Java中抛出的带有空格的Antlr NoViableAltException
我在Antlr 3中定义了一个简单的语法,如下所示:
grammar StringProcessor;
options {
output=AST;
}
@header {
package com.processor;
}
@rulecatch {
// ANTLR does not generate its normal rule try/catch
catch(RecognitionException e) {
throw e;
}
}
truevalue : 'true';
falsevalue : 'false';
nullvalue : 'null';
simpleValue : truevalue | falsevalue | nullvalue | STRING | INTEGER | FLOAT;
INTEGER : '0'..'9'+;
FLOAT : INTEGER'.'INTEGER;
QUOTE : '"';
SPECIALCHAR : '-'|':'|';'|'('|')'|'£'|'&'|'@'|','|'!'|'['|']'|'{'|'}'|'#'|'^'|'*'|'+'|'='|'_'|'<'|'>'|'€'|'$'|'%'|'/'|'.'|'?'|'~'|'|';
STRING : QUOTE('a'..'z'|'A'..'Z'|INTEGER|SPECIALCHAR|WS)+QUOTE;
WS : (' '|'\t'|'\f'|'\n'|'\r')+ {skip();}; // handle white space between keywords
当我在intrepreter的AntlWorks中尝试以下字符串时:
“5Java开发者”
这很管用。它包括空格。但当我试图从Java程序中解析它时,它抛出了一个NoviableException。我看过其他帖子,但这些解决方案不适用于我的问题。WS是字符串的一部分。问题是Java程序不解析任何带有空格的内容,而解释器显示正确
下面是一个显示异常的示例:
public static void main(String[] args) throws Exception {
String input = ("\"5Java Developer\"");
StringProcessorParser parser = buildParser(input);
CommonTree commonTree = (CommonTree) parser.simpleValue().getTree(); // exception thrown
}
public static StringProcessorParser buildParser(String query) {
CharStream cs = new ANTLRStringStream(query);
// the input needs to be lexed
StringProcessorLexer lexer = new StingProcessorLexer(cs);
CommonTokenStream tokens = new CommonTokenStream();
StringProcessorParser parser = new StringProcessorParser(tokens);
tokens.setTokenSource(lexer);
// use the ASTTreeAdaptor so that the grammar is aware to build tree in AST format
parser.setTreeAdaptor((TreeAdaptor) new ASTTreeAdaptor().getASTTreeAdaptor());
return parser;
}
拥有:
input = new String("\"5JavaDeveloper\""); correctly parses.
你知道为什么这不管用吗
编辑:
我还尝试添加$channel=HIDDEN
但它仍然不起作用
WS : (' '|'\t'|'\f'|'\n'|'\r')+ { $channel = HIDDEN; skip();}; // handle white space between keywords
# 1 楼答案
删除skip()已修复我的问题