ANTLR4-需要对此字符串文字的解释 [英] ANTLR4 - Need an explanation on this String Literals

问题描述

在我的作业中，我对String Lexer的描述如下:

On my assignment, I have this description for the String Lexer:

字符串文字包含零个或多个由双精度字符括起来的字符 引号().使用转义序列(下面列出)表示特殊字符 字符串中的字符.这是新行的编译时错误 或EOF字符出现在字符串文字中.

"String literals consist zero or more characters enclosed by double quotes ("). Use escape sequences (listed below) to represent special characters within a string. It is a compile-time error for a new line or EOF character to appear inside a string literal.

所有受支持的转义序列如下:

All the supported escape sequences are as follows:

\ b退格键

\ f换页

\ r回车

\ n换行符

\ t水平制表符

\双引号

\反斜杠

以下是字符串文字的有效示例:

The following are valid examples of string literals:

这是一个包含制表符\ t的字符串"

"This is a string containing tab \t"

他问我:\"约翰在哪里?\"

"He asked me: \"Where is John?\""

字符串文字具有字符串类型."

A string literal has a type of string."

这是我的String词法分析器:

And this is my String lexer:

STRINGLIT: '"'(('\\'('b'|'t'|'n'|'f'|'r'|'\"'|'\\'))|~('\n'))*'"';

任何人都可以检查我的词法分析器是否符合要求?如果不是，请告诉我您的更正，我不是很了解该要求和ANTLR4.

Can anybody check for my lexer if it meets the requirement or not? If it's not, please tell me your correction, I don't really understand the requirement and ANTLR4.

推荐答案

使用ANTLR4，您可以编写\\ [btn]，而不是编写\\ ('b' | 't' | 'n').另外，正如J Earls在评论中提到的那样，您将希望在报价单中包括引号以及\r和文字\.

With ANTLR4, instead of writing \\ ('b' | 't' | 'n'), you can write \\ [btn]. Also, as J Earls mentioned in a comment, you'll want to include the quote in your negated set, as well as the \r and the literal \.

这应该可以解决问题:

STRINGLIT
 : '"' ( '\\' [btnfr"'\\] | ~[\r\n\\"] )* '"'
 ;

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