fix the backup state reverse

src/lexer.js

@@ -84,13 +84,16 @@ Lexer.prototype.unlex = function (state) {
   if (!state) {
     state = this.backup;
   }
+  this.backup = null;
   if (state) {
     this.offset = state.offset;
     this.text = state.text;
     this.token = state.token;
     this.line = state.line;
+    if (state.backup) {
+      this.backup = state.backup;
+    }
   }
-  this.backup = null;
   return this.token;
 };
 
@@ -103,7 +106,8 @@ Lexer.prototype.state = function () {
     offset: this.offset,
     text: this.text,
     token: this.token,
-    line: this.line
+    line: this.line,
+    backup: this.backup
   };
 };
 /**

src/parser.js

@@ -303,7 +303,6 @@ Parser.prototype.parseRule = function (rule) {
     var result = this.parsers[rule.parser].apply(this, []);
     if (result === null) {
       this.lexer.unlex(backup);
-      this.lexer.backup = backup;
       if (typeof rule.default !== 'undefined') {
         return rule.default;
       }

test/parser.js

@@ -108,4 +108,17 @@ describe('Test parser', function () {
     ast.body[0].name.should.be.exactly('var');
     ast.body[0].description.should.be.exactly('Foo is Bar');
   });
+
+  it('test param defaults', function () {
+    var ast = doc.parse([
+      '/**',
+      ' * Description',
+      ' * @param String Foo is Bar',
+      ' */'
+    ].join('\n'));
+    ast.body[0].kind.should.be.exactly('param');
+    ast.body[0].type.name.should.be.exactly('String');
+    should.equal(ast.body[0].name, null);
+    ast.body[0].description.should.be.exactly('Foo is Bar');
+  });
 });