (when = $re(/^when/))) || (e = this.element())) {
                     if (when) {
@@ -1390,7 +1391,7 @@ less.Parser = function Parser(env) {
                     }
                 }
 
-                if (elements) { return new(tree.Selector)(elements, extendList, condition, i, env.currentFileInfo); }
+                if (elements) { return new(tree.Selector)(elements, extendList, condition, index, env.currentFileInfo); }
                 if (extendList) { error("Extend must be used to extend a selector, it cannot be used on its own"); }
             },
             attribute: function () {
@@ -1639,7 +1640,7 @@ less.Parser = function Parser(env) {
             //     @charset "utf-8";
             //
             directive: function () {
-                var name, value, rules, nonVendorSpecificName,
+                var index = i, name, value, rules, nonVendorSpecificName,
                     hasBlock, hasIdentifier, hasExpression, identifier;
 
                 if (input.charAt(i) !== '@') { return; }
@@ -1706,12 +1707,12 @@ less.Parser = function Parser(env) {
                 if (hasBlock) {
                     rules = this.block();
                     if (rules) {
-                        return new(tree.Directive)(name, rules, i, env.currentFileInfo);
+                        return new(tree.Directive)(name, rules, index, env.currentFileInfo);
                     }
                 } else {
                     value = hasExpression ? this.expression() : this.entity();
                     if (value && $char(';')) {
-                        var directive = new(tree.Directive)(name, value, i, env.currentFileInfo);
+                        var directive = new(tree.Directive)(name, value, index, env.currentFileInfo);
                         if (env.dumpLineNumbers) {
                             directive.debugInfo = getDebugInfo(i, input, env);
                         }
diff --git a/lib/less/tree/directive.js b/lib/less/tree/directive.js
index 45ea96b4..a4404bd7 100644
--- a/lib/less/tree/directive.js
+++ b/lib/less/tree/directive.js
@@ -9,6 +9,7 @@ tree.Directive = function (name, value, index, currentFileInfo) {
     } else {
         this.value = value;
     }
+    this.index = index;
     this.currentFileInfo = currentFileInfo;
 
 };