fixed stacktraces line number when used multiline js expressions

Signed-off-by: Tj Holowaychuk <tj@vision-media.ca>

ejs.js

@@ -190,6 +190,11 @@ var parse = exports.parse = function(str, options){
       var start = i;
       var end = str.indexOf(close, i);
       var js = str.substring(i, end);
+      var n = 0;
+      while ((n = js.indexOf("\n", n)) > -1) {
+        n++;
+        lineno++;
+      }
       if (js[0] == ':') js = filtered(js);
       buf.push(prefix, js, postfix);
       i += end - start + close.length - 1;

lib/ejs.js

@@ -141,6 +141,11 @@ var parse = exports.parse = function(str, options){
       var start = i;
       var end = str.indexOf(close, i);
       var js = str.substring(i, end);
+      var n = 0;
+      while ((n = js.indexOf("\n", n)) > -1) {
+        n++;
+        lineno++;
+      }
       if (js[0] == ':') js = filtered(js);
       buf.push(prefix, js, postfix);
       i += end - start + close.length - 1;

test/ejs.test.js

@@ -241,5 +241,28 @@ module.exports = {
       var lineno = parseInt(err.toString().match(/ejs:(\d+)\n/)[1]);
       assert.eql(lineno,3,"Error should been thrown on line 3, was thrown on line "+lineno);
     }
+  },
+
+  'test useful stack traces multiline': function(assert){  
+    var str = [
+      "A little somethin'",
+      "somethin'",
+      "<% var some = 'pretty';",
+      "   var multiline = 'javascript';",
+      "%>",
+      "<% if (name) { %>", // Failing line 
+      "  <p><%= name %></p>",
+      "  <p><%= email %></p>",
+      "<% } %>"
+    ].join("\n");
+
+    try {
+      ejs.render(str)
+    } catch( err ){
+      assert.includes(err.message,"name is not defined");
+      assert.eql(err.name,"ReferenceError");
+      var lineno = parseInt(err.toString().match(/ejs:(\d+)\n/)[1]);
+      assert.eql(lineno,6,"Error should been thrown on line 3, was thrown on line "+lineno);
+    }
   }
 };