标记子规则后，用于规则的ANTLR4.7侦听器 [英] ANTLR4.7 listener for a rule when sub rules are labeled

问题描述

我有这样的 antlr4.7 语法，其中所有子规则都标记了.

I have an antlr4.7 grammar like this, where all sub rules are labeled.

date_expr
    :   attr op=( '+' | '-' ) dt_interval=ISO8601_INTERVAL
        #dateexpr_Op
    |   DATETIME_NAME
        #dateexpr_Named
    |   d=( DATETIME_LITERAL | DATE_LITERAL | TIME_LITERAL ) 
        #dateexpr_Literal
    |   attr
        #dateexpr_Attr
    |   '(' date_expr ')'
        #dateexpr_Paren
    ;

当 date_expr 规则完成时，我想对树进行注释.但是，查看生成的侦听器类，我看不到 exitDate_expr .如何添加呢?或者，我是否必须使用访问者界面.我对语法工具不太熟悉.

I would like to annotate the tree when a date_expr rule completes. However, looking at the generated listener class, I see no exitDate_expr. How can I add this? Or, do I have to use a visitor interface for it. I am not much familiar with grammar tools.

谢谢.

推荐答案

要实现 beforeAllLabledAlts 和 afterAllLabledAlts 访问点，请将带标签的alt规则包装在单例规则中:

To achieve beforeAllLabledAlts and afterAllLabledAlts visit points, wrap the labeled alt rule in a singleton rule:

anyDate : dateExpr ;
dateExpr
    :   attr op=( '+' | '-' ) dt_interval=ISO8601_INTERVAL    #dateexpr_Op
    |   DATETIME_NAME                                         #dateexpr_Named
    |   d=( DATETIME_LITERAL | DATE_LITERAL | TIME_LITERAL )  #dateexpr_Literal
    |   attr                                                  #dateexpr_Attr
    |   '(' date_expr ')'                                     #dateexpr_Paren
    ;

然后，ANTLR工具将使用 AnyDateContext onEntry 和 onExit 方法生成侦听器接口(和/或访客接口).

The ANTLR tool will then generate the listener interface (and/or visitor interface) with AnyDateContext onEntry and onExit methods.

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