by qianjun

Summary: code review and to find why

Test Plan: test

Reviewers: zhengxin

Differential Revision: http://ufo.sogou-inc.com:8080/D38
by qianjun;将赋值语句左侧变量名和右侧语句拆分，正确编译右侧语句
by qianjun;修复声明变量赋值逻辑；修复自定义语法界定符bug