我将这个问题发布到 anltr-interest,Andrew Haritonkin 回答了。巴特·K 说对了一半。您需要重写recoverFromMismatchedSet(),但也需要重写recoverFromMismatchedToken()。
如果您还希望词法分析器在出现第一个错误时退出,有一个 wiki 页面解释了该怎么做:
http://www.antlr.org/wiki/pages/viewpage.action?pageId=5341217
简而言之,它指出:
- 如果你想抛出 RecognitionException (或任何继承自 Exception 的东西),那么你必须使用一些偷偷摸摸的 java 技巧,因为相关方法不会声明任何异常
- 如果可以抛出 RuntimeException 或 Error,那么您可以重写 nextToken() 以抛出异常,而不是调用recoverError(),或者您可以重写recoverError()。抛出异常。
以下是在出现第一个词法分析器或解析器错误时退出的示例语法:
grammar Test;
@parser::members {
public static void main(String[] args) throws Exception {
String text = args[0];
ANTLRStringStream in = new ANTLRStringStream(text);
TestLexer lexer = new TestLexer(in);
CommonTokenStream tokens = new CommonTokenStream(lexer);
System.out.println(new TestParser(tokens).mainRule());
}
@Override
protected Object recoverFromMismatchedToken(IntStream input, int ttype, BitSet follow) throws RecognitionException {
throw new MismatchedTokenException(ttype, input);
}
@Override
public Object recoverFromMismatchedSet(IntStream input, RecognitionException e, BitSet follow) throws RecognitionException {
throw e;
}
}
@rulecatch {
catch (RecognitionException e) {
throw e;
}
}
@lexer::members {
@Override
public void reportError(RecognitionException e) {
throw new RuntimeException(e);
}
}
mainRule returns [List<String> words]
@init{$words = new ArrayList<String>();}
: w=Atom {$words.add($w.text);} (',' w=Atom {$words.add($w.text);} )* EOF
;
Atom: '0' | '1';
WS : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+ { $channel = HIDDEN; } ;
示例输出:
C:\Users\dan\workspace\antlrtest>java -cp .;antlr-3.2.jar TestParser "1,0"
[1, 0]
C:\Users\dan\workspace\antlrtest>java -cp .;antlr-3.2.jar TestParser "1,,0"
Exception in thread "main" MismatchedTokenException(6!=4)
at TestParser.recoverFromMismatchedToken(TestParser.java:45)
at org.antlr.runtime.BaseRecognizer.match(BaseRecognizer.java:115)
at TestParser.mainRule(TestParser.java:86)
at TestParser.main(TestParser.java:40)
C:\Users\dan\workspace\antlrtest>java -cp .;antlr-3.2.jar TestParser "1,+0"
Exception in thread "main" java.lang.RuntimeException: NoViableAltException('+@[])
at TestLexer.reportError(TestLexer.java:16)
at org.antlr.runtime.Lexer.nextToken(Lexer.java:94)
at org.antlr.runtime.CommonTokenStream.fillBuffer(CommonTokenStream.java:119) at org.antlr.runtime.CommonTokenStream.LT(CommonTokenStream.java:238)
at org.antlr.runtime.Parser.getCurrentInputSymbol(Parser.java:54)
at org.antlr.runtime.BaseRecognizer.match(BaseRecognizer.java:104)
at TestParser.mainRule(TestParser.java:68)
at TestParser.main(TestParser.java:40)
Caused by: NoViableAltException('+'@[])
at TestLexer.mTokens(TestLexer.java:165)
at org.antlr.runtime.Lexer.nextToken(Lexer.java:84)
... 6 more