如何使用〜＆gt;和＆lt;〜在Scala中的语法规则定义？

Question

如何使用〜＆gt;的正确位置忽略这些语法规则中的所有字符串？或者＆lt;〜运营商？

def typeDefBody = ident ~ ":" ~ ident ~ "{" ~ fieldBody ~ "}"

def fieldBody = "validation" ~ "{" ~ validationBody ~ "}"

def validationBody = length ~ pattern

def length = "length" ~ "=" ~ wholeNumber ~ "to" ~ wholeNumber

def pattern = "pattern" ~ "=" ~ stringLiteral

Answer 1

我找到了解决方案，我应该将typeDefBody分解为3无终端规则，如下所示

def typeDefBody =  ident ~ typeDefBodySequence1

def typeDefBodySequence1 = ":" ~> ident ~ typeDefBodySequence2

def typeDefBodySequence2 = "{" ~> fieldBody <~ "}"

def fieldBody = "validation" ~ "{" ~> validationBody <~ "}"

def validationBody = length ~ pattern

def length = "length" ~ "=" ~> wholeNumber ~ "to" ~ wholeNumber

def pattern = "pattern" ~ "=" ~> stringLiteral