在C＃VHDL语言解析器 [英] Vhdl parser on C#

问题描述

我需要做一个VHDL解析器。我决定用ANTLR解析器发电机和语法VHDL从他们的网站 HTTP：// WWW。 antlr.org/grammar/1202750770887/vhdl.g 。我检查语法和时遇到问题
具有这个错误：

I need to make a vhdl parser. I decided to use the antlr parser generator and the vhdl grammar from their website http://www.antlr.org/grammar/1202750770887/vhdl.g. I am having problems when checking the grammar and have this error:

下面的标记定义决不能因为之前$匹配b $ b令牌匹配相同的输入：字母，INTEGER，数字...

The following token definitions can never be matched because prior tokens match the same input: LETTER,INTEGER,DIGIT...

如果任何人有这个工作之前，请告诉我如果语法不正确，或者如果我做别的事情不正确。

If anyone has worked with this before, please tell me if the grammar is incorrect or if I'm doing something else incorrectly.

推荐答案

从vhdl.g

BASIC_IDENTIFIER
   :   LETTER ( '_' | LETTER | DIGIT )*
   ;

...

LETTER  
  :  'a'..'z' | 'A'..'Z'
  ;

LETTER，INTEGER，数字看起来都像他们应该是一个片段，因为他们永远不会被解析器称为规则。

LETTER, INTEGER and DIGIT all look like they should be a fragment, as they are never called by parser rules.

fragment LETTER 
  :  'a'..'z' | 'A'..'Z'
  ;

编辑：由于巴特曾表示，由于BASIC_IDENTIFIER在语法LETTER上市前，覆盖所有的情况下，信中，词法分析器将永远不会创建任何字母标记。这是什么原因造成的警告。

As Bart has stated, since BASIC_IDENTIFIER is listed before LETTER in the grammar and covers all the cases LETTER does, the lexer will never create any LETTER tokens. This is what is causing the warnings.

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