从Antlr3转换为Antlr4

本文介绍了从Antlr3转换为Antlr4的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在将antlr3语法转换为antlr4语法.我删除了所有语法谓词.我正在努力对此进行正确的转换

I am in the process of converting an antlr3 to antlr4 grammar. I have stripped out all the syntactic predicates. I am struggling to make a correct conversion of this

    relaxed_date_month_first
  : relaxed_day_of_week? relaxed_month COMMA? WHITE_SPACE relaxed_day_of_month (relaxed_year_prefix relaxed_year)?
      -> ^(EXPLICIT_DATE relaxed_day_of_month relaxed_month relaxed_day_of_week? relaxed_year?)

到antlr4语法.

每当antlr4工具遇到->"字符时，它都会说外部输入'->'，期望{TOKEN_REF，RULE_REF ... ACTION}".

to antlr4 grammar.

Everytime the antlr4 tool runs into "->" character it says "extraneous input '->' expecting {TOKEN_REF, RULE_REF...ACTION}".

我该如何解决?

推荐答案

ANTLR4没有树重写.因此，请完全删除-> ...:

ANTLR4 has no tree-rewriting. So, remove -> ... entirely:

relaxed_date_month_first
 : relaxed_day_of_week? relaxed_month COMMA? WHITE_SPACE relaxed_day_of_month (relaxed_year_prefix relaxed_year)?
 ;

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Grammar