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！
这篇关于为一个字符的标识符定义 antlr 规则的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！