Antlr4 导入组合语法失败 [英] Antlr4 import of combined grammar failing

问题描述

我现在正在……

error(56): AqlCommentTest.g4:12:4: 对未定义规则的引用:htmlCommentDeclaration错误(56):AqlCommentTest.g4:13:4:对未定义规则的引用:mdCommentDeclaration

词法分析器语法的导入似乎正在加载.以下文件存在问题.

AqlCommentTest.g4

grammar AqlCommentTest;导入 AqlLexerRules；导入 AqlComment；程序:commentDeclaration+；评论声明:htmlCommentDeclaration #Comment_HTML|mdCommentDeclaration #Comment_MD;

AqlComment.g4

grammar AqlComment;导入 AqlLexerRules；htmlCommentDeclaration: 'html' '{' '(*' STRING '*)' '}';mdCommentDeclaration: 'md' '{' '(*' STRING '*)' '}';

AqlLexerRules.g4

词法语法AqlLexerRules;字符串 : '"' [a-z]? '"' ;

可以通过删除import AqlLexerRules;"来停止错误来自AqlCommentTest.g4"文件.

为什么这可以解决"问题?

如何检查是否实际应用了 antlr4 导入语句以及如何应用?

解决方案

如果导入词法规则排在最后:

import AqlComment;导入 AqlLexerRules；

错误变为:

error(54): AqlCommentTest.g4:4:0: 重复语法前传规范(选项、标记或导入)；请合并

因此问题:导入是否有限制?

在 Definitive ANTLR 4 Reference 15.2 语法结构或doc 你可以找到:

<块引用>

选项、导入和令牌规范中最多只能有一个.

如果我将导入更改为:

import AqlComment, AqlLexerRules;

它编译.<​​/p>

I am presently getting...

error(56): AqlCommentTest.g4:12:4: reference to undefined rule: htmlCommentDeclaration
error(56): AqlCommentTest.g4:13:4: reference to undefined rule: mdCommentDeclaration

The import for the lexer grammar does seem to be loading. The following files present the problem.

AqlCommentTest.g4

grammar AqlCommentTest;
import AqlLexerRules;
import AqlComment;

program: commentDeclaration+;

commentDeclaration:
    htmlCommentDeclaration     #Comment_HTML
  | mdCommentDeclaration       #Comment_MD
;

AqlComment.g4

grammar AqlComment;
import AqlLexerRules;

htmlCommentDeclaration: 'html' '{' '(*' STRING '*)' '}';

mdCommentDeclaration: 'md' '{' '(*' STRING '*)' '}';

AqlLexerRules.g4

lexer grammar AqlLexerRules;
STRING :  '"' [a-z]? '"' ;

The errors can be stopped by removing the 'import AqlLexerRules;' from the 'AqlCommentTest.g4' file.

Why does this "fix" the problem?

How can I check to see if and how an antlr4 import statement is actually applied?

解决方案

If the import lexer rules comes last :

import AqlComment;
import AqlLexerRules;

the error changes to :

error(54): AqlCommentTest.g4:4:0: repeated grammar prequel spec (options, tokens, or import); please merge

Hence the question : is there a constraint about import ?

In the Definitive ANTLR 4 Reference 15.2 Grammar Structure or doc you can find :

There can be at most one each of options, imports, and token specifications.

If I change the import to :

import AqlComment, AqlLexerRules;

it compiles.

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