如何修复“不允许使用多字符文字"antlr4 词法分析器规则中的错误? [英] How to fix the "multi-character literals are not allowed" error in antlr4 lexer rule?

问题描述

我想写的规则是:

Character : '\u0000'..'\u10FFF';

但是当尝试针对定义它的词法分析器文件运行 antlr 工具时，我收到以下错误:

But when trying to run antlr tool against the lexer file where it is defined I get the following error:

multi-character literals are not allowed in lexer sets: '\u10FFF'

如何解决这个问题?

推荐答案

尝试用 { 和 } 包装多字符文字，并使用 v4 样式字符集[...]:

Try wrapping the multi-char literal with { and }, and use the v4 style character set [...]:

Character : [\u0000-\u{10FFF}];

来自 https://github.com/antlr/antlr4/blob/master/doc/lexer-rules.md#lexer-rule-elements:

[...] 匹配字符集中指定的字符之一.将 x-y 解释为范围 x 和 y 之间的字符集，包括.以下转义字符被解释为单个特殊字符:\n、\r、\b、\t、\f、\uXXXX 和 \u{XXXXXX}.要获得 ]、\ 或 -，您必须使用 \ 对它们进行转义.

[...] Match one of the characters specified in the character set. Interpret x-y as the set of characters between range x and y, inclusively. The following escaped characters are interpreted as single special characters: \n, \r, \b, \t, \f, \uXXXX, and \u{XXXXXX}. To get ], \, or - you must escape them with \.

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