单引号兼作运算符的 Antlr 语法
我正在研究 Antlr 语法，其中单引号既用作运算符又在字符串文字中使用，例如：
operand: DIGIT | STRINGLIT | reference;
expression: operand SQUOTE;
STRINGLIT: '\'' ~('\\'|'\'')* '\'';
像 1' 这样的表达式可以正确解析，但是当存在与 ~( 匹配的输入时'\\'|'\'')* 在引号后，例如 1'+2，词法分析器尝试匹配 STRINGLIT 并失败。我希望能够恢复并发出 SQUOTE。有什么想法如何实现它吗？
谢谢。
I am working on an Antlr grammar in which single quotes are used both as operators and in string literals, something like:
operand: DIGIT | STRINGLIT | reference;
expression: operand SQUOTE;
STRINGLIT: '\'' ~('\\'|'\'')* '\'';
Expressions like 1' parse correctly, but when there is input that matches ~('\\'|'\'')* after the quote, such as 1'+2, the lexer attempts to match STRINGLIT and fails. I'd like to be able to recover and emit SQUOTE. Any ideas how to accomplish it?
Thanks.
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在 Antlrworks 中测试了这个语法之后，我认为你的问题是你在这里限制太多了。如果您有一个规则在看到
操作数 SQUOTE后接受某些内容，Antlr 将能够解析1'+2。由于 ANTLR 不知道如何处理+2，因此它会抛出异常。After testing this grammar a bit in Antlrworks, I think that your problem is that you are being too restrictive here. Antlr would be able to parse
1'+2if you had a rule that accepted something after it has seenoperand SQUOTE. Since ANTLR doesn't know what to do with the+2, it throws an exception.