实现Calculator

git-svn-id: https://qlanguage.googlecode.com/svn/trunk@175 6d982bb3-a5a7-393d-ffc5-582415be9c85
修正一些规约冲突

git-svn-id: https://qlanguage.googlecode.com/svn/trunk@176 6d982bb3-a5a7-393d-ffc5-582415be9c85


git-svn-id: https://qlanguage.googlecode.com/svn/trunk@177 6d982bb3-a5a7-393d-ffc5-582415be9c85


git-svn-id: https://qlanguage.googlecode.com/svn/trunk@178 6d982bb3-a5a7-393d-ffc5-582415be9c85