Xtext，每个空格的错误，如果它是倒置的逗号

Question

我正在使用xtext来制作语法。目前我有这样的代码：

Model:  (commands+=Commands)*;

Commands:   
    SetCommand|CommentCommand|WhileCommand|OutputCommand
   |SelectCommand|OptionCommand|InsertAfterCommand|AdaptCommand;  

OptionCommand:  
    '#option' EXPRESSION((EXPRESSION)|(WS)|(InsertAfterCommand)|('='))* '#endoption'  ;       

terminal EXPRESSION:   
    ('a'..'z'|'A'..'Z'|'0'..'9'|'-'|'@'
    |'.'|'?'|'\''|':'|'\"'|'>'
    |'<'|'/'|'_'|';'|'('|')'
    |'&'|'!'|'#'|'*'|'+'|'['|']'|'{'|'}')
    ('a'..'z'|'A'..'Z'|'0'..'9'|'-'|'@'
    |'.'|'?'|'\''|':'|'\"'|'>'
    |'<'|'/'|'_'|';'|'('|')'
    |'&'|'!'|'#'|'%'|'*'|'+'|'['|']'|'{'|'}')* ;     

但如果有像a="he is a good boy"这样的代码，它总是会在每个空格上出错。