“FOLLOW_set_in_"...在生成的解析器中未定义 [英] "FOLLOW_set_in_"... is undefined in generated parser

问题描述

我已经为模糊的类似 Java 的 DSL 编写了语法.虽然它仍然存在一些问题(它不能像我希望的那样识别所有输入)，但我最担心的是生成的 C 代码不可编译.

I have written a grammar for vaguely Java-like DSL. While there are still some issues with it (it doesn't recognize all the inputs as I would want it to), what concerns me most is that the generated C code is not compilable.

我使用 AntlrWorks 1.5 和 Antlr 3.5(Antlr 4 显然不支持 C 目标).

I use AntlrWorks 1.5 with Antlr 3.5 (Antlr 4 apparently does not support C target).

问题在于表达式规则.我有规则 prio14Expression 到 prio0Expression 处理运算符优先级.问题的优先级为 2，它评估前缀和后缀运算符:

The problem is with expression rules. I have rules prio14Expression to prio0Expression which handle operator precedence. To problem is at priority 2, which evaluates prefix and postfix operators:

...
prio3Expression: prio2Expression (('*' | '/' | '%') prio2Expression)*;

prio2Expression: ('++' | '--' | '!' | '+' | '-')* prio1Expression ('++' | '--')*;  

prio1Expression:
    prio0Expression (
        ('.' prio0Expression) |
        ('(' (expression (',' expression)*)? ')') |
        ('[' expression (',' expression)* ']')
    )*;

prio0Expression: 
    /*('(') => */('(' expression ')') |
    IDENTIFIER |
    //collectionLiteral |
    coordinateLiteral |
    'true' |
    'false' |
    NUMBER |
    STRING 
    ;
...

Expression 是 prio14Expression 的标签.你可以看到完整的语法 这里.

Expression is a label for prio14Expression. You can see the full grammar here.

代码生成本身是成功的(没有任何错误或严重警告).它生成以下代码:

The code generation itself is successful (without any errors or serious warnings). It generates following code:

CONSTRUCTEX();
EXCEPTION->type         = ANTLR3_MISMATCHED_SET_EXCEPTION;
EXCEPTION->name         = (void *)ANTLR3_MISMATCHED_SET_NAME;
EXCEPTION->expectingSet = &FOLLOW_set_in_prio2Expression962;

RECOVERFROMMISMATCHEDSET(&FOLLOW_set_in_prio2Expression962);
goto ruleprio2ExpressionEx;

构建时不会出现错误Error 5 error C2065: 'FOLLOW_set_in_prio2Expression962': undeclared identifier".

Which does not build with error "Error 5 error C2065: 'FOLLOW_set_in_prio2Expression962' : undeclared identifier".

我在语法上做错了吗?没有其他规则会导致此错误，如果我稍微重新制定相关规则，生成的代码是有效的(但语法不符合我的要求).我该怎么做才能解决这个问题?

Did I do something wrong in the grammar? No other rules cause this error and if I somewhat reformulate the rule concerned, the generated code is valid (but then the grammar doesn't do what I want it to). What can I do to fix this issue?

感谢您的帮助.

推荐答案

我遇到了同样的问题.

我认为如果解析器规则具有像这样的简单 OR-ed 标记的一部分，就会发生这种情况:

I think it happens if parser rule has a part of simple OR-ed token like this:

problem_case: problematic_rule;
problematic_rule: 'A' | 'B' ;

如果是词法分析器规则，则不会发生这种情况.

This doesn't happen if it is lexer rule.

workaround1: As_lexer_rule;
As_lexer_rule: 'A' | 'B' ;

或者，如果它是复杂的规则(不是简单的 OR ed token).

Or, if it is complicated rule (not simple OR-ed token).

workaround2: make_it_complicated_needlessly;
make_it_complicated_needlessly: 'A' | 'B' | {false}? NeverUsedRule;
NeverUsedRule: /* don't care*/ ;

(我使用语义谓词{false}?"进行此修改.我相信它不会改变目标语言的语法.)

( I used semantic predicate "{false}?" for this modification. I believe it doesn't change the grammar of target language.)

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