为一个字符的标识符定义 antlr 规则 [英] Defining antlr rule for identifiers with one character

问题描述

我喜欢定义一个非常简单的规则，它应该代表标识符.这对于长度超过一个字符的标识符非常有效，但对于只有一个字符的标识符，我得到 MismatchedTokenException(64!=45).这是规则:

i like to define a very simple rule, which should represent identifiers. This works quite well for identifiers which are longer than one characters, but for identifiers with exactly one character I get a MismatchedTokenException(64!=45). This is the rule:

ID : ('a'..'z' | 'A'..'Z')+;

ID : ('a'..'z' | 'A'..'Z')+ ;

这有什么问题?

谢谢！

推荐答案

你说得对，规则本身没问题，但我发现 ANTLR 中的很多都取决于规则的顺序.我之前有另一个规则，它已经匹配了 ID 规则.终于说得通了，因为 Lexer 无法决定采用哪条规则.

You're absolutely right, the rule on its own is fine, but I figured out that a lot in ANTLR depends on the order of rules. I had another rule before, which did already match the ID rule. Finally it makes sense, because the Lexer cannot decide which rule to take.

谢谢！

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