Antlr4：如何确定匹配了哪个规则选项？

Question

我的语法如下：

node: '{' type ',' '"expression"' ':' rightSide '}' ;
rightSide:
    call         # callAlternative
    | identifier # identifierAlternative
    ;

现在在我的访问者中，我实现了方法 visitNode(Parser.NodeContext ctx) 并希望访问 rightSide 规则的正确方法，无论哪个匹配。 # 标签用于为每个备选方案生成专用方法，而 righSide 规则不再有访问方法。还有visitNode中的ctx只有ctx.rightSide()，没有ctx.callAlternative()and/orctx.identifierAlternative().

如何做到这一点？

@Override
public SomeObj visitNode(Parser.NodeContext ctx) {
    // how to detect which of the two alternatives was matched? ctx only has ctx.rightSide()
    // What is the something in ctx.something ?
    if(....){ // how to decide here??
        visitIdentifierAlternative(ctx.something);
    } else visitCallAlternative(ctx.something);
    return new SomeObj();
}
@Override
public SomeObj visitIdentifierAlternative(Parser.IdentifierAlternativeContext ctx) {
    // Do things only to be done for IdentifierAlternative
    return new SomeObj();
}
@Override
public SomeObj visitCallAlternative(Parser.CallAlternativeContext ctx) {
    // Do things only to be done for CallAlternative
    return new SomeObj();
}

Answer 1

您不要直接调用 visitIdentifierAlternative 或 visitCallAlternative。您只需调用 visit，然后它将 select 自己的适当方法。

Antlr4：如何确定匹配了哪个规则选项？

Antlr4: How to identify which rule alternative was matched?

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antlr4