ANTLR:消除混乱

I know next to no VHDL, so let's say you want to replace all single line comments in a (Java) source file with multi-line comments://foo应成为:/* foo */当然，您需要让词法分析器匹配单行注释.但是，您还应确保它可以识别多行注释，因为您不希望在以下情况下将//bar识别为单行注释:You need to let the lexer match single line comments, of course. But you should also make sure it recognizes multi-line comments because you don't want //bar to be recognized as a single line comment in:/*//bar*/字符串文字也是如此:String s = "no // comment";最后，您应该在词法分析器中创建某种与所有字符匹配的包罗万象的规则.Finally, you should create some sort of catch-all rule in the lexer that will match any character.快速演示:grammar T;parse : (t=. {System.out.print($t.text);})* EOF ;Str : '"' ('\\' . | ~('\\' | '"'))* '"' ;MLComment : '/*' .* '*/' ;SLComment : '//' ~('\r' | '\n')* { setText("/* " + getText().substring(2) + " */"); } ;Any : . // fall through rule, matches any character ;如果您现在这样分析输入内容:If you now parse input like this://comment 1class Foo { //comment 2 /* * not // a comment */ String s = "not // a // comment"; //comment 3}以下内容将打印到您的控制台上:the following will be printed to your console:/* comment 1 */class Foo { /* comment 2 */ /* * not // a comment */ String s = "not // a // comment"; /* comment 3 */}请注意，这只是一个快速演示:Java中的字符串文字可能包含Unicode转义，我的演示不支持该转义，并且我的演示也不处理字符文字(字符文字char c = '"';会破坏它) ).当然，所有这些东西都很容易修复.Note that this is just a quick demo: a string literal in Java could contain Unicode escapes, which my demo doesn't support, and my demo also does not handle char-literals (the char literal char c = '"'; would break it). All of these things are quite easy to fix, of course. 这篇关于ANTLR:消除混乱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！