ANTLR4-需要对此字符串文字的解释

Question

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

"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.

All the supported escape sequences are as follows:

\\b backspace

\\f formfeed

\\r carriage return

\\n newline

\\t horizontal tab

\\" double quote

\\ backslash

The following are valid examples of string literals:

"This is a string containing tab \\t"

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

A string literal has a type of string."

And this is my String lexer:

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

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.

Answer 1

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 \\ .

This ought to do the trick:

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