change location storing in SyntaxMatchError

- Changed property to store mismatch offset to `mismatchOffset`
- Changed `offset` property to store bad node offset in source CSS if
any
- Added `loc` property that stores bad node `loc` if any

lib/syntax/error.js

@@ -16,6 +16,16 @@ function contains(node, searchFor) {
     return found;
 }
 
+function getLocation(node, point) {
+    var loc = node && node.loc && node.loc[point];
+
+    return loc
+        ? { offset: loc.offset,
+            line: loc.line,
+            column: loc.column }
+        : null;
+}
+
 var SyntaxParseError = function(message, syntaxStr, offset) {
     var error = new SyntaxError();
     error.name = 'SyntaxParseError';
@@ -32,6 +42,9 @@ var SyntaxParseError = function(message, syntaxStr, offset) {
 var MatchError = function(message, syntax, value, badNode) {
     var errorOffset = -1;
     var css = '';
+    var error = new SyntaxError(message);
+    var start = getLocation(badNode, 'start');
+    var end = getLocation(badNode, 'end');
 
     value.children.each(function(node) {
         if (badNode === node || (badNode && contains(node, badNode))) {
@@ -45,18 +58,23 @@ var MatchError = function(message, syntax, value, badNode) {
         errorOffset = css.length;
     }
 
-    var error = new SyntaxError(message);
     error.name = 'SyntaxMatchError';
     error.rawMessage = message;
     error.syntax = syntax ? translateSyntax(syntax) : '<generic>';
     error.css = css;
-    error.line = badNode && badNode.loc && badNode.loc.start ? badNode.loc.start.line : undefined;
-    error.column = badNode && badNode.loc && badNode.loc.start ? badNode.loc.start.column : undefined;
-    error.offset = errorOffset;
+    error.mismatchOffset = errorOffset;
+    error.loc = {
+        source: badNode && badNode.loc && badNode.loc.source || '<unknown>',
+        start: start,
+        end: end
+    };
+    error.line = start ? start.line : undefined;
+    error.column = start ? start.column : undefined;
+    error.offset = start ? start.offset : undefined;
     error.message = message + '\n' +
         '  syntax: ' + error.syntax + '\n' +
         '   value: ' + (error.css || '<empty string>') + '\n' +
-        '  --------' + new Array(error.offset + 1).join('-') + '^';
+        '  --------' + new Array(error.mismatchOffset + 1).join('-') + '^';
 
     return error;
 };